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* [PATCH^5] gdb: mips: Add MIPSR6 support
@ 2024-05-15 20:19 Milos Kalicanin
  2024-06-24 14:24 ` Milos Kalicanin
  2024-06-24 22:40 ` Maciej W. Rozycki
  0 siblings, 2 replies; 3+ messages in thread
From: Milos Kalicanin @ 2024-05-15 20:19 UTC (permalink / raw)
  To: gdb-patches
  Cc: Djordje Todorovic, Dragan Mladjenovic, Andrew Burgess,
	Simon Marchi, Maciej W . Rozycki, Chao-ying Fu

Introduce new instruction encodings from Release 6 of the MIPS
architecture [1]. Support breakpoints and single stepping with
compact branches, forbidden slots, new branch instruction and
new atomic load-store instruction encodings.

Changes from v4: Apply code formatting as Andrew Burgess suggested.

[1] "MIPS64 Architecture for Programmers Volume II-A: The MIPS64
    Instruction Set Reference Manual", Document Number: MD00087,
    Revision 6.06, December 15, 2016, Section 3 "The MIPS64
    Instruction Set", pp. 42-530
https://s3-eu-west-1.amazonaws.com/downloads-mips/documents/MD00087-2B-MIPS64BIS-AFP-6.06.pdf

2024-05-15
Andrew Bennett  <andrew.bennett@imgtec.com>
Matthew Fortune  <matthew.fortune@mips.com>
Faraz Shahbazker  <fshahbazker@wavecomp.com>

gdb/ChangeLog:
	* mips-tdep.c (is_mipsr6_isa): New.
	(b0s21_imm): New define.
	(mips32_relative_offset21, mips32_relative_offset26): New.
	(is_add32bit_overflow, is_add64bit_overflow): New.
	(mips32_next_pc): Handle r6 compact and fpu coprocessor branches.
	Move handling of BLEZ, BGTZ opcode into ...
	(mips32_blez_pc): New.
	(mips32_instruction_is_compact_branch): New.
	(mips32_insn_at_pc_has_forbidden_slot):  New.
	(mips32_scan_prologue): Ignore pre-r6 addi encoding on r6.
	Stop at compact branch also.
	(LLSC_R6_OPCODE,LL_R6_FUNCT,LLE_FUNCT,
	LLD_R6_FUNCT,SC_R6_FUNCT,SCE_FUNCT,
	SCD_R6_FUNCT: New defines.
	(is_ll_insn, is_sc_insn): New.
	(mips_deal_with_atomic_sequence): Use is_ll_insn/is_sc_insn.
	Handle compact branches.
	(mips_about_to_return): Handle jrc and macro jr.
	(mips32_stack_frame_destroyed_p): Likewise.
	(mips32_instruction_has_delay_slot): Don't handle JALX on r6.
	Handle compact branches and coprocessor branches.
	(mips_adjust_breakpoint_address): Skip forbidden slot for
	compact branches.
---
 gdb/mips-tdep.c                       | 532 +++++++++++++--
 gdb/testsuite/gdb.arch/mips-64-r6.c   | 918 ++++++++++++++++++++++++++
 gdb/testsuite/gdb.arch/mips-64-r6.exp |  76 +++
 3 files changed, 1483 insertions(+), 43 deletions(-)
 create mode 100644 gdb/testsuite/gdb.arch/mips-64-r6.c
 create mode 100644 gdb/testsuite/gdb.arch/mips-64-r6.exp

diff --git a/gdb/mips-tdep.c b/gdb/mips-tdep.c
index ae58d7c8720..bdaeb6a8999 100644
--- a/gdb/mips-tdep.c
+++ b/gdb/mips-tdep.c
@@ -76,6 +76,10 @@ static int mips16_insn_at_pc_has_delay_slot (struct gdbarch *gdbarch,
 static void mips_print_float_info (struct gdbarch *, struct ui_file *,
 				   const frame_info_ptr &, const char *);
 
+static void
+mips_read_fp_register_single (const frame_info_ptr &frame, int regno,
+			      gdb_byte *rare_buffer);
+
 /* A useful bit in the CP0 status register (MIPS_PS_REGNUM).  */
 /* This bit is set if we are emulating 32-bit FPRs on a 64-bit chip.  */
 #define ST0_FR (1 << 26)
@@ -325,6 +329,16 @@ mips_abi_regsize (struct gdbarch *gdbarch)
     }
 }
 
+/* Return true if the gdbarch is based on MIPS Release 6.  */
+static bool
+is_mipsr6_isa (struct gdbarch *gdbarch)
+{
+  const struct bfd_arch_info *info = gdbarch_bfd_arch_info (gdbarch);
+
+  return (info->mach == bfd_mach_mipsisa32r6
+	  || info->mach == bfd_mach_mipsisa64r6);
+}
+
 /* MIPS16/microMIPS function addresses are odd (bit 0 is set).  Here
    are some functions to handle addresses associated with compressed
    code including but not limited to testing, setting, or clearing
@@ -1500,6 +1514,7 @@ mips_fetch_instruction (struct gdbarch *gdbarch,
   return extract_unsigned_integer (buf, instlen, byte_order);
 }
 
+
 /* These are the fields of 32 bit mips instructions.  */
 #define mips32_op(x) (x >> 26)
 #define itype_op(x) (x >> 26)
@@ -1542,6 +1557,7 @@ mips_fetch_instruction (struct gdbarch *gdbarch,
 #define b0s11_op(x) ((x) & 0x7ff)
 #define b0s12_imm(x) ((x) & 0xfff)
 #define b0s16_imm(x) ((x) & 0xffff)
+#define b0s21_imm(x) ((x) & 0x1fffff)
 #define b0s26_imm(x) ((x) & 0x3ffffff)
 #define b6s10_ext(x) (((x) >> 6) & 0x3ff)
 #define b11s5_reg(x) (((x) >> 11) & 0x1f)
@@ -1578,6 +1594,18 @@ mips32_relative_offset (ULONGEST inst)
   return ((itype_immediate (inst) ^ 0x8000) - 0x8000) << 2;
 }
 
+static LONGEST
+mips32_relative_offset21 (ULONGEST insn)
+{
+  return ((b0s21_imm (insn) ^ 0x100000) - 0x100000) << 2;
+}
+
+static LONGEST
+mips32_relative_offset26 (ULONGEST insn)
+{
+  return ((b0s26_imm (insn) ^ 0x2000000) - 0x2000000) << 2;
+}
+
 /* Determine the address of the next instruction executed after the INST
    floating condition branch instruction at PC.  COUNT specifies the
    number of the floating condition bits tested by the branch.  */
@@ -1636,6 +1664,71 @@ is_octeon_bbit_op (int op, struct gdbarch *gdbarch)
   return 0;
 }
 
+static int
+is_add32bit_overflow (int32_t a, int32_t b)
+{
+  int32_t r = (uint32_t) a + (uint32_t) b;
+  return (a < 0 && b < 0 && r >= 0) || (a >= 0 && b >= 0 && r < 0);
+}
+
+static int
+is_add64bit_overflow (int64_t a, int64_t b)
+{
+  if (a != (int32_t)a)
+    return 1;
+  if (b != (int32_t)b)
+    return 1;
+  return is_add32bit_overflow ((int32_t)a, (int32_t)b);
+}
+
+/* Calculate address of next instruction after BLEZ.  */
+
+static CORE_ADDR
+mips32_blez_pc (struct gdbarch *gdbarch, struct regcache *regcache,
+		ULONGEST inst, CORE_ADDR pc, int invert)
+{
+  int rs = itype_rs (inst);
+  int rt = itype_rt (inst);
+  LONGEST val_rs = regcache_raw_get_signed (regcache, rs);
+  LONGEST val_rt = regcache_raw_get_signed (regcache, rt);
+  ULONGEST uval_rs = regcache_raw_get_unsigned (regcache, rs);
+  ULONGEST uval_rt = regcache_raw_get_unsigned (regcache, rt);
+  int taken = 0;
+  int delay_slot_size = 4;
+
+  /* BLEZ, BLEZL, BGTZ, BGTZL  */
+  if (rt == 0)
+    taken = (val_rs <= 0);
+  else if (is_mipsr6_isa (gdbarch))
+    {
+      /* BLEZALC, BGTZALC  */
+      if (rs == 0 && rt != 0)
+	taken = (val_rt <= 0);
+      /* BGEZALC, BLTZALC  */
+      else if (rs == rt && rt != 0)
+	taken = (val_rt >= 0);
+      /* BGEUC, BLTUC  */
+      else if (rs != rt && rs != 0 && rt != 0)
+	taken = (uval_rs >= uval_rt);
+
+      /* Step through the forbidden slot to avoid repeated exceptions we do
+	 not currently have access to the BD bit when hitting a breakpoint
+	 and therefore cannot tell if the breakpoint hit on the branch or the
+	 forbidden slot.  */
+      /* delay_slot_size = 0;  */
+    }
+
+  if (invert)
+    taken = !taken;
+
+  /* Calculate branch target.  */
+  if (taken)
+    pc += mips32_relative_offset (inst);
+  else
+    pc += delay_slot_size;
+
+  return pc;
+}
 
 /* Determine where to set a single step breakpoint while considering
    branch prediction.  */
@@ -1646,12 +1739,17 @@ mips32_next_pc (struct regcache *regcache, CORE_ADDR pc)
   struct gdbarch *gdbarch = regcache->arch ();
   unsigned long inst;
   int op;
+  int mips64bitreg = 0;
+
+  if (mips_isa_regsize (gdbarch) == 8)
+    mips64bitreg = 1;
+
   inst = mips_fetch_instruction (gdbarch, ISA_MIPS, pc, NULL);
   op = itype_op (inst);
   if ((inst & 0xe0000000) != 0)		/* Not a special, jump or branch
 					   instruction.  */
     {
-      if (op >> 2 == 5)
+      if (op >> 2 == 5 && ((op & 0x02) == 0 || itype_rt (inst) == 0))
 	/* BEQL, BNEL, BLEZL, BGTZL: bits 0101xx */
 	{
 	  switch (op & 0x03)
@@ -1661,7 +1759,7 @@ mips32_next_pc (struct regcache *regcache, CORE_ADDR pc)
 	    case 1:		/* BNEL */
 	      goto neq_branch;
 	    case 2:		/* BLEZL */
-	      goto less_branch;
+	      goto lez_branch;
 	    case 3:		/* BGTZL */
 	      goto greater_branch;
 	    default:
@@ -1671,15 +1769,19 @@ mips32_next_pc (struct regcache *regcache, CORE_ADDR pc)
       else if (op == 17 && itype_rs (inst) == 8)
 	/* BC1F, BC1FL, BC1T, BC1TL: 010001 01000 */
 	pc = mips32_bc1_pc (gdbarch, regcache, inst, pc + 4, 1);
-      else if (op == 17 && itype_rs (inst) == 9
+      else if (!is_mipsr6_isa (gdbarch)
+	       && op == 17
+	       && itype_rs (inst) == 9
 	       && (itype_rt (inst) & 2) == 0)
 	/* BC1ANY2F, BC1ANY2T: 010001 01001 xxx0x */
 	pc = mips32_bc1_pc (gdbarch, regcache, inst, pc + 4, 2);
-      else if (op == 17 && itype_rs (inst) == 10
+      else if (!is_mipsr6_isa (gdbarch)
+	       && op == 17
+	       && itype_rs (inst) == 10
 	       && (itype_rt (inst) & 2) == 0)
 	/* BC1ANY4F, BC1ANY4T: 010001 01010 xxx0x */
 	pc = mips32_bc1_pc (gdbarch, regcache, inst, pc + 4, 4);
-      else if (op == 29)
+      else if (!is_mipsr6_isa (gdbarch) && op == 29)
 	/* JALX: 011101 */
 	/* The new PC will be alternate mode.  */
 	{
@@ -1707,7 +1809,128 @@ mips32_next_pc (struct regcache *regcache, CORE_ADDR pc)
 	  else
 	    pc += 8;        /* After the delay slot.  */
 	}
+      else if (is_mipsr6_isa (gdbarch))
+	{
+	  /* BOVC, BEQZALC, BEQC and BNVC, BNEZALC, BNEC  */
+	  if (op == 8 || op == 24)
+	    {
+	      int rs = rtype_rs (inst);
+	      int rt = rtype_rt (inst);
+	      LONGEST val_rs = regcache_raw_get_signed (regcache, rs);
+	      LONGEST val_rt = regcache_raw_get_signed (regcache, rt);
+	      int taken = 0;
+	      /* BOVC (BNVC)  */
+	      if (rs >= rt)
+		{
+		  if (mips64bitreg == 1)
+		    taken = is_add64bit_overflow (val_rs, val_rt);
+		  else
+		    taken = is_add32bit_overflow (val_rs, val_rt);
+		}
+	      /* BEQZALC (BNEZALC)  */
+	      else if (rs < rt && rs == 0)
+		taken = (val_rt == 0);
+	      /* BEQC (BNEC)  */
+	      else
+		taken = (val_rs == val_rt);
+
+	      /* BNVC, BNEZALC, BNEC  */
+	      if (op == 24)
+		taken = !taken;
 
+	      if (taken)
+		pc += mips32_relative_offset (inst) + 4;
+	      else
+		/* Step through the forbidden slot to avoid repeated exceptions
+		   we do not currently have access to the BD bit when hitting a
+		   breakpoint and therefore cannot tell if the breakpoint
+		   hit on the branch or the forbidden slot.  */
+		pc += 8;
+	    }
+	  /* BC1EQZ, BC1NEZ  */
+	  else if (op == 17 && (itype_rs (inst) == 9 || itype_rs (inst) == 13))
+	    {
+	      gdb_byte status;
+	      gdb_byte true_val = 0;
+	      unsigned int fp = (gdbarch_num_regs (gdbarch)
+				 + mips_regnum (gdbarch)->fp0
+				 + itype_rt (inst));
+	      struct frame_info_ptr frame = get_current_frame ();
+	      gdb_byte *raw_buffer = (gdb_byte *) alloca (sizeof (gdb_byte) * 4);
+	      mips_read_fp_register_single (frame, fp, raw_buffer);
+
+	      if (gdbarch_byte_order (gdbarch) == BFD_ENDIAN_BIG)
+		status = *(raw_buffer + 3);
+	      else
+		status = *(raw_buffer);
+
+	      if (itype_rs (inst) == 13)
+		true_val = 1;
+
+	      if ((status & 0x1) == true_val)
+		pc += mips32_relative_offset (inst) + 4;
+	      else
+		pc += 8;
+	    }
+	  else if (op == 22 || op == 23)
+	  /* BLEZC, BGEZC, BGEC, BGTZC, BLTZC, BLTC  */
+	    {
+	      int rs = rtype_rs (inst);
+	      int rt = rtype_rt (inst);
+	      LONGEST val_rs = regcache_raw_get_signed (regcache, rs);
+	      LONGEST val_rt = regcache_raw_get_signed (regcache, rt);
+	      int taken = 0;
+	      /* The R5 rt == 0 case is handled above so we treat it as
+		 an unknown instruction here for future ISA usage.  */
+	      if (rs == 0 && rt != 0)
+		taken = (val_rt <= 0);
+	      else if (rs == rt && rt != 0)
+		taken = (val_rt >= 0);
+	      else if (rs != rt && rs != 0 && rt != 0)
+		taken = (val_rs >= val_rt);
+
+	      if (op == 23)
+		taken = !taken;
+
+	      if (taken)
+		pc += mips32_relative_offset (inst) + 4;
+	      else
+		/* Step through the forbidden slot to avoid repeated exceptions
+		   we do not currently have access to the BD bit when hitting a
+		   breakpoint and therefore cannot tell if the breakpoint
+		   hit on the branch or the forbidden slot.  */
+		pc += 8;
+	    }
+	  else if (op == 50 || op == 58)
+	  /* BC, BALC  */
+	    pc += mips32_relative_offset26 (inst) + 4;
+	  else if ((op == 54 || op == 62)
+		   && rtype_rs (inst) == 0)
+	  /* JIC, JIALC  */
+	    {
+	      pc = regcache_raw_get_signed (regcache, itype_rt (inst));
+	      pc += (itype_immediate (inst) ^ 0x8000) - 0x8000;
+	    }
+	  else if (op == 54 || op == 62)
+	  /* BEQZC, BNEZC  */
+	    {
+	      int rs = itype_rs (inst);
+	      LONGEST rs_val = regcache_raw_get_signed (regcache, rs);
+	      int taken = (rs_val == 0);
+	      if (op == 62)
+		taken = !taken;
+	      if (taken)
+		pc += mips32_relative_offset21 (inst) + 4;
+	      else
+		/* Step through the forbidden slot to avoid repeated exceptions
+		   we do not currently have access to the BD bit when hitting a
+		   breakpoint and therefore cannot tell if the breakpoint
+		   hit on the branch or the forbidden slot.  */
+		pc += 8;
+	    }
+	  else
+	    pc += 4;		/* Not a branch, next instruction is easy.  */
+	}
       else
 	pc += 4;		/* Not a branch, next instruction is easy.  */
     }
@@ -1751,7 +1974,6 @@ mips32_next_pc (struct regcache *regcache, CORE_ADDR pc)
 	      case 2:		/* BLTZL */
 	      case 16:		/* BLTZAL */
 	      case 18:		/* BLTZALL */
-	      less_branch:
 		if (regcache_raw_get_signed (regcache, itype_rs (inst)) < 0)
 		  pc += mips32_relative_offset (inst) + 4;
 		else
@@ -1767,22 +1989,38 @@ mips32_next_pc (struct regcache *regcache, CORE_ADDR pc)
 		  pc += 8;	/* after the delay slot */
 		break;
 	      case 0x1c:	/* BPOSGE32 */
+	      case 0x1d:	/* BPOSGE32C  */
 	      case 0x1e:	/* BPOSGE64 */
 		pc += 4;
 		if (itype_rs (inst) == 0)
 		  {
 		    unsigned int pos = (op & 2) ? 64 : 32;
 		    int dspctl = mips_regnum (gdbarch)->dspctl;
+		    int delay_slot_size = 4;
 
 		    if (dspctl == -1)
 		      /* No way to handle; it'll most likely trap anyway.  */
 		      break;
 
