746 lines
17 KiB
Diff
746 lines
17 KiB
Diff
From 4ba65586847751372520a36757c17f114588794e Mon Sep 17 00:00:00 2001
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From: Noah Goldstein <goldstein.w.n@gmail.com>
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Date: Mon, 19 Apr 2021 19:36:06 -0400
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Subject: [PATCH] x86: Optimize strlen-evex.S
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Content-type: text/plain; charset=UTF-8
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No bug. This commit optimizes strlen-evex.S. The
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optimizations are mostly small things but they add up to roughly
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10-30% performance improvement for strlen. The results for strnlen are
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bit more ambiguous. test-strlen, test-strnlen, test-wcslen, and
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test-wcsnlen are all passing.
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Signed-off-by: Noah Goldstein <goldstein.w.n@gmail.com>
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---
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sysdeps/x86_64/multiarch/strlen-evex.S | 581 ++++++++++++++-----------
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1 file changed, 317 insertions(+), 264 deletions(-)
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diff --git a/sysdeps/x86_64/multiarch/strlen-evex.S b/sysdeps/x86_64/multiarch/strlen-evex.S
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index 05838190..4bf6874b 100644
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--- a/sysdeps/x86_64/multiarch/strlen-evex.S
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+++ b/sysdeps/x86_64/multiarch/strlen-evex.S
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@@ -29,11 +29,13 @@
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# ifdef USE_AS_WCSLEN
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# define VPCMP vpcmpd
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# define VPMINU vpminud
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-# define SHIFT_REG r9d
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+# define SHIFT_REG ecx
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+# define CHAR_SIZE 4
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# else
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# define VPCMP vpcmpb
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# define VPMINU vpminub
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-# define SHIFT_REG ecx
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+# define SHIFT_REG edx
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+# define CHAR_SIZE 1
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# endif
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# define XMMZERO xmm16
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@@ -46,132 +48,165 @@
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# define YMM6 ymm22
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# define VEC_SIZE 32
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+# define PAGE_SIZE 4096
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+# define CHAR_PER_VEC (VEC_SIZE / CHAR_SIZE)
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.section .text.evex,"ax",@progbits
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ENTRY (STRLEN)
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# ifdef USE_AS_STRNLEN
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- /* Check for zero length. */
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+ /* Check zero length. */
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test %RSI_LP, %RSI_LP
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jz L(zero)
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-# ifdef USE_AS_WCSLEN
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- shl $2, %RSI_LP
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-# elif defined __ILP32__
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+# ifdef __ILP32__
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/* Clear the upper 32 bits. */
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movl %esi, %esi
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# endif
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mov %RSI_LP, %R8_LP
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# endif
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- movl %edi, %ecx
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- movq %rdi, %rdx
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+ movl %edi, %eax
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vpxorq %XMMZERO, %XMMZERO, %XMMZERO
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-
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+ /* Clear high bits from edi. Only keeping bits relevant to page
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+ cross check. */
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+ andl $(PAGE_SIZE - 1), %eax
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/* Check if we may cross page boundary with one vector load. */
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- andl $(2 * VEC_SIZE - 1), %ecx
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- cmpl $VEC_SIZE, %ecx
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- ja L(cros_page_boundary)
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+ cmpl $(PAGE_SIZE - VEC_SIZE), %eax
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+ ja L(cross_page_boundary)
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/* Check the first VEC_SIZE bytes. Each bit in K0 represents a
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null byte. */
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VPCMP $0, (%rdi), %YMMZERO, %k0
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kmovd %k0, %eax
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- testl %eax, %eax
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-
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# ifdef USE_AS_STRNLEN
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- jnz L(first_vec_x0_check)
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- /* Adjust length and check the end of data. */
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- subq $VEC_SIZE, %rsi
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- jbe L(max)
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-# else
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- jnz L(first_vec_x0)
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+ /* If length < CHAR_PER_VEC handle special. */
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+ cmpq $CHAR_PER_VEC, %rsi
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+ jbe L(first_vec_x0)
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# endif
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-
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- /* Align data for aligned loads in the loop. */
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- addq $VEC_SIZE, %rdi
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- andl $(VEC_SIZE - 1), %ecx
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- andq $-VEC_SIZE, %rdi
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-
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+ testl %eax, %eax
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+ jz L(aligned_more)
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+ tzcntl %eax, %eax
