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* [glibc] x86: Use VMM API in memcmpeq-evex.S and minor changes
@ 2022-11-09 4:33 Noah Goldstein
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From: Noah Goldstein @ 2022-11-09 4:33 UTC (permalink / raw)
To: glibc-cvs
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=2d2493a644092dd3d32dd3b8f6aa3adad351db3c
commit 2d2493a644092dd3d32dd3b8f6aa3adad351db3c
Author: Noah Goldstein <goldstein.w.n@gmail.com>
Date: Sat Oct 29 15:19:59 2022 -0500
x86: Use VMM API in memcmpeq-evex.S and minor changes
Changes to generated code are:
1. In a few places use `vpcmpeqb` instead of `vpcmpneq` to save a
byte of code size.
2. Add a branch for length <= (VEC_SIZE * 6) as opposed to doing
the entire block of [VEC_SIZE * 4 + 1, VEC_SIZE * 8] in a
single basic-block (the space to add the extra branch without
changing code size is bought with the above change).
Change (2) has roughly a 20-25% speedup for sizes in [VEC_SIZE * 4 +
1, VEC_SIZE * 6] and negligible to no-cost for [VEC_SIZE * 6 + 1,
VEC_SIZE * 8]
From N=10 runs on Tigerlake:
align1,align2 ,length ,result ,New Time ,Cur Time ,New Time / Old Time
0 ,0 ,129 ,0 ,5.404 ,6.887 ,0.785
0 ,0 ,129 ,1 ,5.308 ,6.826 ,0.778
0 ,0 ,129 ,18446744073709551615 ,5.359 ,6.823 ,0.785
0 ,0 ,161 ,0 ,5.284 ,6.827 ,0.774
0 ,0 ,161 ,1 ,5.317 ,6.745 ,0.788
0 ,0 ,161 ,18446744073709551615 ,5.406 ,6.778 ,0.798
0 ,0 ,193 ,0 ,6.804 ,6.802 ,1.000
0 ,0 ,193 ,1 ,6.950 ,6.754 ,1.029
0 ,0 ,193 ,18446744073709551615 ,6.792 ,6.719 ,1.011
0 ,0 ,225 ,0 ,6.625 ,6.699 ,0.989
0 ,0 ,225 ,1 ,6.776 ,6.735 ,1.003
0 ,0 ,225 ,18446744073709551615 ,6.758 ,6.738 ,0.992
0 ,0 ,256 ,0 ,5.402 ,5.462 ,0.989
0 ,0 ,256 ,1 ,5.364 ,5.483 ,0.978
0 ,0 ,256 ,18446744073709551615 ,5.341 ,5.539 ,0.964
Rewriting with VMM API allows for memcmpeq-evex 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/memcmpeq-evex.S | 255 +++++++++++++++++++------------
1 file changed, 155 insertions(+), 100 deletions(-)
diff --git a/sysdeps/x86_64/multiarch/memcmpeq-evex.S b/sysdeps/x86_64/multiarch/memcmpeq-evex.S
index 41124ef1d3..671d19393e 100644
--- a/sysdeps/x86_64/multiarch/memcmpeq-evex.S
+++ b/sysdeps/x86_64/multiarch/memcmpeq-evex.S
@@ -41,24 +41,53 @@
# define MEMCMPEQ __memcmpeq_evex
# endif
+# ifndef VEC_SIZE
+# include "x86-evex512-vecs.h"
+# endif
+# include "reg-macros.h"
+
+
+# if VEC_SIZE == 32
+
+# define TEST_ZERO_VCMP(reg) inc %VGPR(reg)
+# define TEST_ZERO(reg) test %VGPR(reg), %VGPR(reg)
+
+# define TO_32BIT_P1(reg) /* Do nothing. */
+# define TO_32BIT_P2(reg) /* Do nothing. */
+# define TO_32BIT(reg) /* Do nothing. */
+
+# define VEC_CMP VPCMPEQ
+
+# elif VEC_SIZE == 64
+
+# define TEST_ZERO_VCMP(reg) TEST_ZERO(reg)
+# define TEST_ZERO(reg) neg %VGPR(reg)
+
+