+		    /* BPOSGE32C  */
+		    if (op == 0x1d)
+		      {
+			if (!is_mipsr6_isa (gdbarch))
+			  break;
+
+			/* Step through the forbidden slot to avoid repeated
+			   exceptions we do not currently have access to the BD
+			   bit when hitting a breakpoint and therefore cannot
+			   tell if the breakpoint hit on the branch or the
+			   forbidden slot.  */
+			/* delay_slot_size = 0;  */
+		      }
+
 		    if ((regcache_raw_get_unsigned (regcache,
 						    dspctl) & 0x7f) >= pos)
 		      pc += mips32_relative_offset (inst);
 		    else
-		      pc += 4;
+		      pc += delay_slot_size;
 		  }
 		break;
 		/* All of the other instructions in the REGIMM category */
@@ -1816,19 +2054,14 @@ mips32_next_pc (struct regcache *regcache, CORE_ADDR pc)
 	  else
 	    pc += 8;
 	  break;
-	case 6:		/* BLEZ, BLEZL */
-	  if (regcache_raw_get_signed (regcache, itype_rs (inst)) <= 0)
-	    pc += mips32_relative_offset (inst) + 4;
-	  else
-	    pc += 8;
+	case 6:		/* BLEZ, BLEZL, BLEZALC, BGEZALC, BGEUC  */
+	lez_branch:
+	  pc = mips32_blez_pc (gdbarch, regcache, inst, pc + 4, 0);
 	  break;
 	case 7:
 	default:
-	greater_branch:	/* BGTZ, BGTZL */
-	  if (regcache_raw_get_signed (regcache, itype_rs (inst)) > 0)
-	    pc += mips32_relative_offset (inst) + 4;
-	  else
-	    pc += 8;
+	greater_branch:	/* BGTZ, BGTZL, BGTZALC, BLTZALC, BLTUC  */
+	  pc = mips32_blez_pc (gdbarch, regcache, inst, pc + 4, 1);
 	  break;
 	}			/* switch */
     }				/* else */
@@ -2451,6 +2684,72 @@ micromips_instruction_is_compact_branch (unsigned short insn)
     }
 }
 
+/* Return non-zero if the MIPS instruction INSN is a compact branch
+   or jump.  A value of 1 indicates an unconditional compact branch
+   and a value of 2 indicates a conditional compact branch.  */
+
+static int
+mips32_instruction_is_compact_branch (struct gdbarch *gdbarch, ULONGEST insn)
+{
+  switch (itype_op (insn))
+    {
+    /* BC  */
+    case 50:
+    /* BALC  */
+    case 58:
+      if (is_mipsr6_isa (gdbarch))
+	return 1;
+      break;
+    /* BOVC, BEQZALC, BEQC  */
+    case 8:
+    /* BNVC, BNEZALC, BNEC  */
+    case 24:
+      if (is_mipsr6_isa (gdbarch))
+	return 2;
+      break;
+    /* BEQZC, JIC  */
+    case 54:
+    /* BNEZC, JIALC  */
+    case 62:
+      if (is_mipsr6_isa (gdbarch))
+	/* JIC, JIALC are unconditional  */
+	return (itype_rs (insn) == 0) ? 1 : 2;
+      break;
+    /* BLEZC, BGEZC, BGEC  */
+    case 22:
+    /* BGTZC, BLTZC, BLTC  */
+    case 23:
+    /* BLEZALC, BGEZALC, BGEUC  */
+    case 6:
+    /* BGTZALC, BLTZALC, BLTUC  */
+    case 7:
+      if (is_mipsr6_isa (gdbarch)
+	  && itype_rt (insn) != 0)
+	return 2;
+      break;
+    /* BPOSGE32C  */
+    case 1:
+      if (is_mipsr6_isa (gdbarch)
+	  && itype_rt (insn) == 0x1d && itype_rs (insn) == 0)
+	return 2;
+    }
+  return 0;
+}
+
+/* Return true if a standard MIPS instruction at ADDR has a branch
+   forbidden slot (i.e. it is a conditional compact branch instruction).  */
+
+static bool
+mips32_insn_at_pc_has_forbidden_slot (struct gdbarch *gdbarch, CORE_ADDR addr)
+{
+  int status;
+  ULONGEST insn = mips_fetch_instruction (gdbarch, ISA_MIPS, addr, &status);
+  if (status)
+    return false;
+
+  return mips32_instruction_is_compact_branch (gdbarch, insn) == 2;
+}
+
 struct mips_frame_cache
 {
   CORE_ADDR base;
@@ -3494,7 +3793,8 @@ mips32_scan_prologue (struct gdbarch *gdbarch,
       reg = high_word & 0x1f;
 
       if (high_word == 0x27bd		/* addiu $sp,$sp,-i */
-	  || high_word == 0x23bd	/* addi $sp,$sp,-i */
+	  || (high_word == 0x23bd	/* addi $sp,$sp,-i  */
+	      && !is_mipsr6_isa (gdbarch))
 	  || high_word == 0x67bd)	/* daddiu $sp,$sp,-i */
 	{
 	  if (offset < 0)		/* Negative stack adjustment?  */
@@ -3632,7 +3932,9 @@ mips32_scan_prologue (struct gdbarch *gdbarch,
 
       /* A jump or branch, or enough non-prologue insns seen?  If so,
 	 then we must have reached the end of the prologue by now.  */
-      if (prev_delay_slot || non_prologue_insns > 1)
+      if (prev_delay_slot
+	  || non_prologue_insns > 1
+	  || mips32_instruction_is_compact_branch (gdbarch, inst))
 	break;
 
       prev_non_prologue_insn = this_non_prologue_insn;
@@ -3938,6 +4240,67 @@ mips_addr_bits_remove (struct gdbarch *gdbarch, CORE_ADDR addr)
 #define LLD_OPCODE 0x34
 #define SC_OPCODE 0x38
 #define SCD_OPCODE 0x3c
+#define LLSC_R6_OPCODE 0x1f
+#define LL_R6_FUNCT 0x36
+#define LLE_FUNCT 0x2e
+#define LLD_R6_FUNCT 0x37
+#define SC_R6_FUNCT 0x26
+#define SCE_FUNCT 0x1e
+#define SCD_R6_FUNCT 0x27
+
+/* Determine whether instruction 'insn' is of 'load linked X' type.
+   LL/SC instructions provide primitives to implement atomic 
+   read-modify-write operations for synchronizable memory locations.  */
+
+static bool
+is_ll_insn (struct gdbarch *gdbarch, ULONGEST insn)
+{
+  if (itype_op (insn) == LL_OPCODE
+      || itype_op (insn) == LLD_OPCODE)
+    return true;
+
+  if (rtype_op (insn) == LLSC_R6_OPCODE
+      && rtype_funct (insn) == LLE_FUNCT
+      && (insn & 0x40) == 0)
+    return true;
+
+  /* Handle LL and LLP varieties.  */
+  if (is_mipsr6_isa (gdbarch)
+      && rtype_op (insn) == LLSC_R6_OPCODE
+      && (rtype_funct (insn) == LL_R6_FUNCT
+	  || rtype_funct (insn) == LLD_R6_FUNCT
+	  || rtype_funct (insn) == LLE_FUNCT))
+    return true;
+
+  return false;
+}
+
+/* Determine whether instruction 'insn' is of 'store conditional X' type.
+   SC instructions and varieties perform completion of read-modify-write
+   atomic sequence.  */
+
+static bool
+is_sc_insn (struct gdbarch *gdbarch, ULONGEST insn)
+{
+  if (itype_op (insn) == SC_OPCODE
+      || itype_op (insn) == SCD_OPCODE)
+    return true;
+
+  if (rtype_op (insn) == LLSC_R6_OPCODE
+      && rtype_funct (insn) == SCE_FUNCT
+      && (insn & 0x40) == 0)
+    return true;
+
+  /* Handle SC and SCP varieties.  */
+  if (is_mipsr6_isa (gdbarch)
+      && rtype_op (insn) == LLSC_R6_OPCODE
+      && (rtype_funct (insn) == SC_R6_FUNCT
+	  || rtype_funct (insn) == SCD_R6_FUNCT
+	  || rtype_funct (insn) == SCE_FUNCT))
+    return true;
+
+  return false;
+}
 
 static std::vector<CORE_ADDR>
 mips_deal_with_atomic_sequence (struct gdbarch *gdbarch, CORE_ADDR pc)
@@ -3950,10 +4313,11 @@ mips_deal_with_atomic_sequence (struct gdbarch *gdbarch, CORE_ADDR pc)
   int index;
   int last_breakpoint = 0; /* Defaults to 0 (no breakpoints placed).  */  
   const int atomic_sequence_length = 16; /* Instruction sequence length.  */
+  bool is_mipsr6 = is_mipsr6_isa (gdbarch);
 
   insn = mips_fetch_instruction (gdbarch, ISA_MIPS, loc, NULL);
   /* Assume all atomic sequences start with a ll/lld instruction.  */
-  if (itype_op (insn) != LL_OPCODE && itype_op (insn) != LLD_OPCODE)
+  if (!is_ll_insn (gdbarch, insn))
     return {};
 
   /* Assume that no atomic sequence is longer than "atomic_sequence_length" 
@@ -3983,28 +4347,72 @@ mips_deal_with_atomic_sequence (struct gdbarch *gdbarch, CORE_ADDR pc)
 	  return {}; /* fallback to the standard single-step code.  */
 	case 4: /* BEQ */
 	case 5: /* BNE */
-	case 6: /* BLEZ */
-	case 7: /* BGTZ */
 	case 20: /* BEQL */
 	case 21: /* BNEL */
-	case 22: /* BLEZL */
-	case 23: /* BGTTL */
+	case 22: /* BLEZL (BLEZC, BGEZC, BGEC)  */
+	case 23: /* BGTZL (BGTZC, BLTZC, BLTC)  */
 	  is_branch = 1;
 	  break;
+	case 6: /* BLEZ (BLEZALC, BGEZALC, BGEUC)  */
+	case 7: /* BGTZ (BGTZALC, BLTZALC, BLTUC)  */
+	  if (is_mipsr6)
+	    {
+	      /* BLEZALC, BGTZALC  */
+	      if (itype_rs (insn) == 0 && itype_rt (insn) != 0)
+		return {}; /* fallback to the standard single-step code.  */
+	      /* BGEZALC, BLTZALC  */
+	      else if (itype_rs (insn) == itype_rt (insn)
+		       && itype_rt (insn) != 0)
+		return {}; /* fallback to the standard single-step code.  */
+	    }
+	  is_branch = 1;
+	  break;
+	case 8: /* BOVC, BEQZALC, BEQC  */
+	case 24: /* BNVC, BNEZALC, BNEC  */
+	  if (is_mipsr6)
+	    is_branch = 1;
+	  break;
+	case 50: /* BC  */
+	case 58: /* BALC  */
+	  if (is_mipsr6)
+	    return {}; /* fallback to the standard single-step code.  */
+	  break;
+	case 54: /* BEQZC, JIC  */
+	case 62: /* BNEZC, JIALC  */
+	  if (is_mipsr6)
+	    {
+	      if (itype_rs (insn) == 0) /* JIC, JIALC  */
+		return {}; /* fallback to the standard single-step code.  */
+	      else
+		is_branch = 2; /* Marker for branches with a 21-bit offset.  */
+	    }
+	  break;
 	case 17: /* COP1 */
-	  is_branch = ((itype_rs (insn) == 9 || itype_rs (insn) == 10)
-		       && (itype_rt (insn) & 0x2) == 0);
-	  if (is_branch) /* BC1ANY2F, BC1ANY2T, BC1ANY4F, BC1ANY4T */
+	  is_branch = ((!is_mipsr6
+			/* BC1ANY2F, BC1ANY2T, BC1ANY4F, BC1ANY4T  */
+			&& (itype_rs (insn) == 9 || itype_rs (insn) == 10)
+			&& (itype_rt (insn) & 0x2) == 0)
+		       /* BZ.df:  010001 110xx  */
+		       || (itype_rs (insn) & 0x18) == 0x18);
+	  if (is_branch != 0)
 	    break;
 	  [[fallthrough]];
 	case 18: /* COP2 */
 	case 19: /* COP3 */
-	  is_branch = (itype_rs (insn) == 8); /* BCzF, BCzFL, BCzT, BCzTL */
+	  /* BCzF, BCzFL, BCzT, BCzTL, BC*EQZ, BC*NEZ  */
+	  is_branch = ((itype_rs (insn) == 8)
+		       || (is_mipsr6
+			   && (itype_rs (insn) == 9
+			       || itype_rs (insn) == 13)));
 	  break;
 	}
-      if (is_branch)
+      if (is_branch != 0)
 	{
-	  branch_bp = loc + mips32_relative_offset (insn) + 4;
+	  /* Is this a special PC21_S2 branch?  */
+	  if (is_branch == 2)
+	    branch_bp = loc + mips32_relative_offset21 (insn) + 4;
+	  else
+	    branch_bp = loc + mips32_relative_offset (insn) + 4;
 	  if (last_breakpoint >= 1)
 	    return {}; /* More than one branch found, fallback to the
 			  standard single-step code.  */
@@ -4012,12 +4420,12 @@ mips_deal_with_atomic_sequence (struct gdbarch *gdbarch, CORE_ADDR pc)
 	  last_breakpoint++;
 	}
 
-      if (itype_op (insn) == SC_OPCODE || itype_op (insn) == SCD_OPCODE)
+      if (is_sc_insn (gdbarch, insn))
 	break;
     }
 
   /* Assume that the atomic sequence ends with a sc/scd instruction.  */
-  if (itype_op (insn) != SC_OPCODE && itype_op (insn) != SCD_OPCODE)
+  if (!is_sc_insn (gdbarch, insn))
     return {};
 
   loc += MIPS_INSN32_SIZE;
@@ -4166,7 +4574,7 @@ micromips_deal_with_atomic_sequence (struct gdbarch *gdbarch,
 	    }
 	  break;
 	}
-      if (is_branch)
+      if (is_branch != 0)
 	{
 	  if (last_breakpoint >= 1)
 	    return {}; /* More than one branch found, fallback to the
@@ -4242,8 +4650,14 @@ mips_about_to_return (struct gdbarch *gdbarch, CORE_ADDR pc)
   gdb_assert (mips_pc_is_mips (pc));
 
   insn = mips_fetch_instruction (gdbarch, ISA_MIPS, pc, NULL);
-  hint = 0x7c0;
-  return (insn & ~hint) == 0x3e00008;			/* jr(.hb) $ra */
+  /* Mask the hint and the jalr/jr bit.  */
+  hint = 0x7c1;
+
+  if (is_mipsr6_isa (gdbarch) && insn == 0xd81f0000) /* jrc $31  */
+    return 1;
+
+  /* jr(.hb) $ra and "jalr(.hb) $ra"  */
+  return ((insn & ~hint) == 0x3e00008);
 }
 
 
@@ -6760,7 +7174,9 @@ mips32_stack_frame_destroyed_p (struct gdbarch *gdbarch, CORE_ADDR pc)
 
 	  if (high_word != 0x27bd	/* addiu $sp,$sp,offset */
 	      && high_word != 0x67bd	/* daddiu $sp,$sp,offset */
-	      && inst != 0x03e00008	/* jr $ra */
+	      && (inst & ~0x1) != 0x03e00008 /* jr $31 or jalr $0, $31  */
+	      && (!is_mipsr6_isa (gdbarch)
+		  || inst != 0xd81f0000) /* jrc $31  */
 	      && inst != 0x00000000)	/* nop */
 	    return 0;
 	}
@@ -7139,22 +7555,31 @@ mips32_instruction_has_delay_slot (struct gdbarch *gdbarch, ULONGEST inst)
   int op;
   int rs;
   int rt;
+  bool is_mipsr6 = is_mipsr6_isa (gdbarch);
 
   op = itype_op (inst);
   if ((inst & 0xe0000000) != 0)
     {
       rs = itype_rs (inst);
       rt = itype_rt (inst);
-      return (is_octeon_bbit_op (op, gdbarch) 
-	      || op >> 2 == 5	/* BEQL, BNEL, BLEZL, BGTZL: bits 0101xx  */
-	      || op == 29	/* JALX: bits 011101  */
+      return (is_octeon_bbit_op (op, gdbarch)
+	      || (op >> 1 == 10) /* BEQL, BNEL: bits 01010x  */
+	      || (op >> 1 == 11 && rt == 0) /* BLEZL, BGTZL: bits 01011x  */
+	      || (!is_mipsr6 && op == 29)	/* JALX: bits 011101  */
 	      || (op == 17
 		  && (rs == 8
 				/* BC1F, BC1FL, BC1T, BC1TL: 010001 01000  */
-		      || (rs == 9 && (rt & 0x2) == 0)
+		      || (!is_mipsr6 && rs == 9 && (rt & 0x2) == 0)
 				/* BC1ANY2F, BC1ANY2T: bits 010001 01001  */
-		      || (rs == 10 && (rt & 0x2) == 0))));
+		      || (!is_mipsr6 && rs == 10 && (rt & 0x2) == 0)))
 				/* BC1ANY4F, BC1ANY4T: bits 010001 01010  */
+	      || (is_mipsr6
+		  && ((op == 17
+		       && (rs == 9  /* BC1EQZ: 010001 01001  */
+			   || rs == 13))  /* BC1NEZ: 010001 01101  */
+		      || (op == 18
+			  && (rs == 9  /* BC2EQZ: 010010 01001  */
+			      || rs == 13)))));  /* BC2NEZ: 010010 01101  */
     }
   else
     switch (op & 0x07)		/* extract bits 28,27,26  */
@@ -7173,7 +7598,11 @@ mips32_instruction_has_delay_slot (struct gdbarch *gdbarch, ULONGEST inst)
 		|| ((rt & 0x1e) == 0x1c && rs == 0));
 				/* BPOSGE32, BPOSGE64: bits 1110x  */
 	break;			/* end REGIMM  */
-      default:			/* J, JAL, BEQ, BNE, BLEZ, BGTZ  */
+	case 6:			/* BLEZ  */
+	case 7:			/* BGTZ  */
+	 return (itype_rt (inst) == 0);
+	 break;
+      default:			/* J, JAL, BEQ, BNE  */
 	return 1;
 	break;
       }
@@ -7385,7 +7814,18 @@ mips_adjust_breakpoint_address (struct gdbarch *gdbarch, CORE_ADDR bpaddr)
 
      So, we'll use the second solution.  To do this we need to know if
      the instruction we're trying to set the breakpoint on is in the
-     branch delay slot.  */
+     branch delay slot.
+
+     A similar problem occurs for breakpoints on forbidden slots where
+     the trap will be reported for the branch with the BD bit set.
+     In this case it would be ideal to recover using solution 1 from
+     above as there is no problem with the branch being skipped
+     (since the forbidden slot only exists on not-taken branches).
+     However, the BD bit is not available in all scenarios currently
+     so instead we move the breakpoint on to the next instruction.
+     This means that it is not possible to stop on an instruction
+     that can be in a forbidden slot even if that instruction is
+     jumped to directly.  */
 
   boundary = mips_segment_boundary (bpaddr);
 
