public inbox for gcc-patches@gcc.gnu.org
 help / color / mirror / Atom feed
* [PATCH] x86: Add cmpmemsi for -mgeneral-regs-only
@ 2020-05-17 17:06 H.J. Lu
  2020-05-19  8:48 ` Uros Bizjak
  0 siblings, 1 reply; 10+ messages in thread
From: H.J. Lu @ 2020-05-17 17:06 UTC (permalink / raw)
  To: gcc-patches; +Cc: Uros Bizjak

Duplicate the cmpstrn pattern for cmpmem.  The only difference is that
the length argument of cmpmem is guaranteed to be less than or equal to
lengths of 2 memory areas.  Since "repz cmpsb" can be much slower than
memcmp function implemented with vector instruction, see

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=43052

expand cmpmem to "repz cmpsb" only with -mgeneral-regs-only.

Tested on Linux/x86 and Linux/x86-64.  OK for master?

Thanks.

H.J.
---
gcc/

	PR target/95151
	* config/i386/i386-expand.c (ix86_expand_cmpstrn_or_cmpmem): New
	function.  Duplicated from the cmpstrn pattern.  Expand memcmp
	to "repz cmpsb" only with -mgeneral-regs-only.
	* config/i386/i386-protos.h (ix86_expand_cmpstrn_or_cmpmem): New
	prototype.
	* config/i386/i386.md (cmpmemsi): New pattern.
	(cmpstrnsi): Use ix86_expand_cmpstrn_or_cmpmem.

gcc/testsuite/

	PR target/95151
	* gcc.target/i386/pr95151-1.c: New test.
	* gcc.target/i386/pr95151-2.c: Likewise.
	* gcc.target/i386/pr95151-3.c: Likewise.
	* gcc.target/i386/pr95151-4.c: Likewise.
---
 gcc/config/i386/i386-expand.c             | 80 +++++++++++++++++++++++
 gcc/config/i386/i386-protos.h             |  1 +
 gcc/config/i386/i386.md                   | 80 ++++++-----------------
 gcc/testsuite/gcc.target/i386/pr95151-1.c | 18 +++++
 gcc/testsuite/gcc.target/i386/pr95151-2.c | 11 ++++
 gcc/testsuite/gcc.target/i386/pr95151-3.c | 18 +++++
 gcc/testsuite/gcc.target/i386/pr95151-4.c | 11 ++++
 7 files changed, 160 insertions(+), 59 deletions(-)
 create mode 100644 gcc/testsuite/gcc.target/i386/pr95151-1.c
 create mode 100644 gcc/testsuite/gcc.target/i386/pr95151-2.c
 create mode 100644 gcc/testsuite/gcc.target/i386/pr95151-3.c
 create mode 100644 gcc/testsuite/gcc.target/i386/pr95151-4.c

diff --git a/gcc/config/i386/i386-expand.c b/gcc/config/i386/i386-expand.c
index 26531585c5f..05d3c33720c 100644
--- a/gcc/config/i386/i386-expand.c
+++ b/gcc/config/i386/i386-expand.c
@@ -7651,6 +7651,86 @@ ix86_expand_set_or_cpymem (rtx dst, rtx src, rtx count_exp, rtx val_exp,
   return true;
 }
 
