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* [glibc] x86: Use VMM API in memcmp-evex-movbe.S and minor changes
@ 2022-11-09 4:33 Noah Goldstein
0 siblings, 0 replies; only message in thread
From: Noah Goldstein @ 2022-11-09 4:33 UTC (permalink / raw)
To: glibc-cvs
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=419c832aba43276e285586998261d1db06033193
commit 419c832aba43276e285586998261d1db06033193
Author: Noah Goldstein <goldstein.w.n@gmail.com>
Date: Sat Oct 29 15:19:58 2022 -0500
x86: Use VMM API in memcmp-evex-movbe.S and minor changes
The only change to the existing generated code is `tzcnt` -> `bsf` to
save a byte of code size here and there.
Rewriting with VMM API allows for memcmp-evex-movbe to be used with
evex512 by including "x86-evex512-vecs.h" at the top.
Complete check passes on x86-64.
Diff:
---
sysdeps/x86_64/multiarch/memcmp-evex-movbe.S | 308 +++++++++++++++------------
1 file changed, 175 insertions(+), 133 deletions(-)
diff --git a/sysdeps/x86_64/multiarch/memcmp-evex-movbe.S b/sysdeps/x86_64/multiarch/memcmp-evex-movbe.S
index bc017768be..f6c379831e 100644
--- a/sysdeps/x86_64/multiarch/memcmp-evex-movbe.S
+++ b/sysdeps/x86_64/multiarch/memcmp-evex-movbe.S
@@ -62,44 +62,38 @@ Latency:
# define MEMCMP __memcmp_evex_movbe
# endif
-# define VMOVU vmovdqu64
+# ifndef VEC_SIZE
+# include "x86-evex256-vecs.h"
+# endif
# ifdef USE_AS_WMEMCMP
# define VMOVU_MASK vmovdqu32
# define CHAR_SIZE 4
# define VPCMP vpcmpd
+# define VPCMPEQ vpcmpeqd
# define VPTEST vptestmd
+
+# define USE_WIDE_CHAR
# else
# define VMOVU_MASK vmovdqu8
# define CHAR_SIZE 1
# define VPCMP vpcmpub
+# define VPCMPEQ vpcmpeqb
# define VPTEST vptestmb
# endif
+# include "reg-macros.h"
-# define VEC_SIZE 32
# define PAGE_SIZE 4096
# define CHAR_PER_VEC (VEC_SIZE / CHAR_SIZE)
-# define XMM0 xmm16
-# define XMM1 xmm17
-# define XMM2 xmm18
-# define YMM0 ymm16
-# define XMM1 xmm17
-# define XMM2 xmm18
-# define YMM1 ymm17
-# define YMM2 ymm18
-# define YMM3 ymm19
-# define YMM4 ymm20
-# define YMM5 ymm21
-# define YMM6 ymm22
/* Warning!
wmemcmp has to use SIGNED comparison for elements.
memcmp has to use UNSIGNED comparison for elemnts.
