Re: [RFC][V2] RISC-V: Support -mcmodel=large.

[KuanLin Chen <best124612@gmail.com>]

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Hi Jeff,

Sorry for this missing.
I've removed riscv_asm_output_pool_epilogue because the pool beginning is
always aligned from FUNCTION_BOUNDARY.
Please find attached. Thank you.

Jeff Law <jeffreyalaw@gmail.com> 於 2023年12月18日 週一 上午3:15寫道：

>
>
> On 11/10/23 02:10, KuanLin Chen wrote:
> > Sorry. It missed a semicolon in the previos patch. Please find the new
> > one in the attachment. Thanks.
> Thanks.  I was going to do some final testing with the plan to integrate
> this patch today, but I think there's a piece missing.  Specifically I
> think it's missing a definition for riscv_asm_output_pool_epilogue.
>
> Can you please send an updated patch that includes that function?
>
> Thanks,
> Jeff
>

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From d4ddb60c48a80bd67032df97b3dbfe862641b456 Mon Sep 17 00:00:00 2001
From: Kuan-Lin Chen <rufus@andestech.com>
Date: Sun, 18 Feb 2018 20:19:49 +0800
Subject: [PATCH] RISC-V: Support -mcmodel=large.

---
 gcc/config/riscv/predicates.md               | 23 +++++-
 gcc/config/riscv/riscv-c.cc                  |  4 +
 gcc/config/riscv/riscv-opts.h                |  1 +
 gcc/config/riscv/riscv-protos.h              |  1 +
 gcc/config/riscv/riscv.cc                    | 86 +++++++++++++++++++-
 gcc/config/riscv/riscv.md                    |  9 ++
 gcc/config/riscv/riscv.opt                   |  3 +
 gcc/testsuite/gcc.target/riscv/large-model.c | 11 +++
 8 files changed, 131 insertions(+), 7 deletions(-)
 create mode 100644 gcc/testsuite/gcc.target/riscv/large-model.c

diff --git a/gcc/config/riscv/predicates.md b/gcc/config/riscv/predicates.md
index ff213e5f8a3..8af3027cdaf 100644
--- a/gcc/config/riscv/predicates.md
+++ b/gcc/config/riscv/predicates.md
@@ -289,7 +289,8 @@
     case SYMBOL_REF:
     case LABEL_REF:
       return riscv_symbolic_constant_p (op, &symbol_type)
-	      && !riscv_split_symbol_type (symbol_type);
+	     && !riscv_split_symbol_type (symbol_type)
+	     && symbol_type != SYMBOL_FORCE_TO_MEM;
 
     case HIGH:
       op = XEXP (op, 0);
@@ -326,9 +327,15 @@
 })
 
 (define_predicate "call_insn_operand"
-  (ior (match_operand 0 "absolute_symbolic_operand")
-       (match_operand 0 "plt_symbolic_operand")
-       (match_operand 0 "register_operand")))
+  (match_operand 0 "general_operand")
+{
+  if (riscv_cmodel == CM_LARGE)
+    return register_operand (op, mode);
+  else
+    return (absolute_symbolic_operand (op, mode)
+	    || plt_symbolic_operand (op, mode)
+	    || register_operand (op, mode));
+})
 
 (define_predicate "modular_operator"
   (match_code "plus,minus,mult,ashift"))
@@ -611,3 +618,11 @@
   (and (match_code "const_int")
        (ior (match_operand 0 "not_uimm_extra_bit_operand")
 	    (match_operand 0 "const_nottwobits_not_arith_operand"))))
+
+(define_predicate "pcrel_symbol_operand"
+  (match_code "symbol_ref")
+{
+  enum riscv_symbol_type type;
+  return (riscv_symbolic_constant_p (op, &type)
+         && type == SYMBOL_PCREL);
+})
diff --git a/gcc/config/riscv/riscv-c.cc b/gcc/config/riscv/riscv-c.cc
index dd1bd0596fc..08fe56cce59 100644
--- a/gcc/config/riscv/riscv-c.cc
+++ b/gcc/config/riscv/riscv-c.cc
@@ -101,6 +101,10 @@ riscv_cpu_cpp_builtins (cpp_reader *pfile)
       builtin_define ("__riscv_cmodel_medlow");
       break;
 
