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653 lines
18 KiB
653 lines
18 KiB
commit 5ec3416853c4150c4d13312e05f93a053586d528 |
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Author: Noah Goldstein <goldstein.w.n@gmail.com> |
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Date: Tue Sep 21 18:45:03 2021 -0500 |
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x86: Optimize memcmp-evex-movbe.S for frontend behavior and size |
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No bug. |
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The frontend optimizations are to: |
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1. Reorganize logically connected basic blocks so they are either in |
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the same cache line or adjacent cache lines. |
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2. Avoid cases when basic blocks unnecissarily cross cache lines. |
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3. Try and 32 byte align any basic blocks possible without sacrificing |
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code size. Smaller / Less hot basic blocks are used for this. |
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Overall code size shrunk by 168 bytes. This should make up for any |
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extra costs due to aligning to 64 bytes. |
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In general performance before deviated a great deal dependending on |
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whether entry alignment % 64 was 0, 16, 32, or 48. These changes |
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essentially make it so that the current implementation is at least |
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equal to the best alignment of the original for any arguments. |
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The only additional optimization is in the page cross case. Branch on |
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equals case was removed from the size == [4, 7] case. As well the [4, |
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7] and [2, 3] case where swapped as [4, 7] is likely a more hot |
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argument size. |
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test-memcmp and test-wmemcmp are both passing. |
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(cherry picked from commit 1bd8b8d58fc9967cc073d2c13bfb6befefca2faa) |
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diff --git a/sysdeps/x86_64/multiarch/memcmp-evex-movbe.S b/sysdeps/x86_64/multiarch/memcmp-evex-movbe.S |
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index 654dc7ac8ccb9445..2761b54f2e7dea9f 100644 |
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--- a/sysdeps/x86_64/multiarch/memcmp-evex-movbe.S |
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+++ b/sysdeps/x86_64/multiarch/memcmp-evex-movbe.S |
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@@ -34,7 +34,24 @@ |
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area. |
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7. Use 2 vector compares when size is 2 * CHAR_PER_VEC or less. |
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8. Use 4 vector compares when size is 4 * CHAR_PER_VEC or less. |
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- 9. Use 8 vector compares when size is 8 * CHAR_PER_VEC or less. */ |
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+ 9. Use 8 vector compares when size is 8 * CHAR_PER_VEC or less. |
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+ |
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+When possible the implementation tries to optimize for frontend in the |
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+following ways: |
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+Throughput: |
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+ 1. All code sections that fit are able to run optimally out of the |
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+ LSD. |
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+ 2. All code sections that fit are able to run optimally out of the |
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+ DSB |
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+ 3. Basic blocks are contained in minimum number of fetch blocks |
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+ necessary. |
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+ |
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+Latency: |
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+ 1. Logically connected basic blocks are put in the same |
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+ cache-line. |
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+ 2. Logically connected basic blocks that do not fit in the same |
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+ cache-line are put in adjacent lines. This can get beneficial |
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+ L2 spatial prefetching and L1 next-line prefetching. */ |
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# include <sysdep.h> |
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@@ -47,9 +64,11 @@ |
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# ifdef USE_AS_WMEMCMP |
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# define CHAR_SIZE 4 |
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# define VPCMP vpcmpd |
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+# define VPTEST vptestmd |
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# else |
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# define CHAR_SIZE 1 |
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# define VPCMP vpcmpub |
