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glibc/SOURCES/glibc-RHEL-15696-45.patch

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From 16d12015c57701b08d7bbed6ec536641bcafb428 Mon Sep 17 00:00:00 2001
From: Noah Goldstein <goldstein.w.n@gmail.com>
Date: Mon, 17 May 2021 13:56:52 -0400
Subject: [PATCH] x86: Optimize memcmp-avx2-movbe.S
Content-type: text/plain; charset=UTF-8
No bug. This commit optimizes memcmp-avx2.S. The optimizations include
adding a new vec compare path for small sizes, reorganizing the entry
control flow, and removing some unnecissary ALU instructions from the
main loop. 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>
---
sysdeps/x86_64/multiarch/ifunc-impl-list.c | 6 +
sysdeps/x86_64/multiarch/ifunc-memcmp.h | 1 +
sysdeps/x86_64/multiarch/memcmp-avx2-movbe.S | 676 +++++++++++--------
3 files changed, 402 insertions(+), 281 deletions(-)
diff --git a/sysdeps/x86_64/multiarch/ifunc-impl-list.c b/sysdeps/x86_64/multiarch/ifunc-impl-list.c
index ac097e8d..8be0d78a 100644
--- a/sysdeps/x86_64/multiarch/ifunc-impl-list.c
+++ b/sysdeps/x86_64/multiarch/ifunc-impl-list.c
@@ -63,16 +63,19 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
IFUNC_IMPL (i, name, memcmp,
IFUNC_IMPL_ADD (array, i, memcmp,
(CPU_FEATURE_USABLE (AVX2)
+ && CPU_FEATURE_USABLE (BMI2)
&& CPU_FEATURE_USABLE (MOVBE)),
__memcmp_avx2_movbe)
IFUNC_IMPL_ADD (array, i, memcmp,
(CPU_FEATURE_USABLE (AVX2)
+ && CPU_FEATURE_USABLE (BMI2)
&& CPU_FEATURE_USABLE (MOVBE)
&& CPU_FEATURE_USABLE (RTM)),
__memcmp_avx2_movbe_rtm)
IFUNC_IMPL_ADD (array, i, memcmp,
(CPU_FEATURE_USABLE (AVX512VL)
&& CPU_FEATURE_USABLE (AVX512BW)
+ && CPU_FEATURE_USABLE (BMI2)
&& CPU_FEATURE_USABLE (MOVBE)),
__memcmp_evex_movbe)
IFUNC_IMPL_ADD (array, i, memcmp, CPU_FEATURE_USABLE (SSE4_1),
@@ -732,16 +735,19 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
IFUNC_IMPL (i, name, wmemcmp,
IFUNC_IMPL_ADD (array, i, wmemcmp,
(CPU_FEATURE_USABLE (AVX2)
+ && CPU_FEATURE_USABLE (BMI2)
&& CPU_FEATURE_USABLE (MOVBE)),
__wmemcmp_avx2_movbe)
IFUNC_IMPL_ADD (array, i, wmemcmp,
(CPU_FEATURE_USABLE (AVX2)
+ && CPU_FEATURE_USABLE (BMI2)
&& CPU_FEATURE_USABLE (MOVBE)
&& CPU_FEATURE_USABLE (RTM)),
__wmemcmp_avx2_movbe_rtm)
IFUNC_IMPL_ADD (array, i, wmemcmp,
(CPU_FEATURE_USABLE (AVX512VL)
&& CPU_FEATURE_USABLE (AVX512BW)
+ && CPU_FEATURE_USABLE (BMI2)
&& CPU_FEATURE_USABLE (MOVBE)),
__wmemcmp_evex_movbe)
IFUNC_IMPL_ADD (array, i, wmemcmp, CPU_FEATURE_USABLE (SSE4_1),
diff --git a/sysdeps/x86_64/multiarch/ifunc-memcmp.h b/sysdeps/x86_64/multiarch/ifunc-memcmp.h
index 8043c635..690dffe8 100644
--- a/sysdeps/x86_64/multiarch/ifunc-memcmp.h
+++ b/sysdeps/x86_64/multiarch/ifunc-memcmp.h
@@ -33,6 +33,7 @@ IFUNC_SELECTOR (void)
if (CPU_FEATURE_USABLE_P (cpu_features, AVX2)
&& CPU_FEATURE_USABLE_P (cpu_features, MOVBE)
+ && CPU_FEATURE_USABLE_P (cpu_features, BMI2)
&& CPU_FEATURES_ARCH_P (cpu_features, AVX_Fast_Unaligned_Load))
{
if (CPU_FEATURE_USABLE_P (cpu_features, AVX512VL)
diff --git a/sysdeps/x86_64/multiarch/memcmp-avx2-movbe.S b/sysdeps/x86_64/multiarch/memcmp-avx2-movbe.S
index 9d5c9c72..16fc673e 100644
--- a/sysdeps/x86_64/multiarch/memcmp-avx2-movbe.S
+++ b/sysdeps/x86_64/multiarch/memcmp-avx2-movbe.S
@@ -19,17 +19,23 @@
#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 < VEC_SIZE
+ 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 * VEC_SIZE 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 * VEC_SIZE or less.