*/
- .section .text.evex,"ax",@progbits
+ .section SECTION(.text), "ax", @progbits
/* Cache align memcmp entry. This allows for much more thorough
frontend optimization. */
ENTRY_P2ALIGN (MEMCMP, 6)
@@ -111,23 +105,40 @@ ENTRY_P2ALIGN (MEMCMP, 6)
/* Fall through for [0, VEC_SIZE] as its the hottest. */
ja L(more_1x_vec)
- /* Create mask for CHAR's we want to compare. This allows us to
- avoid having to include page cross logic. */
- movl $-1, %ecx
- bzhil %edx, %ecx, %ecx
- kmovd %ecx, %k2
+ /* Create mask of bytes that are guranteed to be valid because
+ of length (edx). Using masked movs allows us to skip checks
+ for page crosses/zero size. */
+ mov $-1, %VRAX
+ bzhi %VRDX, %VRAX, %VRAX
+ /* NB: A `jz` might be useful here. Page-faults that are
+ invalidated by predicate execution (the evex mask) can be
+ very slow. The expectation is this is not the norm so and
+ "most" code will not regularly call 'memcmp' with length = 0
+ and memory that is not wired up. */
+ KMOV %VRAX, %k2
+
+
/* Safe to load full ymm with mask. */
- VMOVU_MASK (%rsi), %YMM2{%k2}
- VPCMP $4,(%rdi), %YMM2, %k1{%k2}
- kmovd %k1, %eax
- testl %eax, %eax
+ VMOVU_MASK (%rsi), %VMM(2){%k2}{z}
+ /* Slightly different method for VEC_SIZE == 64 to save a bit of
+ code size. This allows us to fit L(return_vec_0) entirely in
+ the first cache line. */
+# if VEC_SIZE == 64
+ VPCMPEQ (%rdi), %VMM(2), %k1{%k2}
+ KMOV %k1, %VRCX
+ sub %VRCX, %VRAX
+# else
+ VPCMP $4, (%rdi), %VMM(2), %k1{%k2}
+ KMOV %k1, %VRAX
+ test %VRAX, %VRAX
+# endif
jnz L(return_vec_0)
ret
- .p2align 4
+ .p2align 4,, 11
L(return_vec_0):
- tzcntl %eax, %eax
+ bsf %VRAX, %VRAX
# ifdef USE_AS_WMEMCMP
movl (%rdi, %rax, CHAR_SIZE), %ecx
xorl %edx, %edx
@@ -138,33 +149,36 @@ L(return_vec_0):
leal -1(%rdx, %rdx), %eax
# else
movzbl (%rsi, %rax), %ecx
+# if VEC_SIZE == 64
+ movb (%rdi, %rax), %al
+# else
movzbl (%rdi, %rax), %eax
+# endif
subl %ecx, %eax
# endif
ret
-
- .p2align 4
+ .p2align 4,, 11
L(more_1x_vec):
/* From VEC to 2 * VEC. No branch when size == VEC_SIZE. */
- VMOVU (%rsi), %YMM1
+ VMOVU (%rsi), %VMM(1)
/* Use compare not equals to directly check for mismatch. */
- VPCMP $4,(%rdi), %YMM1, %k1
- kmovd %k1, %eax
+ VPCMP $4, (%rdi), %VMM(1), %k1
+ KMOV %k1, %VRAX
/* NB: eax must be destination register if going to
- L(return_vec_[0,2]). For L(return_vec_3) destination register
- must be ecx. */
- testl %eax, %eax
+ L(return_vec_[0,2]). For L(return_vec_3) destination
+ register must be ecx. */
+ test %VRAX, %VRAX
jnz L(return_vec_0)
cmpq $(CHAR_PER_VEC * 2), %rdx
jbe L(last_1x_vec)