+    case CM_LARGE:
+      builtin_define ("__riscv_cmodel_large");
+      break;
+
     case CM_PIC:
     case CM_MEDANY:
       builtin_define ("__riscv_cmodel_medany");
diff --git a/gcc/config/riscv/riscv-opts.h b/gcc/config/riscv/riscv-opts.h
index 0b242f068e1..0db9b363a43 100644
--- a/gcc/config/riscv/riscv-opts.h
+++ b/gcc/config/riscv/riscv-opts.h
@@ -35,6 +35,7 @@ extern enum riscv_abi_type riscv_abi;
 enum riscv_code_model {
   CM_MEDLOW,
   CM_MEDANY,
+  CM_LARGE,
   CM_PIC
 };
 extern enum riscv_code_model riscv_cmodel;
diff --git a/gcc/config/riscv/riscv-protos.h b/gcc/config/riscv/riscv-protos.h
index 52097fe48cf..5d3f83685e6 100644
--- a/gcc/config/riscv/riscv-protos.h
+++ b/gcc/config/riscv/riscv-protos.h
@@ -28,6 +28,7 @@ along with GCC; see the file COPYING3.  If not see
    the unspec enum in riscv.md, subsequent to UNSPEC_ADDRESS_FIRST.  */
 enum riscv_symbol_type {
   SYMBOL_ABSOLUTE,
+  SYMBOL_FORCE_TO_MEM,
   SYMBOL_PCREL,
   SYMBOL_GOT_DISP,
   SYMBOL_TLS,
diff --git a/gcc/config/riscv/riscv.cc b/gcc/config/riscv/riscv.cc
index d0efb939bf2..acbe4424a4f 100644
--- a/gcc/config/riscv/riscv.cc
+++ b/gcc/config/riscv/riscv.cc
@@ -295,6 +295,9 @@ bool riscv_user_wants_strict_align;
 /* Stack alignment to assume/maintain.  */
 unsigned riscv_stack_boundary;
 
+/* Whether in riscv_output_mi_thunk. */
+static bool riscv_in_thunk_func = false;
+
 /* If non-zero, this is an offset to be added to SP to redefine the CFA
    when restoring the FP register from the stack.  Only valid when generating
    the epilogue.  */
@@ -832,7 +835,17 @@ riscv_classify_symbol (const_rtx x)
   if (GET_CODE (x) == SYMBOL_REF && flag_pic && !riscv_symbol_binds_local_p (x))
     return SYMBOL_GOT_DISP;
 
-  return riscv_cmodel == CM_MEDLOW ? SYMBOL_ABSOLUTE : SYMBOL_PCREL;
+  switch (riscv_cmodel)
+    {
+    case CM_MEDLOW:
+      return SYMBOL_ABSOLUTE;
+    case CM_LARGE:
+      if (SYMBOL_REF_P (x))
+	return CONSTANT_POOL_ADDRESS_P (x) ? SYMBOL_PCREL : SYMBOL_FORCE_TO_MEM;
+      return SYMBOL_PCREL;
+    default:
+      return SYMBOL_PCREL;
+    }
 }
 
