From 2d8eaea7ad74328d806d3f1a377f1168eaa2f348 Mon Sep 17 00:00:00 2001
From: Noah Goldstein <goldstein.w.n@gmail.com>
Date: Mon, 17 May 2021 13:57:24 -0400
Subject: [PATCH] x86: Optimize memcmp-evex-movbe.S
No bug. This commit optimizes memcmp-evex.S. The optimizations include
adding a new vec compare path for small sizes, reorganizing the entry
control flow, removing some unnecissary ALU instructions from the main
loop, and most importantly replacing the heavy use of vpcmp + kand
logic with vpxor + vptern. test-memcmp and test-wmemcmp are both
passing.
Signed-off-by: Noah Goldstein <goldstein.w.n@gmail.com>
Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
(cherry picked from commit 4ad473e97acdc5f6d811755b67c09f2128a644ce)
---
sysdeps/x86_64/multiarch/memcmp-evex-movbe.S | 710 +++++++++++--------
1 file changed, 408 insertions(+), 302 deletions(-)
diff --git a/sysdeps/x86_64/multiarch/memcmp-evex-movbe.S b/sysdeps/x86_64/multiarch/memcmp-evex-movbe.S
index 9c093972..654dc7ac 100644
--- a/sysdeps/x86_64/multiarch/memcmp-evex-movbe.S
+++ b/sysdeps/x86_64/multiarch/memcmp-evex-movbe.S
@@ -19,17 +19,22 @@
#if IS_IN (libc)
/* memcmp/wmemcmp is implemented as:
- 1. For size from 2 to 7 bytes, load as big endian with movbe and bswap
- to avoid branches.
- 2. Use overlapping compare to avoid branch.
- 3. Use vector compare when size >= 4 bytes for memcmp or size >= 8
- bytes for wmemcmp.
- 4. If size is 8 * VEC_SIZE or less, unroll the loop.
- 5. Compare 4 * VEC_SIZE at a time with the aligned first memory
+ 1. Use ymm vector compares when possible. The only case where
+ vector compares is not possible for when size < CHAR_PER_VEC
+ and loading from either s1 or s2 would cause a page cross.
+ 2. For size from 2 to 7 bytes on page cross, load as big endian
+ with movbe and bswap to avoid branches.
+ 3. Use xmm vector compare when size >= 4 bytes for memcmp or
+ size >= 8 bytes for wmemcmp.
+ 4. Optimistically compare up to first 4 * CHAR_PER_VEC one at a
+ to check for early mismatches. Only do this if its guranteed the
+ work is not wasted.
+ 5. If size is 8 * VEC_SIZE or less, unroll the loop.
+ 6. Compare 4 * VEC_SIZE at a time with the aligned first memory
area.
- 6. Use 2 vector compares when size is 2 * VEC_SIZE or less.
- 7. Use 4 vector compares when size is 4 * VEC_SIZE or less.
- 8. Use 8 vector compares when size is 8 * VEC_SIZE or less. */
+ 7. Use 2 vector compares when size is 2 * CHAR_PER_VEC or less.
+ 8. Use 4 vector compares when size is 4 * CHAR_PER_VEC or less.
+ 9. Use 8 vector compares when size is 8 * CHAR_PER_VEC or less. */
# include <sysdep.h>
@@ -40,11 +45,21 @@
# define VMOVU vmovdqu64
# ifdef USE_AS_WMEMCMP
-# define VPCMPEQ vpcmpeqd
+# define CHAR_SIZE 4
+# define VPCMP vpcmpd
# else
-# define VPCMPEQ vpcmpeqb
+# define CHAR_SIZE 1
+# define VPCMP vpcmpub
# endif
+# 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
@@ -54,15 +69,6 @@
# define YMM5 ymm21
# define YMM6 ymm22
-# define VEC_SIZE 32
-# ifdef USE_AS_WMEMCMP
-# define VEC_MASK 0xff
-# define XMM_MASK 0xf
-# else
-# define VEC_MASK 0xffffffff
-# define XMM_MASK 0xffff
-# endif
-
/* Warning!
wmemcmp has to use SIGNED comparison for elements.
memcmp has to use UNSIGNED comparison for elemnts.