+ 8. Use 4 vector compares when size is 4 * VEC_SIZE or less.
+ 9. Use 8 vector compares when size is 8 * VEC_SIZE or less. */
+
# include <sysdep.h>
@@ -38,8 +44,10 @@
# endif
# ifdef USE_AS_WMEMCMP
+# define CHAR_SIZE 4
# define VPCMPEQ vpcmpeqd
# else
+# define CHAR_SIZE 1
# define VPCMPEQ vpcmpeqb
# endif
@@ -52,7 +60,7 @@
# endif
# define VEC_SIZE 32
-# define VEC_MASK ((1 << VEC_SIZE) - 1)
+# define PAGE_SIZE 4096
/* Warning!
wmemcmp has to use SIGNED comparison for elements.
@@ -71,136 +79,359 @@ ENTRY (MEMCMP)
jb L(less_vec)
/* From VEC to 2 * VEC. No branch when size == VEC_SIZE. */
- vmovdqu (%rsi), %ymm2
- VPCMPEQ (%rdi), %ymm2, %ymm2
- vpmovmskb %ymm2, %eax
- subl $VEC_MASK, %eax
- jnz L(first_vec)
+ vmovdqu (%rsi), %ymm1
+ VPCMPEQ (%rdi), %ymm1, %ymm1
+ vpmovmskb %ymm1, %eax
+ /* NB: eax must be destination register if going to
+ L(return_vec_[0,2]). For L(return_vec_3 destination register
+ must be ecx. */
+ incl %eax
+ jnz L(return_vec_0)
cmpq $(VEC_SIZE * 2), %rdx
- jbe L(last_vec)
-
- VPCMPEQ %ymm0, %ymm0, %ymm0
- /* More than 2 * VEC. */
- cmpq $(VEC_SIZE * 8), %rdx
- ja L(more_8x_vec)
- cmpq $(VEC_SIZE * 4), %rdx
- jb L(last_4x_vec)
-
- /* From 4 * VEC to 8 * VEC, inclusively. */
- vmovdqu (%rsi), %ymm1
- VPCMPEQ (%rdi), %ymm1, %ymm1
+ jbe L(last_1x_vec)
+ /* Check second VEC no matter what. */
vmovdqu VEC_SIZE(%rsi), %ymm2
- VPCMPEQ VEC_SIZE(%rdi), %ymm2, %ymm2
+ VPCMPEQ VEC_SIZE(%rdi), %ymm2, %ymm2
+ vpmovmskb %ymm2, %eax
+ /* If all 4 VEC where equal eax will be all 1s so incl will
+ overflow and set zero flag. */
+ incl %eax
+ jnz L(return_vec_1)
- vmovdqu (VEC_SIZE * 2)(%rsi), %ymm3
- VPCMPEQ (VEC_SIZE * 2)(%rdi), %ymm3, %ymm3
+ /* Less than 4 * VEC. */
+ cmpq $(VEC_SIZE * 4), %rdx
+ jbe L(last_2x_vec)
+ /* Check third and fourth VEC no matter what. */
+ vmovdqu (VEC_SIZE * 2)(%rsi), %ymm3
+ VPCMPEQ (VEC_SIZE * 2)(%rdi), %ymm3, %ymm3
+ vpmovmskb %ymm3, %eax
+ incl %eax
+ jnz L(return_vec_2)
vmovdqu (VEC_SIZE * 3)(%rsi), %ymm4
- VPCMPEQ (VEC_SIZE * 3)(%rdi), %ymm4, %ymm4
+ VPCMPEQ (VEC_SIZE * 3)(%rdi), %ymm4, %ymm4
+ vpmovmskb %ymm4, %ecx
+ incl %ecx
+ jnz L(return_vec_3)
- vpand %ymm1, %ymm2, %ymm5
- vpand %ymm3, %ymm4, %ymm6
- vpand %ymm5, %ymm6, %ymm5
+ /* Go to 4x VEC loop. */
+ cmpq $(VEC_SIZE * 8), %rdx
+ ja L(more_8x_vec)
- vptest %ymm0, %ymm5
- jnc L(4x_vec_end)
