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140 lines
4.3 KiB

commit 3605c744078bb048d876298aaf12a2869e8071b8
Author: Noah Goldstein <goldstein.w.n@gmail.com>
Date: Wed Mar 23 16:57:38 2022 -0500
x86: Optimize str{n}casecmp TOLOWER logic in strcmp-sse42.S
Slightly faster method of doing TOLOWER that saves an
instruction.
Also replace the hard coded 5-byte no with .p2align 4. On builds with
CET enabled this misaligned entry to strcasecmp.
geometric_mean(N=40) of all benchmarks New / Original: .920
All string/memory tests pass.
Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
(cherry picked from commit d154758e618ec9324f5d339c46db0aa27e8b1226)
diff --git a/sysdeps/x86_64/multiarch/strcmp-sse42.S b/sysdeps/x86_64/multiarch/strcmp-sse42.S
index 6197a723b9e0606e..a6825de8195ad8c6 100644
--- a/sysdeps/x86_64/multiarch/strcmp-sse42.S
+++ b/sysdeps/x86_64/multiarch/strcmp-sse42.S
@@ -89,9 +89,8 @@ ENTRY (GLABEL(__strcasecmp))
movq __libc_tsd_LOCALE@gottpoff(%rip),%rax
mov %fs:(%rax),%RDX_LP
- // XXX 5 byte should be before the function
- /* 5-byte NOP. */
- .byte 0x0f,0x1f,0x44,0x00,0x00
+ /* Either 1 or 5 bytes (dependeing if CET is enabled). */
+ .p2align 4
END (GLABEL(__strcasecmp))
/* FALLTHROUGH to strcasecmp_l. */
#endif
@@ -100,9 +99,8 @@ ENTRY (GLABEL(__strncasecmp))
movq __libc_tsd_LOCALE@gottpoff(%rip),%rax
mov %fs:(%rax),%RCX_LP
- // XXX 5 byte should be before the function
- /* 5-byte NOP. */
- .byte 0x0f,0x1f,0x44,0x00,0x00
+ /* Either 1 or 5 bytes (dependeing if CET is enabled). */
+ .p2align 4
END (GLABEL(__strncasecmp))
/* FALLTHROUGH to strncasecmp_l. */
#endif
@@ -170,27 +168,22 @@ STRCMP_SSE42:
#if defined USE_AS_STRCASECMP_L || defined USE_AS_STRNCASECMP_L
.section .rodata.cst16,"aM",@progbits,16
.align 16
-LABEL(belowupper):
- .quad 0x4040404040404040
- .quad 0x4040404040404040
-LABEL(topupper):
-# ifdef USE_AVX
- .quad 0x5a5a5a5a5a5a5a5a
- .quad 0x5a5a5a5a5a5a5a5a
-# else
- .quad 0x5b5b5b5b5b5b5b5b
- .quad 0x5b5b5b5b5b5b5b5b
-# endif
-LABEL(touppermask):
+LABEL(lcase_min):
+ .quad 0x3f3f3f3f3f3f3f3f
+ .quad 0x3f3f3f3f3f3f3f3f
+LABEL(lcase_max):
+ .quad 0x9999999999999999
+ .quad 0x9999999999999999
+LABEL(case_add):
.quad 0x2020202020202020
.quad 0x2020202020202020
.previous
- movdqa LABEL(belowupper)(%rip), %xmm4
-# define UCLOW_reg %xmm4
- movdqa LABEL(topupper)(%rip), %xmm5
-# define UCHIGH_reg %xmm5
- movdqa LABEL(touppermask)(%rip), %xmm6
-# define LCQWORD_reg %xmm6
+ movdqa LABEL(lcase_min)(%rip), %xmm4
+# define LCASE_MIN_reg %xmm4
+ movdqa LABEL(lcase_max)(%rip), %xmm5
+# define LCASE_MAX_reg %xmm5
+ movdqa LABEL(case_add)(%rip), %xmm6
+# define CASE_ADD_reg %xmm6
#endif
cmp $0x30, %ecx
ja LABEL(crosscache)/* rsi: 16-byte load will cross cache line */
@@ -201,32 +194,26 @@ LABEL(touppermask):
#if defined USE_AS_STRCASECMP_L || defined USE_AS_STRNCASECMP_L
# ifdef USE_AVX
# define TOLOWER(reg1, reg2) \
- vpcmpgtb UCLOW_reg, reg1, %xmm7; \
- vpcmpgtb UCHIGH_reg, reg1, %xmm8; \
- vpcmpgtb UCLOW_reg, reg2, %xmm9; \
- vpcmpgtb UCHIGH_reg, reg2, %xmm10; \
- vpandn %xmm7, %xmm8, %xmm8; \
- vpandn %xmm9, %xmm10, %xmm10; \
- vpand LCQWORD_reg, %xmm8, %xmm8; \
- vpand LCQWORD_reg, %xmm10, %xmm10; \
- vpor reg1, %xmm8, reg1; \
- vpor reg2, %xmm10, reg2
+ vpaddb LCASE_MIN_reg, reg1, %xmm7; \
+ vpaddb LCASE_MIN_reg, reg2, %xmm8; \
+ vpcmpgtb LCASE_MAX_reg, %xmm7, %xmm7; \
+ vpcmpgtb LCASE_MAX_reg, %xmm8, %xmm8; \
+ vpandn CASE_ADD_reg, %xmm7, %xmm7; \
+ vpandn CASE_ADD_reg, %xmm8, %xmm8; \
+ vpaddb %xmm7, reg1, reg1; \
+ vpaddb %xmm8, reg2, reg2
# else
# define TOLOWER(reg1, reg2) \
- movdqa reg1, %xmm7; \
- movdqa UCHIGH_reg, %xmm8; \
- movdqa reg2, %xmm9; \
- movdqa UCHIGH_reg, %xmm10; \
- pcmpgtb UCLOW_reg, %xmm7; \
- pcmpgtb reg1, %xmm8; \
- pcmpgtb UCLOW_reg, %xmm9; \
- pcmpgtb reg2, %xmm10; \
- pand %xmm8, %xmm7; \
- pand %xmm10, %xmm9; \
- pand LCQWORD_reg, %xmm7; \
- pand LCQWORD_reg, %xmm9; \
- por %xmm7, reg1; \
- por %xmm9, reg2
+ movdqa LCASE_MIN_reg, %xmm7; \
+ movdqa LCASE_MIN_reg, %xmm8; \
+ paddb reg1, %xmm7; \
+ paddb reg2, %xmm8; \
+ pcmpgtb LCASE_MAX_reg, %xmm7; \
+ pcmpgtb LCASE_MAX_reg, %xmm8; \
+ pandn CASE_ADD_reg, %xmm7; \
+ pandn CASE_ADD_reg, %xmm8; \
+ paddb %xmm7, reg1; \
+ paddb %xmm8, reg2
# endif
TOLOWER (%xmm1, %xmm2)
#else