We used to expand memcmp to "repz cmpsb" via cmpstrnsi. It was changed
by
commit 9b0f6f5e511ca512e4faeabc81d2fd3abad9b02f
Author: Nick Clifton <ni...@redhat.com>
Date: Fri Aug 12 16:26:11 2011 +0000
builtins.c (expand_builtin_memcmp): Do not use cmpstrnsi pattern.
* builtins.c (expand_builtin_memcmp): Do not use cmpstrnsi
pattern.
* doc/md.texi (cmpstrn): Note that the comparison stops if both
fetched bytes are zero.
(cmpstr): Likewise.
(cmpmem): Note that the comparison does not stop if both of the
fetched bytes are zero.
Duplicate the cmpstrn pattern for cmpmem and expand cmpmem to "repz cmpsb"
for -minline-all-stringops. The only difference is that the length
argument of cmpmem is guaranteed to be less than or equal to lengths of
2 memory areas.
gcc/
PR target/95151
* config/i386/i386-expand.c (ix86_expand_cmpstrn_or_cmpmem): New
function.
* config/i386/i386-protos.h (ix86_expand_cmpstrn_or_cmpmem): New
prototype.
* config/i386/i386.md (cmpmemsi): New pattern.
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 | 84 +++++++++++++++++++++++
gcc/config/i386/i386-protos.h | 1 +
gcc/config/i386/i386.md | 84 ++++++-----------------
gcc/testsuite/gcc.target/i386/pr95151-1.c | 17 +++++
gcc/testsuite/gcc.target/i386/pr95151-2.c | 10 +++
gcc/testsuite/gcc.target/i386/pr95151-3.c | 18 +++++
gcc/testsuite/gcc.target/i386/pr95151-4.c | 11 +++
7 files changed, 162 insertions(+), 63 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 270585decb2..9e27564037b 100644
--- a/gcc/config/i386/i386-expand.c
+++ b/gcc/config/i386/i386-expand.c
@@ -7656,6 +7656,90 @@ 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 -minline-all-stringops
+ 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_INLINE_ALL_STRINGOPS)
+ 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);
+
+ /* NB: Make a copy of the data length to avoid changing the original
+ data length by cmpstrnqi patterns. */
+ length = ix86_zero_extend_to_Pmode (length);
+ rtx lengthreg = gen_reg_rtx (Pmode);
+ emit_move_insn (lengthreg, 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 c2de1bdaf42..dec8dd17168 100644
--- a/gcc/config/i386/i386.md
+++ b/gcc/config/i386/i386.md
@@ -17777,6 +17777,22 @@ (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")
@@ -17785,70 +17801,12 @@ (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);
-
- /* NB: Make a copy of the data length to avoid changing the original
- data length by cmpstrnqi patterns. */
- rtx count = ix86_zero_extend_to_Pmode (operands[3]);
- countreg = gen_reg_rtx (Pmode);
- emit_move_insn (countreg, count);
-
- /* %%% 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..54a7510042a
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr95151-1.c
@@ -0,0 +1,17 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -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" } } */
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..8f9d8ee1bf4
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr95151-2.c
@@ -0,0 +1,10 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -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" } } */
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..14cbdec4c93
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr95151-3.c
@@ -0,0 +1,18 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -msse2 -mno-inline-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 "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..c93b2b60c5b
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr95151-4.c
@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -msse2 -mno-inline-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 "cmpsb" } } */
--
2.26.2