+ /* Handle remainder of size = 4 * VEC + 1 to 8 * VEC without any
+ branches. */
+ /* Load first two VEC from s2 before adjusting addresses. */
+ vmovdqu -(VEC_SIZE * 4)(%rsi, %rdx), %ymm1
+ vmovdqu -(VEC_SIZE * 3)(%rsi, %rdx), %ymm2
leaq -(4 * VEC_SIZE)(%rdi, %rdx), %rdi
leaq -(4 * VEC_SIZE)(%rsi, %rdx), %rsi
- vmovdqu (%rsi), %ymm1
- VPCMPEQ (%rdi), %ymm1, %ymm1
- vmovdqu VEC_SIZE(%rsi), %ymm2
- VPCMPEQ VEC_SIZE(%rdi), %ymm2, %ymm2
- vpand %ymm2, %ymm1, %ymm5
+ /* Wait to load from s1 until addressed adjust due to
+ unlamination of microfusion with complex address mode. */
+ VPCMPEQ (%rdi), %ymm1, %ymm1
+ VPCMPEQ (VEC_SIZE)(%rdi), %ymm2, %ymm2
vmovdqu (VEC_SIZE * 2)(%rsi), %ymm3
- VPCMPEQ (VEC_SIZE * 2)(%rdi), %ymm3, %ymm3
- vpand %ymm3, %ymm5, %ymm5
-
+ VPCMPEQ (VEC_SIZE * 2)(%rdi), %ymm3, %ymm3
vmovdqu (VEC_SIZE * 3)(%rsi), %ymm4
- VPCMPEQ (VEC_SIZE * 3)(%rdi), %ymm4, %ymm4
- vpand %ymm4, %ymm5, %ymm5
+ VPCMPEQ (VEC_SIZE * 3)(%rdi), %ymm4, %ymm4
- vptest %ymm0, %ymm5
- jnc L(4x_vec_end)
- xorl %eax, %eax
+ /* Reduce VEC0 - VEC4. */
+ vpand %ymm1, %ymm2, %ymm5
+ vpand %ymm3, %ymm4, %ymm6
+ vpand %ymm5, %ymm6, %ymm7
+ vpmovmskb %ymm7, %ecx
+ incl %ecx
+ jnz L(return_vec_0_1_2_3)
+ /* NB: eax must be zero to reach here. */
+ VZEROUPPER_RETURN
+
+ .p2align 4
+L(return_vec_0):
+ tzcntl %eax, %eax
+# ifdef USE_AS_WMEMCMP
+ movl (%rdi, %rax), %ecx
+ xorl %edx, %edx
+ cmpl (%rsi, %rax), %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
L(return_vzeroupper):
ZERO_UPPER_VEC_REGISTERS_RETURN
.p2align 4
-L(last_2x_vec):
- /* From VEC to 2 * VEC. No branch when size == VEC_SIZE. */
- vmovdqu (%rsi), %ymm2
- VPCMPEQ (%rdi), %ymm2, %ymm2
- vpmovmskb %ymm2, %eax
- subl $VEC_MASK, %eax
- jnz L(first_vec)
+L(return_vec_1):
+ tzcntl %eax, %eax
+# ifdef USE_AS_WMEMCMP
+ movl VEC_SIZE(%rdi, %rax), %ecx
+ xorl %edx, %edx
+ cmpl VEC_SIZE(%rsi, %rax), %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
+ VZEROUPPER_RETURN
+
+ .p2align 4
+L(return_vec_2):
+ tzcntl %eax, %eax
+# ifdef USE_AS_WMEMCMP
+ movl (VEC_SIZE * 2)(%rdi, %rax), %ecx
+ xorl %edx, %edx
+ cmpl (VEC_SIZE * 2)(%rsi, %rax), %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
+ VZEROUPPER_RETURN
+
+ /* NB: p2align 5 here to ensure 4x loop is 32 byte aligned. */
+ .p2align 5
+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):