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+ ret
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# ifdef USE_AS_STRNLEN
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- /* Adjust length. */
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- addq %rcx, %rsi
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+L(zero):
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+ xorl %eax, %eax
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+ ret
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- subq $(VEC_SIZE * 4), %rsi
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- jbe L(last_4x_vec_or_less)
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+ .p2align 4
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+L(first_vec_x0):
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+ /* Set bit for max len so that tzcnt will return min of max len
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+ and position of first match. */
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+ btsq %rsi, %rax
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+ tzcntl %eax, %eax
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+ ret
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# endif
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- jmp L(more_4x_vec)
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.p2align 4
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-L(cros_page_boundary):
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- andl $(VEC_SIZE - 1), %ecx
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- andq $-VEC_SIZE, %rdi
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-
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-# ifdef USE_AS_WCSLEN
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- /* NB: Divide shift count by 4 since each bit in K0 represent 4
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- bytes. */
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- movl %ecx, %SHIFT_REG
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- sarl $2, %SHIFT_REG
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+L(first_vec_x1):
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+ tzcntl %eax, %eax
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+ /* Safe to use 32 bit instructions as these are only called for
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+ size = [1, 159]. */
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+# ifdef USE_AS_STRNLEN
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+ /* Use ecx which was computed earlier to compute correct value.
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+ */
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+ leal -(CHAR_PER_VEC * 4 + 1)(%rcx, %rax), %eax
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+# else
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+ subl %edx, %edi
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+# ifdef USE_AS_WCSLEN
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+ /* NB: Divide bytes by 4 to get the wchar_t count. */
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+ sarl $2, %edi
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+# endif
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+ leal CHAR_PER_VEC(%rdi, %rax), %eax
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# endif
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- VPCMP $0, (%rdi), %YMMZERO, %k0
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- kmovd %k0, %eax
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+ ret
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- /* Remove the leading bytes. */
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- sarxl %SHIFT_REG, %eax, %eax
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- testl %eax, %eax
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- jz L(aligned_more)
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+ .p2align 4
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+L(first_vec_x2):
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tzcntl %eax, %eax
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-# ifdef USE_AS_WCSLEN
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- /* NB: Multiply wchar_t count by 4 to get the number of bytes. */
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- sall $2, %eax
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-# endif
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+ /* Safe to use 32 bit instructions as these are only called for
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+ size = [1, 159]. */
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# ifdef USE_AS_STRNLEN
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- /* Check the end of data. */
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- cmpq %rax, %rsi
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- jbe L(max)
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-# endif
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- addq %rdi, %rax
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- addq %rcx, %rax
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- subq %rdx, %rax
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-# ifdef USE_AS_WCSLEN
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- shrq $2, %rax
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+ /* Use ecx which was computed earlier to compute correct value.
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+ */
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+ leal -(CHAR_PER_VEC * 3 + 1)(%rcx, %rax), %eax
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+# else
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+ subl %edx, %edi
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+# ifdef USE_AS_WCSLEN
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+ /* NB: Divide bytes by 4 to get the wchar_t count. */
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+ sarl $2, %edi
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+# endif
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+ leal (CHAR_PER_VEC * 2)(%rdi, %rax), %eax
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# endif
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ret
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.p2align 4
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-L(aligned_more):
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+L(first_vec_x3):
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+ tzcntl %eax, %eax
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+ /* Safe to use 32 bit instructions as these are only called for
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+ size = [1, 159]. */
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# ifdef USE_AS_STRNLEN
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- /* "rcx" is less than VEC_SIZE. Calculate "rdx + rcx - VEC_SIZE"
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- with "rdx - (VEC_SIZE - rcx)" instead of "(rdx + rcx) - VEC_SIZE"
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- to void possible addition overflow. */
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- negq %rcx
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- addq $VEC_SIZE, %rcx
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-
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- /* Check the end of data. */
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- subq %rcx, %rsi
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- jbe L(max)
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+ /* Use ecx which was computed earlier to compute correct value.