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+# define VPTEST vptestmb |
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# endif |
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# define VEC_SIZE 32 |
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@@ -75,7 +94,9 @@ |
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*/ |
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.section .text.evex,"ax",@progbits |
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-ENTRY (MEMCMP) |
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+/* Cache align memcmp entry. This allows for much more thorough |
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+ frontend optimization. */ |
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+ENTRY_P2ALIGN (MEMCMP, 6) |
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# ifdef __ILP32__ |
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/* Clear the upper 32 bits. */ |
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movl %edx, %edx |
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@@ -89,7 +110,7 @@ ENTRY (MEMCMP) |
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VPCMP $4, (%rdi), %YMM1, %k1 |
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kmovd %k1, %eax |
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/* NB: eax must be destination register if going to |
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- L(return_vec_[0,2]). For L(return_vec_3 destination register |
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+ L(return_vec_[0,2]). For L(return_vec_3) destination register |
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must be ecx. */ |
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testl %eax, %eax |
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jnz L(return_vec_0) |
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@@ -121,10 +142,6 @@ ENTRY (MEMCMP) |
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testl %ecx, %ecx |
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jnz L(return_vec_3) |
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- /* Zero YMM0. 4x VEC reduction is done with vpxor + vtern so |
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- compare with zero to get a mask is needed. */ |
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- vpxorq %XMM0, %XMM0, %XMM0 |
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- |
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/* Go to 4x VEC loop. */ |
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cmpq $(CHAR_PER_VEC * 8), %rdx |
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ja L(more_8x_vec) |
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@@ -148,47 +165,61 @@ ENTRY (MEMCMP) |
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VMOVU (VEC_SIZE * 2)(%rsi), %YMM3 |
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vpxorq (VEC_SIZE * 2)(%rdi), %YMM3, %YMM3 |
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- /* Or together YMM1, YMM2, and YMM3 into YMM3. */ |
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- vpternlogd $0xfe, %YMM1, %YMM2, %YMM3 |
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VMOVU (VEC_SIZE * 3)(%rsi), %YMM4 |
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/* Ternary logic to xor (VEC_SIZE * 3)(%rdi) with YMM4 while |
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- oring with YMM3. Result is stored in YMM4. */ |
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- vpternlogd $0xde, (VEC_SIZE * 3)(%rdi), %YMM3, %YMM4 |
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- /* Compare YMM4 with 0. If any 1s s1 and s2 don't match. */ |
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- VPCMP $4, %YMM4, %YMM0, %k1 |
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+ oring with YMM1. Result is stored in YMM4. */ |
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+ vpternlogd $0xde, (VEC_SIZE * 3)(%rdi), %YMM1, %YMM4 |
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+ |
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+ /* Or together YMM2, YMM3, and YMM4 into YMM4. */ |
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+ vpternlogd $0xfe, %YMM2, %YMM3, %YMM4 |
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+ |
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+ /* Test YMM4 against itself. Store any CHAR mismatches in k1. |
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+ */ |
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+ VPTEST %YMM4, %YMM4, %k1 |
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+ /* k1 must go to ecx for L(return_vec_0_1_2_3). */ |
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kmovd %k1, %ecx |
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testl %ecx, %ecx |
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jnz L(return_vec_0_1_2_3) |
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/* NB: eax must be zero to reach here. */ |
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ret |
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- /* NB: aligning 32 here allows for the rest of the jump targets |
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- to be tuned for 32 byte alignment. Most important this ensures |
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- the L(more_8x_vec) loop is 32 byte aligned. */ |
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- .p2align 5 |
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-L(less_vec): |
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- /* Check if one or less CHAR. This is necessary for size = 0 but |
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- is also faster for size = CHAR_SIZE. */ |
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- cmpl $1, %edx |