 /* Classify the base of symbolic expression X.  */
@@ -896,6 +909,7 @@ static int riscv_symbol_insns (enum riscv_symbol_type type)
     case SYMBOL_PCREL: return 2; /* AUIPC + the reference.  */
     case SYMBOL_TLS_LE: return 3; /* LUI + ADD TP + the reference.  */
     case SYMBOL_GOT_DISP: return 3; /* AUIPC + LD GOT + the reference.  */
+    case SYMBOL_FORCE_TO_MEM: return 3; /* AUIPC + LD + the reference.  */
     default: gcc_unreachable ();
     }
 }
@@ -1065,6 +1079,9 @@ riscv_cannot_force_const_mem (machine_mode mode ATTRIBUTE_UNUSED, rtx x)
   split_const (x, &base, &offset);
   if (riscv_symbolic_constant_p (base, &type))
     {
+      if (type == SYMBOL_FORCE_TO_MEM)
+	return false;
+
       /* As an optimization, don't spill symbolic constants that are as
 	 cheap to rematerialize as to access in the constant pool.  */
       if (SMALL_OPERAND (INTVAL (offset)) && riscv_symbol_insns (type) > 0)
@@ -1892,6 +1909,9 @@ riscv_split_symbol (rtx temp, rtx addr, machine_mode mode, rtx *low_out)
   if (low_out)
     switch (symbol_type)
       {
+      case SYMBOL_FORCE_TO_MEM:
+	return false;
+
       case SYMBOL_ABSOLUTE:
 	{
 	  rtx high = gen_rtx_HIGH (Pmode, copy_rtx (addr));
@@ -2049,7 +2069,20 @@ static rtx
 riscv_force_address (rtx x, machine_mode mode)
 {
   if (!riscv_legitimate_address_p (mode, x, false))
-    x = force_reg (Pmode, x);
+    {
+      if (can_create_pseudo_p ())
+	return force_reg (Pmode, x);
+      else
+	{
+	  /* It's only safe for the thunk function.
+	     Use ra as the temp regiater.  */
+	  gcc_assert (riscv_in_thunk_func);
+	  rtx reg = RISCV_PROLOGUE_TEMP2 (Pmode);
+	  riscv_emit_move (reg, x);
+	  return reg;
+	}
+    }
+
   return x;
 }
 
@@ -5868,6 +5901,12 @@ riscv_size_ok_for_small_data_p (int size)
 static bool
 riscv_in_small_data_p (const_tree x)
 {
+  /* Because default_use_anchors_for_symbol_p doesn't gather small data to use
+     the anchor symbol to address nearby objects.  In large model, it can get
+     the better result using the anchor optiomization.  */
+  if (riscv_cmodel == CM_LARGE)
+    return false;
+
   if (TREE_CODE (x) == STRING_CST || TREE_CODE (x) == FUNCTION_DECL)
     return false;
 
@@ -5933,12 +5972,32 @@ riscv_unique_section (tree decl, int reloc)
   default_unique_section (decl, reloc);
 }
 
+/* Constant pools are per-function when in large code model.  */
+
+static inline bool
+riscv_can_use_per_function_literal_pools_p (void)
+{
+  return riscv_cmodel == CM_LARGE;
+}
+
+static bool
+riscv_use_blocks_for_constant_p (machine_mode, const_rtx)
+{
+  /* We can't use blocks for constants when we're using a per-function
+     constant pool.  */
+  return !riscv_can_use_per_function_literal_pools_p ();
+}
+
 /* Return a section for X, handling small data. */
 
 static section *
 riscv_elf_select_rtx_section (machine_mode mode, rtx x,
 			      unsigned HOST_WIDE_INT align)
 {
+  /* The literal pool stays with the function.  */
+  if (riscv_can_use_per_function_literal_pools_p ())
+    return function_section (current_function_decl);
+
   section *s = default_elf_select_rtx_section (mode, x, align);
 
   if (riscv_size_ok_for_small_data_p (GET_MODE_SIZE (mode).to_constant ()))
@@ -8442,6 +8501,8 @@ riscv_output_mi_thunk (FILE *file, tree thunk_fndecl ATTRIBUTE_UNUSED,
   rtx this_rtx, temp1, temp2, fnaddr;
   rtx_insn *insn;
 
+  riscv_in_thunk_func = true;
+
   /* Pretend to be a post-reload pass while generating rtl.  */
   reload_completed = 1;
 
@@ -8508,6 +8569,7 @@ riscv_output_mi_thunk (FILE *file, tree thunk_fndecl ATTRIBUTE_UNUSED,
   /* Clean up the vars set above.  Note that final_end_function resets
      the global pointer for us.  */
   reload_completed = 0;
+  riscv_in_thunk_func = false;
 }
 
 /* Allocate a chunk of memory for per-function machine-dependent data.  */
@@ -8650,6 +8712,18 @@ riscv_option_override (void)
   if (flag_pic)
     g_switch_value = 0;
 
