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glibc/SOURCES/glibc-RHEL-15696-39.patch

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From 1a8605b6cd257e8a74e29b5b71c057211f5fb847 Mon Sep 17 00:00:00 2001
From: noah <goldstein.w.n@gmail.com>
Date: Sat, 3 Apr 2021 04:12:15 -0400
Subject: [PATCH] x86: Update large memcpy case in memmove-vec-unaligned-erms.S
Content-type: text/plain; charset=UTF-8
No Bug. This commit updates the large memcpy case (no overlap). The
update is to perform memcpy on either 2 or 4 contiguous pages at
once. This 1) helps to alleviate the affects of false memory aliasing
when destination and source have a close 4k alignment and 2) In most
cases and for most DRAM units is a modestly more efficient access
pattern. These changes are a clear performance improvement for
VEC_SIZE =16/32, though more ambiguous for VEC_SIZE=64. test-memcpy,
test-memccpy, test-mempcpy, test-memmove, and tst-memmove-overflow all
pass.
Signed-off-by: Noah Goldstein <goldstein.w.n@gmail.com>
---
.../multiarch/memmove-vec-unaligned-erms.S | 338 ++++++++++++++----
1 file changed, 265 insertions(+), 73 deletions(-)
Conflicts:
sysdeps/x86_64/multiarch/memmove-vec-unaligned-erms.S
(different number of sections)
diff --git a/sysdeps/x86_64/multiarch/memmove-vec-unaligned-erms.S b/sysdeps/x86_64/multiarch/memmove-vec-unaligned-erms.S
index c475fed4..3e2dd6bc 100644
--- a/sysdeps/x86_64/multiarch/memmove-vec-unaligned-erms.S
+++ b/sysdeps/x86_64/multiarch/memmove-vec-unaligned-erms.S
@@ -32,7 +32,16 @@
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. */
+ instead of aligned store copying from either 2 or 4 pages at
+ once.
+ 8. For point 7) if size < 16 * __x86_shared_non_temporal_threshold
+ and source and destination do not page alias, copy from 2 pages
+ at once using non-temporal stores. Page aliasing in this case is
+ considered true if destination's page alignment - sources' page
+ alignment is less than 8 * VEC_SIZE.
+ 9. If size >= 16 * __x86_shared_non_temporal_threshold or source
+ and destination do page alias copy from 4 pages at once using
+ non-temporal stores. */
#include <sysdep.h>
@@ -64,6 +73,34 @@
# endif
#endif
+#ifndef PAGE_SIZE
+# define PAGE_SIZE 4096
+#endif
+
+#if PAGE_SIZE != 4096
+# error Unsupported PAGE_SIZE
+#endif
+
+#ifndef LOG_PAGE_SIZE
+# define LOG_PAGE_SIZE 12
+#endif
+
+#if PAGE_SIZE != (1 << LOG_PAGE_SIZE)
+# error Invalid LOG_PAGE_SIZE
+#endif
+
+/* Byte per page for large_memcpy inner loop. */
+#if VEC_SIZE == 64
+# define LARGE_LOAD_SIZE (VEC_SIZE * 2)
+#else
+# define LARGE_LOAD_SIZE (VEC_SIZE * 4)