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- jbe L(one_or_less) |
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+ .p2align 4 |
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+L(8x_end_return_vec_0_1_2_3): |
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+ movq %rdx, %rdi |
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+L(8x_return_vec_0_1_2_3): |
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+ addq %rdi, %rsi |
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+L(return_vec_0_1_2_3): |
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+ VPTEST %YMM1, %YMM1, %k0 |
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+ kmovd %k0, %eax |
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+ testl %eax, %eax |
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+ jnz L(return_vec_0) |
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- /* Check if loading one VEC from either s1 or s2 could cause a |
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- page cross. This can have false positives but is by far the |
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- fastest method. */ |
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- movl %edi, %eax |
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- orl %esi, %eax |
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- andl $(PAGE_SIZE - 1), %eax |
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- cmpl $(PAGE_SIZE - VEC_SIZE), %eax |
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- jg L(page_cross_less_vec) |
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+ VPTEST %YMM2, %YMM2, %k0 |
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+ kmovd %k0, %eax |
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+ testl %eax, %eax |
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+ jnz L(return_vec_1) |
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- /* No page cross possible. */ |
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- VMOVU (%rsi), %YMM2 |
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- VPCMP $4, (%rdi), %YMM2, %k1 |
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- kmovd %k1, %eax |
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- /* Create mask in ecx for potentially in bound matches. */ |
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- bzhil %edx, %eax, %eax |
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- jnz L(return_vec_0) |
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+ VPTEST %YMM3, %YMM3, %k0 |
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+ kmovd %k0, %eax |
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+ testl %eax, %eax |
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+ jnz L(return_vec_2) |
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+L(return_vec_3): |
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+ /* bsf saves 1 byte from tzcnt. This keep L(return_vec_3) in one |
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+ fetch block and the entire L(*return_vec_0_1_2_3) in 1 cache |
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+ line. */ |
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+ bsfl %ecx, %ecx |
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+# ifdef USE_AS_WMEMCMP |
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+ movl (VEC_SIZE * 3)(%rdi, %rcx, CHAR_SIZE), %eax |
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+ xorl %edx, %edx |
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+ cmpl (VEC_SIZE * 3)(%rsi, %rcx, CHAR_SIZE), %eax |
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+ setg %dl |
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+ leal -1(%rdx, %rdx), %eax |
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+# else |
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+ movzbl (VEC_SIZE * 3)(%rdi, %rcx), %eax |
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+ movzbl (VEC_SIZE * 3)(%rsi, %rcx), %ecx |
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+ subl %ecx, %eax |
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+# endif |
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ret |
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.p2align 4 |
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@@ -209,10 +240,11 @@ L(return_vec_0): |
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# endif |
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ret |
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- /* NB: No p2align necessary. Alignment % 16 is naturally 1 |
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- which is good enough for a target not in a loop. */ |
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+ .p2align 4 |
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L(return_vec_1): |
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- tzcntl %eax, %eax |
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+ /* bsf saves 1 byte over tzcnt and keeps L(return_vec_1) in one |
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+ fetch block. */ |
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+ bsfl %eax, %eax |
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# ifdef USE_AS_WMEMCMP |
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movl VEC_SIZE(%rdi, %rax, CHAR_SIZE), %ecx |
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xorl %edx, %edx |
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@@ -226,10 +258,11 @@ L(return_vec_1): |
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# endif |
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ret |
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- /* NB: No p2align necessary. Alignment % 16 is naturally 2 |
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- which is good enough for a target not in a loop. */ |