+ vpmovmskb %ymm1, %eax
+ incl %eax
+ jnz L(return_vec_0)
-L(last_vec):
- /* Use overlapping loads to avoid branches. */
- leaq -VEC_SIZE(%rdi, %rdx), %rdi
- leaq -VEC_SIZE(%rsi, %rdx), %rsi
- vmovdqu (%rsi), %ymm2
- VPCMPEQ (%rdi), %ymm2, %ymm2
vpmovmskb %ymm2, %eax
- subl $VEC_MASK, %eax
- jnz L(first_vec)
+ incl %eax
+ jnz L(return_vec_1)
+
+ vpmovmskb %ymm3, %eax
+ incl %eax
+ jnz L(return_vec_2)
+L(return_vec_3):
+ tzcntl %ecx, %ecx
+# ifdef USE_AS_WMEMCMP
+ movl (VEC_SIZE * 3)(%rdi, %rcx), %eax
+ xorl %edx, %edx
+ cmpl (VEC_SIZE * 3)(%rsi, %rcx), %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
+ VZEROUPPER_RETURN
+
+ .p2align 4
+L(more_8x_vec):
+ /* Set end of s1 in rdx. */
+ leaq -(VEC_SIZE * 4)(%rdi, %rdx), %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):
+ /* rsi has s2 - s1 so get correct address by adding s1 (in rdi).
+ */
+ vmovdqu (%rsi, %rdi), %ymm1
+ VPCMPEQ (%rdi), %ymm1, %ymm1
+
+ vmovdqu VEC_SIZE(%rsi, %rdi), %ymm2
+ VPCMPEQ VEC_SIZE(%rdi), %ymm2, %ymm2
+
+ vmovdqu (VEC_SIZE * 2)(%rsi, %rdi), %ymm3
+ VPCMPEQ (VEC_SIZE * 2)(%rdi), %ymm3, %ymm3
+
+ vmovdqu (VEC_SIZE * 3)(%rsi, %rdi), %ymm4
+ VPCMPEQ (VEC_SIZE * 3)(%rdi), %ymm4, %ymm4
+
+ vpand %ymm1, %ymm2, %ymm5
+ vpand %ymm3, %ymm4, %ymm6
+ vpand %ymm5, %ymm6, %ymm7
+ vpmovmskb %ymm7, %ecx
+ incl %ecx
+ jnz L(8x_return_vec_0_1_2_3)
+ subq $-(VEC_SIZE * 4), %rdi
+ /* Check if s1 pointer at end. */
+ 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. */
+ vmovdqu (VEC_SIZE * 2)(%rsi, %rdx), %ymm3
+ cmpl $(VEC_SIZE * 2), %edi
+ jae L(8x_last_2x_vec)
+
+ /* Check last 4 VEC. */
+ vmovdqu (%rsi, %rdx), %ymm1
+ VPCMPEQ (%rdx), %ymm1, %ymm1
+
+ vmovdqu VEC_SIZE(%rsi, %rdx), %ymm2
+ VPCMPEQ VEC_SIZE(%rdx), %ymm2, %ymm2
+
+ VPCMPEQ (VEC_SIZE * 2)(%rdx), %ymm3, %ymm3
+
+ vmovdqu (VEC_SIZE * 3)(%rsi, %rdx), %ymm4
+ VPCMPEQ (VEC_SIZE * 3)(%rdx), %ymm4, %ymm4
+
+ vpand %ymm1, %ymm2, %ymm5
+ vpand %ymm3, %ymm4, %ymm6
+ vpand %ymm5, %ymm6, %ymm7
+ vpmovmskb %ymm7, %ecx
+ /* Restore s1 pointer to rdi. */
+ movq %rdx, %rdi
+ incl %ecx
+ jnz L(8x_return_vec_0_1_2_3)
+ /* NB: eax must be zero to reach here. */
+ VZEROUPPER_RETURN
+
+ /* Only entry is from L(more_8x_vec). */
+ .p2align 4
+L(8x_last_2x_vec):
+ /* Check second to last VEC. rdx store end pointer of s1 and
+ ymm3 has already been loaded with second to last VEC from s2.