/* Check second VEC no matter what. */
- VMOVU VEC_SIZE(%rsi), %YMM2
- VPCMP $4, VEC_SIZE(%rdi), %YMM2, %k1
- kmovd %k1, %eax
- testl %eax, %eax
+ VMOVU VEC_SIZE(%rsi), %VMM(2)
+ VPCMP $4, VEC_SIZE(%rdi), %VMM(2), %k1
+ KMOV %k1, %VRAX
+ test %VRAX, %VRAX
jnz L(return_vec_1)
/* Less than 4 * VEC. */
@@ -172,16 +186,16 @@ L(more_1x_vec):
jbe L(last_2x_vec)
/* Check third and fourth VEC no matter what. */
- VMOVU (VEC_SIZE * 2)(%rsi), %YMM3
- VPCMP $4,(VEC_SIZE * 2)(%rdi), %YMM3, %k1
- kmovd %k1, %eax
- testl %eax, %eax
+ VMOVU (VEC_SIZE * 2)(%rsi), %VMM(3)
+ VPCMP $4, (VEC_SIZE * 2)(%rdi), %VMM(3), %k1
+ KMOV %k1, %VRAX
+ test %VRAX, %VRAX
jnz L(return_vec_2)
- VMOVU (VEC_SIZE * 3)(%rsi), %YMM4
- VPCMP $4,(VEC_SIZE * 3)(%rdi), %YMM4, %k1
- kmovd %k1, %ecx
- testl %ecx, %ecx
+ VMOVU (VEC_SIZE * 3)(%rsi), %VMM(4)
+ VPCMP $4, (VEC_SIZE * 3)(%rdi), %VMM(4), %k1
+ KMOV %k1, %VRCX
+ test %VRCX, %VRCX
jnz L(return_vec_3)
/* Go to 4x VEC loop. */
@@ -192,8 +206,8 @@ L(more_1x_vec):
branches. */
/* Load first two VEC from s2 before adjusting addresses. */
- VMOVU -(VEC_SIZE * 4)(%rsi, %rdx, CHAR_SIZE), %YMM1
- VMOVU -(VEC_SIZE * 3)(%rsi, %rdx, CHAR_SIZE), %YMM2
+ VMOVU -(VEC_SIZE * 4)(%rsi, %rdx, CHAR_SIZE), %VMM(1)
+ VMOVU -(VEC_SIZE * 3)(%rsi, %rdx, CHAR_SIZE), %VMM(2)
leaq -(4 * VEC_SIZE)(%rdi, %rdx, CHAR_SIZE), %rdi
leaq -(4 * VEC_SIZE)(%rsi, %rdx, CHAR_SIZE), %rsi
@@ -202,56 +216,61 @@ L(more_1x_vec):
/* vpxor will be all 0s if s1 and s2 are equal. Otherwise it
will have some 1s. */
- vpxorq (%rdi), %YMM1, %YMM1
- vpxorq (VEC_SIZE)(%rdi), %YMM2, %YMM2
+ vpxorq (%rdi), %VMM(1), %VMM(1)
+ vpxorq (VEC_SIZE)(%rdi), %VMM(2), %VMM(2)
- VMOVU (VEC_SIZE * 2)(%rsi), %YMM3
- vpxorq (VEC_SIZE * 2)(%rdi), %YMM3, %YMM3
+ VMOVU (VEC_SIZE * 2)(%rsi), %VMM(3)
+ vpxorq (VEC_SIZE * 2)(%rdi), %VMM(3), %VMM(3)
- VMOVU (VEC_SIZE * 3)(%rsi), %YMM4
- /* Ternary logic to xor (VEC_SIZE * 3)(%rdi) with YMM4 while
- oring with YMM1. Result is stored in YMM4. */
- vpternlogd $0xde,(VEC_SIZE * 3)(%rdi), %YMM1, %YMM4
+ VMOVU (VEC_SIZE * 3)(%rsi), %VMM(4)
+ /* Ternary logic to xor (VEC_SIZE * 3)(%rdi) with VEC(4) while
+ oring with VEC(1). Result is stored in VEC(4). */
+ vpternlogd $0xde, (VEC_SIZE * 3)(%rdi), %VMM(1), %VMM(4)
- /* Or together YMM2, YMM3, and YMM4 into YMM4. */
- vpternlogd $0xfe, %YMM2, %YMM3, %YMM4
+ /* Or together VEC(2), VEC(3), and VEC(4) into VEC(4). */
+ vpternlogd $0xfe, %VMM(2), %VMM(3), %VMM(4)
- /* Test YMM4 against itself. Store any CHAR mismatches in k1.
+ /* Test VEC(4) against itself. Store any CHAR mismatches in k1.
