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Date: Thu, 1 Aug 2013 15:52:17 -0400
From: Chris Metcalf <cmetcalf@...era.com>
To: <linux-kernel@...r.kernel.org>
Subject: [PATCH] tile: optimize and clean up string functions
This change cleans up the string code in a number of ways:
- For memcpy(), fix bug in prefetch and increase distance to 3 lines;
optimize for unaligned data; do all loads before wh64 to make memcpy
safe for forward-overlapping calls; etc. Performance is improved.
- Use new copy_byte() function on tilegx to spread a single byte value
out into a full word using the shufflebytes instruction.
- Clean up header include ordering to be more canonical, and remove
spurious #undefs of function names.
Signed-off-by: Chris Metcalf <cmetcalf@...era.com>
---
arch/tile/lib/memchr_64.c | 2 +-
arch/tile/lib/memcpy_64.c | 261 +++++++++++++++++++++++++++++++-----------
arch/tile/lib/memset_32.c | 5 +-
arch/tile/lib/memset_64.c | 9 +-
arch/tile/lib/strchr_32.c | 2 -
arch/tile/lib/strchr_64.c | 2 +-
arch/tile/lib/string-endian.h | 13 ++-
arch/tile/lib/strlen_32.c | 2 -
8 files changed, 212 insertions(+), 84 deletions(-)
diff --git a/arch/tile/lib/memchr_64.c b/arch/tile/lib/memchr_64.c
index 6f867db..f8196b3 100644
--- a/arch/tile/lib/memchr_64.c
+++ b/arch/tile/lib/memchr_64.c
@@ -36,7 +36,7 @@ void *memchr(const void *s, int c, size_t n)
p = (const uint64_t *)(s_int & -8);
/* Create eight copies of the byte for which we are looking. */
- goal = 0x0101010101010101ULL * (uint8_t) c;
+ goal = copy_byte(c);
/* Read the first word, but munge it so that bytes before the array
* will not match goal.
diff --git a/arch/tile/lib/memcpy_64.c b/arch/tile/lib/memcpy_64.c
index c79b8e7..46fc160 100644
--- a/arch/tile/lib/memcpy_64.c
+++ b/arch/tile/lib/memcpy_64.c
@@ -18,14 +18,17 @@
/* EXPORT_SYMBOL() is in arch/tile/lib/exports.c since this should be asm. */
/* Must be 8 bytes in size. */
-#define word_t uint64_t
+#define op_t uint64_t
-#if CHIP_L2_LINE_SIZE() != 64 && CHIP_L2_LINE_SIZE() != 128
-#error "Assumes 64 or 128 byte line size"
+/* Threshold value for when to enter the unrolled loops. */
+#define OP_T_THRES 16
+
+#if CHIP_L2_LINE_SIZE() != 64
+#error "Assumes 64 byte line size"
#endif
/* How many cache lines ahead should we prefetch? */
-#define PREFETCH_LINES_AHEAD 3
+#define PREFETCH_LINES_AHEAD 4
/*
* Provide "base versions" of load and store for the normal code path.
@@ -58,8 +61,8 @@ int USERCOPY_FUNC(void *__restrict dstv, const void *__restrict srcv, size_t n)
const char *__restrict src1 = (const char *)srcv;
const char *__restrict src1_end;
const char *__restrict prefetch;
- word_t *__restrict dst8; /* 8-byte pointer to destination memory. */
- word_t final; /* Final bytes to write to trailing word, if any */
+ op_t *__restrict dst8; /* 8-byte pointer to destination memory. */
+ op_t final; /* Final bytes to write to trailing word, if any */
long i;
if (n < 16) {
@@ -79,104 +82,228 @@ int USERCOPY_FUNC(void *__restrict dstv, const void *__restrict srcv, size_t n)
for (i = 0; i < PREFETCH_LINES_AHEAD; i++) {
__insn_prefetch(prefetch);
prefetch += CHIP_L2_LINE_SIZE();
- prefetch = (prefetch > src1_end) ? prefetch : src1;
+ prefetch = (prefetch < src1_end) ? prefetch : src1;
}
/* Copy bytes until dst is word-aligned. */
- for (; (uintptr_t)dst1 & (sizeof(word_t) - 1); n--)
+ for (; (uintptr_t)dst1 & (sizeof(op_t) - 1); n--)
ST1(dst1++, LD1(src1++));
/* 8-byte pointer to destination memory. */
- dst8 = (word_t *)dst1;
-
- if (__builtin_expect((uintptr_t)src1 & (sizeof(word_t) - 1), 0)) {
- /*
- * Misaligned copy. Copy 8 bytes at a time, but don't
- * bother with other fanciness.
- *
- * TODO: Consider prefetching and using wh64 as well.