+ */
+ VPCMPEQ (VEC_SIZE * 2)(%rdx), %ymm3, %ymm3
+ vpmovmskb %ymm3, %eax
+ incl %eax
+ jnz L(8x_return_vec_2)
+ /* Check last VEC. */
+ .p2align 4
+L(8x_last_1x_vec):
+ vmovdqu (VEC_SIZE * 3)(%rsi, %rdx), %ymm4
+ VPCMPEQ (VEC_SIZE * 3)(%rdx), %ymm4, %ymm4
+ vpmovmskb %ymm4, %eax
+ incl %eax
+ jnz L(8x_return_vec_3)
VZEROUPPER_RETURN
.p2align 4
-L(first_vec):
- /* A byte or int32 is different within 16 or 32 bytes. */
- tzcntl %eax, %ecx
+L(last_2x_vec):
+ /* Check second to last VEC. */
+ vmovdqu -(VEC_SIZE * 2)(%rsi, %rdx), %ymm1
+ VPCMPEQ -(VEC_SIZE * 2)(%rdi, %rdx), %ymm1, %ymm1
+ vpmovmskb %ymm1, %eax
+ incl %eax
+ jnz L(return_vec_1_end)
+ /* Check last VEC. */
+L(last_1x_vec):
+ vmovdqu -(VEC_SIZE * 1)(%rsi, %rdx), %ymm1
+ VPCMPEQ -(VEC_SIZE * 1)(%rdi, %rdx), %ymm1, %ymm1
+ vpmovmskb %ymm1, %eax
+ incl %eax
+ jnz L(return_vec_0_end)
+ VZEROUPPER_RETURN
+
+ .p2align 4
+L(8x_return_vec_2):
+ subq $VEC_SIZE, %rdx
+L(8x_return_vec_3):
+ tzcntl %eax, %eax
+ addq %rdx, %rax
# ifdef USE_AS_WMEMCMP
- xorl %eax, %eax
- movl (%rdi, %rcx), %edx
- cmpl (%rsi, %rcx), %edx
-L(wmemcmp_return):
- setl %al
- negl %eax
- orl $1, %eax
+ movl (VEC_SIZE * 3)(%rax), %ecx
+ xorl %edx, %edx
+ cmpl (VEC_SIZE * 3)(%rsi, %rax), %ecx
+ setg %dl
+ leal -1(%rdx, %rdx), %eax
# else
- movzbl (%rdi, %rcx), %eax
- movzbl (%rsi, %rcx), %edx
- sub %edx, %eax
+ movzbl (VEC_SIZE * 3)(%rsi, %rax), %ecx
+ movzbl (VEC_SIZE * 3)(%rax), %eax
+ subl %ecx, %eax
# endif
VZEROUPPER_RETURN
-# ifdef USE_AS_WMEMCMP
.p2align 4
-L(4):
- xorl %eax, %eax
- movl (%rdi), %edx
- cmpl (%rsi), %edx
- jne L(wmemcmp_return)
- ret
+L(return_vec_1_end):
+ tzcntl %eax, %eax
+ addl %edx, %eax
+# ifdef USE_AS_WMEMCMP
+ movl -(VEC_SIZE * 2)(%rdi, %rax), %ecx
+ xorl %edx, %edx
+ cmpl -(VEC_SIZE * 2)(%rsi, %rax), %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
+ VZEROUPPER_RETURN
+
.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
- ret
+L(return_vec_0_end):
+ tzcntl %eax, %eax
+ addl %edx, %eax
+# ifdef USE_AS_WMEMCMP
+ movl -VEC_SIZE(%rdi, %rax), %ecx
+ xorl %edx, %edx
+ cmpl -VEC_SIZE(%rsi, %rax), %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
+ VZEROUPPER_RETURN
.p2align 4
-L(exit):
- ret
+L(less_vec):
+ /* Check if one or less CHAR. This is necessary for size = 0 but
+ is also faster for size = CHAR_SIZE. */
+ cmpl $CHAR_SIZE, %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. */
+ vmovdqu (%rsi), %ymm2
+ VPCMPEQ (%rdi), %ymm2, %ymm2
