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* [gcc r14-227] riscv: relax splitter restrictions for creating pseudos
@ 2023-04-25 17:09 Vineet Gupta
  0 siblings, 0 replies; only message in thread
From: Vineet Gupta @ 2023-04-25 17:09 UTC (permalink / raw)
  To: gcc-cvs

https://gcc.gnu.org/g:0530254413f8d356805442f659c6d2921739284d

commit r14-227-g0530254413f8d356805442f659c6d2921739284d
Author: Vineet Gupta <vineetg@rivosinc.com>
Date:   Tue Apr 11 14:05:29 2023 -0700

    riscv: relax splitter restrictions for creating pseudos
    
    [partial addressing of PR/109279]
    
    RISCV splitters have restrictions to not create pesudos due to a combine
    limitatation. And despite this being a split-during-combine limitation,
    all split passes take the hit due to way define*_split are used in gcc.
    
    With the original combine issue being fixed 61bee6aed2 ("combine: Don't
    record for UNDO_MODE pointers into regno_reg_rtx array [PR104985]")
    the RV splitters can now be relaxed.
    
    This improves the codegen in general. e.g.
    
            long long f(void) { return 0x0101010101010101ull; }
    
    Before
    
            li      a0,0x01010000
            addi    a0,0x0101
            slli    a0,a0,16
            addi    a0,a0,0x0101
            slli    a0,a0,16
            addi    a0,a0,0x0101
            ret
    
    With patch
    
            li      a5,0x01010000
            addi    a5,a5,0x0101
            mv      a0,a5
            slli    a5,a5,32
            add     a0,a5,a0
            ret
    
    This reduces the qemu icounts, even if slightly, across SPEC2017.
    
    500.perlbench_r 0       1235310737733   1231742384460   0.29%
                    1       744489708820    743515759958
                    2       714072106766    712875768625    0.17%
    502.gcc_r       0       197365353269    197178223030
                    1       235614445254    235465240341
                    2       226769189971    226604663947
                    3       188315686133    188123584015
                    4       289372107644    289187945424
    503.bwaves_r    0       326291538768    326291539697
                    1       515809487294    515809488863
                    2       401647004144    401647005463
                    3       488750661035    488750662484
    505.mcf_r       0       681926695281    681925418147
    507.cactuBSSN_r 0       3832240965352   3832226068734
    508.namd_r      0       1919838790866   1919832527292
    510.parest_r    0       3515999635520   3515878553435
    511.povray_r    0       3073889223775   3074758622749
    519.lbm_r       0       1194077464296   1194077464041
    520.omnetpp_r   0       1014144252460   1011530791131   0.26%
    521.wrf_r       0       3966715533120   3966265425092
    523.xalancbmk_r 0       1064914296949   1064506711802
    525.x264_r      0       509290028335    509258131632
                    1       2001424246635   2001677767181
                    2       1914660798226   1914869407575
    526.blender_r   0       1726083839515   1725974286174
    527.cam4_r      0       2336526136415   2333656336419
    531.deepsjeng_r 0       1689007489539   1686541299243   0.15%
    538.imagick_r   0       3247960667520   3247942048723
    541.leela_r     0       2072315300365   2070248271250
    544.nab_r       0       1527909091282   1527906483039
    548.exchange2_r 0       2086120304280   2086314757502
    549.fotonik3d_r 0       2261694058444   2261670330720
    554.roms_r      0       2640547903140   2640512733483
    557.xz_r        0       388736881767    386880875636    0.48%
                    1       959356981818    959993132842
                    2       547643353034    546374038310    0.23%
    997.specrand_fr 0       512881578       512599641
    999.specrand_ir 0       512881578       512599641
    
    This is testsuite clean, no regression w/ patch.
    