- */
-
- /* Create an aligned src8. */
- const word_t *__restrict src8 =
- (const word_t *)((uintptr_t)src1 & -sizeof(word_t));
- word_t b;
-
- word_t a = LD8(src8++);
- for (; n >= sizeof(word_t); n -= sizeof(word_t)) {
- b = LD8(src8++);
- a = __insn_dblalign(a, b, src1);
- ST8(dst8++, a);
- a = b;
+ dst8 = (op_t *)dst1;
+
+ if (__builtin_expect((uintptr_t)src1 & (sizeof(op_t) - 1), 0)) {
+ /* Unaligned copy. */
+
+ op_t tmp0 = 0, tmp1 = 0, tmp2, tmp3;
+ const op_t *src8 = (const op_t *) ((uintptr_t)src1 &
+ -sizeof(op_t));
+ const void *srci = (void *)src1;
+ int m;
+
+ m = (CHIP_L2_LINE_SIZE() << 2) -
+ (((uintptr_t)dst8) & ((CHIP_L2_LINE_SIZE() << 2) - 1));
+ m = (n < m) ? n : m;
+ m /= sizeof(op_t);
+
+ /* Copy until 'dst' is cache-line-aligned. */
+ n -= (sizeof(op_t) * m);
+
+ switch (m % 4) {
+ case 0:
+ if (__builtin_expect(!m, 0))
+ goto _M0;
+ tmp1 = LD8(src8++);
+ tmp2 = LD8(src8++);
+ goto _8B3;
+ case 2:
+ m += 2;
+ tmp3 = LD8(src8++);
+ tmp0 = LD8(src8++);
+ goto _8B1;
+ case 3:
+ m += 1;
+ tmp2 = LD8(src8++);
+ tmp3 = LD8(src8++);
+ goto _8B2;
+ case 1:
+ m--;
+ tmp0 = LD8(src8++);
+ tmp1 = LD8(src8++);
+ if (__builtin_expect(!m, 0))
+ goto _8B0;
+ }
+
+ do {
+ tmp2 = LD8(src8++);
+ tmp0 = __insn_dblalign(tmp0, tmp1, srci);
+ ST8(dst8++, tmp0);
+_8B3:
+ tmp3 = LD8(src8++);
+ tmp1 = __insn_dblalign(tmp1, tmp2, srci);
+ ST8(dst8++, tmp1);
+_8B2:
+ tmp0 = LD8(src8++);
+ tmp2 = __insn_dblalign(tmp2, tmp3, srci);
+ ST8(dst8++, tmp2);
+_8B1:
+ tmp1 = LD8(src8++);
+ tmp3 = __insn_dblalign(tmp3, tmp0, srci);
+ ST8(dst8++, tmp3);
+ m -= 4;
+ } while (m);
+
+_8B0:
+ tmp0 = __insn_dblalign(tmp0, tmp1, srci);
+ ST8(dst8++, tmp0);
+ src8--;
+
+_M0:
+ if (__builtin_expect(n >= CHIP_L2_LINE_SIZE(), 0)) {
+ op_t tmp4, tmp5, tmp6, tmp7, tmp8;
+
+ prefetch = ((const char *)src8) +
+ CHIP_L2_LINE_SIZE() * PREFETCH_LINES_AHEAD;
+
+ for (tmp0 = LD8(src8++); n >= CHIP_L2_LINE_SIZE();
+ n -= CHIP_L2_LINE_SIZE()) {
+ /* Prefetch and advance to next line to
+ prefetch, but don't go past the end. */
+ __insn_prefetch(prefetch);
+
+ /* Make sure prefetch got scheduled
+ earlier. */
+ __asm__ ("" : : : "memory");
+
+ prefetch += CHIP_L2_LINE_SIZE();
+ prefetch = (prefetch < src1_end) ? prefetch :
+ (const char *) src8;
+
+ tmp1 = LD8(src8++);
+ tmp2 = LD8(src8++);
+ tmp3 = LD8(src8++);
+ tmp4 = LD8(src8++);
+ tmp5 = LD8(src8++);
+ tmp6 = LD8(src8++);
+ tmp7 = LD8(src8++);
+ tmp8 = LD8(src8++);
+
+ tmp0 = __insn_dblalign(tmp0, tmp1, srci);
+ tmp1 = __insn_dblalign(tmp1, tmp2, srci);
+ tmp2 = __insn_dblalign(tmp2, tmp3, srci);
+ tmp3 = __insn_dblalign(tmp3, tmp4, srci);
+ tmp4 = __insn_dblalign(tmp4, tmp5, srci);
+ tmp5 = __insn_dblalign(tmp5, tmp6, srci);
+ tmp6 = __insn_dblalign(tmp6, tmp7, srci);
+ tmp7 = __insn_dblalign(tmp7, tmp8, srci);
+
+ __insn_wh64(dst8);
+
+ ST8(dst8++, tmp0);
+ ST8(dst8++, tmp1);
+ ST8(dst8++, tmp2);
+ ST8(dst8++, tmp3);
+ ST8(dst8++, tmp4);
+ ST8(dst8++, tmp5);
+ ST8(dst8++, tmp6);
+ ST8(dst8++, tmp7);
+
+ tmp0 = tmp8;
+ }
+ src8--;
+ }
+
+ /* Copy the rest 8-byte chunks. */
+ if (n >= sizeof(op_t)) {
+ tmp0 = LD8(src8++);
+ for (; n >= sizeof(op_t); n -= sizeof(op_t)) {
+ tmp1 = LD8(src8++);
+ tmp0 = __insn_dblalign(tmp0, tmp1, srci);
+ ST8(dst8++, tmp0);
+ tmp0 = tmp1;
+ }
+ src8--;
}
if (n == 0)
return RETVAL;
- b = ((const char *)src8 <= src1_end) ? *src8 : 0;
+ tmp0 = LD8(src8++);
+ tmp1 = ((const char *)src8 <= src1_end)
+ ? LD8((op_t *)src8) : 0;
+ final = __insn_dblalign(tmp0, tmp1, srci);
- /*
- * Final source bytes to write to trailing partial
- * word, if any.