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+ */
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+ leal -(CHAR_PER_VEC * 2 + 1)(%rcx, %rax), %eax
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+# else
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+ subl %edx, %edi
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+# ifdef USE_AS_WCSLEN
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+ /* NB: Divide bytes by 4 to get the wchar_t count. */
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+ sarl $2, %edi
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+# endif
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+ leal (CHAR_PER_VEC * 3)(%rdi, %rax), %eax
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# endif
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+ ret
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- addq $VEC_SIZE, %rdi
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-
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+ .p2align 4
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+L(first_vec_x4):
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+ tzcntl %eax, %eax
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+ /* Safe to use 32 bit instructions as these are only called for
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+ size = [1, 159]. */
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# ifdef USE_AS_STRNLEN
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- subq $(VEC_SIZE * 4), %rsi
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- jbe L(last_4x_vec_or_less)
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+ /* Use ecx which was computed earlier to compute correct value.
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+ */
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+ leal -(CHAR_PER_VEC + 1)(%rcx, %rax), %eax
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+# else
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+ subl %edx, %edi
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+# ifdef USE_AS_WCSLEN
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+ /* NB: Divide bytes by 4 to get the wchar_t count. */
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+ sarl $2, %edi
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+# endif
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+ leal (CHAR_PER_VEC * 4)(%rdi, %rax), %eax
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# endif
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+ ret
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-L(more_4x_vec):
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+ .p2align 5
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+L(aligned_more):
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+ movq %rdi, %rdx
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+ /* Align data to VEC_SIZE. */
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+ andq $-(VEC_SIZE), %rdi
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+L(cross_page_continue):
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/* Check the first 4 * VEC_SIZE. Only one VEC_SIZE at a time
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since data is only aligned to VEC_SIZE. */
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- VPCMP $0, (%rdi), %YMMZERO, %k0
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- kmovd %k0, %eax
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- testl %eax, %eax
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- jnz L(first_vec_x0)
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-
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+# ifdef USE_AS_STRNLEN
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+ /* + CHAR_SIZE because it simplies the logic in
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+ last_4x_vec_or_less. */
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+ leaq (VEC_SIZE * 5 + CHAR_SIZE)(%rdi), %rcx
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+ subq %rdx, %rcx
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+# ifdef USE_AS_WCSLEN
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+ /* NB: Divide bytes by 4 to get the wchar_t count. */