                   ========= Summary of gcc testsuite =========
                                | # of unexpected case / # of unique unexpected case
                                |          gcc |          g++ |     gfortran |
     rv64imafdc/  lp64d/ medlow |    2 /     2 |    1 /     1 |    6 /     1 |
       rv64imac/   lp64/ medlow |    3 /     3 |    1 /     1 |   43 /     8 |
     rv32imafdc/ ilp32d/ medlow |    1 /     1 |    3 /     2 |    6 /     1 |
       rv32imac/  ilp32/ medlow |    1 /     1 |    3 /     2 |   43 /     8 |
    
    This came up as part of IRC chat on PR/109279 and was suggested by
    Andrew Pinski.
    
    gcc/ChangeLog:
    
            * config/riscv/riscv.md: riscv_move_integer() drop in_splitter arg.
            riscv_split_symbol() drop in_splitter arg.
            * config/riscv/riscv.cc: riscv_move_integer() drop in_splitter arg.
            riscv_split_symbol() drop in_splitter arg.
            riscv_force_temporary() drop in_splitter arg.
            * config/riscv/riscv-protos.h: riscv_move_integer() drop in_splitter arg.
            riscv_split_symbol() drop in_splitter arg.
    
    Signed-off-by: Vineet Gupta <vineetg@rivosinc.com>

Diff:
---
 gcc/config/riscv/riscv-protos.h |  4 ++--
 gcc/config/riscv/riscv.cc       | 46 ++++++++++++++++-------------------------
 gcc/config/riscv/riscv.md       |  8 +++----
 3 files changed, 24 insertions(+), 34 deletions(-)

diff --git a/gcc/config/riscv/riscv-protos.h b/gcc/config/riscv/riscv-protos.h
index 5244e8dcbf0..607ff6ea697 100644
--- a/gcc/config/riscv/riscv-protos.h
+++ b/gcc/config/riscv/riscv-protos.h
@@ -44,10 +44,10 @@ extern int riscv_const_insns (rtx);
 extern int riscv_split_const_insns (rtx);
 extern int riscv_load_store_insns (rtx, rtx_insn *);
 extern rtx riscv_emit_move (rtx, rtx);
-extern bool riscv_split_symbol (rtx, rtx, machine_mode, rtx *, bool);
+extern bool riscv_split_symbol (rtx, rtx, machine_mode, rtx *);
 extern bool riscv_split_symbol_type (enum riscv_symbol_type);
 extern rtx riscv_unspec_address (rtx, enum riscv_symbol_type);
-extern void riscv_move_integer (rtx, rtx, HOST_WIDE_INT, machine_mode, bool);
+extern void riscv_move_integer (rtx, rtx, HOST_WIDE_INT, machine_mode);
 extern bool riscv_legitimize_move (machine_mode, rtx, rtx);
 extern rtx riscv_subword (rtx, bool);
 extern bool riscv_split_64bit_move_p (rtx, rtx);
diff --git a/gcc/config/riscv/riscv.cc b/gcc/config/riscv/riscv.cc
index 5d2550871c7..ac8e4420896 100644
--- a/gcc/config/riscv/riscv.cc
+++ b/gcc/config/riscv/riscv.cc
@@ -689,8 +689,8 @@ riscv_split_integer (HOST_WIDE_INT val, machine_mode mode)
   unsigned HOST_WIDE_INT hival = sext_hwi ((val - loval) >> 32, 32);
   rtx hi = gen_reg_rtx (mode), lo = gen_reg_rtx (mode);
 
-  riscv_move_integer (hi, hi, hival, mode, FALSE);
-  riscv_move_integer (lo, lo, loval, mode, FALSE);
+  riscv_move_integer (hi, hi, hival, mode);
+  riscv_move_integer (lo, lo, loval, mode);
 
   hi = gen_rtx_fmt_ee (ASHIFT, mode, hi, GEN_INT (32));
   hi = force_reg (mode, hi);
@@ -1342,12 +1342,9 @@ riscv_swap_instruction (rtx inst)
    are allowed, copy it into a new register, otherwise use DEST.  */
 
 static rtx
-riscv_force_temporary (rtx dest, rtx value, bool in_splitter)
+riscv_force_temporary (rtx dest, rtx value)
 {
-  /* We can't call gen_reg_rtx from a splitter, because this might realloc
-     the regno_reg_rtx array, which would invalidate reg rtx pointers in the
-     combine undo buffer.  */
-  if (can_create_pseudo_p () && !in_splitter)
+  if (can_create_pseudo_p ())
     return force_reg (Pmode, value);
   else
     {
@@ -1406,7 +1403,7 @@ static rtx
 riscv_unspec_offset_high (rtx temp, rtx addr, enum riscv_symbol_type symbol_type)
 {
   addr = gen_rtx_HIGH (Pmode, riscv_unspec_address (addr, symbol_type));
-  return riscv_force_temporary (temp, addr, FALSE);
+  return riscv_force_temporary (temp, addr);
 }
 