+/* Expand cmpstrn or memcmp.  */
+
+bool
+ix86_expand_cmpstrn_or_cmpmem (rtx result, rtx src1, rtx src2,
+			       rtx length, rtx align, bool is_cmpstrn)
+{
+  if (optimize_insn_for_size_p () && !TARGET_INLINE_ALL_STRINGOPS)
+    return false;
+
+  /* Can't use this if the user has appropriated ecx, esi or edi.  */
+  if (fixed_regs[CX_REG] || fixed_regs[SI_REG] || fixed_regs[DI_REG])
+    return false;
+
+  if (is_cmpstrn)
+    {
+      /* For strncmp, length is the maximum length, which can be larger
+	 than actual string lengths.  We can expand the cmpstrn pattern
+	 to "repz cmpsb" only if one of the strings is a constant so
+	 that expand_builtin_strncmp() can write the length argument to
+	 be the minimum of the const string length and the actual length
+	 argument.  Otherwise, "repz cmpsb" may pass the 0 byte.  */
+      tree t1 = MEM_EXPR (src1);
+      tree t2 = MEM_EXPR (src2);
+      if (!((t1 && TREE_CODE (t1) == MEM_REF
+	     && TREE_CODE (TREE_OPERAND (t1, 0)) == ADDR_EXPR
+	     && (TREE_CODE (TREE_OPERAND (TREE_OPERAND (t1, 0), 0))
+		 == STRING_CST))
+	    || (t2 && TREE_CODE (t2) == MEM_REF
+		&& TREE_CODE (TREE_OPERAND (t2, 0)) == ADDR_EXPR
+		&& (TREE_CODE (TREE_OPERAND (TREE_OPERAND (t2, 0), 0))
+		    == STRING_CST))))
+	return false;
+    }
+  else
+    {
+      /* Expand memcmp to "repz cmpsb" only for -mgeneral-regs-only
+	 since "repz cmpsb" can be much slower than memcmp function
+	 implemented with vector instructions, see
+
+	 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=43052
+       */
+      if (!TARGET_GENERAL_REGS_ONLY)
+	return false;
+    }
+
+  rtx addr1 = copy_addr_to_reg (XEXP (src1, 0));
+  rtx addr2 = copy_addr_to_reg (XEXP (src2, 0));
+  if (addr1 != XEXP (src1, 0))
+    src1 = replace_equiv_address_nv (src1, addr1);
+  if (addr2 != XEXP (src2, 0))
+    src2 = replace_equiv_address_nv (src2, addr2);
+
+  rtx lengthreg = ix86_zero_extend_to_Pmode (length);
+
+  /* If we are testing strict equality, we can use known alignment to
+     good advantage.  This may be possible with combine, particularly
+     once cc0 is dead.  */
+  if (CONST_INT_P (length))
+    {
+      if (length == const0_rtx)
+	{
+	  emit_move_insn (result, const0_rtx);
+	  return true;
+	}
+      emit_insn (gen_cmpstrnqi_nz_1 (addr1, addr2, lengthreg, align,
+				     src1, src2));
+    }
+  else
+    {
+      emit_insn (gen_cmp_1 (Pmode, lengthreg, lengthreg));
+      emit_insn (gen_cmpstrnqi_1 (addr1, addr2, lengthreg, align,
+				  src1, src2));
+    }
+
+  rtx out = gen_lowpart (QImode, result);
+  emit_insn (gen_cmpintqi (out));
+  emit_move_insn (result, gen_rtx_SIGN_EXTEND (SImode, out));
+
+  return true;
+}
 
 /* Expand the appropriate insns for doing strlen if not just doing
    repnz; scasb
diff --git a/gcc/config/i386/i386-protos.h b/gcc/config/i386/i386-protos.h
index 39fcaa0ad5f..238aa650b61 100644
--- a/gcc/config/i386/i386-protos.h
+++ b/gcc/config/i386/i386-protos.h
@@ -71,6 +71,7 @@ extern int avx_vperm2f128_parallel (rtx par, machine_mode mode);
 extern bool ix86_expand_strlen (rtx, rtx, rtx, rtx);
 extern bool ix86_expand_set_or_cpymem (rtx, rtx, rtx, rtx, rtx, rtx,
 				       rtx, rtx, rtx, rtx, bool);
+extern bool ix86_expand_cmpstrn_or_cmpmem (rtx, rtx, rtx, rtx, rtx, bool);
 
 extern bool constant_address_p (rtx);
 extern bool legitimate_pic_operand_p (rtx);
diff --git a/gcc/config/i386/i386.md b/gcc/config/i386/i386.md
index 1bf0c1a7f01..7fb97db1e6e 100644
--- a/gcc/config/i386/i386.md
+++ b/gcc/config/i386/i386.md
@@ -17761,6 +17761,22 @@ (define_insn "*rep_stosqi"
 	  (const_string "*")))
    (set_attr "mode" "QI")])
 