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+ sarl $2, %ecx
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+# endif
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+# endif
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+ /* Load first VEC regardless. */
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VPCMP $0, VEC_SIZE(%rdi), %YMMZERO, %k0
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+# ifdef USE_AS_STRNLEN
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+ /* Adjust length. If near end handle specially. */
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+ subq %rcx, %rsi
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+ jb L(last_4x_vec_or_less)
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+# endif
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kmovd %k0, %eax
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testl %eax, %eax
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jnz L(first_vec_x1)
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VPCMP $0, (VEC_SIZE * 2)(%rdi), %YMMZERO, %k0
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kmovd %k0, %eax
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- testl %eax, %eax
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+ test %eax, %eax
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jnz L(first_vec_x2)
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VPCMP $0, (VEC_SIZE * 3)(%rdi), %YMMZERO, %k0
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@@ -179,258 +214,276 @@ L(more_4x_vec):
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testl %eax, %eax
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jnz L(first_vec_x3)
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- addq $(VEC_SIZE * 4), %rdi
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-
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-# ifdef USE_AS_STRNLEN
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- subq $(VEC_SIZE * 4), %rsi
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- jbe L(last_4x_vec_or_less)
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-# endif
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-
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- /* Align data to 4 * VEC_SIZE. */
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- movq %rdi, %rcx
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- andl $(4 * VEC_SIZE - 1), %ecx
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- andq $-(4 * VEC_SIZE), %rdi
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+ VPCMP $0, (VEC_SIZE * 4)(%rdi), %YMMZERO, %k0
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+ kmovd %k0, %eax
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+ testl %eax, %eax
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+ jnz L(first_vec_x4)
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+ addq $VEC_SIZE, %rdi
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# ifdef USE_AS_STRNLEN
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- /* Adjust length. */
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+ /* Check if at last VEC_SIZE * 4 length. */
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+ cmpq $(CHAR_PER_VEC * 4 - 1), %rsi
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+ jbe L(last_4x_vec_or_less_load)
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+ movl %edi, %ecx
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+ andl $(VEC_SIZE * 4 - 1), %ecx
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+# ifdef USE_AS_WCSLEN
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+ /* NB: Divide bytes by 4 to get the wchar_t count. */
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+ sarl $2, %ecx
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+# endif
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+ /* Readjust length. */
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addq %rcx, %rsi
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# endif
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+ /* Align data to VEC_SIZE * 4. */
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+ andq $-(VEC_SIZE * 4), %rdi