+#endif
+
+/* Amount to shift rdx by to compare for memcpy_large_4x. */
+#ifndef LOG_4X_MEMCPY_THRESH
+# define LOG_4X_MEMCPY_THRESH 4
+#endif
+
/* Avoid short distance rep movsb only with non-SSE vector. */
#ifndef AVOID_SHORT_DISTANCE_REP_MOVSB
# define AVOID_SHORT_DISTANCE_REP_MOVSB (VEC_SIZE > 16)
@@ -103,6 +140,28 @@
# error Unsupported PREFETCH_SIZE!
#endif
+#if LARGE_LOAD_SIZE == (VEC_SIZE * 2)
+# define LOAD_ONE_SET(base, offset, vec0, vec1, ...) \
+ VMOVU (offset)base, vec0; \
+ VMOVU ((offset) + VEC_SIZE)base, vec1;
+# define STORE_ONE_SET(base, offset, vec0, vec1, ...) \
+ VMOVNT vec0, (offset)base; \
+ VMOVNT vec1, ((offset) + VEC_SIZE)base;
+#elif LARGE_LOAD_SIZE == (VEC_SIZE * 4)
+# define LOAD_ONE_SET(base, offset, vec0, vec1, vec2, vec3) \
+ VMOVU (offset)base, vec0; \
+ VMOVU ((offset) + VEC_SIZE)base, vec1; \
+ VMOVU ((offset) + VEC_SIZE * 2)base, vec2; \
+ VMOVU ((offset) + VEC_SIZE * 3)base, vec3;
+# define STORE_ONE_SET(base, offset, vec0, vec1, vec2, vec3) \
+ VMOVNT vec0, (offset)base; \
+ VMOVNT vec1, ((offset) + VEC_SIZE)base; \
+ VMOVNT vec2, ((offset) + VEC_SIZE * 2)base; \
+ VMOVNT vec3, ((offset) + VEC_SIZE * 3)base;
+#else
+# error Invalid LARGE_LOAD_SIZE
+#endif
+
#ifndef SECTION
# error SECTION is not defined!
#endif
@@ -390,6 +449,15 @@ L(last_4x_vec):
VZEROUPPER_RETURN
L(more_8x_vec):
+ /* Check if non-temporal move candidate. */
+#if (defined USE_MULTIARCH || VEC_SIZE == 16) && IS_IN (libc)
+ /* Check non-temporal store threshold. */
+ cmp __x86_shared_non_temporal_threshold(%rip), %RDX_LP
+ ja L(large_memcpy_2x)
+#endif
+ /* Entry if rdx is greater than non-temporal threshold but there
+ is overlap. */
+L(more_8x_vec_check):
cmpq %rsi, %rdi
ja L(more_8x_vec_backward)
/* Source == destination is less common. */
@@ -416,24 +484,21 @@ L(more_8x_vec):
subq %r8, %rdi
/* Adjust length. */
addq %r8, %rdx
-#if (defined USE_MULTIARCH || VEC_SIZE == 16) && IS_IN (libc)
- /* Check non-temporal store threshold. */
- cmp __x86_shared_non_temporal_threshold(%rip), %RDX_LP
- ja L(large_forward)
-#endif
+
+ .p2align 4
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
+ subq $-(VEC_SIZE * 4), %rsi
+ addq $-(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
+ subq $-(VEC_SIZE * 4), %rdi
cmpq $(VEC_SIZE * 4), %rdx
ja L(loop_4x_vec_forward)
/* Store the last 4 * VEC. */
@@ -467,24 +532,21 @@ L(more_8x_vec_backward):
subq %r8, %r9
/* Adjust length. */
subq %r8, %rdx
-#if (defined USE_MULTIARCH || VEC_SIZE == 16) && IS_IN (libc)