*/
- VPTEST %YMM4, %YMM4, %k1
+ VPTEST %VMM(4), %VMM(4), %k1
/* k1 must go to ecx for L(return_vec_0_1_2_3). */
- kmovd %k1, %ecx
- testl %ecx, %ecx
+ KMOV %k1, %VRCX
+ test %VRCX, %VRCX
jnz L(return_vec_0_1_2_3)
/* NB: eax must be zero to reach here. */
ret
- .p2align 4,, 8
+ .p2align 4,, 9
L(8x_end_return_vec_0_1_2_3):
movq %rdx, %rdi
L(8x_return_vec_0_1_2_3):
+ /* L(loop_4x_vec) leaves result in `k1` for VEC_SIZE == 64. */
+# if VEC_SIZE == 64
+ KMOV %k1, %VRCX
+# endif
addq %rdi, %rsi
L(return_vec_0_1_2_3):
- VPTEST %YMM1, %YMM1, %k0
- kmovd %k0, %eax
- testl %eax, %eax
+ VPTEST %VMM(1), %VMM(1), %k0
+ KMOV %k0, %VRAX
+ test %VRAX, %VRAX
jnz L(return_vec_0)
- VPTEST %YMM2, %YMM2, %k0
- kmovd %k0, %eax
- testl %eax, %eax
+ VPTEST %VMM(2), %VMM(2), %k0
+ KMOV %k0, %VRAX
+ test %VRAX, %VRAX
jnz L(return_vec_1)
- VPTEST %YMM3, %YMM3, %k0
- kmovd %k0, %eax
- testl %eax, %eax
+ VPTEST %VMM(3), %VMM(3), %k0
+ KMOV %k0, %VRAX
+ test %VRAX, %VRAX
jnz L(return_vec_2)
+ .p2align 4,, 2
L(return_vec_3):
/* bsf saves 1 byte from tzcnt. This keep L(return_vec_3) in one
fetch block and the entire L(*return_vec_0_1_2_3) in 1 cache
line. */
- bsfl %ecx, %ecx
+ bsf %VRCX, %VRCX
# ifdef USE_AS_WMEMCMP
movl (VEC_SIZE * 3)(%rdi, %rcx, CHAR_SIZE), %eax
xorl %edx, %edx
@@ -266,11 +285,11 @@ L(return_vec_3):
ret
- .p2align 4
+ .p2align 4,, 8
L(return_vec_1):
/* bsf saves 1 byte over tzcnt and keeps L(return_vec_1) in one
fetch block. */
- bsfl %eax, %eax
+ bsf %VRAX, %VRAX
# ifdef USE_AS_WMEMCMP
movl VEC_SIZE(%rdi, %rax, CHAR_SIZE), %ecx
xorl %edx, %edx
@@ -284,11 +303,11 @@ L(return_vec_1):
# endif
ret
- .p2align 4,, 10
+ .p2align 4,, 7
L(return_vec_2):
/* bsf saves 1 byte over tzcnt and keeps L(return_vec_2) in one
fetch block. */
- bsfl %eax, %eax
+ bsf %VRAX, %VRAX
# ifdef USE_AS_WMEMCMP
movl (VEC_SIZE * 2)(%rdi, %rax, CHAR_SIZE), %ecx
xorl %edx, %edx
@@ -302,7 +321,7 @@ L(return_vec_2):
# endif
ret
- .p2align 4
+ .p2align 4,, 8
L(more_8x_vec):
/* Set end of s1 in rdx. */
leaq -(VEC_SIZE * 4)(%rdi, %rdx, CHAR_SIZE), %rdx
@@ -316,62 +335,82 @@ L(more_8x_vec):
.p2align 4
L(loop_4x_vec):
- VMOVU (%rsi, %rdi), %YMM1
- vpxorq (%rdi), %YMM1, %YMM1
- VMOVU VEC_SIZE(%rsi, %rdi), %YMM2
- vpxorq VEC_SIZE(%rdi), %YMM2, %YMM2
- VMOVU (VEC_SIZE * 2)(%rsi, %rdi), %YMM3
- vpxorq (VEC_SIZE * 2)(%rdi), %YMM3, %YMM3
- VMOVU (VEC_SIZE * 3)(%rsi, %rdi), %YMM4
- vpternlogd $0xde,(VEC_SIZE * 3)(%rdi), %YMM1, %YMM4
- vpternlogd $0xfe, %YMM2, %YMM3, %YMM4
- VPTEST %YMM4, %YMM4, %k1
- kmovd %k1, %ecx
- testl %ecx, %ecx
+ VMOVU (%rsi, %rdi), %VMM(1)