 /* Load an entry from the GOT for a TLS GD access.  */
@@ -1454,8 +1451,7 @@ static rtx riscv_tls_add_tp_le (rtx dest, rtx base, rtx sym)
    is guaranteed to be a legitimate address for mode MODE.  */
 
 bool
-riscv_split_symbol (rtx temp, rtx addr, machine_mode mode, rtx *low_out,
-		    bool in_splitter)
+riscv_split_symbol (rtx temp, rtx addr, machine_mode mode, rtx *low_out)
 {
   enum riscv_symbol_type symbol_type;
 
@@ -1471,7 +1467,7 @@ riscv_split_symbol (rtx temp, rtx addr, machine_mode mode, rtx *low_out,
       case SYMBOL_ABSOLUTE:
 	{
 	  rtx high = gen_rtx_HIGH (Pmode, copy_rtx (addr));
-	  high = riscv_force_temporary (temp, high, in_splitter);
+	  high = riscv_force_temporary (temp, high);
 	  *low_out = gen_rtx_LO_SUM (Pmode, high, addr);
 	}
 	break;
@@ -1530,9 +1526,8 @@ riscv_add_offset (rtx temp, rtx reg, HOST_WIDE_INT offset)
 	 overflow, so we need to force a sign-extension check.  */
       high = gen_int_mode (CONST_HIGH_PART (offset), Pmode);
       offset = CONST_LOW_PART (offset);
-      high = riscv_force_temporary (temp, high, FALSE);
-      reg = riscv_force_temporary (temp, gen_rtx_PLUS (Pmode, high, reg),
-				   FALSE);
+      high = riscv_force_temporary (temp, high);
+      reg = riscv_force_temporary (temp, gen_rtx_PLUS (Pmode, high, reg));
     }
   return plus_constant (Pmode, reg, offset);
 }
@@ -1662,7 +1657,7 @@ riscv_legitimize_address (rtx x, rtx oldx ATTRIBUTE_UNUSED,
     return riscv_legitimize_tls_address (x);
 
   /* See if the address can split into a high part and a LO_SUM.  */
-  if (riscv_split_symbol (NULL, x, mode, &addr, FALSE))
+  if (riscv_split_symbol (NULL, x, mode, &addr))
     return riscv_force_address (addr, mode);
 
   /* Handle BASE + OFFSET.  */
@@ -1693,24 +1688,19 @@ riscv_legitimize_address (rtx x, rtx oldx ATTRIBUTE_UNUSED,
 
 void
 riscv_move_integer (rtx temp, rtx dest, HOST_WIDE_INT value,
-		    machine_mode orig_mode, bool in_splitter)
+		    machine_mode orig_mode)
 {
   struct riscv_integer_op codes[RISCV_MAX_INTEGER_OPS];
   machine_mode mode;
   int i, num_ops;
   rtx x;
 
-  /* We can't call gen_reg_rtx from a splitter, because this might realloc
-     the regno_reg_rtx array, which would invalidate reg rtx pointers in the
-     combine undo buffer.  */
-  bool can_create_pseudo = can_create_pseudo_p () && ! in_splitter;
-
   mode = GET_MODE (dest);
   /* We use the original mode for the riscv_build_integer call, because HImode
      values are given special treatment.  */
   num_ops = riscv_build_integer (codes, value, orig_mode);
 