@@ -70,145 +76,370 @@
.section .text.evex,"ax",@progbits
ENTRY (MEMCMP)
-# ifdef USE_AS_WMEMCMP
- shl $2, %RDX_LP
-# elif defined __ILP32__
+# ifdef __ILP32__
/* Clear the upper 32 bits. */
movl %edx, %edx
# endif
- cmp $VEC_SIZE, %RDX_LP
+ cmp $CHAR_PER_VEC, %RDX_LP
jb L(less_vec)
/* From VEC to 2 * VEC. No branch when size == VEC_SIZE. */
- VMOVU (%rsi), %YMM2
- VPCMPEQ (%rdi), %YMM2, %k1
+ VMOVU (%rsi), %YMM1
+ /* Use compare not equals to directly check for mismatch. */
+ VPCMP $4, (%rdi), %YMM1, %k1
kmovd %k1, %eax
- subl $VEC_MASK, %eax
- jnz L(first_vec)
-
- cmpq $(VEC_SIZE * 2), %rdx
- jbe L(last_vec)
-
- /* More than 2 * VEC. */
- cmpq $(VEC_SIZE * 8), %rdx
- ja L(more_8x_vec)
- cmpq $(VEC_SIZE * 4), %rdx
- jb L(last_4x_vec)
+ /* 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
+ jnz L(return_vec_0)
- /* From 4 * VEC to 8 * VEC, inclusively. */
- VMOVU (%rsi), %YMM1
- VPCMPEQ (%rdi), %YMM1, %k1
+ cmpq $(CHAR_PER_VEC * 2), %rdx
+ jbe L(last_1x_vec)
+ /* Check second VEC no matter what. */
VMOVU VEC_SIZE(%rsi), %YMM2
- VPCMPEQ VEC_SIZE(%rdi), %YMM2, %k2
+ VPCMP $4, VEC_SIZE(%rdi), %YMM2, %k1
+ kmovd %k1, %eax
+ testl %eax, %eax
+ jnz L(return_vec_1)
+
+ /* Less than 4 * VEC. */
+ cmpq $(CHAR_PER_VEC * 4), %rdx
+ jbe L(last_2x_vec)
+ /* Check third and fourth VEC no matter what. */
VMOVU (VEC_SIZE * 2)(%rsi), %YMM3
- VPCMPEQ (VEC_SIZE * 2)(%rdi), %YMM3, %k3
+ VPCMP $4, (VEC_SIZE * 2)(%rdi), %YMM3, %k1
+ kmovd %k1, %eax
+ testl %eax, %eax
+ jnz L(return_vec_2)
VMOVU (VEC_SIZE * 3)(%rsi), %YMM4
- VPCMPEQ (VEC_SIZE * 3)(%rdi), %YMM4, %k4
+ VPCMP $4, (VEC_SIZE * 3)(%rdi), %YMM4, %k1
+ kmovd %k1, %ecx
+ testl %ecx, %ecx
+ jnz L(return_vec_3)
- kandd %k1, %k2, %k5
- kandd %k3, %k4, %k6
- kandd %k5, %k6, %k6
+ /* Zero YMM0. 4x VEC reduction is done with vpxor + vtern so
+ compare with zero to get a mask is needed. */
+ vpxorq %XMM0, %XMM0, %XMM0
- kmovd %k6, %eax
- cmpl $VEC_MASK, %eax
- jne L(4x_vec_end)
+ /* Go to 4x VEC loop. */
+ cmpq $(CHAR_PER_VEC * 8), %rdx
+ ja L(more_8x_vec)
- leaq -(4 * VEC_SIZE)(%rdi, %rdx), %rdi
- leaq -(4 * VEC_SIZE)(%rsi, %rdx), %rsi
- VMOVU (%rsi), %YMM1
- VPCMPEQ (%rdi), %YMM1, %k1
+ /* Handle remainder of size = 4 * VEC + 1 to 8 * VEC without any
+ branches. */
- VMOVU VEC_SIZE(%rsi), %YMM2
- VPCMPEQ VEC_SIZE(%rdi), %YMM2, %k2
- kandd %k1, %k2, %k5
+ /* 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
+ leaq -(4 * VEC_SIZE)(%rdi, %rdx, CHAR_SIZE), %rdi
