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x86: Optimize memset-vec-unaligned-erms.S
No bug. Optimization are 1. change control flow for L(more_2x_vec) to fall through to loop and jump for L(less_4x_vec) and L(less_8x_vec). This uses less code size and saves jumps for length > 4x VEC_SIZE. 2. For EVEX/AVX512 move L(less_vec) closer to entry. 3. Avoid complex address mode for length > 2x VEC_SIZE 4. Slightly better aligning code for the loop from the perspective of code size and uops. 5. Align targets so they make full use of their fetch block and if possible cache line. 6. Try and reduce total number of icache lines that will need to be pulled in for a given length. 7. Include "local" version of stosb target. For AVX2/EVEX/AVX512 jumping to the stosb target in the sse2 code section will almost certainly be to a new page. The new version does increase code size marginally by duplicating the target but should get better iTLB behavior as a result. test-memset, test-wmemset, and test-bzero are all passing. Signed-off-by: Noah Goldstein <goldstein.w.n@gmail.com> Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
This commit is contained in:
Noah Goldstein
parent
1bd8b8d58f
commit
e59ced2384
@ -18,13 +18,15 @@
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<https://www.gnu.org/licenses/>. */
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#include <sysdep.h>
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#define USE_WITH_SSE2 1
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#define VEC_SIZE 16
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#define MOV_SIZE 3
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#define RET_SIZE 1
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#define VEC(i) xmm##i
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/* Don't use movups and movaps since it will get larger nop paddings for
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alignment. */
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#define VMOVU movdqu
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#define VMOVA movdqa
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#define VMOVU movups
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#define VMOVA movaps
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#define MEMSET_VDUP_TO_VEC0_AND_SET_RETURN(d, r) \
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movd d, %xmm0; \
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@ -1,8 +1,14 @@
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#if IS_IN (libc)
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# define USE_WITH_AVX2 1
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# define VEC_SIZE 32
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# define MOV_SIZE 4
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# define RET_SIZE 4
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# define VEC(i) ymm##i
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# define VMOVU vmovdqu
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# define VMOVA vmovdqa
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# define VMOVU vmovdqu
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# define VMOVA vmovdqa
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# define MEMSET_VDUP_TO_VEC0_AND_SET_RETURN(d, r) \
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vmovd d, %xmm0; \
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@ -1,11 +1,18 @@
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#if IS_IN (libc)
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# define USE_WITH_AVX512 1
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# define VEC_SIZE 64
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# define MOV_SIZE 6
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# define RET_SIZE 1
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# define XMM0 xmm16
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# define YMM0 ymm16
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# define VEC0 zmm16
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# define VEC(i) VEC##i
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# define VMOVU vmovdqu64
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# define VMOVA vmovdqa64
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# define VMOVU vmovdqu64
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# define VMOVA vmovdqa64
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# define VZEROUPPER
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# define MEMSET_VDUP_TO_VEC0_AND_SET_RETURN(d, r) \
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@ -1,11 +1,18 @@
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#if IS_IN (libc)
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# define USE_WITH_EVEX 1
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# define VEC_SIZE 32
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# define MOV_SIZE 6
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# define RET_SIZE 1
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# define XMM0 xmm16
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# define YMM0 ymm16
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# define VEC0 ymm16
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# define VEC(i) VEC##i
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# define VMOVU vmovdqu64
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# define VMOVA vmovdqa64
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# define VMOVU vmovdqu64
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# define VMOVA vmovdqa64
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# define VZEROUPPER
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# define MEMSET_VDUP_TO_VEC0_AND_SET_RETURN(d, r) \
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@ -63,8 +63,27 @@
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# endif
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#endif
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#if VEC_SIZE == 64
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# define LOOP_4X_OFFSET (VEC_SIZE * 4)
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#else
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# define LOOP_4X_OFFSET (0)
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#endif
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#if defined USE_WITH_EVEX || defined USE_WITH_AVX512
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# define END_REG rcx
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# define LOOP_REG rdi
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#else
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# define END_REG rdi
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# define LOOP_REG rdx
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#endif
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#define PAGE_SIZE 4096
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/* Macro to calculate size of small memset block for aligning
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purposes. */
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#define SMALL_MEMSET_ALIGN(mov_sz, ret_sz) (2 * (mov_sz) + (ret_sz) + 1)
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#ifndef SECTION
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# error SECTION is not defined!