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+ /* Compare 4 * VEC at a time forward. */
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.p2align 4
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L(loop_4x_vec):
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- /* Compare 4 * VEC at a time forward. */
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- VMOVA (%rdi), %YMM1
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- VMOVA VEC_SIZE(%rdi), %YMM2
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- VMOVA (VEC_SIZE * 2)(%rdi), %YMM3
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- VMOVA (VEC_SIZE * 3)(%rdi), %YMM4
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-
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- VPMINU %YMM1, %YMM2, %YMM5
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- VPMINU %YMM3, %YMM4, %YMM6
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+ /* Load first VEC regardless. */
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+ VMOVA (VEC_SIZE * 4)(%rdi), %YMM1
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+# ifdef USE_AS_STRNLEN
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+ /* Break if at end of length. */
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+ subq $(CHAR_PER_VEC * 4), %rsi
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+ jb L(last_4x_vec_or_less_cmpeq)
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+# endif
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+ /* Save some code size by microfusing VPMINU with the load. Since
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+ the matches in ymm2/ymm4 can only be returned if there where no
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+ matches in ymm1/ymm3 respectively there is no issue with overlap.
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+ */
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+ VPMINU (VEC_SIZE * 5)(%rdi), %YMM1, %YMM2
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+ VMOVA (VEC_SIZE * 6)(%rdi), %YMM3
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+ VPMINU (VEC_SIZE * 7)(%rdi), %YMM3, %YMM4
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+
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+ VPCMP $0, %YMM2, %YMMZERO, %k0
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+ VPCMP $0, %YMM4, %YMMZERO, %k1
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+ subq $-(VEC_SIZE * 4), %rdi
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+ kortestd %k0, %k1
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+ jz L(loop_4x_vec)
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+
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+ /* Check if end was in first half. */
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+ kmovd %k0, %eax
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+ subq %rdx, %rdi
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+# ifdef USE_AS_WCSLEN
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+ shrq $2, %rdi
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+# endif
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+ testl %eax, %eax
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+ jz L(second_vec_return)
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- VPMINU %YMM5, %YMM6, %YMM5
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- VPCMP $0, %YMM5, %YMMZERO, %k0
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- ktestd %k0, %k0
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- jnz L(4x_vec_end)
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+ VPCMP $0, %YMM1, %YMMZERO, %k2
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+ kmovd %k2, %edx
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+ /* Combine VEC1 matches (edx) with VEC2 matches (eax). */
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+# ifdef USE_AS_WCSLEN
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+ sall $CHAR_PER_VEC, %eax
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+ orl %edx, %eax
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+ tzcntl %eax, %eax
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+# else