-  if (can_create_pseudo && num_ops > 2 /* not a simple constant */
+  if (can_create_pseudo_p () && num_ops > 2 /* not a simple constant */
       && num_ops >= riscv_split_integer_cost (value))
     x = riscv_split_integer (value, mode);
   else
@@ -1721,7 +1711,7 @@ riscv_move_integer (rtx temp, rtx dest, HOST_WIDE_INT value,
 
       for (i = 1; i < num_ops; i++)
 	{
-	  if (!can_create_pseudo)
+	  if (!can_create_pseudo_p ())
 	    x = riscv_emit_set (temp, x);
 	  else
 	    x = force_reg (mode, x);
@@ -1745,12 +1735,12 @@ riscv_legitimize_const_move (machine_mode mode, rtx dest, rtx src)
   /* Split moves of big integers into smaller pieces.  */
   if (splittable_const_int_operand (src, mode))
     {
-      riscv_move_integer (dest, dest, INTVAL (src), mode, FALSE);
+      riscv_move_integer (dest, dest, INTVAL (src), mode);
       return;
     }
 
   /* Split moves of symbolic constants into high/low pairs.  */
-  if (riscv_split_symbol (dest, src, MAX_MACHINE_MODE, &src, FALSE))
+  if (riscv_split_symbol (dest, src, MAX_MACHINE_MODE, &src))
     {
       riscv_emit_set (dest, src);
       return;
@@ -1771,7 +1761,7 @@ riscv_legitimize_const_move (machine_mode mode, rtx dest, rtx src)
   if (offset != const0_rtx
       && (targetm.cannot_force_const_mem (mode, src) || can_create_pseudo_p ()))
     {
-      base = riscv_force_temporary (dest, base, FALSE);
+      base = riscv_force_temporary (dest, base);
       riscv_emit_move (dest, riscv_add_offset (NULL, base, INTVAL (offset)));
       return;
     }
@@ -1780,7 +1770,7 @@ riscv_legitimize_const_move (machine_mode mode, rtx dest, rtx src)
 
   /* When using explicit relocs, constant pool references are sometimes
      not legitimate addresses.  */
-  riscv_split_symbol (dest, XEXP (src, 0), mode, &XEXP (src, 0), FALSE);
+  riscv_split_symbol (dest, XEXP (src, 0), mode, &XEXP (src, 0));
   riscv_emit_move (dest, src);
 }
 
@@ -2129,7 +2119,7 @@ riscv_legitimize_move (machine_mode mode, rtx dest, rtx src)
 	  if (splittable_const_int_operand (src, mode))
 	    {
 	      reg = gen_reg_rtx (promoted_mode);
-	      riscv_move_integer (reg, reg, INTVAL (src), mode, FALSE);
+	      riscv_move_integer (reg, reg, INTVAL (src), mode);
 	    }
 	  else
 	    reg = force_reg (promoted_mode, src);
diff --git a/gcc/config/riscv/riscv.md b/gcc/config/riscv/riscv.md
index 0c69407ac09..dd845cc1ed3 100644
--- a/gcc/config/riscv/riscv.md
+++ b/gcc/config/riscv/riscv.md
@@ -1669,7 +1669,7 @@
   [(const_int 0)]
 {
   riscv_move_integer (operands[2], operands[0], INTVAL (operands[1]),
-		      <GPR:MODE>mode, TRUE);
+		      <GPR:MODE>mode);
   DONE;
 })
 
@@ -1678,11 +1678,11 @@
   [(set (match_operand:P 0 "register_operand")
 	(match_operand:P 1))
    (clobber (match_operand:P 2 "register_operand"))]
-  "riscv_split_symbol (operands[2], operands[1], MAX_MACHINE_MODE, NULL, TRUE)"
+  "riscv_split_symbol (operands[2], operands[1], MAX_MACHINE_MODE, NULL)"
   [(set (match_dup 0) (match_dup 3))]
 {
   riscv_split_symbol (operands[2], operands[1],
-		      MAX_MACHINE_MODE, &operands[3], TRUE);
+		      MAX_MACHINE_MODE, &operands[3]);
 })
 
 ;; Pretend to have the ability to load complex const_int in order to get
@@ -1699,7 +1699,7 @@
   [(const_int 0)]
 {
   riscv_move_integer (operands[0], operands[0], INTVAL (operands[1]),
-                      <MODE>mode, TRUE);
+                      <MODE>mode);
   DONE;
 })

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