- /* Check non-temporal store threshold. */
- cmp __x86_shared_non_temporal_threshold(%rip), %RDX_LP
- ja L(large_backward)
-#endif
+
+ .p2align 4
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
+ addq $-(VEC_SIZE * 4), %rcx
+ addq $-(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
+ addq $-(VEC_SIZE * 4), %r9
cmpq $(VEC_SIZE * 4), %rdx
ja L(loop_4x_vec_backward)
/* Store the first 4 * VEC. */
@@ -497,72 +559,202 @@ L(loop_4x_vec_backward):
VZEROUPPER_RETURN
#if (defined USE_MULTIARCH || VEC_SIZE == 16) && IS_IN (libc)
-L(large_forward):
+ .p2align 4
+L(large_memcpy_2x):
+ /* Compute absolute value of difference between source and
+ destination. */
+ movq %rdi, %r9
+ subq %rsi, %r9
+ movq %r9, %r8
+ leaq -1(%r9), %rcx
+ sarq $63, %r8
+ xorq %r8, %r9
+ subq %r8, %r9
/* 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):
+ destination and source since destination may be in cache when
+ source is loaded. */
+ cmpq %r9, %rdx
+ ja L(more_8x_vec_check)
+
+ /* Cache align destination. First store the first 64 bytes then
+ adjust alignments. */
+ VMOVU (%rsi), %VEC(8)
+#if VEC_SIZE < 64
+ VMOVU VEC_SIZE(%rsi), %VEC(9)
+#if VEC_SIZE < 32
+ VMOVU (VEC_SIZE * 2)(%rsi), %VEC(10)
+ VMOVU (VEC_SIZE * 3)(%rsi), %VEC(11)
+#endif
+#endif
+ VMOVU %VEC(8), (%rdi)
+#if VEC_SIZE < 64
+ VMOVU %VEC(9), VEC_SIZE(%rdi)
+#if VEC_SIZE < 32
+ VMOVU %VEC(10), (VEC_SIZE * 2)(%rdi)
+ VMOVU %VEC(11), (VEC_SIZE * 3)(%rdi)
+#endif
+#endif
+ /* Adjust source, destination, and size. */
+ movq %rdi, %r8
+ andq $63, %r8
+ /* Get the negative of offset for alignment. */
+ subq $64, %r8
+ /* Adjust source. */
+ subq %r8, %rsi
+ /* Adjust destination which should be aligned now. */
+ subq %r8, %rdi
+ /* Adjust length. */
+ addq %r8, %rdx
+
+ /* Test if source and destination addresses will alias. If they do
+ the larger pipeline in large_memcpy_4x alleviated the
+ performance drop. */
+ testl $(PAGE_SIZE - VEC_SIZE * 8), %ecx
+ jz L(large_memcpy_4x)
+
+ movq %rdx, %r10
+ shrq $LOG_4X_MEMCPY_THRESH, %r10
+ cmp __x86_shared_non_temporal_threshold(%rip), %r10
+ jae L(large_memcpy_4x)
+
+ /* edx will store remainder size for copying tail. */
+ andl $(PAGE_SIZE * 2 - 1), %edx
+ /* r10 stores outer loop counter. */
+ shrq $((LOG_PAGE_SIZE + 1) - LOG_4X_MEMCPY_THRESH), %r10
+ /* Copy 4x VEC at a time from 2 pages. */
+ .p2align 4
+L(loop_large_memcpy_2x_outer):
+ /* ecx stores inner loop counter. */
+ movl $(PAGE_SIZE / LARGE_LOAD_SIZE), %ecx
+L(loop_large_memcpy_2x_inner):