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#endif
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@ -74,6 +93,7 @@
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ENTRY (__bzero)
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mov %RDI_LP, %RAX_LP /* Set return value. */
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mov %RSI_LP, %RDX_LP /* Set n. */
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xorl %esi, %esi
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pxor %XMM0, %XMM0
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jmp L(entry_from_bzero)
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END (__bzero)
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@ -158,7 +178,7 @@ ENTRY_CHK (MEMSET_CHK_SYMBOL (__memset_chk, unaligned_erms))
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END_CHK (MEMSET_CHK_SYMBOL (__memset_chk, unaligned_erms))
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# endif
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ENTRY (MEMSET_SYMBOL (__memset, unaligned_erms))
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ENTRY_P2ALIGN (MEMSET_SYMBOL (__memset, unaligned_erms), 6)
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MEMSET_VDUP_TO_VEC0_AND_SET_RETURN (%esi, %rdi)
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# ifdef __ILP32__
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/* Clear the upper 32 bits. */
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@ -168,75 +188,43 @@ ENTRY (MEMSET_SYMBOL (__memset, unaligned_erms))
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jb L(less_vec)
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cmp $(VEC_SIZE * 2), %RDX_LP
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ja L(stosb_more_2x_vec)
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/* From VEC and to 2 * VEC. No branch when size == VEC_SIZE. */
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VMOVU %VEC(0), -VEC_SIZE(%rdi,%rdx)
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VMOVU %VEC(0), (%rdi)
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/* From VEC and to 2 * VEC. No branch when size == VEC_SIZE.
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*/
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VMOVU %VEC(0), (%rax)
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VMOVU %VEC(0), -VEC_SIZE(%rax, %rdx)
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VZEROUPPER_RETURN
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#endif
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.p2align 4,, 10
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L(last_2x_vec):
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#ifdef USE_LESS_VEC_MASK_STORE
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VMOVU %VEC(0), (VEC_SIZE * 2 + LOOP_4X_OFFSET)(%rcx)
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VMOVU %VEC(0), (VEC_SIZE * 3 + LOOP_4X_OFFSET)(%rcx)
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#else
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VMOVU %VEC(0), (VEC_SIZE * -2)(%rdi)
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VMOVU %VEC(0), (VEC_SIZE * -1)(%rdi)
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#endif
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VZEROUPPER_RETURN
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.p2align 4
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L(stosb_more_2x_vec):
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cmp __x86_rep_stosb_threshold(%rip), %RDX_LP
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ja L(stosb)
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#else
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.p2align 4
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#endif
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L(more_2x_vec):
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/* Stores to first 2x VEC before cmp as any path forward will
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require it. */
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VMOVU %VEC(0), (%rdi)
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VMOVU %VEC(0), VEC_SIZE(%rdi)
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cmpq $(VEC_SIZE * 4), %rdx
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ja L(loop_start)
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VMOVU %VEC(0), -(VEC_SIZE * 2)(%rdi,%rdx)
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VMOVU %VEC(0), -VEC_SIZE(%rdi,%rdx)
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L(return):
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#if VEC_SIZE > 16
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ZERO_UPPER_VEC_REGISTERS_RETURN
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#else
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ret
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#endif
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L(loop_start):
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VMOVU %VEC(0), (VEC_SIZE * 2)(%rdi)
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VMOVU %VEC(0), (VEC_SIZE * 3)(%rdi)
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cmpq $(VEC_SIZE * 8), %rdx
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jbe L(loop_end)
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andq $-(VEC_SIZE * 2), %rdi
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subq $-(VEC_SIZE * 4), %rdi
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leaq -(VEC_SIZE * 4)(%rax, %rdx), %rcx
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.p2align 4
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L(loop):
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VMOVA %VEC(0), (%rdi)
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VMOVA %VEC(0), VEC_SIZE(%rdi)
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VMOVA %VEC(0), (VEC_SIZE * 2)(%rdi)
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VMOVA %VEC(0), (VEC_SIZE * 3)(%rdi)
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subq $-(VEC_SIZE * 4), %rdi
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cmpq %rcx, %rdi
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jb L(loop)
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L(loop_end):
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/* NB: rax is set as ptr in MEMSET_VDUP_TO_VEC0_AND_SET_RETURN.