+ /* VEC_SIZE == 64 needs to reduce the 64-bit mask to a 32-bit
+ int. We have two methods for this. If the mask with branched
+ on, we use `neg` for the branch then `sbb` to get the 32-bit
+ return. If the mask was no branched on, we just use
+ `popcntq`. */
+# define TO_32BIT_P1(reg) TEST_ZERO(reg)
+# define TO_32BIT_P2(reg) sbb %VGPR_SZ(reg, 32), %VGPR_SZ(reg, 32)
+# define TO_32BIT(reg) popcntq %reg, %reg
+
+# define VEC_CMP VPCMPNEQ
+
+# else
+# error "Unsupported VEC_SIZE"
+# endif
+
+
# define VMOVU_MASK vmovdqu8
-# define VMOVU vmovdqu64
-# define VPCMP vpcmpub
+# define VPCMPNEQ vpcmpneqb
+# define VPCMPEQ vpcmpeqb
# define VPTEST vptestmb
-# define VEC_SIZE 32
# define PAGE_SIZE 4096
-# define YMM0 ymm16
-# define YMM1 ymm17
-# define YMM2 ymm18
-# define YMM3 ymm19
-# define YMM4 ymm20
-# define YMM5 ymm21
-# define YMM6 ymm22
-
-
- .section .text.evex, "ax", @progbits
+ .section SECTION(.text), "ax", @progbits
ENTRY_P2ALIGN (MEMCMPEQ, 6)
# ifdef __ILP32__
/* Clear the upper 32 bits. */
@@ -69,47 +98,54 @@ ENTRY_P2ALIGN (MEMCMPEQ, 6)
ja L(more_1x_vec)
/* 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. */
- movl $-1, %ecx
- bzhil %edx, %ecx, %ecx
- kmovd %ecx, %k2
+ 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
/* Use masked loads as VEC_SIZE could page cross where length
(edx) would not. */
- VMOVU_MASK (%rsi), %YMM2{%k2}
- VPCMP $4,(%rdi), %YMM2, %k1{%k2}
- kmovd %k1, %eax
+ VMOVU_MASK (%rsi), %VMM(2){%k2}{z}
+ VPCMPNEQ (%rdi), %VMM(2), %k1{%k2}
+ KMOV %k1, %VRAX
+ TO_32BIT (VRAX)
ret
-
+ .p2align 4,, 3
L(last_1x_vec):
- VMOVU -(VEC_SIZE * 1)(%rsi, %rdx), %YMM1
- VPCMP $4, -(VEC_SIZE * 1)(%rdi, %rdx), %YMM1, %k1
- kmovd %k1, %eax
+ VMOVU -(VEC_SIZE * 1)(%rsi, %rdx), %VMM(1)
+ VPCMPNEQ -(VEC_SIZE * 1)(%rdi, %rdx), %VMM(1), %k1
+ KMOV %k1, %VRAX
+ TO_32BIT_P1 (rax)
L(return_neq0):
+ TO_32BIT_P2 (rax)
ret
-
- .p2align 4
+ .p2align 4,, 12
L(more_1x_vec):
/* From VEC + 1 to 2 * VEC. */
- VMOVU (%rsi), %YMM1
+ VMOVU (%rsi), %VMM(1)
/* Use compare not equals to directly check for mismatch. */
- VPCMP $4,(%rdi), %YMM1, %k1
- kmovd %k1, %eax
- testl %eax, %eax
+ VPCMPNEQ (%rdi), %VMM(1), %k1
+ KMOV %k1, %VRAX
+ TEST_ZERO (rax)
jnz L(return_neq0)
cmpq $(VEC_SIZE * 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)
+ VPCMPNEQ VEC_SIZE(%rdi), %VMM(2), %k1
+ KMOV %k1, %VRAX
+ TEST_ZERO (rax)
jnz L(return_neq0)
/* Less than 4 * VEC. */
@@ -117,16 +153,16 @@ 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)
+ VEC_CMP (VEC_SIZE * 2)(%rdi), %VMM(3), %k1
+ KMOV %k1, %VRAX
+ TEST_ZERO_VCMP (rax)
jnz L(return_neq0)
- VMOVU (VEC_SIZE * 3)(%rsi), %YMM4
- VPCMP $4,(VEC_SIZE * 3)(%rdi), %YMM4, %k1
- kmovd %k1, %eax
- testl %eax, %eax
+ VMOVU (VEC_SIZE * 3)(%rsi), %VMM(4)