+(define_expand "cmpmemsi"
+  [(set (match_operand:SI 0 "register_operand" "")
+        (compare:SI (match_operand:BLK 1 "memory_operand" "")
+                    (match_operand:BLK 2 "memory_operand" "") ) )
+   (use (match_operand 3 "general_operand"))
+   (use (match_operand 4 "immediate_operand"))]
+  ""
+{
+  if (ix86_expand_cmpstrn_or_cmpmem (operands[0], operands[1],
+				     operands[2], operands[3],
+				     operands[4], false))
+    DONE;
+  else
+    FAIL;
+})
+
 (define_expand "cmpstrnsi"
   [(set (match_operand:SI 0 "register_operand")
 	(compare:SI (match_operand:BLK 1 "general_operand")
@@ -17769,66 +17785,12 @@ (define_expand "cmpstrnsi"
    (use (match_operand 4 "immediate_operand"))]
   ""
 {
-  rtx addr1, addr2, countreg, align, out;
-
-  if (optimize_insn_for_size_p () && !TARGET_INLINE_ALL_STRINGOPS)
-    FAIL;
-
-  /* Can't use this if the user has appropriated ecx, esi or edi.  */
-  if (fixed_regs[CX_REG] || fixed_regs[SI_REG] || fixed_regs[DI_REG])
-    FAIL;
-
-  /* One of the strings must be a constant.  If so, expand_builtin_strncmp()
-     will have rewritten the length arg to be the minimum of the const string
-     length and the actual length arg.  If both strings are the same and
-     shorter than the length arg, repz cmpsb will not stop at the 0 byte and
-     will incorrectly base the results on chars past the 0 byte.  */
-  tree t1 = MEM_EXPR (operands[1]);
-  tree t2 = MEM_EXPR (operands[2]);
-  if (!((t1 && TREE_CODE (t1) == MEM_REF
-         && TREE_CODE (TREE_OPERAND (t1, 0)) == ADDR_EXPR
-         && TREE_CODE (TREE_OPERAND (TREE_OPERAND (t1, 0), 0)) == STRING_CST)
-      || (t2 && TREE_CODE (t2) == MEM_REF
-          && TREE_CODE (TREE_OPERAND (t2, 0)) == ADDR_EXPR
-          && TREE_CODE (TREE_OPERAND (TREE_OPERAND (t2, 0), 0)) == STRING_CST)))
-    FAIL;
-
-  addr1 = copy_addr_to_reg (XEXP (operands[1], 0));
-  addr2 = copy_addr_to_reg (XEXP (operands[2], 0));
-  if (addr1 != XEXP (operands[1], 0))
-    operands[1] = replace_equiv_address_nv (operands[1], addr1);
-  if (addr2 != XEXP (operands[2], 0))
-    operands[2] = replace_equiv_address_nv (operands[2], addr2);
-
-  countreg = ix86_zero_extend_to_Pmode (operands[3]);
-
-  /* %%% Iff we are testing strict equality, we can use known alignment
-     to good advantage.  This may be possible with combine, particularly
-     once cc0 is dead.  */
-  align = operands[4];
-
-  if (CONST_INT_P (operands[3]))
-    {
-      if (operands[3] == const0_rtx)
-	{
-	  emit_move_insn (operands[0], const0_rtx);
-	  DONE;
-	}
-      emit_insn (gen_cmpstrnqi_nz_1 (addr1, addr2, countreg, align,
-				     operands[1], operands[2]));
-    }
+  if (ix86_expand_cmpstrn_or_cmpmem (operands[0], operands[1],
+				     operands[2], operands[3],
+				     operands[4], true))
+    DONE;
   else
-    {
-      emit_insn (gen_cmp_1 (Pmode, countreg, countreg));
-      emit_insn (gen_cmpstrnqi_1 (addr1, addr2, countreg, align,
-				  operands[1], operands[2]));
-    }
-
-  out = gen_lowpart (QImode, operands[0]);
-  emit_insn (gen_cmpintqi (out));
-  emit_move_insn (operands[0], gen_rtx_SIGN_EXTEND (SImode, out));
-
-  DONE;
+    FAIL;
 })
 