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+ .p2align 4,, 10 |
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L(return_vec_2): |
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- tzcntl %eax, %eax |
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+ /* bsf saves 1 byte over tzcnt and keeps L(return_vec_2) in one |
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+ fetch block. */ |
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+ bsfl %eax, %eax |
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# ifdef USE_AS_WMEMCMP |
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movl (VEC_SIZE * 2)(%rdi, %rax, CHAR_SIZE), %ecx |
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xorl %edx, %edx |
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@@ -243,40 +276,6 @@ L(return_vec_2): |
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# endif |
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ret |
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- .p2align 4 |
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-L(8x_return_vec_0_1_2_3): |
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- /* Returning from L(more_8x_vec) requires restoring rsi. */ |
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- addq %rdi, %rsi |
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-L(return_vec_0_1_2_3): |
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- VPCMP $4, %YMM1, %YMM0, %k0 |
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- kmovd %k0, %eax |
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- testl %eax, %eax |
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- jnz L(return_vec_0) |
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- |
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- VPCMP $4, %YMM2, %YMM0, %k0 |
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- kmovd %k0, %eax |
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- testl %eax, %eax |
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- jnz L(return_vec_1) |
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- |
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- VPCMP $4, %YMM3, %YMM0, %k0 |
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- kmovd %k0, %eax |
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- testl %eax, %eax |
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- jnz L(return_vec_2) |
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-L(return_vec_3): |
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- tzcntl %ecx, %ecx |
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-# ifdef USE_AS_WMEMCMP |
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- movl (VEC_SIZE * 3)(%rdi, %rcx, CHAR_SIZE), %eax |
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- xorl %edx, %edx |
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- cmpl (VEC_SIZE * 3)(%rsi, %rcx, CHAR_SIZE), %eax |
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- setg %dl |
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- leal -1(%rdx, %rdx), %eax |
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-# else |
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- movzbl (VEC_SIZE * 3)(%rdi, %rcx), %eax |
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- movzbl (VEC_SIZE * 3)(%rsi, %rcx), %ecx |
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- subl %ecx, %eax |
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-# endif |
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- ret |
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- |
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.p2align 4 |
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L(more_8x_vec): |
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/* Set end of s1 in rdx. */ |
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@@ -288,21 +287,19 @@ L(more_8x_vec): |
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andq $-VEC_SIZE, %rdi |
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/* Adjust because first 4x vec where check already. */ |
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subq $-(VEC_SIZE * 4), %rdi |
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+ |
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.p2align 4 |
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L(loop_4x_vec): |
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VMOVU (%rsi, %rdi), %YMM1 |
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vpxorq (%rdi), %YMM1, %YMM1 |
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- |
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VMOVU VEC_SIZE(%rsi, %rdi), %YMM2 |
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vpxorq VEC_SIZE(%rdi), %YMM2, %YMM2 |
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- |
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VMOVU (VEC_SIZE * 2)(%rsi, %rdi), %YMM3 |
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vpxorq (VEC_SIZE * 2)(%rdi), %YMM3, %YMM3 |
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- vpternlogd $0xfe, %YMM1, %YMM2, %YMM3 |
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- |
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VMOVU (VEC_SIZE * 3)(%rsi, %rdi), %YMM4 |
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- vpternlogd $0xde, (VEC_SIZE * 3)(%rdi), %YMM3, %YMM4 |
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- VPCMP $4, %YMM4, %YMM0, %k1 |
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+ vpternlogd $0xde, (VEC_SIZE * 3)(%rdi), %YMM1, %YMM4 |
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+ vpternlogd $0xfe, %YMM2, %YMM3, %YMM4 |
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+ VPTEST %YMM4, %YMM4, %k1 |
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kmovd %k1, %ecx |