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+ salq $CHAR_PER_VEC, %rax
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+ orq %rdx, %rax
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+ tzcntq %rax, %rax
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+# endif
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+ addq %rdi, %rax
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+ ret
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- addq $(VEC_SIZE * 4), %rdi
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-# ifndef USE_AS_STRNLEN
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- jmp L(loop_4x_vec)
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-# else
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- subq $(VEC_SIZE * 4), %rsi
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- ja L(loop_4x_vec)
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+# ifdef USE_AS_STRNLEN
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+L(last_4x_vec_or_less_load):
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+ /* Depending on entry adjust rdi / prepare first VEC in YMM1. */
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+ VMOVA (VEC_SIZE * 4)(%rdi), %YMM1
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+L(last_4x_vec_or_less_cmpeq):
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+ VPCMP $0, %YMM1, %YMMZERO, %k0
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+ addq $(VEC_SIZE * 3), %rdi
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L(last_4x_vec_or_less):
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- /* Less than 4 * VEC and aligned to VEC_SIZE. */
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- addl $(VEC_SIZE * 2), %esi
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- jle L(last_2x_vec)
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-
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- VPCMP $0, (%rdi), %YMMZERO, %k0
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kmovd %k0, %eax
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+ /* If remaining length > VEC_SIZE * 2. This works if esi is off by
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+ VEC_SIZE * 4. */
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+ testl $(CHAR_PER_VEC * 2), %esi
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+ jnz L(last_4x_vec)
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+
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+ /* length may have been negative or positive by an offset of
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+ CHAR_PER_VEC * 4 depending on where this was called from. This
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+ fixes that. */
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+ andl $(CHAR_PER_VEC * 4 - 1), %esi
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testl %eax, %eax
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- jnz L(first_vec_x0)
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+ jnz L(last_vec_x1_check)
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- VPCMP $0, VEC_SIZE(%rdi), %YMMZERO, %k0
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- kmovd %k0, %eax
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- testl %eax, %eax
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- jnz L(first_vec_x1)
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+ /* Check the end of data. */
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+ subl $CHAR_PER_VEC, %esi
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+ jb L(max)
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VPCMP $0, (VEC_SIZE * 2)(%rdi), %YMMZERO, %k0
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kmovd %k0, %eax
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- testl %eax, %eax
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- jnz L(first_vec_x2_check)
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- subl $VEC_SIZE, %esi
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- jle L(max)
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+ tzcntl %eax, %eax
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+ /* Check the end of data. */