@@ -7407,6 +7847,12 @@ mips_adjust_breakpoint_address (struct gdbarch *gdbarch, CORE_ADDR bpaddr)
       prev_addr = bpaddr - 4;
       if (mips32_insn_at_pc_has_delay_slot (gdbarch, prev_addr))
 	bpaddr = prev_addr;
+      /* If the previous instruction has a forbidden slot, we have to
+	 move the breakpoint to the following instruction to prevent
+	 breakpoints in forbidden slots being reported as unknown
+	 traps.  */
+      else if (mips32_insn_at_pc_has_forbidden_slot (gdbarch, prev_addr))
+	bpaddr += 4;
     }
   else
     {
diff --git a/gdb/testsuite/gdb.arch/mips-64-r6.c b/gdb/testsuite/gdb.arch/mips-64-r6.c
new file mode 100644
index 00000000000..13f43ee24d0
--- /dev/null
+++ b/gdb/testsuite/gdb.arch/mips-64-r6.c
@@ -0,0 +1,918 @@
+/*
+   Copyright 2023-2024 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#define xstr(s) str(s)
+#define str(s) #s
+
+/* ============ macros from sim/testutils/mips/utils-r6.inc ============= */
+
+/* 58 is local label to exit with errcode != 0, indicating error.  */
+#define fp_assert(a, b) "beq " xstr (a) ", " xstr (b) ", 1f \n\t" \
+  "nop \n\t" \
+  "b 58f \n\t" \
+  "nop \n\t" \
+  "1: \n\t"
+
+/* Clobbers: $4,$6,$7.  */
+#define r6ck_1r(inst, a, ret) \
+  "li $4, " xstr (a) "    \n\t" \
+  "li $6, " xstr (ret) "  \n\t" \
+  xstr (inst) " $7, $4    \n\t" \
+  fp_assert ($6, $7)
+
+/* Clobbers: $4,$6,$7.  */
+#define r6ck_1dr(inst, a, ret) \
+  "ld $4, " xstr (a) "   \n\t" \
+  "ld $6, " xstr (ret) " \n\t" \
+  xstr (inst) " $7, $4   \n\t" \
+  fp_assert ($6, $7)
+
+/* Clobbers: $4,$5,$6,$7.  */
+#define r6ck_2r(inst, a, b, ret) \
+  "li $4, " xstr (a) "   \n\t" \
+  "li $5, " xstr (b) "   \n\t" \
+  "li $6, " xstr (ret) " \n\t" \
+  xstr (inst) " $7, $4, $5   \n\t" \
+  fp_assert ($6, $7)
+
+/* Clobbers: $4,$5,$6,$7.  */
+#define r6ck_2dr(inst, a, b, ret) \
+  "ld $4, " xstr (a) "    \n\t" \
+  "ld $5, " xstr (b) "    \n\t" \
+  "ld $6, " xstr (ret) "  \n\t" \
+  xstr (inst) " $7, $4, $5  \n\t" \
+  fp_assert ($6, $7)
+
+/* Clobbers: $4,$5,$6,$7.  */
+#define r6ck_2dr1i(inst, a, b, imm, ret) \
+  "ld $4, " xstr (a) "      \n\t" \
+  "ld $5, " xstr (b) "      \n\t" \
+  "ld $6, " xstr (ret) "    \n\t" \
+  xstr (inst) " $7, $4, $5, " xstr (imm) "  \n\t" \
+  fp_assert ($6, $7)
+
+/* Clobbers: $4,$6,$7.  */
+#define r6ck_1r1i(inst, a, imm, ret) \
+  "li $4, " xstr (a) "      \n\t" \
+  "li $6, " xstr (ret) "    \n\t" \
+  xstr (inst) " $7, $4, " xstr (imm) "  \n\t" \
+  fp_assert ($6, $7)
+
+/* Clobbers: $4,$6,$7.  */
+#define r6ck_1dr1i(inst, a, imm, ret) \
+  "ld $4, " xstr (a) "     \n\t" \
+  "ld $6, " xstr (ret) "   \n\t" \
+  xstr (inst) " $7, $4, " xstr (imm) "  \n\t" \
+  fp_assert ($6, $7)
+
+/* Clobbers: $4,$6.  */
+#define r6ck_0dr1i(inst, a, imm, ret) \
+  "ld $4, " xstr (a) "     \n\t" \
+  "ld $6, " xstr (ret) "   \n\t" \
+  xstr (inst) " $4, $4, " xstr (imm) "   \n\t" \
+  fp_assert ($6, $4)
+
+/* Clobbers: $4,$5,$6,$7.  */
+#define r6ck_2r1i(inst, a, b, imm, ret) \
+  "li $4, " xstr (a) "     \n\t" \
+  "li $5, " xstr (b) "     \n\t" \
+  "li $6, " xstr (ret) "   \n\t" \
+  xstr (inst) " $7, $4, $5, " xstr (imm) "   \n\t" \
+  fp_assert ($6, $7)
+
+/* Clobbers: $4,$5,$6,$7,$8,$f2,$f4,$f6.  */
+#define r6ck_3s(inst, a, b, c, ret) \
+  "li $4, " xstr (a) "     \n\t" \
+  "li $5, " xstr (b) "     \n\t" \
+  "li $6, " xstr (c) "     \n\t" \
+  "li $7, " xstr (ret) "   \n\t" \
+  "mtc1 $4, $f2           \n\t" \
+  "mtc1 $5, $f4           \n\t" \
+  "mtc1 $6, $f6           \n\t" \
+  xstr (inst) " $f2, $f4, $f6       \n\t" \
+  "mfc1 $8, $f2           \n\t" \
+  fp_assert ($7, $8)
+
+/* Clobbers: $4,$5,$6,$7,$f2,$f4.  */
+#define r6ck_2s(inst, a, b, ret) \
+  "li $4, " xstr (a) "       \n\t" \
+  "li $5, " xstr (b) "       \n\t" \
+  "li $6, " xstr (ret) "     \n\t" \
+  "mtc1 $4, $f2             \n\t" \
+  "mtc1 $5, $f4             \n\t" \
+  xstr (inst) " $f2, $f4     \n\t" \
+  "mfc1 $7, $f2             \n\t" \
+  fp_assert ($6, $7)
+
+/* Clobbers: $4,$5,$6,$7,$8,$9,$10,$f2,$f4.  */
+#define r6ck_2d(inst, a, b, ret) \
+  ".data                  \n\t" \
+  "1: .dword " xstr (a) "    \n\t" \
+  "2: .dword " xstr (b) "    \n\t" \
+  "3: .dword " xstr (ret) "  \n\t" \
+  ".text                   \n\t" \
+  "dla $4, 1b              \n\t" \
+  "dla $5, 2b              \n\t" \
+  "dla $6, 3b              \n\t" \
+  "ldc1 $f2, 0($4)        \n\t" \
+  "ldc1 $f4, 0($5)        \n\t" \
+  "lw $7, 0($6)           \n\t" \
+  "lw $8, 4($6)           \n\t" \
+  xstr (inst) " $f2, $f4   \n\t" \
+  "mfhc1 $9, $f2          \n\t" \
+  "mfc1 $10, $f2          \n\t" \
+  fp_assert ($7, $9) \
+  fp_assert ($8, $10)
+
+/* Clobbers: $2,$4,$5,$6,$7,$8,$9,$10,$f2,$f4,$f6.  */
+#define r6ck_3d(inst, a, b, c, ret) \
+  ".data                                \n\t" \
+  "1: .dword " xstr (a) "                  \n\t" \
+  "2: .dword " xstr (b) "                  \n\t" \
+  "3: .dword " xstr (c) "                  \n\t" \
+  "4: .dword " xstr (ret) "                \n\t" \
+  ".text                                \n\t" \
+  "dla $4, 1b                            \n\t" \
+  "dla $5, 2b                            \n\t" \
+  "dla $6, 3b                            \n\t" \
+  "dla $2, 4b                            \n\t" \
+  "ldc1 $f2, 0($4)                      \n\t" \
+  "ldc1 $f4, 0($5)                      \n\t" \
+  "ldc1 $f6, 0($6)                      \n\t" \
+  "lw $7, 0($2)                         \n\t" \
+  "lw $8, 4($2)                         \n\t" \
+  xstr (inst) " $f2, $f4, $f6            \n\t" \
+  "mfhc1 $9, $f2                        \n\t" \
+  "mfc1 $10, $f2                        \n\t" \
+  fp_assert ($7, $9) \
+  fp_assert ($8, $10)
+
+
+/* ============ macros from sim/testutils/mips/testutils.inc ============= */
+
+/* Put value 'val' into register 'reg'.
+   Clobbers: None.  */
+#define load32(reg, val) \
+  "li  " xstr (reg) ", " xstr (val) "     \n\t"
+
+/* Check whether two registers contain the same value.
+   Clobbers: None.  */
+#define checkreg(reg, expreg) \
+  ".set push         \n\t" \
+  ".set noat         \n\t" \
+  ".set noreorder    \n\t" \
+  "beq "  xstr (expreg) ", " xstr (reg) ", 901f    \n\t" \
+  "nop               \n\t" \
+  "b 58f              \n\t" \
+  "nop                \n\t" \
+  "901:                   \n\t" \
+  ".set pop           \n\t"
+
+/* Check if register 'reg' contains value 'val'.
+   Clobbers: $1.  */
+#define check32(reg, val) \
+  ".set push         \n\t" \
+  ".set noat         \n\t" \
+  load32 ($1, val) \
+  checkreg (reg, $1) \
+  ".set pop          \n\t"
+
+/* Checkpair based on endianess
+   Clobbers: $1.  */
+#define checkpair_xendian(lo, hi, base, ec, w) \
+  ".set noat               \n\t" \
+  "lw   $1, " xstr (ec) "   \n\t" \
+  "andi $1, $1, 0x1        \n\t" \
+  "beqz  $1, 2f            \n\t" \
+  ".set at                 \n\t" \
+  "1:                          \n\t" \
+  checkpair_be_##w (lo, hi, base) \
+  "b 3f                    \n\t" \
+  "nop                     \n\t" \
+  "2:                          \n\t" \
+  checkpair_le_##w (lo, hi, base) \
+  "3:                          \n\t"
+
+
+/* Check hi-lo register pair against data stored at base+o1 and base+o2.
+   Clobbers: $1 - $5.  */
+#define  checkpair(lo, hi, base, w, o1, o2) \
+  "move  $2, " xstr (lo) "   \n\t" \
+  "move  $3, " xstr (hi) "   \n\t" \
+  ".set noat                \n\t" \
+  "dla   $1, " xstr (base) "  \n\t" \
+  "l" xstr (w) " $4, " xstr (o1) "($1)  \n\t" \
+  "l" xstr (w)  " $5, " xstr (o2) "($1)  \n\t" \
+  ".set at                  \n\t" \
+  checkreg ($2, $4) \
+  checkreg ($3, $5)
+
+#define checkpair_le_d(lo, hi, base) \
+  checkpair (lo, hi, base, w, 0, 4)
+
+#define checkpair_be_d(lo, hi, base) \
+  checkpair (lo, hi, base, w, 4, 0)
+
+
+#define checkpair_le_q(lo, hi, base) \
+  checkpair (lo, hi, base, d, 0, 8)
+
+#define checkpair_be_q(lo, hi, base) \
+  checkpair (lo, hi, base, d, 8, 0)
+
+#define checkpair_qword(lo, hi, base, oe) \
+  checkpair_xendian (lo, hi, base, oe, q)
+
+#define checkpair_dword(lo, hi, base, oe) \
+  checkpair_xendian (lo, hi, base, oe, d)
+
+void
+abort (void);
+
+/* Tests branch instructions.  */
+
+int
+test_r6_branch (void)
+{
+/* Using volatile to prevent certain optimizations which could cause
+ * instruction deletion.
+ * 'err' identifies instruction which (eventually) caused error.
+ * (err == 0) ==> all instructions executed successfully.  */
+
+  volatile int err = -1;
+  volatile int a14 = 0xffffffff;
+  volatile int a13 = 0x123;
+  volatile int a12 = 0x45;
+  volatile int a7 = 0x45;
+  volatile int a8 = 0xfffffffe;
+  volatile int a9 = 2147483647;
+  volatile int a11 = 0;
+  volatile int a10 = 0;
+
+  asm (
+  ".set push             \n\t" /* Create new scope for asm configuration.  */
+  ".set noreorder        \n\t" /* Don't allow reordering of instructions.  */
+  "li %[err], 1                  \n\t"
+  "bovc %[a12], %[a13], Lfail    \n\t" /* BOVC */
+  "nop                           \n\t"
+  "bovc %[a9], %[a13], L2        \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L2:                           \n\t"
+  "li %[err], 2                  \n\t"
+  "bnvc %[a9], %[a13], Lfail     \n\t" /* BNVC */
+  "nop                           \n\t"
+  "bnvc %[a12], %[a13], L3       \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L3:                           \n\t"
+  "li %[err], 3                  \n\t"
+  "beqc %[a12], %[a13], Lfail    \n\t" /* BEQC */
+  "nop                           \n\t"
+  "beqc %[a12], %[a7], L4        \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L4:                           \n\t"
+  "li %[err], 4                  \n\t"
+  "bnec %[a12], %[a7], Lfail     \n\t" /* BNEC */
+  "nop                           \n\t"
+  "bnec %[a12], %[a13], L5       \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L5:                           \n\t"
+  "li %[err], 5                  \n\t"
+  "bltc %[a13], %[a12], Lfail    \n\t" /* BLTC */
+  "nop                           \n\t"
+  "bltc %[a12], %[a13], L6       \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L6:                           \n\t"
+  "L7:                           \n\t"
+  "li %[err], 7                  \n\t"
+  "bgec %[a12], %[a13], Lfail    \n\t" /* BGEC */
+  "nop                           \n\t"
+  "bgec %[a13], %[a12], L8       \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L8:                           \n\t"
+  "L9:                           \n\t"
+  "li %[err], 9                  \n\t"
+  "bltuc %[a14], %[a13], Lfail   \n\t" /* BLTUC */
+  "nop                           \n\t"
+  "bltuc %[a8], %[a14], L10      \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L10:                          \n\t"
+  "L11:                          \n\t"
+  "li %[err], 11                 \n\t"
+  "bgeuc %[a13], %[a14], Lfail   \n\t" /* BGEUC */
+  "nop                           \n\t"
+  "bgeuc %[a14], %[a8], L12      \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L12:                          \n\t"
+  "L13:                          \n\t"
+  "li %[err], 13                 \n\t"
+  "bltzc %[a13], Lfail           \n\t" /* BLTZC */
+  "nop                           \n\t"
+  "bltzc %[a11], Lfail           \n\t"
+  "nop                           \n\t"
+  "bltzc %[a14], L14             \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L14:                          \n\t"
+  "li %[err], 14                 \n\t"
+  "blezc %[a13], Lfail           \n\t" /* BLEZC */
+  "nop                           \n\t"
+  "blezc %[a11], L145            \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L145:                         \n\t"
+  "blezc %[a14], L15             \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L15:                          \n\t"
+  "li %[err], 15                 \n\t"
+  "bgezc %[a8], Lfail            \n\t" /* BGEZC */
+  "nop                           \n\t"
+  "bgezc %[a11], L155            \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L155:                         \n\t"
+  "bgezc %[a13], L16             \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L16:                          \n\t"
+  "li %[err], 16                 \n\t"
+  "bgtzc %[a8], Lfail            \n\t" /* BGTZC */
+  "nop                           \n\t"
+  "bgtzc %[a11], Lfail           \n\t"
+  "nop                           \n\t"
+  "bgtzc %[a13], L17             \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "li %[a10], 0                  \n\t"
+  "L17:                          \n\t"
+  "li %[err], 17                 \n\t"
+  "blezalc %[a12], Lfail         \n\t" /* BLEZALC */
+  "nop                           \n\t"
+  "blezalc %[a11], Lret          \n\t"
+  "li %[a10], 1                  \n\t"
+  "beqzc %[a10], L175            \n\t" /* BEQZC */
+  "nop                           \n\t"
+  "li %[err], 8531               \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L175:                         \n\t"
+  "li %[err], 23531              \n\t"
+  "blezalc %[a14], Lret          \n\t"
+  "li %[a10], 1                  \n\t"
+  "beqzc %[a10], L18             \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L18:                          \n\t"
+  "li %[err], 18                 \n\t"
+  "bgezalc %[a14], Lfail         \n\t" /* BGEZALC */
+  "nop                           \n\t"
+  "bgezalc %[a11], Lret          \n\t"
+  "li %[a10], 1                  \n\t"
+  "beqzc %[a10], L185            \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L185:                         \n\t"
+  "bgezalc %[a12], Lret          \n\t"
+  "li %[a10], 1                  \n\t"
+  "beqzc %[a10], L19             \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L19:                          \n\t"
+  "li %[err], 19                 \n\t"
+  "bgtzalc %[a14], Lfail         \n\t" /* BGTZALC */
+  "nop                           \n\t"
+  "bgtzalc %[a11], Lfail         \n\t"
+  "nop                           \n\t"
+  "bgtzalc %[a12], Lret          \n\t"
+  "li %[a10], 1                  \n\t"
+  "beqzc %[a10], L20             \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L20:                          \n\t"
+  "li %[err], 20                 \n\t"
+  "bltzalc %[a12], Lfail         \n\t" /* BLTZALC */
+  "nop                           \n\t"
+  "bltzalc %[a11], Lfail         \n\t"
+  "nop                           \n\t"
+  "bltzalc %[a14], Lret          \n\t"
+  "li %[a10], 1                  \n\t"
+  "beqzc %[a10], L21             \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L21:                          \n\t"
+  "li %[err], 21                 \n\t"
+  "bc L22                        \n\t" /* BC */
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L22:                          \n\t"
+  "li %[err], 22                 \n\t"
+  "balc Lret                     \n\t" /* BALC */
+  "li %[a10], 1                  \n\t"
+  "beqzc %[a10], L23             \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L23:                          \n\t"
+  "li %[err], 23                 \n\t"
+  "jal GetPC                     \n\t" /* JAL */
+  "nop                           \n\t"
+  "jic $6, 4                     \n\t" /* JIC */
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L24:                          \n\t"
+  "li %[err], 24                 \n\t"
+  "li %[a10], 1                  \n\t"
+  "jal GetPC                     \n\t"
+  "nop                           \n\t"
+  "jialc $6, 20                  \n\t" /* JIALC */
+  "nop                           \n\t"
+  "beqzc %[a10], L25             \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "LJIALCRET:                    \n\t"
+  "li %[a10], 0                  \n\t"
+  "jr $31                        \n\t" /* JR */
+  "nop                           \n\t"
+  "L25:                          \n\t"
+  "li %[err], 25                 \n\t"
+  "jal GetPC                     \n\t"
+  "nop                           \n\t"
+  "move %[a11], $6               \n\t"
+  "nal                           \n\t"
+  "nop                           \n\t"
+  "addiu %[a11], 12              \n\t" /* ADDIU */
+  "beqc %[a11], $31, L26         \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L26:                          \n\t"
+  "li %[err], 26                 \n\t"
+  "balc Lret                     \n\t"
+  "li %[a10], 1                  \n\t"
+  "beqzc %[a10], Lend            \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "Lret:                         \n\t"
+  "li %[a10], 0                  \n\t"
+  "daddiu $31, 4                 \n\t" /* DADDIU */
+  "jrc $31                       \n\t" /* JRC */
+  "nop                           \n\t"
+  "GetPC:                        \n\t"
+  "move $6, $31                  \n\t"
+  "jr $31                        \n\t"
+  "Lend:                         \n\t"
+  "li %[err], 0                  \n\t"
+  "Lfail:                        \n\t"
+  ".set pop                      \n\t" /* Restore previous config */
+  : [err] "+r"(err), [a14] "+r"(a14), [a13] "+r"(a13), [a12] "+r"(a12),
+    [a7] "+r"(a7), [a8] "+r"(a8), [a9] "+r"(a9), [a10] "+r"(a10), [a11] "+r"(a11)
+  : /* inputs */
+  : "$31", "$6" /* clobbers */
+  );
+
+  return err;
+}
+
+/* Tests forbidden slot branching i.e. conditional compact branch
+   instructions.  */
+
+int
+test_r6_forbidden (void)
+{
+  volatile int err = -1;
+  volatile int a4 = 0;
+  volatile int a2 = 0;
+  volatile int a1 = 0;
+
+  asm (
+  ".set push                         \n\t"
+  ".set noreorder                    \n\t"
+/* Test if FS is ignored when branch is taken */
+  "li %[err], 1                      \n\t"
+  "li %[a4], 0                       \n\t"
+  "beqzalc %[a4], L41                \n\t"
+  "li %[err], -85                    \n\t"
+  "L42:                              \n\t"
+  "b Lfail2                          \n\t"
+  "nop                               \n\t"
+  "L41:                              \n\t"
+  "blez %[err], Lfail2               \n\t"
+/* Test if FS is used when branch is not taken */
+  "li %[err], 2                      \n\t"
+  "li %[a4], 1                       \n\t"
+  "blezc %[a4], L43                  \n\t"
+  "addiu %[a4], %[a4], 1             \n\t"
+  "li %[a2], 2                       \n\t"
+  "beq %[a4], %[a2], L44             \n\t"
+  "nop                               \n\t"
+  "L43:                              \n\t"
+  "nop                               \n\t"
+  "b Lfail2                          \n\t"
+  "nop                               \n\t"
+  "L44:                              \n\t"
+  "li %[err], 3                      \n\t"
+  "li %[a4], 3                       \n\t"
+  "beqzalc %[a4], Lfail2             \n\t"
+/* Note: 'bc L45' instead nop would cause SegFault: Illegal instruction:
+   Forbidden slot causes an error when it contains a branch.  */
+  "nop                               \n\t"
+  "b Lend2                           \n\t"
+  "nop                               \n\t"
+  "L45:                              \n\t"
+  "nop                               \n\t"
+  "b Lfail2                          \n\t"
+  "nop                               \n\t"
+  "Lend2:                            \n\t"
+  "li %[err], 0                      \n\t"
+  "Lfail2:                           \n\t"
+  "nop                               \n\t"
+  ".set pop                          \n\t"
+  : [err] "+r" (err), [a4] "+r"(a4), [a2] "+r"(a2), [a1] "+r"(a1) /* outputs */
+  : /* inputs */
+  : "$31" /* clobbers */
+  );
+
+  return err;
+}
+
+int
+test_r6_64 (void)
+{
+  volatile int err = 0;
+
+  asm (
+  ".set push                                   \n\t"
+  ".set noreorder                              \n\t"
+  ".data                                       \n\t"
+  "dval: .dword 0xaa55bb66cc77dd88             \n\t"
+  "d1:   .dword 0xaaaabbbbccccdddd             \n\t"
+  "d5:   .dword 0x00000000000000dd             \n\t"
+  "d7:   .dword 0xeeeeffff00001111             \n\t"
+  "d8:   .dword 0xbbccccddddeeeeff             \n\t"
+  "d9:   .dword 0x000000ddaaaabbbb             \n\t"
+  "dval1: .word 0x1234abcd                     \n\t"
+  "dval2: .word 0xffee0000                     \n\t"
+  "dval3: .dword 0xffffffffffffffff            \n\t"
+  "  .fill 240,1,0                             \n\t"
+  "dval4: .dword 0x5555555555555555            \n\t"
+  "  .fill  264,1,0                            \n\t"
+
+/* Register $11 stores instruction currently being tested and hence
+ * identifies error if it occurs.  */
+  ".text                                       \n\t"
+
+  "li $11, 1                                   \n\t" /* Test DALIGN */
+  r6ck_2dr1i (dalign, d7, d1, 3, d8)
+  r6ck_2dr1i (dalign, d1, d5, 4, d9)
+
+  "li $11, 2                                   \n\t" /* Test LDPC */
+  "ld $5, dval                                 \n\t"
+  "nop                                         \n\t"
+  "ldpc $4, dval                               \n\t"
+  fp_assert ($4, $5)
+
+  "li $11, 3                                   \n\t" /* Test LWUPC */
+  "lwu $5, dval1                               \n\t"
+  "lwupc $4, dval1                             \n\t"
+  fp_assert ($4, $5)
+  "lwu $5, dval2                               \n\t"
+  "lwupc $4, dval2                             \n\t"
+  fp_assert ($4, $5)
+
+  "li $11, 4                                   \n\t" /* Test LLD */
+  "ld $5, dval3                                \n\t"
+  "dla $3, dval4                               \n\t"
+  "lld $4, -248($3)                            \n\t"
+  fp_assert ($4, $5)
+
+  "li $11, 5                                   \n\t" /* Test SCD */
+  "lld $4, -248($3)                            \n\t"
+  "dli $4, 0xafaf                              \n\t"
+  "scd $4, -248($3)                            \n\t"
+  "ld $5, dval3                                \n\t"
+  "dli $4, 0xafaf                              \n\t"
+  fp_assert ($4, $5)
+
+  "Lend3:                                      \n\t"
+  "li $11, 0                                   \n\t"
+  "58:                                         \n\t"
+  "move %[err], $11                            \n\t"
+  ".set pop                                    \n\t"
+   : [err] "+r" (err) /* outputs */
+   :                  /* inputs */
+   : "$3", "$4", "$5", "$6", "$7", "$11" /* clobbers */
+  );
+
+  return err;
+}
+
+int
+test_r6 (void)
+{
+  volatile int err = 0;
+
+  asm (
+  ".set push                                                   \n\t"
+  ".set noreorder                                              \n\t"
+  ".data                                                       \n\t"
+  "dval_1:  .word 0xabcd1234                                   \n\t"
+  "dval_2: .word 0x1234eeff                                    \n\t"
+  ".fill 248,1,0                                               \n\t"
+  "dval_3: .word 0x55555555                                    \n\t"
+  ".fill  260,1,0                                              \n\t"
+  "dval_4: .word 0xaaaaaaaa                                    \n\t"
+  ".text                                                       \n\t"
+  "li $11, 1            \n\t" /* ADDIUPC */
+  "jal GetPC_2                                               \n\t"
+  "nop                                                       \n\t"
+  "addiu $4, $6, 8                                           \n\t"
+  "addiupc $5, 4                                             \n\t"
+  fp_assert ($4, $5)
+
+  "li $11, 2            \n\t" /* AUIPC */
+  "jal GetPC_2                                               \n\t"
+  "nop                                                       \n\t"
+  "addiu $4, $6, 8                                           \n\t"
+  "aui $4, $4, 8                                             \n\t"
+  "auipc $5, 8                                               \n\t"
+  fp_assert ($4, $5)
+
+  "li $11, 3            \n\t" /* ALUIPC */
+  "jal GetPC_2                                               \n\t"
+  "nop                                                       \n\t"
+  "addiu $4, $6, 16                                          \n\t"
+  "aui $4, $4, 8                                             \n\t"
+  "li $7, 0xffff0000                                         \n\t"
+  "and $4, $4, $7                                            \n\t"
+  "aluipc $5, 8                                              \n\t"
+  fp_assert ($4, $5)
+
+  "li $11, 4            \n\t" /* LWPC */
+  "lw $5, dval_1                                             \n\t"
+  "lwpc $4, dval_1                                           \n\t"
+  fp_assert ($4, $5)
+  "lw $5, dval_2                                             \n\t"
+  "lwpc $4, dval_2                                           \n\t"
+  fp_assert ($4, $5)
+
+/* Testing LL follows.
+ * NOTE: May be redundant because SC already contains LL in its test.  */
+  "li $11, 5                                                \n\t"
+  "lw $5, dval_2                                             \n\t"
+  "dla $3, dval_3                                            \n\t"
+  "ll $4, -252($3)                                           \n\t"
+  fp_assert ($4, $5)
+
+  "li $11, 6        \n\t"    /* LL-SC sequence */
+  "ll $4, -252($3)                                           \n\t"
+  "li $4, 0xafaf                                             \n\t"
+  "sc $4, -252($3)                                           \n\t"
+  "lw $5, dval_2                                             \n\t"
+  "li $4, 0xafaf                                             \n\t"
+  fp_assert ($4, $5)
+  "b Lend4                                                   \n\t"
+  "nop                                                       \n\t"
+  "GetPC_2:                                                  \n\t"
+  "move $6, $31                                              \n\t"
+  "jr $31                                                    \n\t"
+  "Lend4:                                                    \n\t"
+  "li $11, 0                                                 \n\t"
+  "58:                                                       \n\t"
+  "move %[err], $11                                          \n\t"
+  ".set pop                                                  \n\t"
+  : [err] "+r"(err)  /* outputs */
+  : /* inputs */
+  : "$3", "$4", "$5", "$6", "$7", "$8", "$9", "$10",
+    "$11", "$31" /* clobbers */
+  );
+
+  return err;
+}
+
+/* For fpu-branching testing, bc1eq/eqz are enough.  */
+
+int
+test_r6_fpu (void)
+{
+  volatile int err = 0;
+
+  asm (
+  ".set push                               \n\t"
+  ".set noreorder                          \n\t"
+/* Test qNaN format is 754-2008 */
+  "li $11, 1                               \n\t"
+  "li $4, 0x0                              \n\t"
+  "li $5, 0x0                              \n\t"
+  "li $6, 0x7fc00000                       \n\t"
+  "mtc1 $4, $f2                            \n\t"
+  "mtc1 $5, $f4                            \n\t"
+  "div.s $f6, $f2, $f4                     \n\t"
+  "mfc1 $8, $f6                            \n\t"
+  fp_assert ($6, $8)
+
+  "li $11, 2                                \n\t"  /* bc1eqz */
+  "li $10, 0x01                             \n\t"
+  "mtc1 $10, $f2                            \n\t"
+  "mtc1 $0, $f4                             \n\t"
+  "bc1eqz $f2, 58f                          \n\t"
+  "nop                                      \n\t"
+  "bc1eqz $f4, L62                          \n\t"
+  "nop                                      \n\t"
+  "b 58f                                    \n\t"
+  "nop                                      \n\t"
+"L62:                                       \n\t"
+  "li $11, 3                                \n\t"  /* bc1nez */
+  "bc1nez $f4, 58f                          \n\t"
+  "nop                                      \n\t"
+  "bc1nez $f2, Lend8                        \n\t"
+  "nop                                      \n\t"
+  "b 58f                                    \n\t"
+  "nop                                      \n\t"
+"Lend8:                                     \n\t"
+  "li $11, 0                                \n\t"
+  "58:                                      \n\t"
+  "move %[err], $11                         \n\t"
+  ".set pop                                 \n\t"
+  : [err] "+r"(err)  /* outputs */
+  :                  /* inputs */
+  : "$4", "$5", "$6", "$8", "$10", "$11", "$31",
+    "$f2", "$f4", "$f6" /* clobbers */
+  );
+
+  return err;
+}
+
+/* R6 specific tests for mips64 (64-bit).  */
+
+int
+test_r6_llsc_dp (void)
+{
+  volatile int err = 0;
+
+  asm (
+  ".set push                                            \n\t"
+  ".set noreorder                                       \n\t"
+  ".data                                                \n\t"
+  ".align 16                                            \n\t"
+  "test_data:                                           \n\t"
+  ".word 0xaaaaaaaa                                     \n\t"
+  ".word 0xbbbbbbbb                                     \n\t"
+  ".word 0xcccccccc                                     \n\t"
+  ".word 0xdddddddd                                     \n\t"
+  ".align 16                                            \n\t"
+  "end_check:                                           \n\t"
+  ".byte 0                                              \n\t"
+  ".byte 0                                              \n\t"
+  ".byte 0                                              \n\t"
+  ".byte 0x1                                            \n\t"
+  ".text                                                \n\t"
+  "li $11, 1                                            \n\t" /* LLWP */
+  "llwp $2, $3, test_data                               \n\t"
+  checkpair_dword ($2, $3, test_data, end_check)
+  "sll $2, $2, 1                                        \n\t"
+  "srl $3, $3, 1                                        \n\t"
+  "move  $s0, $2                                        \n\t"
+  "scwp $2, $3, test_data                               \n\t"
+  check32 ($2, 1)
+  checkpair_dword ($s0, $3, test_data, end_check)
+  /* Test SCWP, done */
+  "li $11, 2                                            \n\t"
+  "li $11, 3                                            \n\t" /* LLDP */
+  "lldp $2, $3, test_data                               \n\t"
+  checkpair_qword ($2, $3, test_data, end_check)
+  "dsll $2, $2, 1                                       \n\t"
+  "dsrl $3, $3, 1                                       \n\t"
+  "move $s0, $2                                         \n\t"
+  "scdp $2, $3, test_data                               \n\t"
+  check32 ($2, 1)
+  checkpair_qword ($s0, $3, test_data, end_check)
+  "li $11, 4                                            \n\t" /* SCDP done */
+  "Lend5:                                               \n\t"
+  "li $11, 0                                            \n\t"
+  "58:                                                  \n\t"
+  "move %[err], $11                                     \n\t"
+  ".set pop                                             \n\t"
+  : [err] "+r"(err) /* outputs */
+  : /* inputs */
+  : "$2", "$3", "$4", "$5", "$6", "$7", "$8", "$9", "$10", "$11",
+    "$31", "$s0"  /* clobbers */
+  );
+
+  return err;
+}
+
+/* R6 specific tests for mips32 (32-bit).  */
+
+int
+test_r6_llsc_wp (void)
+{
+  volatile int err = 0;
+
+  asm (
+  ".set push                                            \n\t"
+  ".set noreorder                                       \n\t"
+  ".data                                                \n\t"
+  ".align 8                                             \n\t"
+  "test_data_2:                                         \n\t"
+  ".word 0xaaaaaaaa                                     \n\t"
+  ".word 0xbbbbbbbb                                     \n\t"
+  ".align 8                                             \n\t"
+  "end_check_2:                                         \n\t"
+  ".byte 0                                              \n\t"
+  ".byte 0                                              \n\t"
+  ".byte 0                                              \n\t"
+  ".byte 0x1                                            \n\t"
+  ".text                                                \n\t"
+  "li $11, 1                                            \n\t" /* Test LLWP */
+  "llwp $2, $3, test_data_2                             \n\t"
+  checkpair_dword ($2, $3, test_data_2, end_check_2)
+  "sll $2, $2, 1                                        \n\t"
+  "srl $3, $3, 1                                        \n\t"
+  "move  $s0, $2                                        \n\t"
+  "scwp $2, $3, test_data_2                             \n\t"
+  check32 ($2, 1)
+  checkpair_dword ($s0, $3, test_data_2, end_check_2)
+/* Test SCWP, done.  */
+  "li $11, 2                                            \n\t"
+  "Lend6:                                               \n\t"
+  "li $11, 0                                            \n\t"
+  "58:                                                  \n\t"
+  "move %[err], $11                                     \n\t"
+  ".set pop                                             \n\t"
+  : [err] "+r"(err) /* outputs */
+  : /* inputs */
+  : "$2", "$3", "$4", "$5", "$6", "$7", "$8", "$9", "$10",
+    "$11", "$31", "$s0"  /* clobbers */
+  );
+
+  return err;
+}
+
+/* Any test_r6_* function returns non-zero => failure.  */
+#define EXPECT(X) if ((X)) abort ();
+
+int
+main (void)
+{
+  EXPECT (test_r6_branch ());
+
+  EXPECT (test_r6_forbidden ());
+
+  EXPECT (test_r6_64 ());
+
+  EXPECT (test_r6 ());
+
+  EXPECT (test_r6_fpu ());
+
+  EXPECT (test_r6_llsc_dp ());
+
+  EXPECT (test_r6_llsc_wp ());
+
+  return 0;
+}
diff --git a/gdb/testsuite/gdb.arch/mips-64-r6.exp b/gdb/testsuite/gdb.arch/mips-64-r6.exp
new file mode 100644
index 00000000000..2cce6abc6fa
--- /dev/null
+++ b/gdb/testsuite/gdb.arch/mips-64-r6.exp
@@ -0,0 +1,76 @@
+# Copyright (C) 2023-2024 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, see <http://www.gnu.org/licenses/>.
+
+################################################################
+################## MIPS Release 6 patch tests ##################
+################################################################
+
+# Send 'si' to gdb until inferior exits.
+proc stepi {} {
+    global gdb_prompt
+    set timeout [get_largest_timeout]
+    set start [timestamp]
+    while { [timestamp] - $start < 3*$timeout } {
+	gdb_test_multiple "stepi" ""  {
+	    -re ".*exited normally.*" {
+		pass "success"
+		return
+	    }
+	    -re ".*The program is not being run.*" {
+		fail "failure"
+		return
+	    }
+	    -re ".*Breakpoint.*test_.*$gdb_prompt $" {
+	    }
+	    -re "$gdb_prompt.*" {
+	    }
+	}
+    }
+    fail "test failed"
+    return
+}
+
+require {istarget "*mips*"}
+
+set testfile "mips-64-r6"
+set srcfile ${testfile}.c
+set binfile ${objdir}/${subdir}/${testfile}
+
+if {[prepare_for_testing "failed to prepare" "${binfile}" "${srcfile}" {debug nowarnings}]} {
+    untested "failed to prepare"
+    return
+}
+
+# Native needs run.
+if { ![runto_main] } {
+    untested "couldn't run to main"
+    return
+}
+
+set tests ""
+foreach n [list "r6_branch" "r6_forbidden" "r6_64" "r6" "r6_fpu" "r6_llsc_dp" "r6_llsc_wp"] {
+    lappend tests "test_$n"
+}
+
+# Put breakpoint on each test-function
+foreach func $tests {
+    if {![gdb_breakpoint "$func"]} {
+	untested "couldn't put breakpoint to $func"
+	return
+    }
+}
+
+# Step through the binary
+stepi
-- 
2.40.1