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testl %ecx, %ecx |
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jnz L(8x_return_vec_0_1_2_3) |
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@@ -319,28 +316,25 @@ L(loop_4x_vec): |
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cmpl $(VEC_SIZE * 2), %edi |
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jae L(8x_last_2x_vec) |
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+ vpxorq (VEC_SIZE * 2)(%rdx), %YMM3, %YMM3 |
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+ |
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VMOVU (%rsi, %rdx), %YMM1 |
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vpxorq (%rdx), %YMM1, %YMM1 |
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VMOVU VEC_SIZE(%rsi, %rdx), %YMM2 |
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vpxorq VEC_SIZE(%rdx), %YMM2, %YMM2 |
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- |
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- vpxorq (VEC_SIZE * 2)(%rdx), %YMM3, %YMM3 |
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- vpternlogd $0xfe, %YMM1, %YMM2, %YMM3 |
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- |
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VMOVU (VEC_SIZE * 3)(%rsi, %rdx), %YMM4 |
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- vpternlogd $0xde, (VEC_SIZE * 3)(%rdx), %YMM3, %YMM4 |
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- VPCMP $4, %YMM4, %YMM0, %k1 |
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+ vpternlogd $0xde, (VEC_SIZE * 3)(%rdx), %YMM1, %YMM4 |
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+ vpternlogd $0xfe, %YMM2, %YMM3, %YMM4 |
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+ VPTEST %YMM4, %YMM4, %k1 |
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kmovd %k1, %ecx |
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- /* Restore s1 pointer to rdi. */ |
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- movq %rdx, %rdi |
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testl %ecx, %ecx |
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- jnz L(8x_return_vec_0_1_2_3) |
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+ jnz L(8x_end_return_vec_0_1_2_3) |
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/* NB: eax must be zero to reach here. */ |
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ret |
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/* Only entry is from L(more_8x_vec). */ |
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- .p2align 4 |
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+ .p2align 4,, 10 |
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L(8x_last_2x_vec): |
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VPCMP $4, (VEC_SIZE * 2)(%rdx), %YMM3, %k1 |
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kmovd %k1, %eax |
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@@ -355,7 +349,31 @@ L(8x_last_1x_vec): |
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jnz L(8x_return_vec_3) |
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ret |
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- .p2align 4 |
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+ /* Not ideally aligned (at offset +9 bytes in fetch block) but |
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+ not aligning keeps it in the same cache line as |
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+ L(8x_last_1x/2x_vec) so likely worth it. As well, saves code |
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+ size. */ |
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+ .p2align 4,, 4 |
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+L(8x_return_vec_2): |
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+ subq $VEC_SIZE, %rdx |
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+L(8x_return_vec_3): |
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+ bsfl %eax, %eax |
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+# ifdef USE_AS_WMEMCMP |
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+ leaq (%rdx, %rax, CHAR_SIZE), %rax |
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+ movl (VEC_SIZE * 3)(%rax), %ecx |
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+ xorl %edx, %edx |
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+ cmpl (VEC_SIZE * 3)(%rsi, %rax), %ecx |
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+ setg %dl |
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+ leal -1(%rdx, %rdx), %eax |
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+# else |
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+ addq %rdx, %rax |
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+ movzbl (VEC_SIZE * 3)(%rsi, %rax), %ecx |
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+ movzbl (VEC_SIZE * 3)(%rax), %eax |
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+ subl %ecx, %eax |
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+# endif |
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+ ret |
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+ |
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+ .p2align 4,, 10 |
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L(last_2x_vec): |
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/* Check second to last VEC. */ |
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VMOVU -(VEC_SIZE * 2)(%rsi, %rdx, CHAR_SIZE), %YMM1 |
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@@ -374,26 +392,49 @@ L(last_1x_vec): |
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jnz L(return_vec_0_end) |
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ret |
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- .p2align 4 |