+ VEC_CMP (VEC_SIZE * 3)(%rdi), %VMM(4), %k1
+ KMOV %k1, %VRAX
+ TEST_ZERO_VCMP (rax)
jnz L(return_neq0)
/* Go to 4x VEC loop. */
@@ -136,8 +172,8 @@ L(more_1x_vec):
/* Handle remainder of size = 4 * VEC + 1 to 8 * VEC without any
branches. */
- VMOVU -(VEC_SIZE * 4)(%rsi, %rdx), %YMM1
- VMOVU -(VEC_SIZE * 3)(%rsi, %rdx), %YMM2
+ VMOVU -(VEC_SIZE * 1)(%rsi, %rdx), %VMM(1)
+ VMOVU -(VEC_SIZE * 2)(%rsi, %rdx), %VMM(2)
addq %rdx, %rdi
/* Wait to load from s1 until addressed adjust due to
@@ -145,26 +181,32 @@ L(more_1x_vec):
/* vpxor will be all 0s if s1 and s2 are equal. Otherwise it
will have some 1s. */
- vpxorq -(VEC_SIZE * 4)(%rdi), %YMM1, %YMM1
- /* Ternary logic to xor -(VEC_SIZE * 3)(%rdi) with YMM2 while
- oring with YMM1. Result is stored in YMM1. */
- vpternlogd $0xde, -(VEC_SIZE * 3)(%rdi), %YMM1, %YMM2
-
- VMOVU -(VEC_SIZE * 2)(%rsi, %rdx), %YMM3
- vpxorq -(VEC_SIZE * 2)(%rdi), %YMM3, %YMM3
- /* Or together YMM1, YMM2, and YMM3 into YMM3. */
- VMOVU -(VEC_SIZE)(%rsi, %rdx), %YMM4
- vpxorq -(VEC_SIZE)(%rdi), %YMM4, %YMM4
-
- /* Or together YMM2, YMM3, and YMM4 into YMM4. */
- vpternlogd $0xfe, %YMM2, %YMM3, %YMM4
-
- /* Compare YMM4 with 0. If any 1s s1 and s2 don't match. */
- VPTEST %YMM4, %YMM4, %k1
- kmovd %k1, %eax
+ vpxorq -(VEC_SIZE * 1)(%rdi), %VMM(1), %VMM(1)
+ /* Ternary logic to xor -(VEC_SIZE * 3)(%rdi) with VEC(2) while
+ oring with VEC(1). Result is stored in VEC(1). */
+ vpternlogd $0xde, -(VEC_SIZE * 2)(%rdi), %VMM(1), %VMM(2)
+
+ cmpl $(VEC_SIZE * 6), %edx
+ jbe L(4x_last_2x_vec)
+
+ VMOVU -(VEC_SIZE * 3)(%rsi, %rdx), %VMM(3)
+ vpxorq -(VEC_SIZE * 3)(%rdi), %VMM(3), %VMM(3)
+ /* Or together VEC(1), VEC(2), and VEC(3) into VEC(3). */
+ VMOVU -(VEC_SIZE * 4)(%rsi, %rdx), %VMM(4)
+ vpxorq -(VEC_SIZE * 4)(%rdi), %VMM(4), %VMM(4)
+
+ /* Or together VEC(4), VEC(3), and VEC(2) into VEC(2). */
+ vpternlogd $0xfe, %VMM(4), %VMM(3), %VMM(2)
+
+ /* Compare VEC(4) with 0. If any 1s s1 and s2 don't match. */
+L(4x_last_2x_vec):
+ VPTEST %VMM(2), %VMM(2), %k1
+ KMOV %k1, %VRAX
+ TO_32BIT (VRAX)
ret
- .p2align 4
+
+ .p2align 4,, 10
L(more_8x_vec):
/* Set end of s1 in rdx. */
leaq -(VEC_SIZE * 4)(%rdi, %rdx), %rdx
@@ -175,67 +217,80 @@ L(more_8x_vec):
andq $-VEC_SIZE, %rdi
/* Adjust because first 4x vec where check already. */
subq $-(VEC_SIZE * 4), %rdi
- .p2align 4
+ .p2align 5,, 12
+ .p2align 4,, 8
L(loop_4x_vec):
- VMOVU (%rsi, %rdi), %YMM1
- vpxorq (%rdi), %YMM1, %YMM1
+ VMOVU (%rsi, %rdi), %VMM(1)
+ vpxorq (%rdi), %VMM(1), %VMM(1)
- VMOVU VEC_SIZE(%rsi, %rdi), %YMM2
- vpternlogd $0xde,(VEC_SIZE)(%rdi), %YMM1, %YMM2
+ VMOVU VEC_SIZE(%rsi, %rdi), %VMM(2)
+ vpternlogd $0xde, (VEC_SIZE)(%rdi), %VMM(1), %VMM(2)
- VMOVU (VEC_SIZE * 2)(%rsi, %rdi), %YMM3
- vpxorq (VEC_SIZE * 2)(%rdi), %YMM3, %YMM3