^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: [PATCH^5] gdb: mips: Add MIPSR6 support
  2024-05-15 20:19 [PATCH^5] gdb: mips: Add MIPSR6 support Milos Kalicanin
@ 2024-06-24 14:24 ` Milos Kalicanin
  2024-06-24 22:40 ` Maciej W. Rozycki
  1 sibling, 0 replies; 3+ messages in thread
From: Milos Kalicanin @ 2024-06-24 14:24 UTC (permalink / raw)
  To: gdb-patches
  Cc: Djordje Todorovic, Dragan Mladjenovic, Andrew Burgess,
	Simon Marchi, Maciej W . Rozycki, Chao-ying Fu

Ping.

Please let me know if more corrections are needed.

________________________________________
From: Milos Kalicanin
Sent: Wednesday, May 15, 2024 10:19 PM
To: gdb-patches@sourceware.org
Cc: Djordje Todorovic; Dragan Mladjenovic; Andrew Burgess; Simon Marchi; Maciej W . Rozycki; Chao-ying Fu
Subject: [PATCH^5] gdb: mips: Add MIPSR6 support

Introduce new instruction encodings from Release 6 of the MIPS
architecture [1]. Support breakpoints and single stepping with
compact branches, forbidden slots, new branch instruction and
new atomic load-store instruction encodings.

Changes from v4: Apply code formatting as Andrew Burgess suggested.

[1] "MIPS64 Architecture for Programmers Volume II-A: The MIPS64
    Instruction Set Reference Manual", Document Number: MD00087,
    Revision 6.06, December 15, 2016, Section 3 "The MIPS64
    Instruction Set", pp. 42-530
https://s3-eu-west-1.amazonaws.com/downloads-mips/documents/MD00087-2B-MIPS64BIS-AFP-6.06.pdf

2024-05-15
Andrew Bennett  <andrew.bennett@imgtec.com>
Matthew Fortune  <matthew.fortune@mips.com>
Faraz Shahbazker  <fshahbazker@wavecomp.com>

gdb/ChangeLog:
        * mips-tdep.c (is_mipsr6_isa): New.
        (b0s21_imm): New define.
        (mips32_relative_offset21, mips32_relative_offset26): New.
        (is_add32bit_overflow, is_add64bit_overflow): New.
        (mips32_next_pc): Handle r6 compact and fpu coprocessor branches.
        Move handling of BLEZ, BGTZ opcode into ...
        (mips32_blez_pc): New.
        (mips32_instruction_is_compact_branch): New.
        (mips32_insn_at_pc_has_forbidden_slot):  New.
        (mips32_scan_prologue): Ignore pre-r6 addi encoding on r6.
        Stop at compact branch also.
        (LLSC_R6_OPCODE,LL_R6_FUNCT,LLE_FUNCT,
        LLD_R6_FUNCT,SC_R6_FUNCT,SCE_FUNCT,
        SCD_R6_FUNCT: New defines.
        (is_ll_insn, is_sc_insn): New.
        (mips_deal_with_atomic_sequence): Use is_ll_insn/is_sc_insn.
        Handle compact branches.
        (mips_about_to_return): Handle jrc and macro jr.
        (mips32_stack_frame_destroyed_p): Likewise.
        (mips32_instruction_has_delay_slot): Don't handle JALX on r6.
        Handle compact branches and coprocessor branches.
        (mips_adjust_breakpoint_address): Skip forbidden slot for
        compact branches.
---
 gdb/mips-tdep.c                       | 532 +++++++++++++--
 gdb/testsuite/gdb.arch/mips-64-r6.c   | 918 ++++++++++++++++++++++++++
 gdb/testsuite/gdb.arch/mips-64-r6.exp |  76 +++
 3 files changed, 1483 insertions(+), 43 deletions(-)
 create mode 100644 gdb/testsuite/gdb.arch/mips-64-r6.c
 create mode 100644 gdb/testsuite/gdb.arch/mips-64-r6.exp

diff --git a/gdb/mips-tdep.c b/gdb/mips-tdep.c
index ae58d7c8720..bdaeb6a8999 100644
--- a/gdb/mips-tdep.c
+++ b/gdb/mips-tdep.c
@@ -76,6 +76,10 @@ static int mips16_insn_at_pc_has_delay_slot (struct gdbarch *gdbarch,
 static void mips_print_float_info (struct gdbarch *, struct ui_file *,
                                   const frame_info_ptr &, const char *);

+static void
+mips_read_fp_register_single (const frame_info_ptr &frame, int regno,
+                             gdb_byte *rare_buffer);
+
 /* A useful bit in the CP0 status register (MIPS_PS_REGNUM).  */
 /* This bit is set if we are emulating 32-bit FPRs on a 64-bit chip.  */
 #define ST0_FR (1 << 26)
@@ -325,6 +329,16 @@ mips_abi_regsize (struct gdbarch *gdbarch)
     }
 }

+/* Return true if the gdbarch is based on MIPS Release 6.  */
+static bool
+is_mipsr6_isa (struct gdbarch *gdbarch)
+{
+  const struct bfd_arch_info *info = gdbarch_bfd_arch_info (gdbarch);
+
+  return (info->mach == bfd_mach_mipsisa32r6
+         || info->mach == bfd_mach_mipsisa64r6);
+}
+
 /* MIPS16/microMIPS function addresses are odd (bit 0 is set).  Here
    are some functions to handle addresses associated with compressed
    code including but not limited to testing, setting, or clearing
@@ -1500,6 +1514,7 @@ mips_fetch_instruction (struct gdbarch *gdbarch,
   return extract_unsigned_integer (buf, instlen, byte_order);
 }

+
 /* These are the fields of 32 bit mips instructions.  */
 #define mips32_op(x) (x >> 26)
 #define itype_op(x) (x >> 26)
@@ -1542,6 +1557,7 @@ mips_fetch_instruction (struct gdbarch *gdbarch,
 #define b0s11_op(x) ((x) & 0x7ff)
 #define b0s12_imm(x) ((x) & 0xfff)
 #define b0s16_imm(x) ((x) & 0xffff)
+#define b0s21_imm(x) ((x) & 0x1fffff)
 #define b0s26_imm(x) ((x) & 0x3ffffff)
 #define b6s10_ext(x) (((x) >> 6) & 0x3ff)
 #define b11s5_reg(x) (((x) >> 11) & 0x1f)
@@ -1578,6 +1594,18 @@ mips32_relative_offset (ULONGEST inst)
   return ((itype_immediate (inst) ^ 0x8000) - 0x8000) << 2;
 }

+static LONGEST
+mips32_relative_offset21 (ULONGEST insn)
+{
+  return ((b0s21_imm (insn) ^ 0x100000) - 0x100000) << 2;
+}
+
+static LONGEST
+mips32_relative_offset26 (ULONGEST insn)
+{
+  return ((b0s26_imm (insn) ^ 0x2000000) - 0x2000000) << 2;
+}
+
 /* Determine the address of the next instruction executed after the INST
    floating condition branch instruction at PC.  COUNT specifies the
    number of the floating condition bits tested by the branch.  */
@@ -1636,6 +1664,71 @@ is_octeon_bbit_op (int op, struct gdbarch *gdbarch)
   return 0;
 }

+static int
+is_add32bit_overflow (int32_t a, int32_t b)
+{
+  int32_t r = (uint32_t) a + (uint32_t) b;
+  return (a < 0 && b < 0 && r >= 0) || (a >= 0 && b >= 0 && r < 0);
+}
+
+static int
+is_add64bit_overflow (int64_t a, int64_t b)
+{
+  if (a != (int32_t)a)
+    return 1;
+  if (b != (int32_t)b)
+    return 1;
+  return is_add32bit_overflow ((int32_t)a, (int32_t)b);
+}
+
+/* Calculate address of next instruction after BLEZ.  */
+
+static CORE_ADDR
+mips32_blez_pc (struct gdbarch *gdbarch, struct regcache *regcache,
+               ULONGEST inst, CORE_ADDR pc, int invert)
+{
+  int rs = itype_rs (inst);
+  int rt = itype_rt (inst);
+  LONGEST val_rs = regcache_raw_get_signed (regcache, rs);
+  LONGEST val_rt = regcache_raw_get_signed (regcache, rt);
+  ULONGEST uval_rs = regcache_raw_get_unsigned (regcache, rs);
+  ULONGEST uval_rt = regcache_raw_get_unsigned (regcache, rt);
+  int taken = 0;
+  int delay_slot_size = 4;
+
+  /* BLEZ, BLEZL, BGTZ, BGTZL  */
+  if (rt == 0)
+    taken = (val_rs <= 0);
+  else if (is_mipsr6_isa (gdbarch))
+    {
+      /* BLEZALC, BGTZALC  */
+      if (rs == 0 && rt != 0)
+       taken = (val_rt <= 0);
+      /* BGEZALC, BLTZALC  */
+      else if (rs == rt && rt != 0)
+       taken = (val_rt >= 0);
+      /* BGEUC, BLTUC  */
+      else if (rs != rt && rs != 0 && rt != 0)
+       taken = (uval_rs >= uval_rt);
+
+      /* Step through the forbidden slot to avoid repeated exceptions we do
+        not currently have access to the BD bit when hitting a breakpoint
+        and therefore cannot tell if the breakpoint hit on the branch or the
+        forbidden slot.  */
+      /* delay_slot_size = 0;  */
+    }
+
+  if (invert)
+    taken = !taken;
+
+  /* Calculate branch target.  */
+  if (taken)
+    pc += mips32_relative_offset (inst);
+  else
+    pc += delay_slot_size;
+
+  return pc;
+}

 /* Determine where to set a single step breakpoint while considering
    branch prediction.  */
@@ -1646,12 +1739,17 @@ mips32_next_pc (struct regcache *regcache, CORE_ADDR pc)
   struct gdbarch *gdbarch = regcache->arch ();
   unsigned long inst;
   int op;
+  int mips64bitreg = 0;
+
+  if (mips_isa_regsize (gdbarch) == 8)
+    mips64bitreg = 1;
+
   inst = mips_fetch_instruction (gdbarch, ISA_MIPS, pc, NULL);
   op = itype_op (inst);
   if ((inst & 0xe0000000) != 0)                /* Not a special, jump or branch
                                           instruction.  */
     {
-      if (op >> 2 == 5)
+      if (op >> 2 == 5 && ((op & 0x02) == 0 || itype_rt (inst) == 0))
        /* BEQL, BNEL, BLEZL, BGTZL: bits 0101xx */
        {
          switch (op & 0x03)
@@ -1661,7 +1759,7 @@ mips32_next_pc (struct regcache *regcache, CORE_ADDR pc)
            case 1:             /* BNEL */
              goto neq_branch;
            case 2:             /* BLEZL */
-             goto less_branch;
+             goto lez_branch;
            case 3:             /* BGTZL */
              goto greater_branch;
            default:
@@ -1671,15 +1769,19 @@ mips32_next_pc (struct regcache *regcache, CORE_ADDR pc)
       else if (op == 17 && itype_rs (inst) == 8)
        /* BC1F, BC1FL, BC1T, BC1TL: 010001 01000 */
        pc = mips32_bc1_pc (gdbarch, regcache, inst, pc + 4, 1);
-      else if (op == 17 && itype_rs (inst) == 9
+      else if (!is_mipsr6_isa (gdbarch)
+              && op == 17
+              && itype_rs (inst) == 9
               && (itype_rt (inst) & 2) == 0)
        /* BC1ANY2F, BC1ANY2T: 010001 01001 xxx0x */
        pc = mips32_bc1_pc (gdbarch, regcache, inst, pc + 4, 2);
-      else if (op == 17 && itype_rs (inst) == 10
+      else if (!is_mipsr6_isa (gdbarch)
+              && op == 17
+              && itype_rs (inst) == 10
               && (itype_rt (inst) & 2) == 0)
        /* BC1ANY4F, BC1ANY4T: 010001 01010 xxx0x */
        pc = mips32_bc1_pc (gdbarch, regcache, inst, pc + 4, 4);
-      else if (op == 29)
+      else if (!is_mipsr6_isa (gdbarch) && op == 29)
        /* JALX: 011101 */
        /* The new PC will be alternate mode.  */
        {
@@ -1707,7 +1809,128 @@ mips32_next_pc (struct regcache *regcache, CORE_ADDR pc)
          else
            pc += 8;        /* After the delay slot.  */
        }
+      else if (is_mipsr6_isa (gdbarch))
+       {
+         /* BOVC, BEQZALC, BEQC and BNVC, BNEZALC, BNEC  */
+         if (op == 8 || op == 24)
+           {
+             int rs = rtype_rs (inst);
+             int rt = rtype_rt (inst);
+             LONGEST val_rs = regcache_raw_get_signed (regcache, rs);
+             LONGEST val_rt = regcache_raw_get_signed (regcache, rt);
+             int taken = 0;
+             /* BOVC (BNVC)  */
+             if (rs >= rt)
+               {
+                 if (mips64bitreg == 1)
+                   taken = is_add64bit_overflow (val_rs, val_rt);
+                 else
+                   taken = is_add32bit_overflow (val_rs, val_rt);
+               }
+             /* BEQZALC (BNEZALC)  */
+             else if (rs < rt && rs == 0)
+               taken = (val_rt == 0);
+             /* BEQC (BNEC)  */
+             else
+               taken = (val_rs == val_rt);
+
+             /* BNVC, BNEZALC, BNEC  */
+             if (op == 24)
+               taken = !taken;

+             if (taken)
+               pc += mips32_relative_offset (inst) + 4;
+             else
+               /* Step through the forbidden slot to avoid repeated exceptions
+                  we do not currently have access to the BD bit when hitting a
+                  breakpoint and therefore cannot tell if the breakpoint
+                  hit on the branch or the forbidden slot.  */
+               pc += 8;
+           }
+         /* BC1EQZ, BC1NEZ  */
+         else if (op == 17 && (itype_rs (inst) == 9 || itype_rs (inst) == 13))
+           {
+             gdb_byte status;
+             gdb_byte true_val = 0;
+             unsigned int fp = (gdbarch_num_regs (gdbarch)
+                                + mips_regnum (gdbarch)->fp0
+                                + itype_rt (inst));
+             struct frame_info_ptr frame = get_current_frame ();
+             gdb_byte *raw_buffer = (gdb_byte *) alloca (sizeof (gdb_byte) * 4);
+             mips_read_fp_register_single (frame, fp, raw_buffer);
+
+             if (gdbarch_byte_order (gdbarch) == BFD_ENDIAN_BIG)
+               status = *(raw_buffer + 3);
+             else
+               status = *(raw_buffer);
+
+             if (itype_rs (inst) == 13)
+               true_val = 1;
+
+             if ((status & 0x1) == true_val)
+               pc += mips32_relative_offset (inst) + 4;
+             else
+               pc += 8;
+           }
+         else if (op == 22 || op == 23)
+         /* BLEZC, BGEZC, BGEC, BGTZC, BLTZC, BLTC  */
+           {
+             int rs = rtype_rs (inst);
+             int rt = rtype_rt (inst);
+             LONGEST val_rs = regcache_raw_get_signed (regcache, rs);
+             LONGEST val_rt = regcache_raw_get_signed (regcache, rt);
+             int taken = 0;
+             /* The R5 rt == 0 case is handled above so we treat it as
+                an unknown instruction here for future ISA usage.  */
+             if (rs == 0 && rt != 0)
+               taken = (val_rt <= 0);
+             else if (rs == rt && rt != 0)
+               taken = (val_rt >= 0);
+             else if (rs != rt && rs != 0 && rt != 0)
+               taken = (val_rs >= val_rt);
+
+             if (op == 23)
+               taken = !taken;
+
+             if (taken)
+               pc += mips32_relative_offset (inst) + 4;
+             else
+               /* Step through the forbidden slot to avoid repeated exceptions
+                  we do not currently have access to the BD bit when hitting a
+                  breakpoint and therefore cannot tell if the breakpoint
+                  hit on the branch or the forbidden slot.  */
+               pc += 8;
+           }
+         else if (op == 50 || op == 58)
+         /* BC, BALC  */
+           pc += mips32_relative_offset26 (inst) + 4;
+         else if ((op == 54 || op == 62)
+                  && rtype_rs (inst) == 0)
+         /* JIC, JIALC  */
+           {
+             pc = regcache_raw_get_signed (regcache, itype_rt (inst));
+             pc += (itype_immediate (inst) ^ 0x8000) - 0x8000;
+           }
+         else if (op == 54 || op == 62)
+         /* BEQZC, BNEZC  */
+           {
+             int rs = itype_rs (inst);
+             LONGEST rs_val = regcache_raw_get_signed (regcache, rs);
+             int taken = (rs_val == 0);
+             if (op == 62)
+               taken = !taken;
+             if (taken)
+               pc += mips32_relative_offset21 (inst) + 4;
+             else
+               /* Step through the forbidden slot to avoid repeated exceptions
+                  we do not currently have access to the BD bit when hitting a
+                  breakpoint and therefore cannot tell if the breakpoint
+                  hit on the branch or the forbidden slot.  */
+               pc += 8;
+           }
+         else
+           pc += 4;            /* Not a branch, next instruction is easy.  */
+       }
       else
        pc += 4;                /* Not a branch, next instruction is easy.  */
     }
@@ -1751,7 +1974,6 @@ mips32_next_pc (struct regcache *regcache, CORE_ADDR pc)
              case 2:           /* BLTZL */
              case 16:          /* BLTZAL */
              case 18:          /* BLTZALL */
-             less_branch:
                if (regcache_raw_get_signed (regcache, itype_rs (inst)) < 0)
                  pc += mips32_relative_offset (inst) + 4;
                else
@@ -1767,22 +1989,38 @@ mips32_next_pc (struct regcache *regcache, CORE_ADDR pc)
                  pc += 8;      /* after the delay slot */
                break;
              case 0x1c:        /* BPOSGE32 */
+             case 0x1d:        /* BPOSGE32C  */
              case 0x1e:        /* BPOSGE64 */
                pc += 4;
                if (itype_rs (inst) == 0)
                  {
                    unsigned int pos = (op & 2) ? 64 : 32;
                    int dspctl = mips_regnum (gdbarch)->dspctl;
+                   int delay_slot_size = 4;

                    if (dspctl == -1)
                      /* No way to handle; it'll most likely trap anyway.  */
                      break;

+                   /* BPOSGE32C  */
+                   if (op == 0x1d)
+                     {
+                       if (!is_mipsr6_isa (gdbarch))
+                         break;
+
+                       /* Step through the forbidden slot to avoid repeated
+                          exceptions we do not currently have access to the BD
+                          bit when hitting a breakpoint and therefore cannot
+                          tell if the breakpoint hit on the branch or the
+                          forbidden slot.  */
+                       /* delay_slot_size = 0;  */
+                     }
+
                    if ((regcache_raw_get_unsigned (regcache,
                                                    dspctl) & 0x7f) >= pos)
                      pc += mips32_relative_offset (inst);
                    else
-                     pc += 4;
+                     pc += delay_slot_size;
                  }
                break;
                /* All of the other instructions in the REGIMM category */
@@ -1816,19 +2054,14 @@ mips32_next_pc (struct regcache *regcache, CORE_ADDR pc)
          else
            pc += 8;
          break;
-       case 6:         /* BLEZ, BLEZL */
-         if (regcache_raw_get_signed (regcache, itype_rs (inst)) <= 0)
-           pc += mips32_relative_offset (inst) + 4;
-         else
-           pc += 8;
+       case 6:         /* BLEZ, BLEZL, BLEZALC, BGEZALC, BGEUC  */
+       lez_branch:
+         pc = mips32_blez_pc (gdbarch, regcache, inst, pc + 4, 0);
          break;
        case 7:
        default:
-       greater_branch: /* BGTZ, BGTZL */
-         if (regcache_raw_get_signed (regcache, itype_rs (inst)) > 0)
-           pc += mips32_relative_offset (inst) + 4;
-         else
-           pc += 8;
+       greater_branch: /* BGTZ, BGTZL, BGTZALC, BLTZALC, BLTUC  */
+         pc = mips32_blez_pc (gdbarch, regcache, inst, pc + 4, 1);
          break;
        }                       /* switch */
     }                          /* else */
@@ -2451,6 +2684,72 @@ micromips_instruction_is_compact_branch (unsigned short insn)
     }
 }