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rdx as length is also unchanged. */
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VMOVU %VEC(0), -(VEC_SIZE * 4)(%rax, %rdx)
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VMOVU %VEC(0), -(VEC_SIZE * 3)(%rax, %rdx)
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VMOVU %VEC(0), -(VEC_SIZE * 2)(%rax, %rdx)
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VMOVU %VEC(0), -VEC_SIZE(%rax, %rdx)
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VZEROUPPER_SHORT_RETURN
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.p2align 4
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/* If have AVX512 mask instructions put L(less_vec) close to
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entry as it doesn't take much space and is likely a hot target.
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*/
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#ifdef USE_LESS_VEC_MASK_STORE
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.p2align 4,, 10
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L(less_vec):
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/* Less than 1 VEC. */
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# if VEC_SIZE != 16 && VEC_SIZE != 32 && VEC_SIZE != 64
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# error Unsupported VEC_SIZE!
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# endif
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# ifdef USE_LESS_VEC_MASK_STORE
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/* Clear high bits from edi. Only keeping bits relevant to page
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cross check. Note that we are using rax which is set in
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MEMSET_VDUP_TO_VEC0_AND_SET_RETURN as ptr from here on out.
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*/
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MEMSET_VDUP_TO_VEC0_AND_SET_RETURN as ptr from here on out. */
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andl $(PAGE_SIZE - 1), %edi
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/* Check if VEC_SIZE store cross page. Mask stores suffer serious
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performance degradation when it has to fault supress. */
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/* Check if VEC_SIZE store cross page. Mask stores suffer
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serious performance degradation when it has to fault supress.
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*/
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cmpl $(PAGE_SIZE - VEC_SIZE), %edi
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/* This is generally considered a cold target. */
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ja L(cross_page)
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# if VEC_SIZE > 32
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movq $-1, %rcx
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@ -247,58 +235,185 @@ L(less_vec):
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bzhil %edx, %ecx, %ecx
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kmovd %ecx, %k1
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# endif
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vmovdqu8 %VEC(0), (%rax) {%k1}
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vmovdqu8 %VEC(0), (%rax){%k1}
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VZEROUPPER_RETURN
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.p2align 4
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L(cross_page):
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# endif
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# if VEC_SIZE > 32
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cmpb $32, %dl
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jae L(between_32_63)
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# endif
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# if VEC_SIZE > 16
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cmpb $16, %dl
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jae L(between_16_31)
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# endif
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MOVQ %XMM0, %rcx
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cmpb $8, %dl
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jae L(between_8_15)
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cmpb $4, %dl
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jae L(between_4_7)
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cmpb $1, %dl
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ja L(between_2_3)
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jb 1f
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movb %cl, (%rax)
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1:
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# if defined USE_MULTIARCH && IS_IN (libc)
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/* Include L(stosb_local) here if including L(less_vec) between
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L(stosb_more_2x_vec) and ENTRY. This is to cache align the
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L(stosb_more_2x_vec) target. */
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.p2align 4,, 10
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L(stosb_local):
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movzbl %sil, %eax
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mov %RDX_LP, %RCX_LP
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mov %RDI_LP, %RDX_LP
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rep stosb
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mov %RDX_LP, %RAX_LP
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VZEROUPPER_RETURN
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# if VEC_SIZE > 32
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# endif
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#endif
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#if defined USE_MULTIARCH && IS_IN (libc)
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.p2align 4
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L(stosb_more_2x_vec):
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cmp __x86_rep_stosb_threshold(%rip), %RDX_LP
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ja L(stosb_local)
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#endif
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/* Fallthrough goes to L(loop_4x_vec). Tests for memset (2x, 4x]
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and (4x, 8x] jump to target. */
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L(more_2x_vec):
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/* Two different methods of setting up pointers / compare. The
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two methods are based on the fact that EVEX/AVX512 mov
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instructions take more bytes then AVX2/SSE2 mov instructions. As
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well that EVEX/AVX512 machines also have fast LEA_BID. Both
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setup and END_REG to avoid complex address mode. For EVEX/AVX512
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this saves code size and keeps a few targets in one fetch block.