+ VMOVU (VEC_SIZE * 2)(%rsi, %rdi), %VMM(3)
+ vpxorq (VEC_SIZE * 2)(%rdi), %VMM(3), %VMM(3)
- VMOVU (VEC_SIZE * 3)(%rsi, %rdi), %YMM4
- vpxorq (VEC_SIZE * 3)(%rdi), %YMM4, %YMM4
+ VMOVU (VEC_SIZE * 3)(%rsi, %rdi), %VMM(4)
+ vpxorq (VEC_SIZE * 3)(%rdi), %VMM(4), %VMM(4)
- vpternlogd $0xfe, %YMM2, %YMM3, %YMM4
- VPTEST %YMM4, %YMM4, %k1
- kmovd %k1, %eax
- testl %eax, %eax
+ vpternlogd $0xfe, %VMM(2), %VMM(3), %VMM(4)
+ VPTEST %VMM(4), %VMM(4), %k1
+ KMOV %k1, %VRAX
+ TEST_ZERO (rax)
jnz L(return_neq2)
subq $-(VEC_SIZE * 4), %rdi
cmpq %rdx, %rdi
jb L(loop_4x_vec)
subq %rdx, %rdi
- VMOVU (VEC_SIZE * 3)(%rsi, %rdx), %YMM4
- vpxorq (VEC_SIZE * 3)(%rdx), %YMM4, %YMM4
+
+ VMOVU (VEC_SIZE * 3)(%rsi, %rdx), %VMM(4)
+ vpxorq (VEC_SIZE * 3)(%rdx), %VMM(4), %VMM(4)
/* rdi has 4 * VEC_SIZE - remaining length. */
- cmpl $(VEC_SIZE * 3), %edi
- jae L(8x_last_1x_vec)
+
/* Load regardless of branch. */
- VMOVU (VEC_SIZE * 2)(%rsi, %rdx), %YMM3
- /* Ternary logic to xor (VEC_SIZE * 2)(%rdx) with YMM3 while
- oring with YMM4. Result is stored in YMM4. */
- vpternlogd $0xf6,(VEC_SIZE * 2)(%rdx), %YMM3, %YMM4
+ VMOVU (VEC_SIZE * 2)(%rsi, %rdx), %VMM(3)
+ /* Ternary logic to xor (VEC_SIZE * 2)(%rdx) with VEC(3) while
+ oring with VEC(4). Result is stored in VEC(4). */
+ vpternlogd $0xf6, (VEC_SIZE * 2)(%rdx), %VMM(3), %VMM(4)
+
+ /* 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
- jae L(8x_last_2x_vec)
+ jge L(8x_last_2x_vec)
+# endif
- VMOVU VEC_SIZE(%rsi, %rdx), %YMM2
- vpxorq VEC_SIZE(%rdx), %YMM2, %YMM2
+ VMOVU VEC_SIZE(%rsi, %rdx), %VMM(2)
+ vpxorq VEC_SIZE(%rdx), %VMM(2), %VMM(2)
- VMOVU (%rsi, %rdx), %YMM1
- vpxorq (%rdx), %YMM1, %YMM1
+ VMOVU (%rsi, %rdx), %VMM(1)
+ vpxorq (%rdx), %VMM(1), %VMM(1)
- vpternlogd $0xfe, %YMM1, %YMM2, %YMM4
+ vpternlogd $0xfe, %VMM(1), %VMM(2), %VMM(4)
L(8x_last_1x_vec):
L(8x_last_2x_vec):
- VPTEST %YMM4, %YMM4, %k1
- kmovd %k1, %eax
+ VPTEST %VMM(4), %VMM(4), %k1
+ KMOV %k1, %VRAX
+ TO_32BIT_P1 (rax)
L(return_neq2):
+ TO_32BIT_P2 (rax)
ret
- .p2align 4,, 8
+ .p2align 4,, 4
L(last_2x_vec):
- VMOVU -(VEC_SIZE * 2)(%rsi, %rdx), %YMM1
- vpxorq -(VEC_SIZE * 2)(%rdi, %rdx), %YMM1, %YMM1
- VMOVU -(VEC_SIZE * 1)(%rsi, %rdx), %YMM2
- vpternlogd $0xde, -(VEC_SIZE * 1)(%rdi, %rdx), %YMM1, %YMM2
- VPTEST %YMM2, %YMM2, %k1
- kmovd %k1, %eax
+ VMOVU -(VEC_SIZE * 2)(%rsi, %rdx), %VMM(1)
+ vpxorq -(VEC_SIZE * 2)(%rdi, %rdx), %VMM(1), %VMM(1)
+ VMOVU -(VEC_SIZE * 1)(%rsi, %rdx), %VMM(2)
+ vpternlogd $0xde, -(VEC_SIZE * 1)(%rdi, %rdx), %VMM(1), %VMM(2)
+ VPTEST %VMM(2), %VMM(2), %k1
+ KMOV %k1, %VRAX
+ TO_32BIT (VRAX)
ret
- /* 1 Bytes from next cache line. */
+ /* evex256: 1 Bytes from next cache line. evex512: 15 Bytes from
+ next cache line. */
END (MEMCMPEQ)
#endif
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