+ leaq -(4 * VEC_SIZE)(%rsi, %rdx, CHAR_SIZE), %rsi
+
+ /* Wait to load from s1 until addressed adjust due to
+ unlamination of microfusion with complex address mode. */
+
+ /* 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
VMOVU (VEC_SIZE * 2)(%rsi), %YMM3
- VPCMPEQ (VEC_SIZE * 2)(%rdi), %YMM3, %k3
- kandd %k3, %k5, %k5
+ vpxorq (VEC_SIZE * 2)(%rdi), %YMM3, %YMM3
+ /* Or together YMM1, YMM2, and YMM3 into YMM3. */
+ vpternlogd $0xfe, %YMM1, %YMM2, %YMM3
VMOVU (VEC_SIZE * 3)(%rsi), %YMM4
- VPCMPEQ (VEC_SIZE * 3)(%rdi), %YMM4, %k4
- kandd %k4, %k5, %k5
+ /* Ternary logic to xor (VEC_SIZE * 3)(%rdi) with YMM4 while
+ oring with YMM3. Result is stored in YMM4. */
+ vpternlogd $0xde, (VEC_SIZE * 3)(%rdi), %YMM3, %YMM4
+ /* Compare YMM4 with 0. If any 1s s1 and s2 don't match. */
+ VPCMP $4, %YMM4, %YMM0, %k1
+ kmovd %k1, %ecx
+ testl %ecx, %ecx
+ jnz L(return_vec_0_1_2_3)
+ /* NB: eax must be zero to reach here. */
+ ret
- kmovd %k5, %eax
- cmpl $VEC_MASK, %eax
- jne L(4x_vec_end)
- xorl %eax, %eax
+ /* NB: aligning 32 here allows for the rest of the jump targets
+ to be tuned for 32 byte alignment. Most important this ensures
+ the L(more_8x_vec) loop is 32 byte aligned. */
+ .p2align 5
+L(less_vec):
+ /* Check if one or less CHAR. This is necessary for size = 0 but
+ is also faster for size = CHAR_SIZE. */
+ cmpl $1, %edx
+ jbe L(one_or_less)
+
+ /* Check if loading one VEC from either s1 or s2 could cause a
+ page cross. This can have false positives but is by far the
+ fastest method. */
+ movl %edi, %eax
+ orl %esi, %eax
+ andl $(PAGE_SIZE - 1), %eax
+ cmpl $(PAGE_SIZE - VEC_SIZE), %eax
+ jg L(page_cross_less_vec)
+
+ /* No page cross possible. */
+ VMOVU (%rsi), %YMM2
+ VPCMP $4, (%rdi), %YMM2, %k1
+ kmovd %k1, %eax
+ /* Create mask in ecx for potentially in bound matches. */
+ bzhil %edx, %eax, %eax
+ jnz L(return_vec_0)
ret
.p2align 4
-L(last_2x_vec):
- /* From VEC to 2 * VEC. No branch when size == VEC_SIZE. */
- VMOVU (%rsi), %YMM2
- VPCMPEQ (%rdi), %YMM2, %k2
- kmovd %k2, %eax
- subl $VEC_MASK, %eax
- jnz L(first_vec)
+L(return_vec_0):
+ tzcntl %eax, %eax
+# ifdef USE_AS_WMEMCMP
+ movl (%rdi, %rax, CHAR_SIZE), %ecx
+ xorl %edx, %edx
+ cmpl (%rsi, %rax, CHAR_SIZE), %ecx
+ /* NB: no partial register stall here because xorl zero idiom
+ above. */
+ setg %dl
+ leal -1(%rdx, %rdx), %eax
+# else
+ movzbl (%rsi, %rax), %ecx
+ movzbl (%rdi, %rax), %eax
+ subl %ecx, %eax