+/* Return non-zero if the MIPS instruction INSN is a compact branch
+   or jump.  A value of 1 indicates an unconditional compact branch
+   and a value of 2 indicates a conditional compact branch.  */
+
+static int
+mips32_instruction_is_compact_branch (struct gdbarch *gdbarch, ULONGEST insn)
+{
+  switch (itype_op (insn))
+    {
+    /* BC  */
+    case 50:
+    /* BALC  */
+    case 58:
+      if (is_mipsr6_isa (gdbarch))
+       return 1;
+      break;
+    /* BOVC, BEQZALC, BEQC  */
+    case 8:
+    /* BNVC, BNEZALC, BNEC  */
+    case 24:
+      if (is_mipsr6_isa (gdbarch))
+       return 2;
+      break;
+    /* BEQZC, JIC  */
+    case 54:
+    /* BNEZC, JIALC  */
+    case 62:
+      if (is_mipsr6_isa (gdbarch))
+       /* JIC, JIALC are unconditional  */
+       return (itype_rs (insn) == 0) ? 1 : 2;
+      break;
+    /* BLEZC, BGEZC, BGEC  */
+    case 22:
+    /* BGTZC, BLTZC, BLTC  */
+    case 23:
+    /* BLEZALC, BGEZALC, BGEUC  */
+    case 6:
+    /* BGTZALC, BLTZALC, BLTUC  */
+    case 7:
+      if (is_mipsr6_isa (gdbarch)
+         && itype_rt (insn) != 0)
+       return 2;
+      break;
+    /* BPOSGE32C  */
+    case 1:
+      if (is_mipsr6_isa (gdbarch)
+         && itype_rt (insn) == 0x1d && itype_rs (insn) == 0)
+       return 2;
+    }
+  return 0;
+}
+
+/* Return true if a standard MIPS instruction at ADDR has a branch
+   forbidden slot (i.e. it is a conditional compact branch instruction).  */
+
+static bool
+mips32_insn_at_pc_has_forbidden_slot (struct gdbarch *gdbarch, CORE_ADDR addr)
+{
+  int status;
+  ULONGEST insn = mips_fetch_instruction (gdbarch, ISA_MIPS, addr, &status);
+  if (status)
+    return false;
+
+  return mips32_instruction_is_compact_branch (gdbarch, insn) == 2;
+}
+
 struct mips_frame_cache
 {
   CORE_ADDR base;
@@ -3494,7 +3793,8 @@ mips32_scan_prologue (struct gdbarch *gdbarch,
       reg = high_word & 0x1f;

       if (high_word == 0x27bd          /* addiu $sp,$sp,-i */
-         || high_word == 0x23bd        /* addi $sp,$sp,-i */
+         || (high_word == 0x23bd       /* addi $sp,$sp,-i  */
+             && !is_mipsr6_isa (gdbarch))
          || high_word == 0x67bd)       /* daddiu $sp,$sp,-i */
        {
          if (offset < 0)               /* Negative stack adjustment?  */
@@ -3632,7 +3932,9 @@ mips32_scan_prologue (struct gdbarch *gdbarch,

       /* A jump or branch, or enough non-prologue insns seen?  If so,
         then we must have reached the end of the prologue by now.  */
-      if (prev_delay_slot || non_prologue_insns > 1)
+      if (prev_delay_slot
+         || non_prologue_insns > 1
+         || mips32_instruction_is_compact_branch (gdbarch, inst))
        break;

       prev_non_prologue_insn = this_non_prologue_insn;
@@ -3938,6 +4240,67 @@ mips_addr_bits_remove (struct gdbarch *gdbarch, CORE_ADDR addr)
 #define LLD_OPCODE 0x34
 #define SC_OPCODE 0x38
 #define SCD_OPCODE 0x3c
+#define LLSC_R6_OPCODE 0x1f
+#define LL_R6_FUNCT 0x36
+#define LLE_FUNCT 0x2e
+#define LLD_R6_FUNCT 0x37
+#define SC_R6_FUNCT 0x26
+#define SCE_FUNCT 0x1e
+#define SCD_R6_FUNCT 0x27
+
+/* Determine whether instruction 'insn' is of 'load linked X' type.
+   LL/SC instructions provide primitives to implement atomic
+   read-modify-write operations for synchronizable memory locations.  */
+
+static bool
+is_ll_insn (struct gdbarch *gdbarch, ULONGEST insn)
+{
+  if (itype_op (insn) == LL_OPCODE
+      || itype_op (insn) == LLD_OPCODE)
+    return true;
+
+  if (rtype_op (insn) == LLSC_R6_OPCODE
+      && rtype_funct (insn) == LLE_FUNCT
+      && (insn & 0x40) == 0)
+    return true;
+
+  /* Handle LL and LLP varieties.  */
+  if (is_mipsr6_isa (gdbarch)
+      && rtype_op (insn) == LLSC_R6_OPCODE
+      && (rtype_funct (insn) == LL_R6_FUNCT
+         || rtype_funct (insn) == LLD_R6_FUNCT
+         || rtype_funct (insn) == LLE_FUNCT))
+    return true;
+
+  return false;
+}
+
+/* Determine whether instruction 'insn' is of 'store conditional X' type.
+   SC instructions and varieties perform completion of read-modify-write
+   atomic sequence.  */
+
+static bool
+is_sc_insn (struct gdbarch *gdbarch, ULONGEST insn)
+{
+  if (itype_op (insn) == SC_OPCODE
+      || itype_op (insn) == SCD_OPCODE)
+    return true;
+
+  if (rtype_op (insn) == LLSC_R6_OPCODE
+      && rtype_funct (insn) == SCE_FUNCT
+      && (insn & 0x40) == 0)
+    return true;
+
+  /* Handle SC and SCP varieties.  */
+  if (is_mipsr6_isa (gdbarch)
+      && rtype_op (insn) == LLSC_R6_OPCODE
+      && (rtype_funct (insn) == SC_R6_FUNCT
+         || rtype_funct (insn) == SCD_R6_FUNCT
+         || rtype_funct (insn) == SCE_FUNCT))
+    return true;
+
+  return false;
+}

 static std::vector<CORE_ADDR>
 mips_deal_with_atomic_sequence (struct gdbarch *gdbarch, CORE_ADDR pc)
@@ -3950,10 +4313,11 @@ mips_deal_with_atomic_sequence (struct gdbarch *gdbarch, CORE_ADDR pc)
   int index;
   int last_breakpoint = 0; /* Defaults to 0 (no breakpoints placed).  */
   const int atomic_sequence_length = 16; /* Instruction sequence length.  */
+  bool is_mipsr6 = is_mipsr6_isa (gdbarch);

   insn = mips_fetch_instruction (gdbarch, ISA_MIPS, loc, NULL);
   /* Assume all atomic sequences start with a ll/lld instruction.  */
-  if (itype_op (insn) != LL_OPCODE && itype_op (insn) != LLD_OPCODE)
+  if (!is_ll_insn (gdbarch, insn))
     return {};

   /* Assume that no atomic sequence is longer than "atomic_sequence_length"
@@ -3983,28 +4347,72 @@ mips_deal_with_atomic_sequence (struct gdbarch *gdbarch, CORE_ADDR pc)
          return {}; /* fallback to the standard single-step code.  */
        case 4: /* BEQ */
        case 5: /* BNE */
-       case 6: /* BLEZ */
-       case 7: /* BGTZ */
        case 20: /* BEQL */
        case 21: /* BNEL */
-       case 22: /* BLEZL */
-       case 23: /* BGTTL */
+       case 22: /* BLEZL (BLEZC, BGEZC, BGEC)  */
+       case 23: /* BGTZL (BGTZC, BLTZC, BLTC)  */
          is_branch = 1;
          break;
+       case 6: /* BLEZ (BLEZALC, BGEZALC, BGEUC)  */
+       case 7: /* BGTZ (BGTZALC, BLTZALC, BLTUC)  */
+         if (is_mipsr6)
+           {
+             /* BLEZALC, BGTZALC  */
+             if (itype_rs (insn) == 0 && itype_rt (insn) != 0)
+               return {}; /* fallback to the standard single-step code.  */
+             /* BGEZALC, BLTZALC  */
+             else if (itype_rs (insn) == itype_rt (insn)
+                      && itype_rt (insn) != 0)
+               return {}; /* fallback to the standard single-step code.  */
+           }
+         is_branch = 1;
+         break;
+       case 8: /* BOVC, BEQZALC, BEQC  */
+       case 24: /* BNVC, BNEZALC, BNEC  */
+         if (is_mipsr6)
+           is_branch = 1;
+         break;
+       case 50: /* BC  */
+       case 58: /* BALC  */
+         if (is_mipsr6)
+           return {}; /* fallback to the standard single-step code.  */
+         break;
+       case 54: /* BEQZC, JIC  */
+       case 62: /* BNEZC, JIALC  */
+         if (is_mipsr6)
+           {
+             if (itype_rs (insn) == 0) /* JIC, JIALC  */
+               return {}; /* fallback to the standard single-step code.  */
+             else
+               is_branch = 2; /* Marker for branches with a 21-bit offset.  */
+           }
+         break;
        case 17: /* COP1 */
-         is_branch = ((itype_rs (insn) == 9 || itype_rs (insn) == 10)
-                      && (itype_rt (insn) & 0x2) == 0);
-         if (is_branch) /* BC1ANY2F, BC1ANY2T, BC1ANY4F, BC1ANY4T */
+         is_branch = ((!is_mipsr6
+                       /* BC1ANY2F, BC1ANY2T, BC1ANY4F, BC1ANY4T  */
+                       && (itype_rs (insn) == 9 || itype_rs (insn) == 10)
+                       && (itype_rt (insn) & 0x2) == 0)
+                      /* BZ.df:  010001 110xx  */
+                      || (itype_rs (insn) & 0x18) == 0x18);
+         if (is_branch != 0)
            break;
          [[fallthrough]];
        case 18: /* COP2 */
        case 19: /* COP3 */
-         is_branch = (itype_rs (insn) == 8); /* BCzF, BCzFL, BCzT, BCzTL */
+         /* BCzF, BCzFL, BCzT, BCzTL, BC*EQZ, BC*NEZ  */
+         is_branch = ((itype_rs (insn) == 8)
+                      || (is_mipsr6
+                          && (itype_rs (insn) == 9
+                              || itype_rs (insn) == 13)));
          break;
        }
-      if (is_branch)
+      if (is_branch != 0)
        {
-         branch_bp = loc + mips32_relative_offset (insn) + 4;
+         /* Is this a special PC21_S2 branch?  */
+         if (is_branch == 2)
+           branch_bp = loc + mips32_relative_offset21 (insn) + 4;
+         else
+           branch_bp = loc + mips32_relative_offset (insn) + 4;
          if (last_breakpoint >= 1)
            return {}; /* More than one branch found, fallback to the
                          standard single-step code.  */
@@ -4012,12 +4420,12 @@ mips_deal_with_atomic_sequence (struct gdbarch *gdbarch, CORE_ADDR pc)
          last_breakpoint++;
        }

-      if (itype_op (insn) == SC_OPCODE || itype_op (insn) == SCD_OPCODE)
+      if (is_sc_insn (gdbarch, insn))
        break;
     }

   /* Assume that the atomic sequence ends with a sc/scd instruction.  */
-  if (itype_op (insn) != SC_OPCODE && itype_op (insn) != SCD_OPCODE)
+  if (!is_sc_insn (gdbarch, insn))
     return {};

   loc += MIPS_INSN32_SIZE;
@@ -4166,7 +4574,7 @@ micromips_deal_with_atomic_sequence (struct gdbarch *gdbarch,
            }
          break;
        }
-      if (is_branch)
+      if (is_branch != 0)
        {
          if (last_breakpoint >= 1)
            return {}; /* More than one branch found, fallback to the
@@ -4242,8 +4650,14 @@ mips_about_to_return (struct gdbarch *gdbarch, CORE_ADDR pc)
   gdb_assert (mips_pc_is_mips (pc));

   insn = mips_fetch_instruction (gdbarch, ISA_MIPS, pc, NULL);
-  hint = 0x7c0;
-  return (insn & ~hint) == 0x3e00008;                  /* jr(.hb) $ra */
+  /* Mask the hint and the jalr/jr bit.  */
+  hint = 0x7c1;
+
+  if (is_mipsr6_isa (gdbarch) && insn == 0xd81f0000) /* jrc $31  */
+    return 1;
+
+  /* jr(.hb) $ra and "jalr(.hb) $ra"  */
+  return ((insn & ~hint) == 0x3e00008);
 }


@@ -6760,7 +7174,9 @@ mips32_stack_frame_destroyed_p (struct gdbarch *gdbarch, CORE_ADDR pc)

          if (high_word != 0x27bd       /* addiu $sp,$sp,offset */
              && high_word != 0x67bd    /* daddiu $sp,$sp,offset */
-             && inst != 0x03e00008     /* jr $ra */
+             && (inst & ~0x1) != 0x03e00008 /* jr $31 or jalr $0, $31  */
+             && (!is_mipsr6_isa (gdbarch)
+                 || inst != 0xd81f0000) /* jrc $31  */
              && inst != 0x00000000)    /* nop */
            return 0;
        }
@@ -7139,22 +7555,31 @@ mips32_instruction_has_delay_slot (struct gdbarch *gdbarch, ULONGEST inst)
   int op;
   int rs;
   int rt;
+  bool is_mipsr6 = is_mipsr6_isa (gdbarch);

   op = itype_op (inst);
   if ((inst & 0xe0000000) != 0)
     {
       rs = itype_rs (inst);
       rt = itype_rt (inst);
-      return (is_octeon_bbit_op (op, gdbarch)
-             || op >> 2 == 5   /* BEQL, BNEL, BLEZL, BGTZL: bits 0101xx  */
-             || op == 29       /* JALX: bits 011101  */
+      return (is_octeon_bbit_op (op, gdbarch)
+             || (op >> 1 == 10) /* BEQL, BNEL: bits 01010x  */
+             || (op >> 1 == 11 && rt == 0) /* BLEZL, BGTZL: bits 01011x  */
+             || (!is_mipsr6 && op == 29)       /* JALX: bits 011101  */
              || (op == 17
                  && (rs == 8
                                /* BC1F, BC1FL, BC1T, BC1TL: 010001 01000  */
-                     || (rs == 9 && (rt & 0x2) == 0)
+                     || (!is_mipsr6 && rs == 9 && (rt & 0x2) == 0)
                                /* BC1ANY2F, BC1ANY2T: bits 010001 01001  */
-                     || (rs == 10 && (rt & 0x2) == 0))));
+                     || (!is_mipsr6 && rs == 10 && (rt & 0x2) == 0)))
                                /* BC1ANY4F, BC1ANY4T: bits 010001 01010  */
+             || (is_mipsr6
+                 && ((op == 17
+                      && (rs == 9  /* BC1EQZ: 010001 01001  */
+                          || rs == 13))  /* BC1NEZ: 010001 01101  */
+                     || (op == 18
+                         && (rs == 9  /* BC2EQZ: 010010 01001  */
+                             || rs == 13)))));  /* BC2NEZ: 010010 01101  */
     }
   else
     switch (op & 0x07)         /* extract bits 28,27,26  */
@@ -7173,7 +7598,11 @@ mips32_instruction_has_delay_slot (struct gdbarch *gdbarch, ULONGEST inst)
                || ((rt & 0x1e) == 0x1c && rs == 0));
                                /* BPOSGE32, BPOSGE64: bits 1110x  */
        break;                  /* end REGIMM  */
-      default:                 /* J, JAL, BEQ, BNE, BLEZ, BGTZ  */
+       case 6:                 /* BLEZ  */
+       case 7:                 /* BGTZ  */
+        return (itype_rt (inst) == 0);
+        break;
+      default:                 /* J, JAL, BEQ, BNE  */
        return 1;
        break;
       }
@@ -7385,7 +7814,18 @@ mips_adjust_breakpoint_address (struct gdbarch *gdbarch, CORE_ADDR bpaddr)

      So, we'll use the second solution.  To do this we need to know if
      the instruction we're trying to set the breakpoint on is in the
-     branch delay slot.  */
+     branch delay slot.
+
+     A similar problem occurs for breakpoints on forbidden slots where
+     the trap will be reported for the branch with the BD bit set.
+     In this case it would be ideal to recover using solution 1 from
+     above as there is no problem with the branch being skipped
+     (since the forbidden slot only exists on not-taken branches).
+     However, the BD bit is not available in all scenarios currently
+     so instead we move the breakpoint on to the next instruction.
+     This means that it is not possible to stop on an instruction
+     that can be in a forbidden slot even if that instruction is
+     jumped to directly.  */

   boundary = mips_segment_boundary (bpaddr);