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-L(8x_return_vec_2): |
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- subq $VEC_SIZE, %rdx |
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-L(8x_return_vec_3): |
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- tzcntl %eax, %eax |
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+ .p2align 4,, 10 |
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+L(return_vec_1_end): |
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+ /* Use bsf to save code size. This is necessary to have |
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+ L(one_or_less) fit in aligning bytes between. */ |
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+ bsfl %eax, %eax |
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+ addl %edx, %eax |
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# ifdef USE_AS_WMEMCMP |
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- leaq (%rdx, %rax, CHAR_SIZE), %rax |
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- movl (VEC_SIZE * 3)(%rax), %ecx |
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+ movl -(VEC_SIZE * 2)(%rdi, %rax, CHAR_SIZE), %ecx |
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xorl %edx, %edx |
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- cmpl (VEC_SIZE * 3)(%rsi, %rax), %ecx |
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+ cmpl -(VEC_SIZE * 2)(%rsi, %rax, CHAR_SIZE), %ecx |
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setg %dl |
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leal -1(%rdx, %rdx), %eax |
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# else |
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- addq %rdx, %rax |
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- movzbl (VEC_SIZE * 3)(%rsi, %rax), %ecx |
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- movzbl (VEC_SIZE * 3)(%rax), %eax |
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+ movzbl -(VEC_SIZE * 2)(%rsi, %rax), %ecx |
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+ movzbl -(VEC_SIZE * 2)(%rdi, %rax), %eax |
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subl %ecx, %eax |
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# endif |
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ret |
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|
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+ /* NB: L(one_or_less) fits in alignment padding between |
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+ L(return_vec_1_end) and L(return_vec_0_end). */ |
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+# ifdef USE_AS_WMEMCMP |
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+L(one_or_less): |
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+ jb L(zero) |
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+ movl (%rdi), %ecx |
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+ xorl %edx, %edx |
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+ cmpl (%rsi), %ecx |
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+ je L(zero) |
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+ setg %dl |
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+ leal -1(%rdx, %rdx), %eax |
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+ ret |
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+# else |
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+L(one_or_less): |
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+ jb L(zero) |
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+ movzbl (%rsi), %ecx |
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+ movzbl (%rdi), %eax |
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+ subl %ecx, %eax |
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+ ret |
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+# endif |
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+L(zero): |
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+ xorl %eax, %eax |
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+ ret |
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+ |
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.p2align 4 |
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L(return_vec_0_end): |
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tzcntl %eax, %eax |
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@@ -412,23 +453,56 @@ L(return_vec_0_end): |
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ret |
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.p2align 4 |
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-L(return_vec_1_end): |
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+L(less_vec): |
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+ /* Check if one or less CHAR. This is necessary for size == 0 |
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+ but is also faster for size == CHAR_SIZE. */ |
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+ cmpl $1, %edx |
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+ jbe L(one_or_less) |
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+ |
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+ /* Check if loading one VEC from either s1 or s2 could cause a |
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+ page cross. This can have false positives but is by far the |
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+ fastest method. */ |
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+ movl %edi, %eax |
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+ orl %esi, %eax |
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+ andl $(PAGE_SIZE - 1), %eax |
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+ cmpl $(PAGE_SIZE - VEC_SIZE), %eax |
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+ jg L(page_cross_less_vec) |