+# endif
+ ret
-L(last_vec):
- /* Use overlapping loads to avoid branches. */
- leaq -VEC_SIZE(%rdi, %rdx), %rdi
- leaq -VEC_SIZE(%rsi, %rdx), %rsi
- VMOVU (%rsi), %YMM2
- VPCMPEQ (%rdi), %YMM2, %k2
- kmovd %k2, %eax
- subl $VEC_MASK, %eax
- jnz L(first_vec)
+ /* NB: No p2align necessary. Alignment % 16 is naturally 1
+ which is good enough for a target not in a loop. */
+L(return_vec_1):
+ tzcntl %eax, %eax
+# ifdef USE_AS_WMEMCMP
+ movl VEC_SIZE(%rdi, %rax, CHAR_SIZE), %ecx
+ xorl %edx, %edx
+ cmpl VEC_SIZE(%rsi, %rax, CHAR_SIZE), %ecx
+ setg %dl
+ leal -1(%rdx, %rdx), %eax
+# else
+ movzbl VEC_SIZE(%rsi, %rax), %ecx
+ movzbl VEC_SIZE(%rdi, %rax), %eax
+ subl %ecx, %eax
+# endif
ret
- .p2align 4
-L(first_vec):
- /* A byte or int32 is different within 16 or 32 bytes. */
- tzcntl %eax, %ecx
+ /* NB: No p2align necessary. Alignment % 16 is naturally 2
+ which is good enough for a target not in a loop. */
+L(return_vec_2):
+ tzcntl %eax, %eax
# ifdef USE_AS_WMEMCMP
- xorl %eax, %eax
- movl (%rdi, %rcx, 4), %edx
- cmpl (%rsi, %rcx, 4), %edx
-L(wmemcmp_return):
- setl %al
- negl %eax
- orl $1, %eax
+ movl (VEC_SIZE * 2)(%rdi, %rax, CHAR_SIZE), %ecx
+ xorl %edx, %edx
+ cmpl (VEC_SIZE * 2)(%rsi, %rax, CHAR_SIZE), %ecx
+ setg %dl
+ leal -1(%rdx, %rdx), %eax
# else
- movzbl (%rdi, %rcx), %eax
- movzbl (%rsi, %rcx), %edx
- sub %edx, %eax
+ movzbl (VEC_SIZE * 2)(%rsi, %rax), %ecx
+ movzbl (VEC_SIZE * 2)(%rdi, %rax), %eax
+ subl %ecx, %eax
# endif
ret
+ .p2align 4
+L(8x_return_vec_0_1_2_3):
+ /* Returning from L(more_8x_vec) requires restoring rsi. */
+ addq %rdi, %rsi
+L(return_vec_0_1_2_3):
+ VPCMP $4, %YMM1, %YMM0, %k0
+ kmovd %k0, %eax
+ testl %eax, %eax
+ jnz L(return_vec_0)
+
+ VPCMP $4, %YMM2, %YMM0, %k0
+ kmovd %k0, %eax
+ testl %eax, %eax
+ jnz L(return_vec_1)
+
+ VPCMP $4, %YMM3, %YMM0, %k0
+ kmovd %k0, %eax
+ testl %eax, %eax
+ jnz L(return_vec_2)
+L(return_vec_3):
+ tzcntl %ecx, %ecx
# ifdef USE_AS_WMEMCMP
+ movl (VEC_SIZE * 3)(%rdi, %rcx, CHAR_SIZE), %eax
+ xorl %edx, %edx
+ cmpl (VEC_SIZE * 3)(%rsi, %rcx, CHAR_SIZE), %eax
+ setg %dl
+ leal -1(%rdx, %rdx), %eax
+# else
+ movzbl (VEC_SIZE * 3)(%rdi, %rcx), %eax
+ movzbl (VEC_SIZE * 3)(%rsi, %rcx), %ecx
+ subl %ecx, %eax
+# endif
+ ret
+
.p2align 4
-L(4):
- xorl %eax, %eax
- movl (%rdi), %edx
- cmpl (%rsi), %edx
- jne L(wmemcmp_return)
+L(more_8x_vec):
+ /* Set end of s1 in rdx. */
+ leaq -(VEC_SIZE * 4)(%rdi, %rdx, CHAR_SIZE), %rdx