 ;; Produce a tri-state integer (-1, 0, 1) from condition codes.
diff --git a/gcc/testsuite/gcc.target/i386/pr95151-1.c b/gcc/testsuite/gcc.target/i386/pr95151-1.c
new file mode 100644
index 00000000000..f7ed88e508f
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr95151-1.c
@@ -0,0 +1,18 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -mgeneral-regs-only -minline-all-stringops" } */
+
+struct foo
+{
+  char array[257];
+};
+
+extern struct foo x;
+
+int
+func (struct foo i)
+{
+  return __builtin_memcmp (&x, &i, sizeof (x)) ? 1 : 2;
+}
+
+/* { dg-final { scan-assembler-not "call\[\\t \]*_?memcmp" } } */
+/* { dg-final { scan-assembler "repz cmpsb" } } */
diff --git a/gcc/testsuite/gcc.target/i386/pr95151-2.c b/gcc/testsuite/gcc.target/i386/pr95151-2.c
new file mode 100644
index 00000000000..afd811ae7fb
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr95151-2.c
@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -mgeneral-regs-only -minline-all-stringops" } */
+
+int
+func (void *d, void *s, unsigned int l)
+{
+  return __builtin_memcmp (d, s, l) ? 1 : 2;
+}
+
+/* { dg-final { scan-assembler-not "call\[\\t \]*_?memcmp" } } */
+/* { dg-final { scan-assembler "repz cmpsb" } } */
diff --git a/gcc/testsuite/gcc.target/i386/pr95151-3.c b/gcc/testsuite/gcc.target/i386/pr95151-3.c
new file mode 100644
index 00000000000..bd62db5e640
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr95151-3.c
@@ -0,0 +1,18 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -msse2 -minline-all-stringops" } */
+
+struct foo
+{
+  char array[257];
+};
+
+extern struct foo x;
+
+int
+func (struct foo i)
+{
+  return __builtin_memcmp (&x, &i, sizeof (x)) ? 1 : 2;
+}
+
+/* { dg-final { scan-assembler "call\[\\t \]*_?memcmp" } } */
+/* { dg-final { scan-assembler-not "repz cmpsb" } } */
diff --git a/gcc/testsuite/gcc.target/i386/pr95151-4.c b/gcc/testsuite/gcc.target/i386/pr95151-4.c
new file mode 100644
index 00000000000..b8258f2530a
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr95151-4.c
@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -msse2 -minline-all-stringops" } */
+
+int
+func (void *d, void *s, unsigned int l)
+{
+  return __builtin_memcmp (d, s, l) ? 1 : 2;
+}
+
+/* { dg-final { scan-assembler "call\[\\t \]*_?memcmp" } } */
+/* { dg-final { scan-assembler-not "repz cmpsb" } } */
-- 
2.26.2


^ permalink raw reply	[flat|nested] 10+ messages in thread
end of thread, other threads:[~2020-10-23 12:45 UTC | newest]

Thread overview: 10+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-05-17 17:06 [PATCH] x86: Add cmpmemsi for -mgeneral-regs-only H.J. Lu
2020-05-19  8:48 ` Uros Bizjak
2020-05-19 12:14   ` [PATCH] x86: Add cmpmemsi for -minline-all-stringops H.J. Lu
2020-08-19 13:09     ` PING " H.J. Lu
2020-09-17  5:07       ` PING^2 " H.J. Lu
2020-10-02 13:21         ` PING^3 " H.J. Lu
2020-10-17 21:18           ` H.J. Lu
2020-10-18 15:16             ` Jan Hubicka
2020-10-18 15:27               ` H.J. Lu
2020-10-23 12:45               ` H.J. Lu

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).