@@ -7407,6 +7847,12 @@ mips_adjust_breakpoint_address (struct gdbarch *gdbarch, CORE_ADDR bpaddr)
       prev_addr = bpaddr - 4;
       if (mips32_insn_at_pc_has_delay_slot (gdbarch, prev_addr))
        bpaddr = prev_addr;
+      /* If the previous instruction has a forbidden slot, we have to
+        move the breakpoint to the following instruction to prevent
+        breakpoints in forbidden slots being reported as unknown
+        traps.  */
+      else if (mips32_insn_at_pc_has_forbidden_slot (gdbarch, prev_addr))
+       bpaddr += 4;
     }
   else
     {
diff --git a/gdb/testsuite/gdb.arch/mips-64-r6.c b/gdb/testsuite/gdb.arch/mips-64-r6.c
new file mode 100644
index 00000000000..13f43ee24d0
--- /dev/null
+++ b/gdb/testsuite/gdb.arch/mips-64-r6.c
@@ -0,0 +1,918 @@
+/*
+   Copyright 2023-2024 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#define xstr(s) str(s)
+#define str(s) #s
+
+/* ============ macros from sim/testutils/mips/utils-r6.inc ============= */
+
+/* 58 is local label to exit with errcode != 0, indicating error.  */
+#define fp_assert(a, b) "beq " xstr (a) ", " xstr (b) ", 1f \n\t" \
+  "nop \n\t" \
+  "b 58f \n\t" \
+  "nop \n\t" \
+  "1: \n\t"
+
+/* Clobbers: $4,$6,$7.  */
+#define r6ck_1r(inst, a, ret) \
+  "li $4, " xstr (a) "    \n\t" \
+  "li $6, " xstr (ret) "  \n\t" \
+  xstr (inst) " $7, $4    \n\t" \
+  fp_assert ($6, $7)
+
+/* Clobbers: $4,$6,$7.  */
+#define r6ck_1dr(inst, a, ret) \
+  "ld $4, " xstr (a) "   \n\t" \
+  "ld $6, " xstr (ret) " \n\t" \
+  xstr (inst) " $7, $4   \n\t" \
+  fp_assert ($6, $7)
+
+/* Clobbers: $4,$5,$6,$7.  */
+#define r6ck_2r(inst, a, b, ret) \
+  "li $4, " xstr (a) "   \n\t" \
+  "li $5, " xstr (b) "   \n\t" \
+  "li $6, " xstr (ret) " \n\t" \
+  xstr (inst) " $7, $4, $5   \n\t" \
+  fp_assert ($6, $7)
+
+/* Clobbers: $4,$5,$6,$7.  */
+#define r6ck_2dr(inst, a, b, ret) \
+  "ld $4, " xstr (a) "    \n\t" \
+  "ld $5, " xstr (b) "    \n\t" \
+  "ld $6, " xstr (ret) "  \n\t" \
+  xstr (inst) " $7, $4, $5  \n\t" \
+  fp_assert ($6, $7)
+
+/* Clobbers: $4,$5,$6,$7.  */
+#define r6ck_2dr1i(inst, a, b, imm, ret) \
+  "ld $4, " xstr (a) "      \n\t" \
+  "ld $5, " xstr (b) "      \n\t" \
+  "ld $6, " xstr (ret) "    \n\t" \
+  xstr (inst) " $7, $4, $5, " xstr (imm) "  \n\t" \
+  fp_assert ($6, $7)
+
+/* Clobbers: $4,$6,$7.  */
+#define r6ck_1r1i(inst, a, imm, ret) \
+  "li $4, " xstr (a) "      \n\t" \
+  "li $6, " xstr (ret) "    \n\t" \
+  xstr (inst) " $7, $4, " xstr (imm) "  \n\t" \
+  fp_assert ($6, $7)
+
+/* Clobbers: $4,$6,$7.  */
+#define r6ck_1dr1i(inst, a, imm, ret) \
+  "ld $4, " xstr (a) "     \n\t" \
+  "ld $6, " xstr (ret) "   \n\t" \
+  xstr (inst) " $7, $4, " xstr (imm) "  \n\t" \
+  fp_assert ($6, $7)
+
+/* Clobbers: $4,$6.  */
+#define r6ck_0dr1i(inst, a, imm, ret) \
+  "ld $4, " xstr (a) "     \n\t" \
+  "ld $6, " xstr (ret) "   \n\t" \
+  xstr (inst) " $4, $4, " xstr (imm) "   \n\t" \
+  fp_assert ($6, $4)
+
+/* Clobbers: $4,$5,$6,$7.  */
+#define r6ck_2r1i(inst, a, b, imm, ret) \
+  "li $4, " xstr (a) "     \n\t" \
+  "li $5, " xstr (b) "     \n\t" \
+  "li $6, " xstr (ret) "   \n\t" \
+  xstr (inst) " $7, $4, $5, " xstr (imm) "   \n\t" \
+  fp_assert ($6, $7)
+
+/* Clobbers: $4,$5,$6,$7,$8,$f2,$f4,$f6.  */
+#define r6ck_3s(inst, a, b, c, ret) \
+  "li $4, " xstr (a) "     \n\t" \
+  "li $5, " xstr (b) "     \n\t" \
+  "li $6, " xstr (c) "     \n\t" \
+  "li $7, " xstr (ret) "   \n\t" \
+  "mtc1 $4, $f2           \n\t" \
+  "mtc1 $5, $f4           \n\t" \
+  "mtc1 $6, $f6           \n\t" \
+  xstr (inst) " $f2, $f4, $f6       \n\t" \
+  "mfc1 $8, $f2           \n\t" \
+  fp_assert ($7, $8)
+
+/* Clobbers: $4,$5,$6,$7,$f2,$f4.  */
+#define r6ck_2s(inst, a, b, ret) \
+  "li $4, " xstr (a) "       \n\t" \
+  "li $5, " xstr (b) "       \n\t" \
+  "li $6, " xstr (ret) "     \n\t" \
+  "mtc1 $4, $f2             \n\t" \
+  "mtc1 $5, $f4             \n\t" \
+  xstr (inst) " $f2, $f4     \n\t" \
+  "mfc1 $7, $f2             \n\t" \
+  fp_assert ($6, $7)
+
+/* Clobbers: $4,$5,$6,$7,$8,$9,$10,$f2,$f4.  */
+#define r6ck_2d(inst, a, b, ret) \
+  ".data                  \n\t" \
+  "1: .dword " xstr (a) "    \n\t" \
+  "2: .dword " xstr (b) "    \n\t" \
+  "3: .dword " xstr (ret) "  \n\t" \
+  ".text                   \n\t" \
+  "dla $4, 1b              \n\t" \
+  "dla $5, 2b              \n\t" \
+  "dla $6, 3b              \n\t" \
+  "ldc1 $f2, 0($4)        \n\t" \
+  "ldc1 $f4, 0($5)        \n\t" \
+  "lw $7, 0($6)           \n\t" \
+  "lw $8, 4($6)           \n\t" \
+  xstr (inst) " $f2, $f4   \n\t" \
+  "mfhc1 $9, $f2          \n\t" \
+  "mfc1 $10, $f2          \n\t" \
+  fp_assert ($7, $9) \
+  fp_assert ($8, $10)
+
+/* Clobbers: $2,$4,$5,$6,$7,$8,$9,$10,$f2,$f4,$f6.  */
+#define r6ck_3d(inst, a, b, c, ret) \
+  ".data                                \n\t" \
+  "1: .dword " xstr (a) "                  \n\t" \
+  "2: .dword " xstr (b) "                  \n\t" \
+  "3: .dword " xstr (c) "                  \n\t" \
+  "4: .dword " xstr (ret) "                \n\t" \
+  ".text                                \n\t" \
+  "dla $4, 1b                            \n\t" \
+  "dla $5, 2b                            \n\t" \
+  "dla $6, 3b                            \n\t" \
+  "dla $2, 4b                            \n\t" \
+  "ldc1 $f2, 0($4)                      \n\t" \
+  "ldc1 $f4, 0($5)                      \n\t" \
+  "ldc1 $f6, 0($6)                      \n\t" \
+  "lw $7, 0($2)                         \n\t" \
+  "lw $8, 4($2)                         \n\t" \
+  xstr (inst) " $f2, $f4, $f6            \n\t" \
+  "mfhc1 $9, $f2                        \n\t" \
+  "mfc1 $10, $f2                        \n\t" \
+  fp_assert ($7, $9) \
+  fp_assert ($8, $10)
+
+
+/* ============ macros from sim/testutils/mips/testutils.inc ============= */
+
+/* Put value 'val' into register 'reg'.
+   Clobbers: None.  */
+#define load32(reg, val) \
+  "li  " xstr (reg) ", " xstr (val) "     \n\t"
+
+/* Check whether two registers contain the same value.
+   Clobbers: None.  */
+#define checkreg(reg, expreg) \
+  ".set push         \n\t" \
+  ".set noat         \n\t" \
+  ".set noreorder    \n\t" \
+  "beq "  xstr (expreg) ", " xstr (reg) ", 901f    \n\t" \
+  "nop               \n\t" \
+  "b 58f              \n\t" \
+  "nop                \n\t" \
+  "901:                   \n\t" \
+  ".set pop           \n\t"
+
+/* Check if register 'reg' contains value 'val'.
+   Clobbers: $1.  */
+#define check32(reg, val) \
+  ".set push         \n\t" \
+  ".set noat         \n\t" \
+  load32 ($1, val) \
+  checkreg (reg, $1) \
+  ".set pop          \n\t"
+
+/* Checkpair based on endianess
+   Clobbers: $1.  */
+#define checkpair_xendian(lo, hi, base, ec, w) \
+  ".set noat               \n\t" \
+  "lw   $1, " xstr (ec) "   \n\t" \
+  "andi $1, $1, 0x1        \n\t" \
+  "beqz  $1, 2f            \n\t" \
+  ".set at                 \n\t" \
+  "1:                          \n\t" \
+  checkpair_be_##w (lo, hi, base) \
+  "b 3f                    \n\t" \
+  "nop                     \n\t" \
+  "2:                          \n\t" \
+  checkpair_le_##w (lo, hi, base) \
+  "3:                          \n\t"
+
+
+/* Check hi-lo register pair against data stored at base+o1 and base+o2.
+   Clobbers: $1 - $5.  */
+#define  checkpair(lo, hi, base, w, o1, o2) \
+  "move  $2, " xstr (lo) "   \n\t" \
+  "move  $3, " xstr (hi) "   \n\t" \
+  ".set noat                \n\t" \
+  "dla   $1, " xstr (base) "  \n\t" \
+  "l" xstr (w) " $4, " xstr (o1) "($1)  \n\t" \
+  "l" xstr (w)  " $5, " xstr (o2) "($1)  \n\t" \
+  ".set at                  \n\t" \
+  checkreg ($2, $4) \
+  checkreg ($3, $5)
+
+#define checkpair_le_d(lo, hi, base) \
+  checkpair (lo, hi, base, w, 0, 4)
+
+#define checkpair_be_d(lo, hi, base) \
+  checkpair (lo, hi, base, w, 4, 0)
+
+
+#define checkpair_le_q(lo, hi, base) \
+  checkpair (lo, hi, base, d, 0, 8)
+
+#define checkpair_be_q(lo, hi, base) \
+  checkpair (lo, hi, base, d, 8, 0)
+
+#define checkpair_qword(lo, hi, base, oe) \
+  checkpair_xendian (lo, hi, base, oe, q)
+
+#define checkpair_dword(lo, hi, base, oe) \
+  checkpair_xendian (lo, hi, base, oe, d)
+
+void
+abort (void);
+
+/* Tests branch instructions.  */
+
+int
+test_r6_branch (void)
+{
+/* Using volatile to prevent certain optimizations which could cause
+ * instruction deletion.
+ * 'err' identifies instruction which (eventually) caused error.
+ * (err == 0) ==> all instructions executed successfully.  */
+
+  volatile int err = -1;
+  volatile int a14 = 0xffffffff;
+  volatile int a13 = 0x123;
+  volatile int a12 = 0x45;
+  volatile int a7 = 0x45;
+  volatile int a8 = 0xfffffffe;
+  volatile int a9 = 2147483647;
+  volatile int a11 = 0;
+  volatile int a10 = 0;
+
+  asm (
+  ".set push             \n\t" /* Create new scope for asm configuration.  */
+  ".set noreorder        \n\t" /* Don't allow reordering of instructions.  */
+  "li %[err], 1                  \n\t"
+  "bovc %[a12], %[a13], Lfail    \n\t" /* BOVC */
+  "nop                           \n\t"
+  "bovc %[a9], %[a13], L2        \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L2:                           \n\t"
+  "li %[err], 2                  \n\t"
+  "bnvc %[a9], %[a13], Lfail     \n\t" /* BNVC */
+  "nop                           \n\t"
+  "bnvc %[a12], %[a13], L3       \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L3:                           \n\t"
+  "li %[err], 3                  \n\t"
+  "beqc %[a12], %[a13], Lfail    \n\t" /* BEQC */
+  "nop                           \n\t"
+  "beqc %[a12], %[a7], L4        \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L4:                           \n\t"
+  "li %[err], 4                  \n\t"
+  "bnec %[a12], %[a7], Lfail     \n\t" /* BNEC */
+  "nop                           \n\t"
+  "bnec %[a12], %[a13], L5       \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L5:                           \n\t"
+  "li %[err], 5                  \n\t"
+  "bltc %[a13], %[a12], Lfail    \n\t" /* BLTC */
+  "nop                           \n\t"
+  "bltc %[a12], %[a13], L6       \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L6:                           \n\t"
+  "L7:                           \n\t"
+  "li %[err], 7                  \n\t"
+  "bgec %[a12], %[a13], Lfail    \n\t" /* BGEC */
+  "nop                           \n\t"
+  "bgec %[a13], %[a12], L8       \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L8:                           \n\t"
+  "L9:                           \n\t"
+  "li %[err], 9                  \n\t"
+  "bltuc %[a14], %[a13], Lfail   \n\t" /* BLTUC */
+  "nop                           \n\t"
+  "bltuc %[a8], %[a14], L10      \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L10:                          \n\t"
+  "L11:                          \n\t"
+  "li %[err], 11                 \n\t"
+  "bgeuc %[a13], %[a14], Lfail   \n\t" /* BGEUC */
+  "nop                           \n\t"
+  "bgeuc %[a14], %[a8], L12      \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L12:                          \n\t"
+  "L13:                          \n\t"
+  "li %[err], 13                 \n\t"
+  "bltzc %[a13], Lfail           \n\t" /* BLTZC */
+  "nop                           \n\t"
+  "bltzc %[a11], Lfail           \n\t"
+  "nop                           \n\t"
+  "bltzc %[a14], L14             \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L14:                          \n\t"
+  "li %[err], 14                 \n\t"
+  "blezc %[a13], Lfail           \n\t" /* BLEZC */
+  "nop                           \n\t"
+  "blezc %[a11], L145            \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L145:                         \n\t"
+  "blezc %[a14], L15             \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L15:                          \n\t"
+  "li %[err], 15                 \n\t"
+  "bgezc %[a8], Lfail            \n\t" /* BGEZC */
+  "nop                           \n\t"
+  "bgezc %[a11], L155            \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L155:                         \n\t"
+  "bgezc %[a13], L16             \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L16:                          \n\t"
+  "li %[err], 16                 \n\t"
+  "bgtzc %[a8], Lfail            \n\t" /* BGTZC */
+  "nop                           \n\t"
+  "bgtzc %[a11], Lfail           \n\t"
+  "nop                           \n\t"
+  "bgtzc %[a13], L17             \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "li %[a10], 0                  \n\t"
+  "L17:                          \n\t"
+  "li %[err], 17                 \n\t"
+  "blezalc %[a12], Lfail         \n\t" /* BLEZALC */
+  "nop                           \n\t"
+  "blezalc %[a11], Lret          \n\t"
+  "li %[a10], 1                  \n\t"
+  "beqzc %[a10], L175            \n\t" /* BEQZC */
+  "nop                           \n\t"
+  "li %[err], 8531               \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L175:                         \n\t"
+  "li %[err], 23531              \n\t"
+  "blezalc %[a14], Lret          \n\t"
+  "li %[a10], 1                  \n\t"
+  "beqzc %[a10], L18             \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L18:                          \n\t"
+  "li %[err], 18                 \n\t"
+  "bgezalc %[a14], Lfail         \n\t" /* BGEZALC */
+  "nop                           \n\t"
+  "bgezalc %[a11], Lret          \n\t"
+  "li %[a10], 1                  \n\t"
+  "beqzc %[a10], L185            \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L185:                         \n\t"
+  "bgezalc %[a12], Lret          \n\t"
+  "li %[a10], 1                  \n\t"
+  "beqzc %[a10], L19             \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L19:                          \n\t"
+  "li %[err], 19                 \n\t"
+  "bgtzalc %[a14], Lfail         \n\t" /* BGTZALC */
+  "nop                           \n\t"
+  "bgtzalc %[a11], Lfail         \n\t"
+  "nop                           \n\t"
+  "bgtzalc %[a12], Lret          \n\t"
+  "li %[a10], 1                  \n\t"
+  "beqzc %[a10], L20             \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L20:                          \n\t"
+  "li %[err], 20                 \n\t"
+  "bltzalc %[a12], Lfail         \n\t" /* BLTZALC */
+  "nop                           \n\t"
+  "bltzalc %[a11], Lfail         \n\t"
+  "nop                           \n\t"
+  "bltzalc %[a14], Lret          \n\t"
+  "li %[a10], 1                  \n\t"
+  "beqzc %[a10], L21             \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L21:                          \n\t"
+  "li %[err], 21                 \n\t"
+  "bc L22                        \n\t" /* BC */
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L22:                          \n\t"
+  "li %[err], 22                 \n\t"
+  "balc Lret                     \n\t" /* BALC */
+  "li %[a10], 1                  \n\t"
+  "beqzc %[a10], L23             \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L23:                          \n\t"
+  "li %[err], 23                 \n\t"
+  "jal GetPC                     \n\t" /* JAL */
+  "nop                           \n\t"
+  "jic $6, 4                     \n\t" /* JIC */
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L24:                          \n\t"
+  "li %[err], 24                 \n\t"
+  "li %[a10], 1                  \n\t"
+  "jal GetPC                     \n\t"
+  "nop                           \n\t"
+  "jialc $6, 20                  \n\t" /* JIALC */
+  "nop                           \n\t"
+  "beqzc %[a10], L25             \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "LJIALCRET:                    \n\t"
+  "li %[a10], 0                  \n\t"
+  "jr $31                        \n\t" /* JR */
+  "nop                           \n\t"
+  "L25:                          \n\t"
+  "li %[err], 25                 \n\t"
+  "jal GetPC                     \n\t"
+  "nop                           \n\t"
+  "move %[a11], $6               \n\t"
+  "nal                           \n\t"
+  "nop                           \n\t"
+  "addiu %[a11], 12              \n\t" /* ADDIU */
+  "beqc %[a11], $31, L26         \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "L26:                          \n\t"
+  "li %[err], 26                 \n\t"
+  "balc Lret                     \n\t"
+  "li %[a10], 1                  \n\t"
+  "beqzc %[a10], Lend            \n\t"
+  "nop                           \n\t"
+  "b Lfail                       \n\t"
+  "nop                           \n\t"
+  "Lret:                         \n\t"
+  "li %[a10], 0                  \n\t"
+  "daddiu $31, 4                 \n\t" /* DADDIU */
+  "jrc $31                       \n\t" /* JRC */
+  "nop                           \n\t"
+  "GetPC:                        \n\t"
+  "move $6, $31                  \n\t"
+  "jr $31                        \n\t"
+  "Lend:                         \n\t"
+  "li %[err], 0                  \n\t"
+  "Lfail:                        \n\t"
+  ".set pop                      \n\t" /* Restore previous config */
+  : [err] "+r"(err), [a14] "+r"(a14), [a13] "+r"(a13), [a12] "+r"(a12),
+    [a7] "+r"(a7), [a8] "+r"(a8), [a9] "+r"(a9), [a10] "+r"(a10), [a11] "+r"(a11)
+  : /* inputs */
+  : "$31", "$6" /* clobbers */
+  );
+
+  return err;
+}
+
+/* Tests forbidden slot branching i.e. conditional compact branch
+   instructions.  */
+
+int
+test_r6_forbidden (void)
+{
+  volatile int err = -1;
+  volatile int a4 = 0;
+  volatile int a2 = 0;
+  volatile int a1 = 0;
+
+  asm (
+  ".set push                         \n\t"
+  ".set noreorder                    \n\t"
+/* Test if FS is ignored when branch is taken */
+  "li %[err], 1                      \n\t"
+  "li %[a4], 0                       \n\t"
+  "beqzalc %[a4], L41                \n\t"
+  "li %[err], -85                    \n\t"
+  "L42:                              \n\t"