+ vpmovmskb %ymm2, %eax
+ incl %eax
+ /* Result will be zero if s1 and s2 match. Otherwise first set
+ bit will be first mismatch. */
+ bzhil %edx, %eax, %edx
+ jnz L(return_vec_0)
+ xorl %eax, %eax
+ VZEROUPPER_RETURN
.p2align 4
-L(between_2_3):
+L(page_cross_less_vec):
+ /* if USE_AS_WMEMCMP it can only be 0, 4, 8, 12, 16, 20, 24, 28
+ bytes. */
+ cmpl $16, %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)
+
/* Load as big endian to avoid branches. */
movzwl (%rdi), %eax
movzwl (%rsi), %ecx
@@ -208,223 +439,106 @@ 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
+ /* No ymm register was touched. */
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
+ /* No ymm register was touched. */
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, %xmm2
+ VPCMPEQ %xmm1, %xmm2, %xmm2
vpmovmskb %xmm2, %eax
- subl $0xffff, %eax
- jnz L(first_vec)
+ subl $0xffff, %eax
+ jnz L(return_vec_0)
/* Use overlapping loads to avoid branches. */
leaq -8(%rdi, %rdx), %rdi
leaq -8(%rsi, %rdx), %rsi
vmovq (%rdi), %xmm1
vmovq (%rsi), %xmm2
- VPCMPEQ %xmm1, %xmm2, %xmm2
+ VPCMPEQ %xmm1, %xmm2, %xmm2
vpmovmskb %xmm2, %eax
- subl $0xffff, %eax
- jnz L(first_vec)
+ subl $0xffff, %eax
+ jnz L(return_vec_0)
+ /* No ymm register was touched. */
+ ret
+
+ .p2align 4
+L(zero):
+ xorl %eax, %eax
ret
.p2align 4
L(between_16_31):
/* From 16 to 31 bytes. No branch when size == 16. */
vmovdqu (%rsi), %xmm2
- VPCMPEQ (%rdi), %xmm2, %xmm2
+ VPCMPEQ (%rdi), %xmm2, %xmm2
vpmovmskb %xmm2, %eax
- subl $0xffff, %eax
- jnz L(first_vec)
+ subl $0xffff, %eax
+ jnz L(return_vec_0)
/* Use overlapping loads to avoid branches. */
+
+ vmovdqu -16(%rsi, %rdx), %xmm2
leaq -16(%rdi, %rdx), %rdi
leaq -16(%rsi, %rdx), %rsi
- vmovdqu (%rsi), %xmm2
- VPCMPEQ (%rdi), %xmm2, %xmm2
+ VPCMPEQ (%rdi), %xmm2, %xmm2
vpmovmskb %xmm2, %eax
- subl $0xffff, %eax
- jnz L(first_vec)
+ subl $0xffff, %eax
+ jnz L(return_vec_0)
+ /* No ymm register was touched. */
ret
- .p2align 4
-L(more_8x_vec):
- /* More than 8 * VEC. Check the first VEC. */
- vmovdqu (%rsi), %ymm2
- VPCMPEQ (%rdi), %ymm2, %ymm2
- vpmovmskb %ymm2, %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. */
- vmovdqu (%rsi), %ymm1
- VPCMPEQ (%rdi), %ymm1, %ymm1
-
- vmovdqu VEC_SIZE(%rsi), %ymm2
- VPCMPEQ VEC_SIZE(%rdi), %ymm2, %ymm2
- vpand %ymm2, %ymm1, %ymm5
-
- vmovdqu (VEC_SIZE * 2)(%rsi), %ymm3
- VPCMPEQ (VEC_SIZE * 2)(%rdi), %ymm3, %ymm3
- vpand %ymm3, %ymm5, %ymm5
-