+ PREFETCH_ONE_SET(1, (%rsi), PREFETCHED_LOAD_SIZE)
+ PREFETCH_ONE_SET(1, (%rsi), PREFETCHED_LOAD_SIZE * 2)
+ PREFETCH_ONE_SET(1, (%rsi), PAGE_SIZE + PREFETCHED_LOAD_SIZE)
+ PREFETCH_ONE_SET(1, (%rsi), PAGE_SIZE + PREFETCHED_LOAD_SIZE * 2)
+ /* Load vectors from rsi. */
+ LOAD_ONE_SET((%rsi), 0, %VEC(0), %VEC(1), %VEC(2), %VEC(3))
+ LOAD_ONE_SET((%rsi), PAGE_SIZE, %VEC(4), %VEC(5), %VEC(6), %VEC(7))
+ subq $-LARGE_LOAD_SIZE, %rsi
+ /* Non-temporal store vectors to rdi. */
+ STORE_ONE_SET((%rdi), 0, %VEC(0), %VEC(1), %VEC(2), %VEC(3))
+ STORE_ONE_SET((%rdi), PAGE_SIZE, %VEC(4), %VEC(5), %VEC(6), %VEC(7))
+ subq $-LARGE_LOAD_SIZE, %rdi
+ decl %ecx
+ jnz L(loop_large_memcpy_2x_inner)
+ addq $PAGE_SIZE, %rdi
+ addq $PAGE_SIZE, %rsi
+ decq %r10
+ jne L(loop_large_memcpy_2x_outer)
+ sfence
+
+ /* Check if only last 4 loads are needed. */
+ cmpl $(VEC_SIZE * 4), %edx
+ jbe L(large_memcpy_2x_end)
+
+ /* Handle the last 2 * PAGE_SIZE bytes. */
+L(loop_large_memcpy_2x_tail):
/* 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)
+ PREFETCH_ONE_SET (1, (%rsi), PREFETCHED_LOAD_SIZE)
+ PREFETCH_ONE_SET (1, (%rdi), PREFETCHED_LOAD_SIZE)
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
+ subq $-(VEC_SIZE * 4), %rsi
+ addl $-(VEC_SIZE * 4), %edx
+ VMOVA %VEC(0), (%rdi)
+ VMOVA %VEC(1), VEC_SIZE(%rdi)
+ VMOVA %VEC(2), (VEC_SIZE * 2)(%rdi)
+ VMOVA %VEC(3), (VEC_SIZE * 3)(%rdi)
+ subq $-(VEC_SIZE * 4), %rdi
+ cmpl $(VEC_SIZE * 4), %edx
+ ja L(loop_large_memcpy_2x_tail)
+
+L(large_memcpy_2x_end):
/* 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)
+ VMOVU -(VEC_SIZE * 4)(%rsi, %rdx), %VEC(0)
+ VMOVU -(VEC_SIZE * 3)(%rsi, %rdx), %VEC(1)
+ VMOVU -(VEC_SIZE * 2)(%rsi, %rdx), %VEC(2)
+ VMOVU -VEC_SIZE(%rsi, %rdx), %VEC(3)
+
+ VMOVU %VEC(0), -(VEC_SIZE * 4)(%rdi, %rdx)
+ VMOVU %VEC(1), -(VEC_SIZE * 3)(%rdi, %rdx)
+ VMOVU %VEC(2), -(VEC_SIZE * 2)(%rdi, %rdx)
+ VMOVU %VEC(3), -VEC_SIZE(%rdi, %rdx)
VZEROUPPER_RETURN
-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)
+ .p2align 4
+L(large_memcpy_4x):
+ movq %rdx, %r10
+ /* edx will store remainder size for copying tail. */
+ andl $(PAGE_SIZE * 4 - 1), %edx
+ /* r10 stores outer loop counter. */
+ shrq $(LOG_PAGE_SIZE + 2), %r10
+ /* Copy 4x VEC at a time from 4 pages. */
+ .p2align 4
+L(loop_large_memcpy_4x_outer):
+ /* ecx stores inner loop counter. */
+ movl $(PAGE_SIZE / LARGE_LOAD_SIZE), %ecx
+L(loop_large_memcpy_4x_inner):
+ /* Only one prefetch set per page as doing 4 pages give more time
+ for prefetcher to keep up. */
