/* memmove/memcpy/mempcpy with unaligned load/store and rep movsb Copyright (C) 2016-2020 Free Software Foundation, Inc. This file is part of the GNU C Library. The GNU C Library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. The GNU C Library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with the GNU C Library; if not, see . */ /* memmove/memcpy/mempcpy is implemented as: 1. Use overlapping load and store to avoid branch. 2. Load all sources into registers and store them together to avoid possible address overlap between source and destination. 3. If size is 8 * VEC_SIZE or less, load all sources into registers and store them together. 4. If address of destination > address of source, backward copy 4 * VEC_SIZE at a time with unaligned load and aligned store. Load the first 4 * VEC and last VEC before the loop and store them after the loop to support overlapping addresses. 5. Otherwise, forward copy 4 * VEC_SIZE at a time with unaligned load and aligned store. Load the last 4 * VEC and first VEC before the loop and store them after the loop to support overlapping addresses. 6. If size >= __x86_shared_non_temporal_threshold and there is no overlap between destination and source, use non-temporal store instead of aligned store. */ #include #ifndef MEMCPY_SYMBOL # define MEMCPY_SYMBOL(p,s) MEMMOVE_SYMBOL(p, s) #endif #ifndef MEMPCPY_SYMBOL # define MEMPCPY_SYMBOL(p,s) MEMMOVE_SYMBOL(p, s) #endif #ifndef MEMMOVE_CHK_SYMBOL # define MEMMOVE_CHK_SYMBOL(p,s) MEMMOVE_SYMBOL(p, s) #endif #ifndef VZEROUPPER # if VEC_SIZE > 16 # define VZEROUPPER vzeroupper # else # define VZEROUPPER # endif #endif /* Threshold to use Enhanced REP MOVSB. Since there is overhead to set up REP MOVSB operation, REP MOVSB isn't faster on short data. The memcpy micro benchmark in glibc shows that 2KB is the approximate value above which REP MOVSB becomes faster than SSE2 optimization on processors with Enhanced REP MOVSB. Since larger register size can move more data with a single load and store, the threshold is higher with larger register size. */ #ifndef REP_MOVSB_THRESHOLD # define REP_MOVSB_THRESHOLD (2048 * (VEC_SIZE / 16)) #endif #ifndef PREFETCH # define PREFETCH(addr) prefetcht0 addr #endif /* Assume 64-byte prefetch size. */ #ifndef PREFETCH_SIZE # define PREFETCH_SIZE 64 #endif #define PREFETCHED_LOAD_SIZE (VEC_SIZE * 4) #if PREFETCH_SIZE == 64 # if PREFETCHED_LOAD_SIZE == PREFETCH_SIZE # define PREFETCH_ONE_SET(dir, base, offset) \ PREFETCH ((offset)base) # elif PREFETCHED_LOAD_SIZE == 2 * PREFETCH_SIZE # define PREFETCH_ONE_SET(dir, base, offset) \ PREFETCH ((offset)base); \ PREFETCH ((offset + dir * PREFETCH_SIZE)base) # elif PREFETCHED_LOAD_SIZE == 4 * PREFETCH_SIZE # define PREFETCH_ONE_SET(dir, base, offset) \ PREFETCH ((offset)base); \ PREFETCH ((offset + dir * PREFETCH_SIZE)base); \ PREFETCH ((offset + dir * PREFETCH_SIZE * 2)base); \ PREFETCH ((offset + dir * PREFETCH_SIZE * 3)base) # else # error Unsupported PREFETCHED_LOAD_SIZE! # endif #else # error Unsupported PREFETCH_SIZE! #endif #ifndef SECTION # error SECTION is not defined! #endif .section SECTION(.text),"ax",@progbits #if defined SHARED && IS_IN (libc) ENTRY (MEMMOVE_CHK_SYMBOL (__mempcpy_chk, unaligned)) cmp %RDX_LP, %RCX_LP jb HIDDEN_JUMPTARGET (__chk_fail) END (MEMMOVE_CHK_SYMBOL (__mempcpy_chk, unaligned)) #endif ENTRY (MEMPCPY_SYMBOL (__mempcpy, unaligned)) mov %RDI_LP, %RAX_LP add %RDX_LP, %RAX_LP jmp L(start) END (MEMPCPY_SYMBOL (__mempcpy, unaligned)) #if defined SHARED && IS_IN (libc) ENTRY (MEMMOVE_CHK_SYMBOL (__memmove_chk, unaligned)) cmp %RDX_LP, %RCX_LP jb HIDDEN_JUMPTARGET (__chk_fail) END (MEMMOVE_CHK_SYMBOL (__memmove_chk, unaligned)) #endif ENTRY (MEMMOVE_SYMBOL (__memmove, unaligned)) movq %rdi, %rax L(start): # ifdef __ILP32__ /* Clear the upper 32 bits. */ movl %edx, %edx # endif cmp $VEC_SIZE, %RDX_LP jb L(less_vec) cmp $(VEC_SIZE * 2), %RDX_LP ja L(more_2x_vec) #if !defined USE_MULTIARCH || !IS_IN (libc) L(last_2x_vec): #endif /* From VEC and to 2 * VEC. No branch when size == VEC_SIZE. */ VMOVU (%rsi), %VEC(0) VMOVU -VEC_SIZE(%rsi,%rdx), %VEC(1) VMOVU %VEC(0), (%rdi) VMOVU %VEC(1), -VEC_SIZE(%rdi,%rdx) VZEROUPPER #if !defined USE_MULTIARCH || !IS_IN (libc) L(nop): #endif ret #if defined USE_MULTIARCH && IS_IN (libc) END (MEMMOVE_SYMBOL (__memmove, unaligned)) # if VEC_SIZE == 16 ENTRY (__mempcpy_chk_erms) cmp %RDX_LP, %RCX_LP jb HIDDEN_JUMPTARGET (__chk_fail) END (__mempcpy_chk_erms) /* Only used to measure performance of REP MOVSB. */ ENTRY (__mempcpy_erms) mov %RDI_LP, %RAX_LP /* Skip zero length. */ test %RDX_LP, %RDX_LP jz 2f add %RDX_LP, %RAX_LP jmp L(start_movsb) END (__mempcpy_erms) ENTRY (__memmove_chk_erms) cmp %RDX_LP, %RCX_LP jb HIDDEN_JUMPTARGET (__chk_fail) END (__memmove_chk_erms) ENTRY (__memmove_erms) movq %rdi, %rax /* Skip zero length. */ test %RDX_LP, %RDX_LP jz 2f L(start_movsb): mov %RDX_LP, %RCX_LP cmp %RSI_LP, %RDI_LP jb 1f /* Source == destination is less common. */ je 2f lea (%rsi,%rcx), %RDX_LP cmp %RDX_LP, %RDI_LP jb L(movsb_backward) 1: rep movsb 2: ret