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+ cmpl %eax, %esi
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+ jb L(max)
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- VPCMP $0, (VEC_SIZE * 3)(%rdi), %YMMZERO, %k0
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- kmovd %k0, %eax
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- testl %eax, %eax
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- jnz L(first_vec_x3_check)
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+ subq %rdx, %rdi
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+# ifdef USE_AS_WCSLEN
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+ /* NB: Divide bytes by 4 to get the wchar_t count. */
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+ sarq $2, %rdi
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+# endif
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+ leaq (CHAR_PER_VEC * 2)(%rdi, %rax), %rax
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+ ret
|
|
+L(max):
|
|
movq %r8, %rax
|
|
+ ret
|
|
+# endif
|
|
+
|
|
+ /* Placed here in strnlen so that the jcc L(last_4x_vec_or_less)
|
|
+ in the 4x VEC loop can use 2 byte encoding. */
|
|
+ .p2align 4
|
|
+L(second_vec_return):
|
|
+ VPCMP $0, %YMM3, %YMMZERO, %k0
|
|
+ /* Combine YMM3 matches (k0) with YMM4 matches (k1). */
|
|
+# ifdef USE_AS_WCSLEN
|
|
+ kunpckbw %k0, %k1, %k0
|
|
+ kmovd %k0, %eax
|
|
+ tzcntl %eax, %eax
|
|
+# else
|
|
+ kunpckdq %k0, %k1, %k0
|
|
+ kmovq %k0, %rax
|
|
+ tzcntq %rax, %rax
|
|
+# endif
|
|
+ leaq (CHAR_PER_VEC * 2)(%rdi, %rax), %rax
|
|
+ ret
|
|
+
|
|
+
|
|
+# ifdef USE_AS_STRNLEN
|
|
+L(last_vec_x1_check):
|
|
+ tzcntl %eax, %eax
|
|
+ /* Check the end of data. */
|
|
+ cmpl %eax, %esi
|
|
+ jb L(max)
|
|
+ subq %rdx, %rdi
|
|
# ifdef USE_AS_WCSLEN
|
|
- shrq $2, %rax
|
|
+ /* NB: Divide bytes by 4 to get the wchar_t count. */
|
|
+ sarq $2, %rdi
|
|
# endif
|
|
+ leaq (CHAR_PER_VEC)(%rdi, %rax), %rax
|
|
ret
|
|
|
|
.p2align 4
|
|
-L(last_2x_vec):
|
|
- addl $(VEC_SIZE * 2), %esi
|
|
+L(last_4x_vec):
|
|
+ /* Test first 2x VEC normally. */
|
|
+ testl %eax, %eax
|
|
+ jnz L(last_vec_x1)
|
|
|
|
- VPCMP $0, (%rdi), %YMMZERO, %k0
|
|
+ VPCMP $0, (VEC_SIZE * 2)(%rdi), %YMMZERO, %k0
|
|
kmovd %k0, %eax
|
|
testl %eax, %eax
|
|
- jnz L(first_vec_x0_check)
|
|
- subl $VEC_SIZE, %esi
|
|
- jle L(max)
|
|
+ jnz L(last_vec_x2)
|
|
|
|
- VPCMP $0, VEC_SIZE(%rdi), %YMMZERO, %k0
|
|
+ /* Normalize length. */
|
|
+ andl $(CHAR_PER_VEC * 4 - 1), %esi
|
|
+ VPCMP $0, (VEC_SIZE * 3)(%rdi), %YMMZERO, %k0
|
|
kmovd %k0, %eax
|
|
testl %eax, %eax
|
|
- jnz L(first_vec_x1_check)
|
|
- movq %r8, %rax
|
|
-# ifdef USE_AS_WCSLEN
|
|
- shrq $2, %rax
|
|
-# endif
|
|
- ret
|
|
+ jnz L(last_vec_x3)
|
|
|
|
- .p2align 4
|
|
-L(first_vec_x0_check):
|
|
+ /* Check the end of data. */
|
|
+ subl $(CHAR_PER_VEC * 3), %esi
|
|
+ jb L(max)
|
|
+
|
|
+ VPCMP $0, (VEC_SIZE * 4)(%rdi), %YMMZERO, %k0
|
|
+ kmovd %k0, %eax
|
|
tzcntl %eax, %eax
|
|
-# ifdef USE_AS_WCSLEN
|
|
- /* NB: Multiply wchar_t count by 4 to get the number of bytes. */
|
|
- sall $2, %eax
|
|
-# endif
|
|
/* Check the end of data. */
|
|
- cmpq %rax, %rsi
|
|
- jbe L(max)
|
|
- addq %rdi, %rax
|
|
- subq %rdx, %rax
|
|
+ cmpl %eax, %esi
|
|
+ jb L(max_end)
|
|
+
|
|
+ subq %rdx, %rdi
|
|
# ifdef USE_AS_WCSLEN
|
|
- shrq $2, %rax
|
|
+ /* NB: Divide bytes by 4 to get the wchar_t count. */
|
|
+ sarq $2, %rdi
|
|
# endif
|
|
+ leaq (CHAR_PER_VEC * 4)(%rdi, %rax), %rax
|
|
ret
|
|
|
|
.p2align 4
|
|
-L(first_vec_x1_check):
|
|
+L(last_vec_x1):
|
|
tzcntl %eax, %eax
|
|
+ subq %rdx, %rdi
|
|
# ifdef USE_AS_WCSLEN
|
|
- /* NB: Multiply wchar_t count by 4 to get the number of bytes. */
|
|
- sall $2, %eax
|
|
-# endif
|
|
- /* Check the end of data. */
|
|
- cmpq %rax, %rsi
|
|
- jbe L(max)
|
|
- addq $VEC_SIZE, %rax
|
|
- addq %rdi, %rax
|
|
- subq %rdx, %rax
|
|
-# ifdef USE_AS_WCSLEN
|
|
- shrq $2, %rax
|
|
+ /* NB: Divide bytes by 4 to get the wchar_t count. */
|
|
+ sarq $2, %rdi
|
|
# endif
|
|
+ leaq (CHAR_PER_VEC)(%rdi, %rax), %rax
|
|
ret
|
|
|
|
.p2align 4
|
|
-L(first_vec_x2_check):
|
|
+L(last_vec_x2):
|
|
tzcntl %eax, %eax
|
|
+ subq %rdx, %rdi
|
|
# ifdef USE_AS_WCSLEN
|