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+ |
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+ /* No page cross possible. */ |
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+ VMOVU (%rsi), %YMM2 |
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+ VPCMP $4, (%rdi), %YMM2, %k1 |
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+ kmovd %k1, %eax |
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+ /* Check if any matches where in bounds. Intentionally not |
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+ storing result in eax to limit dependency chain if it goes to |
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+ L(return_vec_0_lv). */ |
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+ bzhil %edx, %eax, %edx |
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+ jnz L(return_vec_0_lv) |
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+ xorl %eax, %eax |
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+ ret |
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+ |
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+ /* Essentially duplicate of L(return_vec_0). Ends up not costing |
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+ any code as shrinks L(less_vec) by allowing 2-byte encoding of |
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+ the jump and ends up fitting in aligning bytes. As well fits on |
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+ same cache line as L(less_vec) so also saves a line from having |
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+ to be fetched on cold calls to memcmp. */ |
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+ .p2align 4,, 4 |
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+L(return_vec_0_lv): |
|
tzcntl %eax, %eax |
|
- addl %edx, %eax |
|
# ifdef USE_AS_WMEMCMP |
|
- movl -(VEC_SIZE * 2)(%rdi, %rax, CHAR_SIZE), %ecx |
|
+ movl (%rdi, %rax, CHAR_SIZE), %ecx |
|
xorl %edx, %edx |
|
- cmpl -(VEC_SIZE * 2)(%rsi, %rax, CHAR_SIZE), %ecx |
|
+ cmpl (%rsi, %rax, CHAR_SIZE), %ecx |
|
+ /* NB: no partial register stall here because xorl zero idiom |
|
+ above. */ |
|
setg %dl |
|
leal -1(%rdx, %rdx), %eax |
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# else |
|
- movzbl -(VEC_SIZE * 2)(%rsi, %rax), %ecx |
|
- movzbl -(VEC_SIZE * 2)(%rdi, %rax), %eax |
|
+ movzbl (%rsi, %rax), %ecx |
|
+ movzbl (%rdi, %rax), %eax |
|
subl %ecx, %eax |
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# endif |
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ret |
|
|
|
- |
|
.p2align 4 |
|
L(page_cross_less_vec): |
|
/* if USE_AS_WMEMCMP it can only be 0, 4, 8, 12, 16, 20, 24, 28 |
|
@@ -439,108 +513,84 @@ L(page_cross_less_vec): |
|
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 |
|
- movzwl (%rsi), %ecx |
|
- shll $8, %eax |
|
- shll $8, %ecx |
|
- bswap %eax |
|
- bswap %ecx |
|
- 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(one_or_less): |
|
- jb L(zero) |
|
- movzbl (%rsi), %ecx |
|
- movzbl (%rdi), %eax |
|
- subl %ecx, %eax |
|
+ jb L(between_2_3) |
|
+ |
|
+ /* 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 |
|
+ /* edx is guranteed to be positive int32 in range [4, 7]. */ |
|
+ cmovne %edx, %eax |
|
+ /* ecx is -1 if rcx > rax. Otherwise 0. */ |
|
+ sbbl %ecx, %ecx |
|
+ /* If rcx > rax, then ecx is 0 and eax is positive. If rcx == |
|
+ rax then eax and ecx are zero. If rax < rax then ecx is -1 so |
|
+ eax doesn't matter. */ |
|
+ orl %ecx, %eax |
|
ret |
|
|
|
- .p2align 4 |
|
+ .p2align 4,, 8 |
|
L(between_8_15): |
|
# endif |
|
/* If USE_AS_WMEMCMP fall through into 8-15 byte case. */ |
|
- vmovq (%rdi), %XMM1 |
|
- vmovq (%rsi), %XMM2 |
|
- VPCMP $4, %XMM1, %XMM2, %k1 |
|
+ vmovq (%rdi), %xmm1 |
|
+ vmovq (%rsi), %xmm2 |
|
+ VPCMP $4, %xmm1, %xmm2, %k1 |
|
kmovd %k1, %eax |
|
testl %eax, %eax |
|
- jnz L(return_vec_0) |
|
+ jnz L(return_vec_0_lv) |
|
/* Use overlapping loads to avoid branches. */ |
|
- leaq -8(%rdi, %rdx, CHAR_SIZE), %rdi |
|
- leaq -8(%rsi, %rdx, CHAR_SIZE), %rsi |
|
- vmovq (%rdi), %XMM1 |
|
- vmovq (%rsi), %XMM2 |
|
- VPCMP $4, %XMM1, %XMM2, %k1 |
|
+ vmovq -8(%rdi, %rdx, CHAR_SIZE), %xmm1 |
|
+ vmovq -8(%rsi, %rdx, CHAR_SIZE), %xmm2 |
|
+ VPCMP $4, %xmm1, %xmm2, %k1 |
|
+ addl $(CHAR_PER_VEC - (8 / CHAR_SIZE)), %edx |
|
kmovd %k1, %eax |
|
testl %eax, %eax |
|
- jnz L(return_vec_0) |
|
- ret |
|
- |
|
- .p2align 4 |
|
-L(zero): |
|
- xorl %eax, %eax |
|
+ jnz L(return_vec_0_end) |
|
ret |
|
|
|
- .p2align 4 |
|
+ .p2align 4,, 8 |
|
L(between_16_31): |
|
/* From 16 to 31 bytes. No branch when size == 16. */ |
|
- VMOVU (%rsi), %XMM2 |
|
- VPCMP $4, (%rdi), %XMM2, %k1 |
|
+ |
|
+ /* Use movups to save code size. */ |
|
+ movups (%rsi), %xmm2 |
|
+ VPCMP $4, (%rdi), %xmm2, %k1 |
|
kmovd %k1, %eax |
|
testl %eax, %eax |
|
- jnz L(return_vec_0) |
|
- |
|
+ jnz L(return_vec_0_lv) |
|
/* Use overlapping loads to avoid branches. */ |
|
- |
|
- 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 |
|
+ movups -16(%rsi, %rdx, CHAR_SIZE), %xmm2 |
|
+ VPCMP $4, -16(%rdi, %rdx, CHAR_SIZE), %xmm2, %k1 |
|
+ addl $(CHAR_PER_VEC - (16 / CHAR_SIZE)), %edx |
|
kmovd %k1, %eax |
|
testl %eax, %eax |
|
- jnz L(return_vec_0) |
|
- ret |
|
- |
|
-# ifdef USE_AS_WMEMCMP |
|
- .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 |
|
+ jnz L(return_vec_0_end) |
|
ret |
|
-# else |
|
|
|
- .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 |
|
- jz L(zero_4_7) |
|
- sbbl %eax, %eax |
|
- orl $1, %eax |
|
-L(zero_4_7): |
|
+# ifndef USE_AS_WMEMCMP |
|
+L(between_2_3): |
|
+ /* Load as big endian to avoid branches. */ |
|
+ movzwl (%rdi), %eax |
|
+ movzwl (%rsi), %ecx |
|
+ shll $8, %eax |
|
+ shll $8, %ecx |
|
+ bswap %eax |
|
+ bswap %ecx |
|
+ 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 |
|
# endif |
|
- |
|
END (MEMCMP) |
|
#endif
|
|
|