L(movsb_backward): leaq -1(%rdi,%rcx), %rdi leaq -1(%rsi,%rcx), %rsi std rep movsb cld ret END (__memmove_erms) strong_alias (__memmove_erms, __memcpy_erms) strong_alias (__memmove_chk_erms, __memcpy_chk_erms) # endif # ifdef SHARED ENTRY (MEMMOVE_CHK_SYMBOL (__mempcpy_chk, unaligned_erms)) cmp %RDX_LP, %RCX_LP jb HIDDEN_JUMPTARGET (__chk_fail) END (MEMMOVE_CHK_SYMBOL (__mempcpy_chk, unaligned_erms)) # endif ENTRY (MEMMOVE_SYMBOL (__mempcpy, unaligned_erms)) mov %RDI_LP, %RAX_LP add %RDX_LP, %RAX_LP jmp L(start_erms) END (MEMMOVE_SYMBOL (__mempcpy, unaligned_erms)) # ifdef SHARED ENTRY (MEMMOVE_CHK_SYMBOL (__memmove_chk, unaligned_erms)) cmp %RDX_LP, %RCX_LP jb HIDDEN_JUMPTARGET (__chk_fail) END (MEMMOVE_CHK_SYMBOL (__memmove_chk, unaligned_erms)) # endif ENTRY (MEMMOVE_SYMBOL (__memmove, unaligned_erms)) movq %rdi, %rax L(start_erms): # ifdef __ILP32__ /* Clear the upper 32 bits. */ movl %edx, %edx # endif cmp $VEC_SIZE, %RDX_LP jb L(less_vec) cmp $(VEC_SIZE * 2), %RDX_LP ja L(movsb_more_2x_vec) L(last_2x_vec): /* From VEC and to 2 * VEC. No branch when size == VEC_SIZE. */ VMOVU (%rsi), %VEC(0) VMOVU -VEC_SIZE(%rsi,%rdx), %VEC(1) VMOVU %VEC(0), (%rdi) VMOVU %VEC(1), -VEC_SIZE(%rdi,%rdx) L(return): VZEROUPPER ret L(movsb): cmpq __x86_shared_non_temporal_threshold(%rip), %rdx jae L(more_8x_vec) cmpq %rsi, %rdi jb 1f /* Source == destination is less common. */ je L(nop) leaq (%rsi,%rdx), %r9 cmpq %r9, %rdi /* Avoid slow backward REP MOVSB. */ # if REP_MOVSB_THRESHOLD <= (VEC_SIZE * 8) # error Unsupported REP_MOVSB_THRESHOLD and VEC_SIZE! # endif jb L(more_8x_vec_backward) 1: mov %RDX_LP, %RCX_LP rep movsb L(nop): ret #endif L(less_vec): /* Less than 1 VEC. */ #if VEC_SIZE != 16 && VEC_SIZE != 32 && VEC_SIZE != 64 # error Unsupported VEC_SIZE! #endif #if VEC_SIZE > 32 cmpb $32, %dl jae L(between_32_63) #endif #if VEC_SIZE > 16 cmpb $16, %dl jae L(between_16_31) #endif cmpb $8, %dl jae L(between_8_15) cmpb $4, %dl jae L(between_4_7) cmpb $1, %dl ja L(between_2_3) jb 1f movzbl (%rsi), %ecx movb %cl, (%rdi) 1: ret #if VEC_SIZE > 32 L(between_32_63): /* From 32 to 63. No branch when size == 32. */ vmovdqu (%rsi), %ymm0 vmovdqu -32(%rsi,%rdx), %ymm1 vmovdqu %ymm0, (%rdi) vmovdqu %ymm1, -32(%rdi,%rdx) VZEROUPPER ret #endif #if VEC_SIZE > 16 /* From 16 to 31. No branch when size == 16. */ L(between_16_31): vmovdqu (%rsi), %xmm0 vmovdqu -16(%rsi,%rdx), %xmm1 vmovdqu %xmm0, (%rdi) vmovdqu %xmm1, -16(%rdi,%rdx) ret #endif L(between_8_15): /* From 8 to 15. No branch when size == 8. */ movq -8(%rsi,%rdx), %rcx