+ vpxorq (%rdi), %VMM(1), %VMM(1)
+ VMOVU VEC_SIZE(%rsi, %rdi), %VMM(2)
+ vpxorq VEC_SIZE(%rdi), %VMM(2), %VMM(2)
+ VMOVU (VEC_SIZE * 2)(%rsi, %rdi), %VMM(3)
+ vpxorq (VEC_SIZE * 2)(%rdi), %VMM(3), %VMM(3)
+ VMOVU (VEC_SIZE * 3)(%rsi, %rdi), %VMM(4)
+ vpternlogd $0xde, (VEC_SIZE * 3)(%rdi), %VMM(1), %VMM(4)
+ vpternlogd $0xfe, %VMM(2), %VMM(3), %VMM(4)
+ VPTEST %VMM(4), %VMM(4), %k1
+ /* If VEC_SIZE == 64 just branch with KTEST. We have free port0
+ space and it allows the loop to fit in 2x cache lines
+ instead of 3. */
+# if VEC_SIZE == 64
+ KTEST %k1, %k1
+# else
+ KMOV %k1, %VRCX
+ test %VRCX, %VRCX
+# endif
jnz L(8x_return_vec_0_1_2_3)
subq $-(VEC_SIZE * 4), %rdi
cmpq %rdx, %rdi
jb L(loop_4x_vec)
-
subq %rdx, %rdi
/* rdi has 4 * VEC_SIZE - remaining length. */
cmpl $(VEC_SIZE * 3), %edi
- jae L(8x_last_1x_vec)
+ jge L(8x_last_1x_vec)
/* Load regardless of branch. */
- VMOVU (VEC_SIZE * 2)(%rsi, %rdx), %YMM3
- cmpl $(VEC_SIZE * 2), %edi
- jae L(8x_last_2x_vec)
+ VMOVU (VEC_SIZE * 2)(%rsi, %rdx), %VMM(3)
- vpxorq (VEC_SIZE * 2)(%rdx), %YMM3, %YMM3
-
- VMOVU (%rsi, %rdx), %YMM1
- vpxorq (%rdx), %YMM1, %YMM1
+ /* Seperate logic as we can only use testb for VEC_SIZE == 64.
+ */
+# if VEC_SIZE == 64
+ testb %dil, %dil
+ js L(8x_last_2x_vec)
+# else
+ cmpl $(VEC_SIZE * 2), %edi
+ jge L(8x_last_2x_vec)
+# endif
- VMOVU VEC_SIZE(%rsi, %rdx), %YMM2
- vpxorq VEC_SIZE(%rdx), %YMM2, %YMM2
- VMOVU (VEC_SIZE * 3)(%rsi, %rdx), %YMM4
- vpternlogd $0xde,(VEC_SIZE * 3)(%rdx), %YMM1, %YMM4
- vpternlogd $0xfe, %YMM2, %YMM3, %YMM4
- VPTEST %YMM4, %YMM4, %k1
- kmovd %k1, %ecx
- testl %ecx, %ecx
+ vpxorq (VEC_SIZE * 2)(%rdx), %VMM(3), %VMM(3)
+
+ VMOVU (%rsi, %rdx), %VMM(1)
+ vpxorq (%rdx), %VMM(1), %VMM(1)
+
+ VMOVU VEC_SIZE(%rsi, %rdx), %VMM(2)
+ vpxorq VEC_SIZE(%rdx), %VMM(2), %VMM(2)
+ VMOVU (VEC_SIZE * 3)(%rsi, %rdx), %VMM(4)
+ vpternlogd $0xde, (VEC_SIZE * 3)(%rdx), %VMM(1), %VMM(4)
+ vpternlogd $0xfe, %VMM(2), %VMM(3), %VMM(4)
+ VPTEST %VMM(4), %VMM(4), %k1
+ /* L(8x_end_return_vec_0_1_2_3) expects bitmask to still be in
+ `k1` if VEC_SIZE == 64. */
+# if VEC_SIZE == 64
+ KTEST %k1, %k1
+# else
+ KMOV %k1, %VRCX
+ test %VRCX, %VRCX
+# endif
jnz L(8x_end_return_vec_0_1_2_3)
/* NB: eax must be zero to reach here. */
ret
/* Only entry is from L(more_8x_vec). */
- .p2align 4,, 10
+ .p2align 4,, 6
L(8x_last_2x_vec):
- VPCMP $4,(VEC_SIZE * 2)(%rdx), %YMM3, %k1
- kmovd %k1, %eax
- testl %eax, %eax
+ VPCMP $4, (VEC_SIZE * 2)(%rdx), %VMM(3), %k1
+ KMOV %k1, %VRAX
+ test %VRAX, %VRAX
jnz L(8x_return_vec_2)
- /* Naturally aligned to 16 bytes. */