+ /* rsi stores s2 - s1. This allows loop to only update one
+ pointer. */
+ subq %rdi, %rsi
+ /* Align s1 pointer. */
+ andq $-VEC_SIZE, %rdi
+ /* Adjust because first 4x vec where check already. */
+ subq $-(VEC_SIZE * 4), %rdi
+ .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
+ vpternlogd $0xfe, %YMM1, %YMM2, %YMM3
+
+ VMOVU (VEC_SIZE * 3)(%rsi, %rdi), %YMM4
+ vpternlogd $0xde, (VEC_SIZE * 3)(%rdi), %YMM3, %YMM4
+ VPCMP $4, %YMM4, %YMM0, %k1
+ kmovd %k1, %ecx
+ testl %ecx, %ecx
+ 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)
+ /* Load regardless of branch. */
+ VMOVU (VEC_SIZE * 2)(%rsi, %rdx), %YMM3
+ cmpl $(VEC_SIZE * 2), %edi
+ jae L(8x_last_2x_vec)
+
+ VMOVU (%rsi, %rdx), %YMM1
+ vpxorq (%rdx), %YMM1, %YMM1
+
+ VMOVU VEC_SIZE(%rsi, %rdx), %YMM2
+ vpxorq VEC_SIZE(%rdx), %YMM2, %YMM2
+
+ vpxorq (VEC_SIZE * 2)(%rdx), %YMM3, %YMM3
+ vpternlogd $0xfe, %YMM1, %YMM2, %YMM3
+
+ VMOVU (VEC_SIZE * 3)(%rsi, %rdx), %YMM4
+ vpternlogd $0xde, (VEC_SIZE * 3)(%rdx), %YMM3, %YMM4
+ VPCMP $4, %YMM4, %YMM0, %k1
+ kmovd %k1, %ecx
+ /* Restore s1 pointer to rdi. */
+ movq %rdx, %rdi
+ testl %ecx, %ecx
+ jnz L(8x_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
+L(8x_last_2x_vec):
+ VPCMP $4, (VEC_SIZE * 2)(%rdx), %YMM3, %k1
+ kmovd %k1, %eax
+ testl %eax, %eax
+ jnz L(8x_return_vec_2)
+ /* Naturally aligned to 16 bytes. */
+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
+ jnz L(8x_return_vec_3)
+ ret
+
+ .p2align 4
+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
+ jnz L(return_vec_1_end)
+
+ /* Check last VEC. */
+ .p2align 4
+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
+ jnz L(return_vec_0_end)
ret
+
+ .p2align 4
+L(8x_return_vec_2):
+ subq $VEC_SIZE, %rdx
+L(8x_return_vec_3):
+ tzcntl %eax, %eax
+# ifdef USE_AS_WMEMCMP
+ leaq (%rdx, %rax, CHAR_SIZE), %rax
+ movl (VEC_SIZE * 3)(%rax), %ecx
+ xorl %edx, %edx
+ cmpl (VEC_SIZE * 3)(%rsi, %rax), %ecx
+ setg %dl
+ leal -1(%rdx, %rdx), %eax
# else
+ addq %rdx, %rax
+ movzbl (VEC_SIZE * 3)(%rsi, %rax), %ecx
+ movzbl (VEC_SIZE * 3)(%rax), %eax
+ subl %ecx, %eax
+# endif
+ ret
+
.p2align 4
-L(between_4_7):
- /* Load as big endian with overlapping movbe to avoid branches. */
- movbe (%rdi), %eax
- movbe (%rsi), %ecx
- shlq $32, %rax
- shlq $32, %rcx
- movbe -4(%rdi, %rdx), %edi
- movbe -4(%rsi, %rdx), %esi
- orq %rdi, %rax
- orq %rsi, %rcx
- subq %rcx, %rax
- je L(exit)
- sbbl %eax, %eax
- orl $1, %eax
