From: Andi Kleen <a...@linux.intel.com>
In my tests the optimized glibc out of line strcmp is always faster than
using inline rep ; cmpsb, even for small strings. The Intel optimization manual
also recommends to not use it. So remove the cmpstrnsi instruction.
Tested on Sandy Bridge, Westmere Intel CPUs.
gcc/:
2014-09-27 Andi Kleen <a...@linux.intel.com>
* config/i386/i386.md (cmpstrnsi, cmpintqi): Remove expanders.
---
gcc/config/i386/i386.md | 85 -------------------------------------------------
1 file changed, 85 deletions(-)
diff --git a/gcc/config/i386/i386.md b/gcc/config/i386/i386.md
index 98df8e1..1d2f1a5 100644
--- a/gcc/config/i386/i386.md
+++ b/gcc/config/i386/i386.md
@@ -16097,91 +16097,6 @@
(const_string "*")))
(set_attr "mode" "QI")])
-(define_expand "cmpstrnsi"
- [(set (match_operand:SI 0 "register_operand")
- (compare:SI (match_operand:BLK 1 "general_operand")
- (match_operand:BLK 2 "general_operand")))
- (use (match_operand 3 "general_operand"))
- (use (match_operand 4 "immediate_operand"))]
- ""
-{
- rtx addr1, addr2, out, outlow, count, countreg, align;
-
- 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;
-
- out = operands[0];
- if (!REG_P (out))
- out = gen_reg_rtx (SImode);
-
- 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);
-
- count = operands[3];
- countreg = ix86_zero_extend_to_Pmode (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 (count))
- {
- if (INTVAL (count) == 0)
- {
- emit_move_insn (operands[0], const0_rtx);
- DONE;
- }
- emit_insn (gen_cmpstrnqi_nz_1 (addr1, addr2, countreg, align,
- operands[1], operands[2]));
- }
- else
- {
- rtx (*gen_cmp) (rtx, rtx);
-
- gen_cmp = (TARGET_64BIT
- ? gen_cmpdi_1 : gen_cmpsi_1);
-
- emit_insn (gen_cmp (countreg, countreg));
- emit_insn (gen_cmpstrnqi_1 (addr1, addr2, countreg, align,
- operands[1], operands[2]));
- }
-
- outlow = gen_lowpart (QImode, out);
- emit_insn (gen_cmpintqi (outlow));
- emit_move_insn (out, gen_rtx_SIGN_EXTEND (SImode, outlow));
-
- if (operands[0] != out)
- emit_move_insn (operands[0], out);
-
- DONE;
-})
-
-;; Produce a tri-state integer (-1, 0, 1) from condition codes.
-
-(define_expand "cmpintqi"
- [(set (match_dup 1)
- (gtu:QI (reg:CC FLAGS_REG) (const_int 0)))
- (set (match_dup 2)
- (ltu:QI (reg:CC FLAGS_REG) (const_int 0)))
- (parallel [(set (match_operand:QI 0 "register_operand")
- (minus:QI (match_dup 1)
- (match_dup 2)))
- (clobber (reg:CC FLAGS_REG))])]
- ""
-{
- operands[1] = gen_reg_rtx (QImode);
- operands[2] = gen_reg_rtx (QImode);
-})
-
;; memcmp recognizers. The `cmpsb' opcode does nothing if the count is
;; zero. Emit extra code to make sure that a zero-length compare is EQ.
--
2.1.1