|
- /* NB: Multiply wchar_t count by 4 to get the number of bytes. */
|
|
- sall $2, %eax
|
|
-# endif
|
|
- /* Check the end of data. */
|
|
- cmpq %rax, %rsi
|
|
- jbe L(max)
|
|
- addq $(VEC_SIZE * 2), %rax
|
|
- addq %rdi, %rax
|
|
- subq %rdx, %rax
|
|
-# ifdef USE_AS_WCSLEN
|
|
- shrq $2, %rax
|
|
+ /* NB: Divide bytes by 4 to get the wchar_t count. */
|
|
+ sarq $2, %rdi
|
|
# endif
|
|
+ leaq (CHAR_PER_VEC * 2)(%rdi, %rax), %rax
|
|
ret
|
|
|
|
.p2align 4
|
|
-L(first_vec_x3_check):
|
|
+L(last_vec_x3):
|
|
tzcntl %eax, %eax
|
|
-# ifdef USE_AS_WCSLEN
|
|
- /* NB: Multiply wchar_t count by 4 to get the number of bytes. */
|
|
- sall $2, %eax
|
|
-# endif
|
|
+ subl $(CHAR_PER_VEC * 2), %esi
|
|
/* Check the end of data. */
|
|
- cmpq %rax, %rsi
|
|
- jbe L(max)
|
|
- addq $(VEC_SIZE * 3), %rax
|
|
- addq %rdi, %rax
|
|
- subq %rdx, %rax
|
|
+ cmpl %eax, %esi
|
|
+ jb L(max_end)
|
|
+ subq %rdx, %rdi
|
|
# ifdef USE_AS_WCSLEN
|
|
- shrq $2, %rax
|
|
+ /* NB: Divide bytes by 4 to get the wchar_t count. */
|
|
+ sarq $2, %rdi
|
|
# endif
|
|
+ leaq (CHAR_PER_VEC * 3)(%rdi, %rax), %rax
|
|
ret
|
|
-
|
|
- .p2align 4
|
|
-L(max):
|
|
+L(max_end):
|
|
movq %r8, %rax
|
|
-# ifdef USE_AS_WCSLEN
|
|
- shrq $2, %rax
|
|
-# endif
|
|
- ret
|
|
-
|
|
- .p2align 4
|
|
-L(zero):
|
|
- xorl %eax, %eax
|
|
ret
|
|
# endif
|
|
|
|
+ /* Cold case for crossing page with first load. */
|
|
.p2align 4
|
|
-L(first_vec_x0):
|
|
- tzcntl %eax, %eax
|
|
-# ifdef USE_AS_WCSLEN
|
|
- /* NB: Multiply wchar_t count by 4 to get the number of bytes. */
|
|
- sall $2, %eax
|
|
-# endif
|
|
- addq %rdi, %rax
|
|
- subq %rdx, %rax
|
|
+L(cross_page_boundary):
|
|
+ movq %rdi, %rdx
|
|
+ /* Align data to VEC_SIZE. */
|
|
+ andq $-VEC_SIZE, %rdi
|
|
+ VPCMP $0, (%rdi), %YMMZERO, %k0
|
|
+ kmovd %k0, %eax
|
|
+ /* Remove the leading bytes. */
|
|
# ifdef USE_AS_WCSLEN
|
|
- shrq $2, %rax
|
|
+ /* NB: Divide shift count by 4 since each bit in K0 represent 4
|
|
+ bytes. */
|
|
+ movl %edx, %ecx
|
|
+ shrl $2, %ecx
|
|
+ andl $(CHAR_PER_VEC - 1), %ecx
|
|
# endif
|
|
- ret
|
|
-
|
|
- .p2align 4
|
|
-L(first_vec_x1):
|
|
+ /* SHIFT_REG is ecx for USE_AS_WCSLEN and edx otherwise. */
|
|
+ sarxl %SHIFT_REG, %eax, %eax
|
|
+ testl %eax, %eax
|
|
+# ifndef USE_AS_STRNLEN
|
|
+ jz L(cross_page_continue)
|
|
tzcntl %eax, %eax
|
|
-# ifdef USE_AS_WCSLEN
|
|
- /* NB: Multiply wchar_t count by 4 to get the number of bytes. */
|
|
- sall $2, %eax
|
|
-# endif
|
|
- addq $VEC_SIZE, %rax
|
|
- addq %rdi, %rax
|
|
- subq %rdx, %rax
|
|
-# ifdef USE_AS_WCSLEN
|
|
- shrq $2, %rax
|
|
-# endif
|
|
ret
|
|
-
|
|
- .p2align 4
|
|
-L(first_vec_x2):
|
|
- tzcntl %eax, %eax
|
|
-# ifdef USE_AS_WCSLEN
|
|
- /* NB: Multiply wchar_t count by 4 to get the number of bytes. */
|
|
- sall $2, %eax
|
|
-# endif
|
|
- addq $(VEC_SIZE * 2), %rax
|
|
- addq %rdi, %rax
|
|
- subq %rdx, %rax
|
|
-# ifdef USE_AS_WCSLEN
|
|
- shrq $2, %rax
|
|
-# endif
|
|
+# else
|
|
+ jnz L(cross_page_less_vec)
|
|
+# ifndef USE_AS_WCSLEN
|
|
+ movl %edx, %ecx
|
|
+ andl $(CHAR_PER_VEC - 1), %ecx
|
|
+# endif
|
|
+ movl $CHAR_PER_VEC, %eax
|
|
+ subl %ecx, %eax
|
|
+ /* Check the end of data. */
|
|
+ cmpq %rax, %rsi
|
|
+ ja L(cross_page_continue)
|
|
+ movl %esi, %eax
|
|
ret
|
|
-
|
|
- .p2align 4
|
|
-L(4x_vec_end):
|
|
- VPCMP $0, %YMM1, %YMMZERO, %k0
|
|
- kmovd %k0, %eax
|
|
- testl %eax, %eax
|
|
- jnz L(first_vec_x0)
|
|
- VPCMP $0, %YMM2, %YMMZERO, %k1
|
|
- kmovd %k1, %eax
|
|
- testl %eax, %eax
|
|
- jnz L(first_vec_x1)
|
|
- VPCMP $0, %YMM3, %YMMZERO, %k2
|
|
- kmovd %k2, %eax
|
|
- testl %eax, %eax
|
|
- jnz L(first_vec_x2)
|
|
- VPCMP $0, %YMM4, %YMMZERO, %k3
|
|
- kmovd %k3, %eax
|
|
-L(first_vec_x3):
|
|
+L(cross_page_less_vec):
|
|
tzcntl %eax, %eax
|
|
-# ifdef USE_AS_WCSLEN
|
|
- /* NB: Multiply wchar_t count by 4 to get the number of bytes. */
|
|
- sall $2, %eax
|
|
-# endif
|
|
- addq $(VEC_SIZE * 3), %rax
|
|
- addq %rdi, %rax
|
|
- subq %rdx, %rax
|
|
-# ifdef USE_AS_WCSLEN
|
|
- shrq $2, %rax
|
|
-# endif
|
|
+ /* Select min of length and position of first null. */
|
|
+ cmpq %rax, %rsi
|
|
+ cmovb %esi, %eax
|
|
ret
|
|
+# endif
|
|
|
|
END (STRLEN)
|
|
#endif
|
|
--
|
|
GitLab
|
|
|