+L(return_vec_0_end):
+ tzcntl %eax, %eax
+ addl %edx, %eax
+# ifdef USE_AS_WMEMCMP
+ movl -VEC_SIZE(%rdi, %rax, CHAR_SIZE), %ecx
+ xorl %edx, %edx
+ cmpl -VEC_SIZE(%rsi, %rax, CHAR_SIZE), %ecx
+ setg %dl
+ leal -1(%rdx, %rdx), %eax
+# else
+ movzbl -VEC_SIZE(%rsi, %rax), %ecx
+ movzbl -VEC_SIZE(%rdi, %rax), %eax
+ subl %ecx, %eax
+# endif
ret
.p2align 4
-L(exit):
+L(return_vec_1_end):
+ tzcntl %eax, %eax
+ addl %edx, %eax
+# ifdef USE_AS_WMEMCMP
+ movl -(VEC_SIZE * 2)(%rdi, %rax, CHAR_SIZE), %ecx
+ xorl %edx, %edx
+ cmpl -(VEC_SIZE * 2)(%rsi, %rax, CHAR_SIZE), %ecx
+ setg %dl
+ leal -1(%rdx, %rdx), %eax
+# else
+ movzbl -(VEC_SIZE * 2)(%rsi, %rax), %ecx
+ movzbl -(VEC_SIZE * 2)(%rdi, %rax), %eax
+ subl %ecx, %eax
+# endif
ret
+
.p2align 4
+L(page_cross_less_vec):
+ /* if USE_AS_WMEMCMP it can only be 0, 4, 8, 12, 16, 20, 24, 28
+ bytes. */
+ cmpl $(16 / CHAR_SIZE), %edx
+ jae L(between_16_31)
+# ifndef USE_AS_WMEMCMP
+ cmpl $8, %edx
+ jae L(between_8_15)
+ cmpl $4, %edx
+ jae L(between_4_7)
L(between_2_3):
/* Load as big endian to avoid branches. */
movzwl (%rdi), %eax
@@ -217,224 +448,99 @@ L(between_2_3):
shll $8, %ecx
bswap %eax
bswap %ecx
- movb -1(%rdi, %rdx), %al
- movb -1(%rsi, %rdx), %cl
+ movzbl -1(%rdi, %rdx), %edi
+ movzbl -1(%rsi, %rdx), %esi
+ orl %edi, %eax
+ orl %esi, %ecx
/* Subtraction is okay because the upper 8 bits are zero. */
subl %ecx, %eax
ret
-
.p2align 4
-L(1):
- movzbl (%rdi), %eax
+L(one_or_less):
+ jb L(zero)
movzbl (%rsi), %ecx
+ movzbl (%rdi), %eax
subl %ecx, %eax
ret
-# endif
-
- .p2align 4
-L(zero):
- xorl %eax, %eax
- ret
.p2align 4
-L(less_vec):
-# ifdef USE_AS_WMEMCMP
- /* It can only be 0, 4, 8, 12, 16, 20, 24, 28 bytes. */
- cmpb $4, %dl
- je L(4)
- jb L(zero)
-# else
- cmpb $1, %dl
- je L(1)
- jb L(zero)
- cmpb $4, %dl
- jb L(between_2_3)
- cmpb $8, %dl
- jb L(between_4_7)
+L(between_8_15):
# endif
- cmpb $16, %dl
- jae L(between_16_31)
- /* It is between 8 and 15 bytes. */
+ /* If USE_AS_WMEMCMP fall through into 8-15 byte case. */
vmovq (%rdi), %XMM1
vmovq (%rsi), %XMM2
- VPCMPEQ %XMM1, %XMM2, %k2
- kmovw %k2, %eax
- subl $XMM_MASK, %eax
- jnz L(first_vec)
+ VPCMP $4, %XMM1, %XMM2, %k1
+ kmovd %k1, %eax
+ testl %eax, %eax
+ jnz L(return_vec_0)
/* Use overlapping loads to avoid branches. */
- leaq -8(%rdi, %rdx), %rdi
- leaq -8(%rsi, %rdx), %rsi
+ leaq -8(%rdi, %rdx, CHAR_SIZE), %rdi
+ leaq -8(%rsi, %rdx, CHAR_SIZE), %rsi
vmovq (%rdi), %XMM1
