258 lines
4.3 KiB
Diff
258 lines
4.3 KiB
Diff
From 244b415d386487521882debb845a040a4758cb18 Mon Sep 17 00:00:00 2001
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From: Noah Goldstein <goldstein.w.n@gmail.com>
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Date: Fri, 25 Mar 2022 17:13:33 -0500
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Subject: [PATCH] x86: Small improvements for wcslen
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Content-type: text/plain; charset=UTF-8
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Just a few QOL changes.
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1. Prefer `add` > `lea` as it has high execution units it can run
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on.
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2. Don't break macro-fusion between `test` and `jcc`
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3. Reduce code size by removing gratuitous padding bytes (-90
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bytes).
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geometric_mean(N=20) of all benchmarks New / Original: 0.959
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All string/memory tests pass.
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Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
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---
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sysdeps/x86_64/wcslen.S | 86 ++++++++++++++++++++---------------------
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1 file changed, 41 insertions(+), 45 deletions(-)
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diff --git a/sysdeps/x86_64/wcslen.S b/sysdeps/x86_64/wcslen.S
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index 9f5f7232..254bb030 100644
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--- a/sysdeps/x86_64/wcslen.S
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+++ b/sysdeps/x86_64/wcslen.S
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@@ -41,82 +41,82 @@ ENTRY (__wcslen)
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pxor %xmm0, %xmm0
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lea 32(%rdi), %rax
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- lea 16(%rdi), %rcx
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+ addq $16, %rdi
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and $-16, %rax
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pcmpeqd (%rax), %xmm0
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pmovmskb %xmm0, %edx
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pxor %xmm1, %xmm1
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+ addq $16, %rax
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test %edx, %edx
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- lea 16(%rax), %rax
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jnz L(exit)
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pcmpeqd (%rax), %xmm1
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pmovmskb %xmm1, %edx
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pxor %xmm2, %xmm2
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+ addq $16, %rax
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test %edx, %edx
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- lea 16(%rax), %rax
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jnz L(exit)
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pcmpeqd (%rax), %xmm2
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pmovmskb %xmm2, %edx
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pxor %xmm3, %xmm3
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+ addq $16, %rax
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test %edx, %edx
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- lea 16(%rax), %rax
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jnz L(exit)
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pcmpeqd (%rax), %xmm3
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pmovmskb %xmm3, %edx
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+ addq $16, %rax
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test %edx, %edx
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- lea 16(%rax), %rax
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jnz L(exit)
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pcmpeqd (%rax), %xmm0
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pmovmskb %xmm0, %edx
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+ addq $16, %rax
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test %edx, %edx
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- lea 16(%rax), %rax
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jnz L(exit)
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pcmpeqd (%rax), %xmm1
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pmovmskb %xmm1, %edx
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+ addq $16, %rax
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test %edx, %edx
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- lea 16(%rax), %rax
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jnz L(exit)
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pcmpeqd (%rax), %xmm2
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pmovmskb %xmm2, %edx
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+ addq $16, %rax
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test %edx, %edx
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- lea 16(%rax), %rax
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jnz L(exit)
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pcmpeqd (%rax), %xmm3
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pmovmskb %xmm3, %edx
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+ addq $16, %rax
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test %edx, %edx
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- lea 16(%rax), %rax
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jnz L(exit)
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pcmpeqd (%rax), %xmm0
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pmovmskb %xmm0, %edx
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+ addq $16, %rax
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test %edx, %edx
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- lea 16(%rax), %rax
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jnz L(exit)
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pcmpeqd (%rax), %xmm1
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pmovmskb %xmm1, %edx
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+ addq $16, %rax
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test %edx, %edx
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- lea 16(%rax), %rax
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jnz L(exit)
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pcmpeqd (%rax), %xmm2
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pmovmskb %xmm2, %edx
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+ addq $16, %rax
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test %edx, %edx
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- lea 16(%rax), %rax
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jnz L(exit)
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pcmpeqd (%rax), %xmm3
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pmovmskb %xmm3, %edx
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+ addq $16, %rax
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test %edx, %edx
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- lea 16(%rax), %rax
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jnz L(exit)
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and $-0x40, %rax
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@@ -133,104 +133,100 @@ L(aligned_64_loop):
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pminub %xmm0, %xmm2
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pcmpeqd %xmm3, %xmm2
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pmovmskb %xmm2, %edx
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+ addq $64, %rax
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test %edx, %edx
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- lea 64(%rax), %rax
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jz L(aligned_64_loop)
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pcmpeqd -64(%rax), %xmm3
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pmovmskb %xmm3, %edx
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+ addq $48, %rdi
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test %edx, %edx
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- lea 48(%rcx), %rcx
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jnz L(exit)
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pcmpeqd %xmm1, %xmm3
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pmovmskb %xmm3, %edx
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+ addq $-16, %rdi
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test %edx, %edx
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- lea -16(%rcx), %rcx
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jnz L(exit)
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pcmpeqd -32(%rax), %xmm3
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pmovmskb %xmm3, %edx
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+ addq $-16, %rdi
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test %edx, %edx
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- lea -16(%rcx), %rcx
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jnz L(exit)
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pcmpeqd %xmm6, %xmm3
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pmovmskb %xmm3, %edx
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+ addq $-16, %rdi
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test %edx, %edx
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- lea -16(%rcx), %rcx
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- jnz L(exit)
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-
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- jmp L(aligned_64_loop)
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+ jz L(aligned_64_loop)
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.p2align 4
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L(exit):
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- sub %rcx, %rax
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+ sub %rdi, %rax
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shr $2, %rax
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test %dl, %dl
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jz L(exit_high)
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- mov %dl, %cl
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- and $15, %cl
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+ andl $15, %edx
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jz L(exit_1)
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ret
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- .p2align 4
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+ /* No align here. Naturally aligned % 16 == 1. */
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L(exit_high):
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- mov %dh, %ch
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- and $15, %ch
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+ andl $(15 << 8), %edx
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jz L(exit_3)
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add $2, %rax
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ret
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- .p2align 4
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+ .p2align 3
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L(exit_1):
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add $1, %rax
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ret
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- .p2align 4
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+ .p2align 3
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L(exit_3):
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add $3, %rax
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ret
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- .p2align 4
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+ .p2align 3
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L(exit_tail0):
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- xor %rax, %rax
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+ xorl %eax, %eax
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ret
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- .p2align 4
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+ .p2align 3
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L(exit_tail1):
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- mov $1, %rax
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+ movl $1, %eax
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ret
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- .p2align 4
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+ .p2align 3
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L(exit_tail2):
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- mov $2, %rax
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+ movl $2, %eax
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ret
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- .p2align 4
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+ .p2align 3
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L(exit_tail3):
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- mov $3, %rax
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+ movl $3, %eax
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ret
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- .p2align 4
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+ .p2align 3
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L(exit_tail4):
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- mov $4, %rax
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+ movl $4, %eax
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ret
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- .p2align 4
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+ .p2align 3
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L(exit_tail5):
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- mov $5, %rax
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+ movl $5, %eax
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ret
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- .p2align 4
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+ .p2align 3
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L(exit_tail6):
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- mov $6, %rax
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+ movl $6, %eax
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ret
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- .p2align 4
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+ .p2align 3
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L(exit_tail7):
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- mov $7, %rax
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+ movl $7, %eax
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ret
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END (__wcslen)
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--
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GitLab
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