From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 7852) id CB6DE3858C27; Mon, 2 May 2022 21:29:53 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org CB6DE3858C27 Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit From: Sunil Pandey To: glibc-cvs@sourceware.org Subject: [glibc/release/2.33/master] x86: Optimize memcmp-evex-movbe.S X-Act-Checkin: glibc X-Git-Author: Noah Goldstein X-Git-Refname: refs/heads/release/2.33/master X-Git-Oldrev: a44a43e998d06100399d2273587d5c330ed0c0e1 X-Git-Newrev: 903190e981e995f9f10063fd717ce72ab1c6cb04 Message-Id: <20220502212953.CB6DE3858C27@sourceware.org> Date: Mon, 2 May 2022 21:29:53 +0000 (GMT) X-BeenThere: glibc-cvs@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Glibc-cvs mailing list List-Unsubscribe: , List-Archive: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 02 May 2022 21:29:53 -0000 https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=903190e981e995f9f10063fd717ce72ab1c6cb04 commit 903190e981e995f9f10063fd717ce72ab1c6cb04 Author: Noah Goldstein Date: Mon May 17 13:57:24 2021 -0400 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 Reviewed-by: H.J. Lu (cherry picked from commit 4ad473e97acdc5f6d811755b67c09f2128a644ce) Diff: --- 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 9c093972e1..654dc7ac8c 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 @@ -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