vmovq (%rsi), %XMM2
- VPCMPEQ %XMM1, %XMM2, %k2
- kmovw %k2, %eax
- subl $XMM_MASK, %eax
- jnz L(first_vec)
+ VPCMP $4, %XMM1, %XMM2, %k1
+ kmovd %k1, %eax
+ testl %eax, %eax
+ jnz L(return_vec_0)
ret
.p2align 4
-L(between_16_31):
- /* From 16 to 31 bytes. No branch when size == 16. */
- VMOVU (%rsi), %XMM2
- VPCMPEQ (%rdi), %XMM2, %k2
- kmovw %k2, %eax
- subl $XMM_MASK, %eax
- jnz L(first_vec)
-
- /* Use overlapping loads to avoid branches. */
- leaq -16(%rdi, %rdx), %rdi
- leaq -16(%rsi, %rdx), %rsi
- VMOVU (%rsi), %XMM2
- VPCMPEQ (%rdi), %XMM2, %k2
- kmovw %k2, %eax
- subl $XMM_MASK, %eax
- jnz L(first_vec)
+L(zero):
+ xorl %eax, %eax
ret
.p2align 4
-L(more_8x_vec):
- /* More than 8 * VEC. Check the first VEC. */
- VMOVU (%rsi), %YMM2
- VPCMPEQ (%rdi), %YMM2, %k2
- kmovd %k2, %eax
- subl $VEC_MASK, %eax
- jnz L(first_vec)
-
- /* Align the first memory area for aligned loads in the loop.
- Compute how much the first memory area is misaligned. */
- movq %rdi, %rcx
- andl $(VEC_SIZE - 1), %ecx
- /* Get the negative of offset for alignment. */
- subq $VEC_SIZE, %rcx
- /* Adjust the second memory area. */
- subq %rcx, %rsi
- /* Adjust the first memory area which should be aligned now. */
- subq %rcx, %rdi
- /* Adjust length. */
- addq %rcx, %rdx
-
-L(loop_4x_vec):
- /* Compare 4 * VEC at a time forward. */
- VMOVU (%rsi), %YMM1
- VPCMPEQ (%rdi), %YMM1, %k1
-
- VMOVU VEC_SIZE(%rsi), %YMM2
- VPCMPEQ VEC_SIZE(%rdi), %YMM2, %k2
- kandd %k2, %k1, %k5
-
- VMOVU (VEC_SIZE * 2)(%rsi), %YMM3
- VPCMPEQ (VEC_SIZE * 2)(%rdi), %YMM3, %k3
- kandd %k3, %k5, %k5
-
- VMOVU (VEC_SIZE * 3)(%rsi), %YMM4
- VPCMPEQ (VEC_SIZE * 3)(%rdi), %YMM4, %k4
- kandd %k4, %k5, %k5
-
- kmovd %k5, %eax
- cmpl $VEC_MASK, %eax
- jne L(4x_vec_end)
-
- addq $(VEC_SIZE * 4), %rdi
- addq $(VEC_SIZE * 4), %rsi
-
- subq $(VEC_SIZE * 4), %rdx
- cmpq $(VEC_SIZE * 4), %rdx
- jae L(loop_4x_vec)
-
- /* Less than 4 * VEC. */
- cmpq $VEC_SIZE, %rdx
- jbe L(last_vec)
- cmpq $(VEC_SIZE * 2), %rdx
- jbe L(last_2x_vec)
-
-L(last_4x_vec):
- /* From 2 * VEC to 4 * VEC. */
- VMOVU (%rsi), %YMM2
- VPCMPEQ (%rdi), %YMM2, %k2
- kmovd %k2, %eax
- subl $VEC_MASK, %eax
- jnz L(first_vec)
-
- addq $VEC_SIZE, %rdi
- addq $VEC_SIZE, %rsi
- VMOVU (%rsi), %YMM2
- VPCMPEQ (%rdi), %YMM2, %k2
- kmovd %k2, %eax
- subl $VEC_MASK, %eax
- jnz L(first_vec)
+L(between_16_31):
+ /* From 16 to 31 bytes. No branch when size == 16. */
+ VMOVU (%rsi), %XMM2
+ VPCMP $4, (%rdi), %XMM2, %k1