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For AVX2/SSE2 this helps prevent AGU bottlenecks. */
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#if defined USE_WITH_EVEX || defined USE_WITH_AVX512
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/* If EVEX/AVX512 compute END_REG - (VEC_SIZE * 4 +
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LOOP_4X_OFFSET) with LEA_BID. */
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/* END_REG is rcx for EVEX/AVX512. */
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leaq -(VEC_SIZE * 4 + LOOP_4X_OFFSET)(%rdi, %rdx), %END_REG
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#endif
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/* Stores to first 2x VEC before cmp as any path forward will
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require it. */
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VMOVU %VEC(0), (%rax)
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VMOVU %VEC(0), VEC_SIZE(%rax)
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#if !(defined USE_WITH_EVEX || defined USE_WITH_AVX512)
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/* If AVX2/SSE2 compute END_REG (rdi) with ALU. */
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addq %rdx, %END_REG
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#endif
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cmpq $(VEC_SIZE * 4), %rdx
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jbe L(last_2x_vec)
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/* Store next 2x vec regardless. */
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VMOVU %VEC(0), (VEC_SIZE * 2)(%rax)
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VMOVU %VEC(0), (VEC_SIZE * 3)(%rax)
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#if defined USE_WITH_EVEX || defined USE_WITH_AVX512
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/* If LOOP_4X_OFFSET don't readjust LOOP_REG (rdi), just add
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extra offset to addresses in loop. Used for AVX512 to save space
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as no way to get (VEC_SIZE * 4) in imm8. */
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# if LOOP_4X_OFFSET == 0
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subq $-(VEC_SIZE * 4), %LOOP_REG
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# endif
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/* Avoid imm32 compare here to save code size. */
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cmpq %rdi, %rcx
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#else
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addq $-(VEC_SIZE * 4), %END_REG
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cmpq $(VEC_SIZE * 8), %rdx
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#endif
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jbe L(last_4x_vec)
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#if !(defined USE_WITH_EVEX || defined USE_WITH_AVX512)
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/* Set LOOP_REG (rdx). */
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leaq (VEC_SIZE * 4)(%rax), %LOOP_REG
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#endif
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/* Align dst for loop. */
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andq $(VEC_SIZE * -2), %LOOP_REG
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.p2align 4
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L(loop):
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VMOVA %VEC(0), LOOP_4X_OFFSET(%LOOP_REG)
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VMOVA %VEC(0), (VEC_SIZE + LOOP_4X_OFFSET)(%LOOP_REG)
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VMOVA %VEC(0), (VEC_SIZE * 2 + LOOP_4X_OFFSET)(%LOOP_REG)
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VMOVA %VEC(0), (VEC_SIZE * 3 + LOOP_4X_OFFSET)(%LOOP_REG)
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subq $-(VEC_SIZE * 4), %LOOP_REG
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cmpq %END_REG, %LOOP_REG
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jb L(loop)
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.p2align 4,, MOV_SIZE
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L(last_4x_vec):
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VMOVU %VEC(0), LOOP_4X_OFFSET(%END_REG)
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VMOVU %VEC(0), (VEC_SIZE + LOOP_4X_OFFSET)(%END_REG)
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VMOVU %VEC(0), (VEC_SIZE * 2 + LOOP_4X_OFFSET)(%END_REG)
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VMOVU %VEC(0), (VEC_SIZE * 3 + LOOP_4X_OFFSET)(%END_REG)
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L(return):
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#if VEC_SIZE > 16
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ZERO_UPPER_VEC_REGISTERS_RETURN
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#else
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ret
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#endif