+ PREFETCH_ONE_SET(1, (%rsi), PREFETCHED_LOAD_SIZE)
+ PREFETCH_ONE_SET(1, (%rsi), PAGE_SIZE + PREFETCHED_LOAD_SIZE)
+ PREFETCH_ONE_SET(1, (%rsi), PAGE_SIZE * 2 + PREFETCHED_LOAD_SIZE)
+ PREFETCH_ONE_SET(1, (%rsi), PAGE_SIZE * 3 + PREFETCHED_LOAD_SIZE)
+ /* Load vectors from rsi. */
+ LOAD_ONE_SET((%rsi), 0, %VEC(0), %VEC(1), %VEC(2), %VEC(3))
+ LOAD_ONE_SET((%rsi), PAGE_SIZE, %VEC(4), %VEC(5), %VEC(6), %VEC(7))
+ LOAD_ONE_SET((%rsi), PAGE_SIZE * 2, %VEC(8), %VEC(9), %VEC(10), %VEC(11))
+ LOAD_ONE_SET((%rsi), PAGE_SIZE * 3, %VEC(12), %VEC(13), %VEC(14), %VEC(15))
+ subq $-LARGE_LOAD_SIZE, %rsi
+ /* Non-temporal store vectors to rdi. */
+ STORE_ONE_SET((%rdi), 0, %VEC(0), %VEC(1), %VEC(2), %VEC(3))
+ STORE_ONE_SET((%rdi), PAGE_SIZE, %VEC(4), %VEC(5), %VEC(6), %VEC(7))
+ STORE_ONE_SET((%rdi), PAGE_SIZE * 2, %VEC(8), %VEC(9), %VEC(10), %VEC(11))
+ STORE_ONE_SET((%rdi), PAGE_SIZE * 3, %VEC(12), %VEC(13), %VEC(14), %VEC(15))
+ subq $-LARGE_LOAD_SIZE, %rdi
+ decl %ecx
+ jnz L(loop_large_memcpy_4x_inner)
+ addq $(PAGE_SIZE * 3), %rdi
+ addq $(PAGE_SIZE * 3), %rsi
+ decq %r10
+ jne L(loop_large_memcpy_4x_outer)
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)
+ /* Check if only last 4 loads are needed. */
+ cmpl $(VEC_SIZE * 4), %edx
+ jbe L(large_memcpy_4x_end)
+
+ /* Handle the last 4 * PAGE_SIZE bytes. */
+L(loop_large_memcpy_4x_tail):
+ /* Copy 4 * VEC a time forward with non-temporal stores. */
+ PREFETCH_ONE_SET (1, (%rsi), PREFETCHED_LOAD_SIZE)
+ PREFETCH_ONE_SET (1, (%rdi), PREFETCHED_LOAD_SIZE)
+ VMOVU (%rsi), %VEC(0)
+ VMOVU VEC_SIZE(%rsi), %VEC(1)
+ VMOVU (VEC_SIZE * 2)(%rsi), %VEC(2)
+ VMOVU (VEC_SIZE * 3)(%rsi), %VEC(3)
+ subq $-(VEC_SIZE * 4), %rsi
+ addl $-(VEC_SIZE * 4), %edx
+ VMOVA %VEC(0), (%rdi)
+ VMOVA %VEC(1), VEC_SIZE(%rdi)
+ VMOVA %VEC(2), (VEC_SIZE * 2)(%rdi)
+ VMOVA %VEC(3), (VEC_SIZE * 3)(%rdi)
+ subq $-(VEC_SIZE * 4), %rdi
+ cmpl $(VEC_SIZE * 4), %edx
+ ja L(loop_large_memcpy_4x_tail)
+
+L(large_memcpy_4x_end):
+ /* Store the last 4 * VEC. */
+ VMOVU -(VEC_SIZE * 4)(%rsi, %rdx), %VEC(0)
+ VMOVU -(VEC_SIZE * 3)(%rsi, %rdx), %VEC(1)
+ VMOVU -(VEC_SIZE * 2)(%rsi, %rdx), %VEC(2)
+ VMOVU -VEC_SIZE(%rsi, %rdx), %VEC(3)
+
+ VMOVU %VEC(0), -(VEC_SIZE * 4)(%rdi, %rdx)
+ VMOVU %VEC(1), -(VEC_SIZE * 3)(%rdi, %rdx)
+ VMOVU %VEC(2), -(VEC_SIZE * 2)(%rdi, %rdx)
+ VMOVU %VEC(3), -VEC_SIZE(%rdi, %rdx)
VZEROUPPER_RETURN
#endif
END (MEMMOVE_SYMBOL (__memmove, unaligned_erms))
--
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