+  /* Always prefer medlow than medany for RV32 since medlow can access
+     full address space. */
+  if (riscv_cmodel == CM_LARGE && !TARGET_64BIT)
+    riscv_cmodel = CM_MEDLOW;
+
+  if (riscv_cmodel == CM_LARGE && TARGET_EXPLICIT_RELOCS)
+    sorry ("code model %qs with %qs", "large", "-mexplicit-relocs");
+
+  if (riscv_cmodel == CM_LARGE && flag_pic)
+    sorry ("code model %qs with %qs", "large",
+	   global_options.x_flag_pic > 1 ? "-fPIC" : "-fpic");
+
   if (flag_pic)
     riscv_cmodel = CM_PIC;
 
@@ -9017,6 +9091,12 @@ riscv_function_ok_for_sibcall (tree decl ATTRIBUTE_UNUSED,
   if (cfun->machine->interrupt_handler_p)
     return false;
 
+  /* Don't use sibcalls in the large model, because a sibcall instruction
+     expanding and a epilogue expanding both use RISCV_PROLOGUE_TEMP
+     register.  */
+  if (riscv_cmodel == CM_LARGE)
+    return false;
+
   return true;
 }
 
@@ -10411,7 +10491,7 @@ extract_base_offset_in_addr (rtx mem, rtx *base, rtx *offset)
 #define TARGET_LEGITIMATE_CONSTANT_P riscv_legitimate_constant_p
 
 #undef TARGET_USE_BLOCKS_FOR_CONSTANT_P
-#define TARGET_USE_BLOCKS_FOR_CONSTANT_P hook_bool_mode_const_rtx_true
+#define TARGET_USE_BLOCKS_FOR_CONSTANT_P riscv_use_blocks_for_constant_p
 
 #undef TARGET_LEGITIMATE_ADDRESS_P
 #define TARGET_LEGITIMATE_ADDRESS_P	riscv_legitimate_address_p
diff --git a/gcc/config/riscv/riscv.md b/gcc/config/riscv/riscv.md
index 935eeb7fd8e..c9a3c7ae078 100644
--- a/gcc/config/riscv/riscv.md
+++ b/gcc/config/riscv/riscv.md
@@ -41,6 +41,7 @@
   ;; Symbolic accesses.  The order of this list must match that of
   ;; enum riscv_symbol_type in riscv-protos.h.
   UNSPEC_ADDRESS_FIRST
+  UNSPEC_FORCE_FOR_MEM
   UNSPEC_PCREL
   UNSPEC_LOAD_GOT
   UNSPEC_TLS
@@ -3735,6 +3736,14 @@
     FAIL;
 })
 
+(define_insn "*large_load_address"
+  [(set (match_operand:DI 0 "register_operand" "=r")
+        (mem:DI (match_operand 1 "pcrel_symbol_operand" "")))]
+  "TARGET_64BIT && riscv_cmodel == CM_LARGE"
+  "ld\t%0,%1"
+  [(set_attr "type" "load")
+   (set (attr "length") (const_int 8))])
+
 (include "bitmanip.md")
 (include "crypto.md")
 (include "sync.md")
diff --git a/gcc/config/riscv/riscv.opt b/gcc/config/riscv/riscv.opt
index 11526f9cc2a..85b5408bf32 100644
--- a/gcc/config/riscv/riscv.opt
+++ b/gcc/config/riscv/riscv.opt
@@ -123,6 +123,9 @@ Enum(code_model) String(medlow) Value(CM_MEDLOW)
 EnumValue
 Enum(code_model) String(medany) Value(CM_MEDANY)
 
+EnumValue
+Enum(code_model) String(large) Value(CM_LARGE)
+
 mexplicit-relocs
 Target Mask(EXPLICIT_RELOCS)
 Use %reloc() operators, rather than assembly macros, to load addresses.
diff --git a/gcc/testsuite/gcc.target/riscv/large-model.c b/gcc/testsuite/gcc.target/riscv/large-model.c
new file mode 100644
index 00000000000..244d14e1878
--- /dev/null
+++ b/gcc/testsuite/gcc.target/riscv/large-model.c
@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+/* { dg-options "-march=rv64gc -mabi=lp64 -fno-section-anchors -mcmodel=large" } */
+/* { dg-skip-if "" { *-*-* } {"-O0"} } */
+int a, b;
+int foo1()
+{
+  return a*b;
+}
+
+/* { dg-final { scan-assembler-times "ld.*LC0" 1 } } */
+/* { dg-final { scan-assembler-times "ld.*LC1" 1 } } */
-- 
2.30.1