+ .p2align 4,, 5
L(8x_last_1x_vec):
- VMOVU (VEC_SIZE * 3)(%rsi, %rdx), %YMM1
- VPCMP $4,(VEC_SIZE * 3)(%rdx), %YMM1, %k1
- kmovd %k1, %eax
- testl %eax, %eax
+ VMOVU (VEC_SIZE * 3)(%rsi, %rdx), %VMM(1)
+ VPCMP $4, (VEC_SIZE * 3)(%rdx), %VMM(1), %k1
+ KMOV %k1, %VRAX
+ test %VRAX, %VRAX
jnz L(8x_return_vec_3)
ret
@@ -383,7 +422,7 @@ L(8x_last_1x_vec):
L(8x_return_vec_2):
subq $VEC_SIZE, %rdx
L(8x_return_vec_3):
- bsfl %eax, %eax
+ bsf %VRAX, %VRAX
# ifdef USE_AS_WMEMCMP
leaq (%rdx, %rax, CHAR_SIZE), %rax
movl (VEC_SIZE * 3)(%rax), %ecx
@@ -399,32 +438,34 @@ L(8x_return_vec_3):
# endif
ret
- .p2align 4,, 10
+ .p2align 4,, 8
L(last_2x_vec):
/* Check second to last VEC. */
- VMOVU -(VEC_SIZE * 2)(%rsi, %rdx, CHAR_SIZE), %YMM1
- VPCMP $4, -(VEC_SIZE * 2)(%rdi, %rdx, CHAR_SIZE), %YMM1, %k1
- kmovd %k1, %eax
- testl %eax, %eax
+ VMOVU -(VEC_SIZE * 2)(%rsi, %rdx, CHAR_SIZE), %VMM(1)
+ VPCMP $4, -(VEC_SIZE * 2)(%rdi, %rdx, CHAR_SIZE), %VMM(1), %k1
+ KMOV %k1, %VRAX
+ test %VRAX, %VRAX
jnz L(return_vec_1_end)
/* Check last VEC. */
- .p2align 4
+ .p2align 4,, 8
L(last_1x_vec):
- VMOVU -(VEC_SIZE * 1)(%rsi, %rdx, CHAR_SIZE), %YMM1
- VPCMP $4, -(VEC_SIZE * 1)(%rdi, %rdx, CHAR_SIZE), %YMM1, %k1
- kmovd %k1, %eax
- testl %eax, %eax
+ VMOVU -(VEC_SIZE * 1)(%rsi, %rdx, CHAR_SIZE), %VMM(1)
+ VPCMP $4, -(VEC_SIZE * 1)(%rdi, %rdx, CHAR_SIZE), %VMM(1), %k1
+ KMOV %k1, %VRAX
+ test %VRAX, %VRAX
jnz L(return_vec_0_end)
ret
- /* Don't align. Takes 2-fetch blocks either way and aligning
- will cause code to spill into another cacheline. */
+ /* Don't fully align. Takes 2-fetch blocks either way and
+ aligning will cause code to spill into another cacheline.
+ */
+ .p2align 4,, 3
L(return_vec_1_end):
/* Use bsf to save code size. This is necessary to have
L(one_or_less) fit in aligning bytes between. */
- bsfl %eax, %eax
+ bsf %VRAX, %VRAX
addl %edx, %eax
# ifdef USE_AS_WMEMCMP
movl -(VEC_SIZE * 2)(%rdi, %rax, CHAR_SIZE), %ecx
@@ -439,10 +480,11 @@ L(return_vec_1_end):
# endif
ret
+ .p2align 4,, 2
/* Don't align. Takes 2-fetch blocks either way and aligning
will cause code to spill into another cacheline. */
L(return_vec_0_end):
- tzcntl %eax, %eax
+ bsf %VRAX, %VRAX
addl %edx, %eax
# ifdef USE_AS_WMEMCMP
movl -VEC_SIZE(%rdi, %rax, CHAR_SIZE), %ecx
@@ -456,7 +498,7 @@ L(return_vec_0_end):
subl %ecx, %eax
# endif
ret
- /* 1-byte until next cache line. */
-
+ /* evex256: 2-byte until next cache line. evex512: 46-bytes
+ until next cache line. */
END (MEMCMP)
#endif
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