movq (%rsi), %rsi movq %rcx, -8(%rdi,%rdx) movq %rsi, (%rdi) ret L(between_4_7): /* From 4 to 7. No branch when size == 4. */ movl -4(%rsi,%rdx), %ecx movl (%rsi), %esi movl %ecx, -4(%rdi,%rdx) movl %esi, (%rdi) ret L(between_2_3): /* From 2 to 3. No branch when size == 2. */ movzwl -2(%rsi,%rdx), %ecx movzwl (%rsi), %esi movw %cx, -2(%rdi,%rdx) movw %si, (%rdi) ret #if defined USE_MULTIARCH && IS_IN (libc) L(movsb_more_2x_vec): cmpq $REP_MOVSB_THRESHOLD, %rdx ja L(movsb) #endif L(more_2x_vec): /* More than 2 * VEC and there may be overlap between destination and source. */ cmpq $(VEC_SIZE * 8), %rdx ja L(more_8x_vec) cmpq $(VEC_SIZE * 4), %rdx jb L(last_4x_vec) /* Copy from 4 * VEC to 8 * VEC, inclusively. */ VMOVU (%rsi), %VEC(0) VMOVU VEC_SIZE(%rsi), %VEC(1) VMOVU (VEC_SIZE * 2)(%rsi), %VEC(2) VMOVU (VEC_SIZE * 3)(%rsi), %VEC(3) VMOVU -VEC_SIZE(%rsi,%rdx), %VEC(4) VMOVU -(VEC_SIZE * 2)(%rsi,%rdx), %VEC(5) VMOVU -(VEC_SIZE * 3)(%rsi,%rdx), %VEC(6) VMOVU -(VEC_SIZE * 4)(%rsi,%rdx), %VEC(7) VMOVU %VEC(0), (%rdi) VMOVU %VEC(1), VEC_SIZE(%rdi) VMOVU %VEC(2), (VEC_SIZE * 2)(%rdi) VMOVU %VEC(3), (VEC_SIZE * 3)(%rdi) VMOVU %VEC(4), -VEC_SIZE(%rdi,%rdx) VMOVU %VEC(5), -(VEC_SIZE * 2)(%rdi,%rdx) VMOVU %VEC(6), -(VEC_SIZE * 3)(%rdi,%rdx) VMOVU %VEC(7), -(VEC_SIZE * 4)(%rdi,%rdx) VZEROUPPER ret L(last_4x_vec): /* Copy from 2 * VEC to 4 * VEC. */ VMOVU (%rsi), %VEC(0) VMOVU VEC_SIZE(%rsi), %VEC(1) VMOVU -VEC_SIZE(%rsi,%rdx), %VEC(2) VMOVU -(VEC_SIZE * 2)(%rsi,%rdx), %VEC(3) VMOVU %VEC(0), (%rdi) VMOVU %VEC(1), VEC_SIZE(%rdi) VMOVU %VEC(2), -VEC_SIZE(%rdi,%rdx) VMOVU %VEC(3), -(VEC_SIZE * 2)(%rdi,%rdx) VZEROUPPER ret L(more_8x_vec): cmpq %rsi, %rdi ja L(more_8x_vec_backward) /* Source == destination is less common. */ je L(nop) /* Load the first VEC and last 4 * VEC to support overlapping addresses. */ VMOVU (%rsi), %VEC(4) VMOVU -VEC_SIZE(%rsi, %rdx), %VEC(5) VMOVU -(VEC_SIZE * 2)(%rsi, %rdx), %VEC(6) VMOVU -(VEC_SIZE * 3)(%rsi, %rdx), %VEC(7) VMOVU -(VEC_SIZE * 4)(%rsi, %rdx), %VEC(8) /* Save start and stop of the destination buffer. */ movq %rdi, %r11 leaq -VEC_SIZE(%rdi, %rdx), %rcx /* Align destination for aligned stores in the loop. Compute how much destination is misaligned. */ movq %rdi, %r8 andq $(VEC_SIZE - 1), %r8 /* Get the negative of offset for alignment. */ subq $VEC_SIZE, %r8 /* Adjust source. */ subq %r8, %rsi /* Adjust destination which should be aligned now. */ subq %r8, %rdi /* Adjust length. */ addq %r8, %rdx #if (defined USE_MULTIARCH || VEC_SIZE == 16) && IS_IN (libc) /* Check non-temporal store threshold. */ cmpq __x86_shared_non_temporal_threshold(%rip), %rdx ja L(large_forward) #endif L(loop_4x_vec_forward): /* Copy 4 * VEC a time forward. */ VMOVU (%rsi), %VEC(0) VMOVU VEC_SIZE(%rsi), %VEC(1) VMOVU (VEC_SIZE * 2)(%rsi), %VEC(2) VMOVU (VEC_SIZE * 3)(%rsi), %VEC(3) addq $(VEC_SIZE * 4), %rsi subq $(VEC_SIZE * 4), %rdx VMOVA %VEC(0), (%rdi) VMOVA %VEC(1), VEC_SIZE(%rdi) VMOVA %VEC(2), (VEC_SIZE * 2)(%rdi) VMOVA %VEC(3), (VEC_SIZE * 3)(%rdi) addq $(VEC_SIZE * 4), %rdi cmpq $(VEC_SIZE * 4), %rdx ja L(loop_4x_vec_forward) /* Store the last 4 * VEC. */ VMOVU %VEC(5), (%rcx) VMOVU %VEC(6), -VEC_SIZE(%rcx) VMOVU %VEC(7), -(VEC_SIZE * 2)(%rcx) VMOVU %VEC(8), -(VEC_SIZE * 3)(%rcx) /* Store the first VEC. */ VMOVU %VEC(4), (%r11) VZEROUPPER ret L(more_8x_vec_backward): /* Load the first 4 * VEC and last VEC to support overlapping addresses. */ VMOVU (%rsi), %VEC(4) VMOVU VEC_SIZE(%rsi), %VEC(5) VMOVU (VEC_SIZE * 2)(%rsi), %VEC(6) VMOVU (VEC_SIZE * 3)(%rsi), %VEC(7) VMOVU -VEC_SIZE(%rsi,%rdx), %VEC(8) /* Save stop of the destination buffer. */ leaq -VEC_SIZE(%rdi, %rdx), %r11 /* Align destination end for aligned stores in the loop. Compute how much destination end is misaligned. */ leaq -VEC_SIZE(%rsi, %rdx), %rcx movq %r11, %r9 movq %r11, %r8 andq $(VEC_SIZE - 1), %r8 /* Adjust source. */ subq %r8, %rcx /* Adjust the end of destination which should be aligned now. */ subq %r8, %r9 /* Adjust length. */ subq %r8, %rdx #if (defined USE_MULTIARCH || VEC_SIZE == 16) && IS_IN (libc) /* Check non-temporal store threshold. */ cmpq __x86_shared_non_temporal_threshold(%rip), %rdx ja L(large_backward) #endif L(loop_4x_vec_backward): /* Copy 4 * VEC a time backward. */ VMOVU (%rcx), %VEC(0) VMOVU -VEC_SIZE(%rcx), %VEC(1) VMOVU -(VEC_SIZE * 2)(%rcx), %VEC(2) VMOVU -(VEC_SIZE * 3)(%rcx), %VEC(3) subq $(VEC_SIZE * 4), %rcx subq $(VEC_SIZE * 4), %rdx VMOVA %VEC(0), (%r9) VMOVA %VEC(1), -VEC_SIZE(%r9) VMOVA %VEC(2), -(VEC_SIZE * 2)(%r9) VMOVA %VEC(3), -(VEC_SIZE * 3)(%r9) subq $(VEC_SIZE * 4), %r9 cmpq $(VEC_SIZE * 4), %rdx ja L(loop_4x_vec_backward) /* Store the first 4 * VEC. */ VMOVU %VEC(4), (%rdi) VMOVU %VEC(5), VEC_SIZE(%rdi) VMOVU %VEC(6), (VEC_SIZE * 2)(%rdi) VMOVU %VEC(7), (VEC_SIZE * 3)(%rdi) /* Store the last VEC. */ VMOVU %VEC(8), (%r11) VZEROUPPER ret #if (defined USE_MULTIARCH || VEC_SIZE == 16) && IS_IN (libc) L(large_forward): /* Don't use non-temporal store if there is overlap between destination and source since destination may be in cache when source is