+ kmovd %k1, %eax
+ testl %eax, %eax
+ jnz L(return_vec_0)
/* Use overlapping loads to avoid branches. */
- leaq -(3 * VEC_SIZE)(%rdi, %rdx), %rdi
- leaq -(3 * VEC_SIZE)(%rsi, %rdx), %rsi
- VMOVU (%rsi), %YMM2
- VPCMPEQ (%rdi), %YMM2, %k2
- kmovd %k2, %eax
- subl $VEC_MASK, %eax
- jnz L(first_vec)
- addq $VEC_SIZE, %rdi
- addq $VEC_SIZE, %rsi
- VMOVU (%rsi), %YMM2
- VPCMPEQ (%rdi), %YMM2, %k2
- kmovd %k2, %eax
- subl $VEC_MASK, %eax
- jnz L(first_vec)
- ret
-
- .p2align 4
-L(4x_vec_end):
+ VMOVU -16(%rsi, %rdx, CHAR_SIZE), %XMM2
+ leaq -16(%rdi, %rdx, CHAR_SIZE), %rdi
+ leaq -16(%rsi, %rdx, CHAR_SIZE), %rsi
+ VPCMP $4, (%rdi), %XMM2, %k1
kmovd %k1, %eax
- subl $VEC_MASK, %eax
- jnz L(first_vec)
- kmovd %k2, %eax
- subl $VEC_MASK, %eax
- jnz L(first_vec_x1)
- kmovd %k3, %eax
- subl $VEC_MASK, %eax
- jnz L(first_vec_x2)
- kmovd %k4, %eax
- subl $VEC_MASK, %eax
- tzcntl %eax, %ecx
-# ifdef USE_AS_WMEMCMP
- xorl %eax, %eax
- movl (VEC_SIZE * 3)(%rdi, %rcx, 4), %edx
- cmpl (VEC_SIZE * 3)(%rsi, %rcx, 4), %edx
- jmp L(wmemcmp_return)
-# else
- movzbl (VEC_SIZE * 3)(%rdi, %rcx), %eax
- movzbl (VEC_SIZE * 3)(%rsi, %rcx), %edx
- sub %edx, %eax
-# endif
+ testl %eax, %eax
+ jnz L(return_vec_0)
ret
- .p2align 4
-L(first_vec_x1):
- tzcntl %eax, %ecx
# ifdef USE_AS_WMEMCMP
- xorl %eax, %eax
- movl VEC_SIZE(%rdi, %rcx, 4), %edx
- cmpl VEC_SIZE(%rsi, %rcx, 4), %edx
- jmp L(wmemcmp_return)
-# else
- movzbl VEC_SIZE(%rdi, %rcx), %eax
- movzbl VEC_SIZE(%rsi, %rcx), %edx
- sub %edx, %eax
-# endif
+ .p2align 4
+L(one_or_less):
+ jb L(zero)
+ movl (%rdi), %ecx
+ xorl %edx, %edx
+ cmpl (%rsi), %ecx
+ je L(zero)
+ setg %dl
+ leal -1(%rdx, %rdx), %eax
ret
+# else
.p2align 4
-L(first_vec_x2):
- tzcntl %eax, %ecx
-# ifdef USE_AS_WMEMCMP
- xorl %eax, %eax
- movl (VEC_SIZE * 2)(%rdi, %rcx, 4), %edx
- cmpl (VEC_SIZE * 2)(%rsi, %rcx, 4), %edx
- jmp L(wmemcmp_return)
-# else
- movzbl (VEC_SIZE * 2)(%rdi, %rcx), %eax
- movzbl (VEC_SIZE * 2)(%rsi, %rcx), %edx
- sub %edx, %eax
-# endif
+L(between_4_7):
+ /* Load as big endian with overlapping movbe to avoid branches.
+ */
+ movbe (%rdi), %eax
+ movbe (%rsi), %ecx
+ shlq $32, %rax
+ shlq $32, %rcx
+ movbe -4(%rdi, %rdx), %edi
+ movbe -4(%rsi, %rdx), %esi
+ orq %rdi, %rax
+ orq %rsi, %rcx
+ subq %rcx, %rax
+ jz L(zero_4_7)
+ sbbl %eax, %eax
+ orl $1, %eax
+L(zero_4_7):
ret
+# endif
+
END (MEMCMP)
#endif
--
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