+  "b Lfail2                          \n\t"
+  "nop                               \n\t"
+  "L41:                              \n\t"
+  "blez %[err], Lfail2               \n\t"
+/* Test if FS is used when branch is not taken */
+  "li %[err], 2                      \n\t"
+  "li %[a4], 1                       \n\t"
+  "blezc %[a4], L43                  \n\t"
+  "addiu %[a4], %[a4], 1             \n\t"
+  "li %[a2], 2                       \n\t"
+  "beq %[a4], %[a2], L44             \n\t"
+  "nop                               \n\t"
+  "L43:                              \n\t"
+  "nop                               \n\t"
+  "b Lfail2                          \n\t"
+  "nop                               \n\t"
+  "L44:                              \n\t"
+  "li %[err], 3                      \n\t"
+  "li %[a4], 3                       \n\t"
+  "beqzalc %[a4], Lfail2             \n\t"
+/* Note: 'bc L45' instead nop would cause SegFault: Illegal instruction:
+   Forbidden slot causes an error when it contains a branch.  */
+  "nop                               \n\t"
+  "b Lend2                           \n\t"
+  "nop                               \n\t"
+  "L45:                              \n\t"
+  "nop                               \n\t"
+  "b Lfail2                          \n\t"
+  "nop                               \n\t"
+  "Lend2:                            \n\t"
+  "li %[err], 0                      \n\t"
+  "Lfail2:                           \n\t"
+  "nop                               \n\t"
+  ".set pop                          \n\t"
+  : [err] "+r" (err), [a4] "+r"(a4), [a2] "+r"(a2), [a1] "+r"(a1) /* outputs */
+  : /* inputs */
+  : "$31" /* clobbers */
+  );
+
+  return err;
+}
+
+int
+test_r6_64 (void)
+{
+  volatile int err = 0;
+
+  asm (
+  ".set push                                   \n\t"
+  ".set noreorder                              \n\t"
+  ".data                                       \n\t"
+  "dval: .dword 0xaa55bb66cc77dd88             \n\t"
+  "d1:   .dword 0xaaaabbbbccccdddd             \n\t"
+  "d5:   .dword 0x00000000000000dd             \n\t"
+  "d7:   .dword 0xeeeeffff00001111             \n\t"
+  "d8:   .dword 0xbbccccddddeeeeff             \n\t"
+  "d9:   .dword 0x000000ddaaaabbbb             \n\t"
+  "dval1: .word 0x1234abcd                     \n\t"
+  "dval2: .word 0xffee0000                     \n\t"
+  "dval3: .dword 0xffffffffffffffff            \n\t"
+  "  .fill 240,1,0                             \n\t"
+  "dval4: .dword 0x5555555555555555            \n\t"
+  "  .fill  264,1,0                            \n\t"
+
+/* Register $11 stores instruction currently being tested and hence
+ * identifies error if it occurs.  */
+  ".text                                       \n\t"
+
+  "li $11, 1                                   \n\t" /* Test DALIGN */
+  r6ck_2dr1i (dalign, d7, d1, 3, d8)
+  r6ck_2dr1i (dalign, d1, d5, 4, d9)
+
+  "li $11, 2                                   \n\t" /* Test LDPC */
+  "ld $5, dval                                 \n\t"
+  "nop                                         \n\t"
+  "ldpc $4, dval                               \n\t"
+  fp_assert ($4, $5)
+
+  "li $11, 3                                   \n\t" /* Test LWUPC */
+  "lwu $5, dval1                               \n\t"
+  "lwupc $4, dval1                             \n\t"
+  fp_assert ($4, $5)
+  "lwu $5, dval2                               \n\t"
+  "lwupc $4, dval2                             \n\t"
+  fp_assert ($4, $5)
+
+  "li $11, 4                                   \n\t" /* Test LLD */
+  "ld $5, dval3                                \n\t"
+  "dla $3, dval4                               \n\t"
+  "lld $4, -248($3)                            \n\t"
+  fp_assert ($4, $5)
+
+  "li $11, 5                                   \n\t" /* Test SCD */
+  "lld $4, -248($3)                            \n\t"
+  "dli $4, 0xafaf                              \n\t"
+  "scd $4, -248($3)                            \n\t"
+  "ld $5, dval3                                \n\t"
+  "dli $4, 0xafaf                              \n\t"
+  fp_assert ($4, $5)
+
+  "Lend3:                                      \n\t"
+  "li $11, 0                                   \n\t"
+  "58:                                         \n\t"
+  "move %[err], $11                            \n\t"
+  ".set pop                                    \n\t"
+   : [err] "+r" (err) /* outputs */
+   :                  /* inputs */
+   : "$3", "$4", "$5", "$6", "$7", "$11" /* clobbers */
+  );
+
+  return err;
+}
+
+int
+test_r6 (void)
+{
+  volatile int err = 0;
+
+  asm (
+  ".set push                                                   \n\t"
+  ".set noreorder                                              \n\t"
+  ".data                                                       \n\t"
+  "dval_1:  .word 0xabcd1234                                   \n\t"
+  "dval_2: .word 0x1234eeff                                    \n\t"
+  ".fill 248,1,0                                               \n\t"
+  "dval_3: .word 0x55555555                                    \n\t"
+  ".fill  260,1,0                                              \n\t"
+  "dval_4: .word 0xaaaaaaaa                                    \n\t"
+  ".text                                                       \n\t"
+  "li $11, 1            \n\t" /* ADDIUPC */
+  "jal GetPC_2                                               \n\t"
+  "nop                                                       \n\t"
+  "addiu $4, $6, 8                                           \n\t"
+  "addiupc $5, 4                                             \n\t"
+  fp_assert ($4, $5)
+
+  "li $11, 2            \n\t" /* AUIPC */
+  "jal GetPC_2                                               \n\t"
+  "nop                                                       \n\t"
+  "addiu $4, $6, 8                                           \n\t"
+  "aui $4, $4, 8                                             \n\t"
+  "auipc $5, 8                                               \n\t"
+  fp_assert ($4, $5)
+
+  "li $11, 3            \n\t" /* ALUIPC */
+  "jal GetPC_2                                               \n\t"
+  "nop                                                       \n\t"
+  "addiu $4, $6, 16                                          \n\t"
+  "aui $4, $4, 8                                             \n\t"
+  "li $7, 0xffff0000                                         \n\t"
+  "and $4, $4, $7                                            \n\t"
+  "aluipc $5, 8                                              \n\t"
+  fp_assert ($4, $5)
+
+  "li $11, 4            \n\t" /* LWPC */
+  "lw $5, dval_1                                             \n\t"
+  "lwpc $4, dval_1                                           \n\t"
+  fp_assert ($4, $5)
+  "lw $5, dval_2                                             \n\t"
+  "lwpc $4, dval_2                                           \n\t"
+  fp_assert ($4, $5)
+
+/* Testing LL follows.
+ * NOTE: May be redundant because SC already contains LL in its test.  */
+  "li $11, 5                                                \n\t"
+  "lw $5, dval_2                                             \n\t"
+  "dla $3, dval_3                                            \n\t"
+  "ll $4, -252($3)                                           \n\t"
+  fp_assert ($4, $5)
+
+  "li $11, 6        \n\t"    /* LL-SC sequence */
+  "ll $4, -252($3)                                           \n\t"
+  "li $4, 0xafaf                                             \n\t"
+  "sc $4, -252($3)                                           \n\t"
+  "lw $5, dval_2                                             \n\t"
+  "li $4, 0xafaf                                             \n\t"
+  fp_assert ($4, $5)
+  "b Lend4                                                   \n\t"
+  "nop                                                       \n\t"
+  "GetPC_2:                                                  \n\t"
+  "move $6, $31                                              \n\t"
+  "jr $31                                                    \n\t"
+  "Lend4:                                                    \n\t"
+  "li $11, 0                                                 \n\t"
+  "58:                                                       \n\t"
+  "move %[err], $11                                          \n\t"
+  ".set pop                                                  \n\t"
+  : [err] "+r"(err)  /* outputs */
+  : /* inputs */
+  : "$3", "$4", "$5", "$6", "$7", "$8", "$9", "$10",
+    "$11", "$31" /* clobbers */
+  );
+
+  return err;
+}
+
+/* For fpu-branching testing, bc1eq/eqz are enough.  */
+
+int
+test_r6_fpu (void)
+{
+  volatile int err = 0;
+
+  asm (
+  ".set push                               \n\t"
+  ".set noreorder                          \n\t"
+/* Test qNaN format is 754-2008 */
+  "li $11, 1                               \n\t"
+  "li $4, 0x0                              \n\t"
+  "li $5, 0x0                              \n\t"
+  "li $6, 0x7fc00000                       \n\t"
+  "mtc1 $4, $f2                            \n\t"
+  "mtc1 $5, $f4                            \n\t"
+  "div.s $f6, $f2, $f4                     \n\t"
+  "mfc1 $8, $f6                            \n\t"
+  fp_assert ($6, $8)
+
+  "li $11, 2                                \n\t"  /* bc1eqz */
+  "li $10, 0x01                             \n\t"
+  "mtc1 $10, $f2                            \n\t"
+  "mtc1 $0, $f4                             \n\t"
+  "bc1eqz $f2, 58f                          \n\t"
+  "nop                                      \n\t"
+  "bc1eqz $f4, L62                          \n\t"
+  "nop                                      \n\t"
+  "b 58f                                    \n\t"
+  "nop                                      \n\t"
+"L62:                                       \n\t"
+  "li $11, 3                                \n\t"  /* bc1nez */
+  "bc1nez $f4, 58f                          \n\t"
+  "nop                                      \n\t"
+  "bc1nez $f2, Lend8                        \n\t"
+  "nop                                      \n\t"
+  "b 58f                                    \n\t"
+  "nop                                      \n\t"
+"Lend8:                                     \n\t"
+  "li $11, 0                                \n\t"
+  "58:                                      \n\t"
+  "move %[err], $11                         \n\t"
+  ".set pop                                 \n\t"
+  : [err] "+r"(err)  /* outputs */
+  :                  /* inputs */
+  : "$4", "$5", "$6", "$8", "$10", "$11", "$31",
+    "$f2", "$f4", "$f6" /* clobbers */
+  );
+
+  return err;
+}
+
+/* R6 specific tests for mips64 (64-bit).  */
+
+int
+test_r6_llsc_dp (void)
+{
+  volatile int err = 0;
+
+  asm (
+  ".set push                                            \n\t"
+  ".set noreorder                                       \n\t"
+  ".data                                                \n\t"
+  ".align 16                                            \n\t"
+  "test_data:                                           \n\t"
+  ".word 0xaaaaaaaa                                     \n\t"
+  ".word 0xbbbbbbbb                                     \n\t"
+  ".word 0xcccccccc                                     \n\t"
+  ".word 0xdddddddd                                     \n\t"
+  ".align 16                                            \n\t"
+  "end_check:                                           \n\t"
+  ".byte 0                                              \n\t"
+  ".byte 0                                              \n\t"
+  ".byte 0                                              \n\t"
+  ".byte 0x1                                            \n\t"
+  ".text                                                \n\t"
+  "li $11, 1                                            \n\t" /* LLWP */
+  "llwp $2, $3, test_data                               \n\t"
+  checkpair_dword ($2, $3, test_data, end_check)
+  "sll $2, $2, 1                                        \n\t"
+  "srl $3, $3, 1                                        \n\t"
+  "move  $s0, $2                                        \n\t"
+  "scwp $2, $3, test_data                               \n\t"
+  check32 ($2, 1)
+  checkpair_dword ($s0, $3, test_data, end_check)
+  /* Test SCWP, done */
+  "li $11, 2                                            \n\t"
+  "li $11, 3                                            \n\t" /* LLDP */
+  "lldp $2, $3, test_data                               \n\t"
+  checkpair_qword ($2, $3, test_data, end_check)
+  "dsll $2, $2, 1                                       \n\t"
+  "dsrl $3, $3, 1                                       \n\t"
+  "move $s0, $2                                         \n\t"
+  "scdp $2, $3, test_data                               \n\t"
+  check32 ($2, 1)
+  checkpair_qword ($s0, $3, test_data, end_check)
+  "li $11, 4                                            \n\t" /* SCDP done */
+  "Lend5:                                               \n\t"
+  "li $11, 0                                            \n\t"
+  "58:                                                  \n\t"
+  "move %[err], $11                                     \n\t"
+  ".set pop                                             \n\t"
+  : [err] "+r"(err) /* outputs */
+  : /* inputs */
+  : "$2", "$3", "$4", "$5", "$6", "$7", "$8", "$9", "$10", "$11",
+    "$31", "$s0"  /* clobbers */
+  );
+
+  return err;
+}
+
+/* R6 specific tests for mips32 (32-bit).  */
+
+int
+test_r6_llsc_wp (void)
+{
+  volatile int err = 0;
+
+  asm (
+  ".set push                                            \n\t"
+  ".set noreorder                                       \n\t"
+  ".data                                                \n\t"
+  ".align 8                                             \n\t"
+  "test_data_2:                                         \n\t"
+  ".word 0xaaaaaaaa                                     \n\t"
+  ".word 0xbbbbbbbb                                     \n\t"
+  ".align 8                                             \n\t"
+  "end_check_2:                                         \n\t"
+  ".byte 0                                              \n\t"
+  ".byte 0                                              \n\t"
+  ".byte 0                                              \n\t"
+  ".byte 0x1                                            \n\t"
+  ".text                                                \n\t"
+  "li $11, 1                                            \n\t" /* Test LLWP */
+  "llwp $2, $3, test_data_2                             \n\t"
+  checkpair_dword ($2, $3, test_data_2, end_check_2)
+  "sll $2, $2, 1                                        \n\t"
+  "srl $3, $3, 1                                        \n\t"
+  "move  $s0, $2                                        \n\t"
+  "scwp $2, $3, test_data_2                             \n\t"
+  check32 ($2, 1)
+  checkpair_dword ($s0, $3, test_data_2, end_check_2)
+/* Test SCWP, done.  */
+  "li $11, 2                                            \n\t"
+  "Lend6:                                               \n\t"
+  "li $11, 0                                            \n\t"
+  "58:                                                  \n\t"
+  "move %[err], $11                                     \n\t"
+  ".set pop                                             \n\t"
+  : [err] "+r"(err) /* outputs */
+  : /* inputs */
+  : "$2", "$3", "$4", "$5", "$6", "$7", "$8", "$9", "$10",
+    "$11", "$31", "$s0"  /* clobbers */
+  );
+
+  return err;
+}
+
+/* Any test_r6_* function returns non-zero => failure.  */
+#define EXPECT(X) if ((X)) abort ();
+
+int
+main (void)
+{
+  EXPECT (test_r6_branch ());
+
+  EXPECT (test_r6_forbidden ());
+
+  EXPECT (test_r6_64 ());
+
+  EXPECT (test_r6 ());
+
+  EXPECT (test_r6_fpu ());
+
+  EXPECT (test_r6_llsc_dp ());
+
+  EXPECT (test_r6_llsc_wp ());
+
+  return 0;
+}
diff --git a/gdb/testsuite/gdb.arch/mips-64-r6.exp b/gdb/testsuite/gdb.arch/mips-64-r6.exp
new file mode 100644
index 00000000000..2cce6abc6fa
--- /dev/null
+++ b/gdb/testsuite/gdb.arch/mips-64-r6.exp
@@ -0,0 +1,76 @@
+# Copyright (C) 2023-2024 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, see <http://www.gnu.org/licenses/>.
+
+################################################################
+################## MIPS Release 6 patch tests ##################
+################################################################
+
+# Send 'si' to gdb until inferior exits.
+proc stepi {} {
+    global gdb_prompt
+    set timeout [get_largest_timeout]
+    set start [timestamp]
+    while { [timestamp] - $start < 3*$timeout } {
+       gdb_test_multiple "stepi" ""  {
+           -re ".*exited normally.*" {
+               pass "success"
+               return
+           }
+           -re ".*The program is not being run.*" {
+               fail "failure"
+               return
+           }
+           -re ".*Breakpoint.*test_.*$gdb_prompt $" {
+           }
+           -re "$gdb_prompt.*" {
+           }
+       }
+    }
+    fail "test failed"
+    return
+}
+
+require {istarget "*mips*"}
+
+set testfile "mips-64-r6"
+set srcfile ${testfile}.c
+set binfile ${objdir}/${subdir}/${testfile}
+
+if {[prepare_for_testing "failed to prepare" "${binfile}" "${srcfile}" {debug nowarnings}]} {
+    untested "failed to prepare"
+    return
+}
+
+# Native needs run.
+if { ![runto_main] } {
+    untested "couldn't run to main"
+    return
+}
+
+set tests ""
+foreach n [list "r6_branch" "r6_forbidden" "r6_64" "r6" "r6_fpu" "r6_llsc_dp" "r6_llsc_wp"] {
+    lappend tests "test_$n"
+}
+
+# Put breakpoint on each test-function
+foreach func $tests {
+    if {![gdb_breakpoint "$func"]} {
+       untested "couldn't put breakpoint to $func"
+       return
+    }
+}
+
+# Step through the binary
+stepi
--
2.40.1