loaded. */ leaq (%rdi, %rdx), %r10 cmpq %r10, %rsi jb L(loop_4x_vec_forward) L(loop_large_forward): /* Copy 4 * VEC a time forward with non-temporal stores. */ PREFETCH_ONE_SET (1, (%rsi), PREFETCHED_LOAD_SIZE * 2) PREFETCH_ONE_SET (1, (%rsi), PREFETCHED_LOAD_SIZE * 3) VMOVU (%rsi), %VEC(0) VMOVU VEC_SIZE(%rsi), %VEC(1) VMOVU (VEC_SIZE * 2)(%rsi), %VEC(2) VMOVU (VEC_SIZE * 3)(%rsi), %VEC(3) addq $PREFETCHED_LOAD_SIZE, %rsi subq $PREFETCHED_LOAD_SIZE, %rdx VMOVNT %VEC(0), (%rdi) VMOVNT %VEC(1), VEC_SIZE(%rdi) VMOVNT %VEC(2), (VEC_SIZE * 2)(%rdi) VMOVNT %VEC(3), (VEC_SIZE * 3)(%rdi) addq $PREFETCHED_LOAD_SIZE, %rdi cmpq $PREFETCHED_LOAD_SIZE, %rdx ja L(loop_large_forward) sfence /* Store the last 4 * VEC. */ VMOVU %VEC(5), (%rcx) VMOVU %VEC(6), -VEC_SIZE(%rcx) VMOVU %VEC(7), -(VEC_SIZE * 2)(%rcx) VMOVU %VEC(8), -(VEC_SIZE * 3)(%rcx) /* Store the first VEC. */ VMOVU %VEC(4), (%r11) VZEROUPPER ret L(large_backward): /* Don't use non-temporal store if there is overlap between destination and source since destination may be in cache when source is loaded. */ leaq (%rcx, %rdx), %r10 cmpq %r10, %r9 jb L(loop_4x_vec_backward) L(loop_large_backward): /* Copy 4 * VEC a time backward with non-temporal stores. */ PREFETCH_ONE_SET (-1, (%rcx), -PREFETCHED_LOAD_SIZE * 2) PREFETCH_ONE_SET (-1, (%rcx), -PREFETCHED_LOAD_SIZE * 3) VMOVU (%rcx), %VEC(0) VMOVU -VEC_SIZE(%rcx), %VEC(1) VMOVU -(VEC_SIZE * 2)(%rcx), %VEC(2) VMOVU -(VEC_SIZE * 3)(%rcx), %VEC(3) subq $PREFETCHED_LOAD_SIZE, %rcx subq $PREFETCHED_LOAD_SIZE, %rdx VMOVNT %VEC(0), (%r9) VMOVNT %VEC(1), -VEC_SIZE(%r9) VMOVNT %VEC(2), -(VEC_SIZE * 2)(%r9) VMOVNT %VEC(3), -(VEC_SIZE * 3)(%r9) subq $PREFETCHED_LOAD_SIZE, %r9 cmpq $PREFETCHED_LOAD_SIZE, %rdx ja L(loop_large_backward) sfence /* Store the first 4 * VEC. */ VMOVU %VEC(4), (%rdi) VMOVU %VEC(5), VEC_SIZE(%rdi) VMOVU %VEC(6), (VEC_SIZE * 2)(%rdi) VMOVU %VEC(7), (VEC_SIZE * 3)(%rdi) /* Store the last VEC. */ VMOVU %VEC(8), (%r11) VZEROUPPER ret #endif END (MEMMOVE_SYMBOL (__memmove, unaligned_erms)) #if IS_IN (libc) # ifdef USE_MULTIARCH strong_alias (MEMMOVE_SYMBOL (__memmove, unaligned_erms), MEMMOVE_SYMBOL (__memcpy, unaligned_erms)) # ifdef SHARED strong_alias (MEMMOVE_SYMBOL (__memmove_chk, unaligned_erms), MEMMOVE_SYMBOL (__memcpy_chk, unaligned_erms)) # endif # endif # ifdef SHARED strong_alias (MEMMOVE_CHK_SYMBOL (__memmove_chk, unaligned), MEMMOVE_CHK_SYMBOL (__memcpy_chk, unaligned)) # endif #endif strong_alias (MEMMOVE_SYMBOL (__memmove, unaligned), MEMCPY_SYMBOL (__memcpy, unaligned))