- vmovdqu (VEC_SIZE * 3)(%rsi), %ymm4
- VPCMPEQ (VEC_SIZE * 3)(%rdi), %ymm4, %ymm4
- vpand %ymm4, %ymm5, %ymm5
-
- vptest %ymm0, %ymm5
- jnc 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. */
- vmovdqu (%rsi), %ymm2
- VPCMPEQ (%rdi), %ymm2, %ymm2
- vpmovmskb %ymm2, %eax
- subl $VEC_MASK, %eax
- jnz L(first_vec)
-
- addq $VEC_SIZE, %rdi
- addq $VEC_SIZE, %rsi
- vmovdqu (%rsi), %ymm2
- VPCMPEQ (%rdi), %ymm2, %ymm2
- vpmovmskb %ymm2, %eax
- subl $VEC_MASK, %eax
- jnz L(first_vec)
-
- /* Use overlapping loads to avoid branches. */
- leaq -(3 * VEC_SIZE)(%rdi, %rdx), %rdi
- leaq -(3 * VEC_SIZE)(%rsi, %rdx), %rsi
- vmovdqu (%rsi), %ymm2
- VPCMPEQ (%rdi), %ymm2, %ymm2
- vpmovmskb %ymm2, %eax
- subl $VEC_MASK, %eax
- jnz L(first_vec)
-
- addq $VEC_SIZE, %rdi
- addq $VEC_SIZE, %rsi
- vmovdqu (%rsi), %ymm2
- VPCMPEQ (%rdi), %ymm2, %ymm2
- vpmovmskb %ymm2, %eax
- subl $VEC_MASK, %eax
- jnz L(first_vec)
- VZEROUPPER_RETURN
-
- .p2align 4
-L(4x_vec_end):
- vpmovmskb %ymm1, %eax
- subl $VEC_MASK, %eax
- jnz L(first_vec)
- vpmovmskb %ymm2, %eax
- subl $VEC_MASK, %eax
- jnz L(first_vec_x1)
- vpmovmskb %ymm3, %eax
- subl $VEC_MASK, %eax
- jnz L(first_vec_x2)
- vpmovmskb %ymm4, %eax
- subl $VEC_MASK, %eax
- tzcntl %eax, %ecx
# ifdef USE_AS_WMEMCMP
- xorl %eax, %eax
- movl (VEC_SIZE * 3)(%rdi, %rcx), %edx
- cmpl (VEC_SIZE * 3)(%rsi, %rcx), %edx
- jmp L(wmemcmp_return)
-# else
- movzbl (VEC_SIZE * 3)(%rdi, %rcx), %eax
- movzbl (VEC_SIZE * 3)(%rsi, %rcx), %edx
- sub %edx, %eax
-# endif
- VZEROUPPER_RETURN
-
.p2align 4
-L(first_vec_x1):
- tzcntl %eax, %ecx
-# ifdef USE_AS_WMEMCMP
- xorl %eax, %eax
- movl VEC_SIZE(%rdi, %rcx), %edx
- cmpl VEC_SIZE(%rsi, %rcx), %edx
- jmp L(wmemcmp_return)
+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
+ /* No ymm register was touched. */
+ ret
# else
- movzbl VEC_SIZE(%rdi, %rcx), %eax
- movzbl VEC_SIZE(%rsi, %rcx), %edx
- sub %edx, %eax
-# endif
- VZEROUPPER_RETURN
.p2align 4
-L(first_vec_x2):
- tzcntl %eax, %ecx
-# ifdef USE_AS_WMEMCMP
- xorl %eax, %eax
- movl (VEC_SIZE * 2)(%rdi, %rcx), %edx
- cmpl (VEC_SIZE * 2)(%rsi, %rcx), %edx
- jmp L(wmemcmp_return)
-# else
- movzbl (VEC_SIZE * 2)(%rdi, %rcx), %eax
- movzbl (VEC_SIZE * 2)(%rsi, %rcx), %edx
- sub %edx, %eax
+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):
+ /* No ymm register was touched. */
+ ret
# endif
- VZEROUPPER_RETURN
+
END (MEMCMP)
#endif
--
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