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.p2align 4,, 10
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#ifndef USE_LESS_VEC_MASK_STORE
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# if defined USE_MULTIARCH && IS_IN (libc)
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/* If no USE_LESS_VEC_MASK put L(stosb_local) here. Will be in
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range for 2-byte jump encoding. */
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L(stosb_local):
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movzbl %sil, %eax
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mov %RDX_LP, %RCX_LP
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mov %RDI_LP, %RDX_LP
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rep stosb
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mov %RDX_LP, %RAX_LP
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VZEROUPPER_RETURN
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# endif
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/* Define L(less_vec) only if not otherwise defined. */
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.p2align 4
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L(less_vec):
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#endif
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L(cross_page):
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#if VEC_SIZE > 32
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cmpl $32, %edx
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jae L(between_32_63)
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#endif
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#if VEC_SIZE > 16
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cmpl $16, %edx
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jae L(between_16_31)
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#endif
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MOVQ %XMM0, %rdi
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cmpl $8, %edx
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jae L(between_8_15)
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cmpl $4, %edx
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jae L(between_4_7)
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cmpl $1, %edx
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ja L(between_2_3)
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jb L(return)
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movb %sil, (%rax)
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VZEROUPPER_RETURN
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/* Align small targets only if not doing so would cross a fetch
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line. */
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#if VEC_SIZE > 32
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.p2align 4,, SMALL_MEMSET_ALIGN(MOV_SIZE, RET_SIZE)
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/* From 32 to 63. No branch when size == 32. */
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L(between_32_63):
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VMOVU %YMM0, -32(%rax,%rdx)
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VMOVU %YMM0, (%rax)
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VMOVU %YMM0, -32(%rax, %rdx)
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VZEROUPPER_RETURN
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# endif
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# if VEC_SIZE > 16
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/* From 16 to 31. No branch when size == 16. */
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#endif
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#if VEC_SIZE >= 32
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.p2align 4,, SMALL_MEMSET_ALIGN(MOV_SIZE, RET_SIZE)
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||||
L(between_16_31):
|
||||
VMOVU %XMM0, -16(%rax,%rdx)
|
||||
/* From 16 to 31. No branch when size == 16. */
|
||||
VMOVU %XMM0, (%rax)
|
||||
VMOVU %XMM0, -16(%rax, %rdx)
|
||||
VZEROUPPER_RETURN
|
||||
# endif
|
||||
/* From 8 to 15. No branch when size == 8. */
|
||||
#endif
|
||||
|
||||
.p2align 4,, SMALL_MEMSET_ALIGN(3, RET_SIZE)
|
||||
L(between_8_15):
|
||||
movq %rcx, -8(%rax,%rdx)
|
||||
movq %rcx, (%rax)
|
||||
/* From 8 to 15. No branch when size == 8. */
|
||||
movq %rdi, (%rax)
|
||||
movq %rdi, -8(%rax, %rdx)
|
||||
VZEROUPPER_RETURN
|
||||
|
||||
.p2align 4,, SMALL_MEMSET_ALIGN(2, RET_SIZE)
|
||||
L(between_4_7):
|
||||
/* From 4 to 7. No branch when size == 4. */
|
||||
movl %ecx, -4(%rax,%rdx)
|
||||
movl %ecx, (%rax)
|
||||
movl %edi, (%rax)
|
||||
movl %edi, -4(%rax, %rdx)
|
||||
VZEROUPPER_RETURN
|
||||
|
||||
.p2align 4,, SMALL_MEMSET_ALIGN(3, RET_SIZE)
|
||||
L(between_2_3):
|
||||
/* From 2 to 3. No branch when size == 2. */
|
||||
movw %cx, -2(%rax,%rdx)
|
||||
movw %cx, (%rax)
|
||||
movw %di, (%rax)
|
||||
movb %dil, -1(%rax, %rdx)
|
||||
VZEROUPPER_RETURN
|
||||
END (MEMSET_SYMBOL (__memset, unaligned_erms))
|
||||
|
||||
Loading…
Reference in New Issue
Block a user