^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: [PATCH^5] gdb: mips: Add MIPSR6 support
  2024-05-15 20:19 [PATCH^5] gdb: mips: Add MIPSR6 support Milos Kalicanin
  2024-06-24 14:24 ` Milos Kalicanin
@ 2024-06-24 22:40 ` Maciej W. Rozycki
  1 sibling, 0 replies; 3+ messages in thread
From: Maciej W. Rozycki @ 2024-06-24 22:40 UTC (permalink / raw)
  To: Milos Kalicanin
  Cc: gdb-patches, Djordje Todorovic, Dragan Mladjenovic,
	Andrew Burgess, Simon Marchi, Chao-ying Fu

On Wed, 15 May 2024, Milos Kalicanin wrote:

> Introduce new instruction encodings from Release 6 of the MIPS
> architecture [1]. Support breakpoints and single stepping with
> compact branches, forbidden slots, new branch instruction and
> new atomic load-store instruction encodings.

 Sadly due to other commitments I cannot promise to get at reviewing the 
change in detail in any foreseeable timeframe, however would you please 
clarify whether the change has been verified anyhow (and if so, then how) 
not to break existing MIPS targets (i.e. pre-R6 ones)?

  Maciej

^ permalink raw reply	[flat|nested] 3+ messages in thread

end of thread, other threads:[~2024-06-24 22:40 UTC | newest]

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2024-05-15 20:19 [PATCH^5] gdb: mips: Add MIPSR6 support Milos Kalicanin
2024-06-24 14:24 ` Milos Kalicanin
2024-06-24 22:40 ` Maciej W. Rozycki

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