- */
- final = __insn_dblalign(a, b, src1);
} else {
/* Aligned copy. */
- const word_t* __restrict src8 = (const word_t *)src1;
+ const op_t *__restrict src8 = (const op_t *)src1;
/* src8 and dst8 are both word-aligned. */
if (n >= CHIP_L2_LINE_SIZE()) {
/* Copy until 'dst' is cache-line-aligned. */
for (; (uintptr_t)dst8 & (CHIP_L2_LINE_SIZE() - 1);
- n -= sizeof(word_t))
+ n -= sizeof(op_t))
ST8(dst8++, LD8(src8++));
for (; n >= CHIP_L2_LINE_SIZE(); ) {
- __insn_wh64(dst8);
+ op_t tmp0, tmp1, tmp2, tmp3;
+ op_t tmp4, tmp5, tmp6, tmp7;
/*
* Prefetch and advance to next line
- * to prefetch, but don't go past the end
+ * to prefetch, but don't go past the
+ * end.
*/
__insn_prefetch(prefetch);
+
+ /* Make sure prefetch got scheduled
+ earlier. */
+ __asm__ ("" : : : "memory");
+
prefetch += CHIP_L2_LINE_SIZE();
- prefetch = (prefetch > src1_end) ? prefetch :
+ prefetch = (prefetch < src1_end) ? prefetch :
(const char *)src8;
/*
- * Copy an entire cache line. Manually
- * unrolled to avoid idiosyncracies of
- * compiler unrolling.
+ * Do all the loads before wh64. This
+ * is necessary if [src8, src8+7] and
+ * [dst8, dst8+7] share the same cache
+ * line and dst8 <= src8, as can be
+ * the case when called from memmove,
+ * or with code tested on x86 whose
+ * memcpy always works with forward
+ * copies.
*/
-#define COPY_WORD(offset) ({ ST8(dst8+offset, LD8(src8+offset)); n -= 8; })
- COPY_WORD(0);
- COPY_WORD(1);
- COPY_WORD(2);
- COPY_WORD(3);
- COPY_WORD(4);
- COPY_WORD(5);
- COPY_WORD(6);
- COPY_WORD(7);
-#if CHIP_L2_LINE_SIZE() == 128
- COPY_WORD(8);
- COPY_WORD(9);
- COPY_WORD(10);
- COPY_WORD(11);
- COPY_WORD(12);
- COPY_WORD(13);
- COPY_WORD(14);
- COPY_WORD(15);
-#elif CHIP_L2_LINE_SIZE() != 64
-# error Fix code that assumes particular L2 cache line sizes
-#endif
+ tmp0 = LD8(src8++);
+ tmp1 = LD8(src8++);
+ tmp2 = LD8(src8++);
+ tmp3 = LD8(src8++);
+ tmp4 = LD8(src8++);
+ tmp5 = LD8(src8++);
+ tmp6 = LD8(src8++);
+ tmp7 = LD8(src8++);
+
+ /* wh64 and wait for tmp7 load completion. */
+ __asm__ ("move %0, %0; wh64 %1\n"
+ : : "r"(tmp7), "r"(dst8));
- dst8 += CHIP_L2_LINE_SIZE() / sizeof(word_t);
- src8 += CHIP_L2_LINE_SIZE() / sizeof(word_t);
+ ST8(dst8++, tmp0);
+ ST8(dst8++, tmp1);
+ ST8(dst8++, tmp2);
+ ST8(dst8++, tmp3);
+ ST8(dst8++, tmp4);
+ ST8(dst8++, tmp5);
+ ST8(dst8++, tmp6);
+ ST8(dst8++, tmp7);
+
+ n -= CHIP_L2_LINE_SIZE();
}
+#if CHIP_L2_LINE_SIZE() != 64
+# error "Fix code that assumes particular L2 cache line size."
+#endif
}
- for (; n >= sizeof(word_t); n -= sizeof(word_t))
+ for (; n >= sizeof(op_t); n -= sizeof(op_t))
ST8(dst8++, LD8(src8++));
if (__builtin_expect(n == 0, 1))
diff --git a/arch/tile/lib/memset_32.c b/arch/tile/lib/memset_32.c
index 57dbb3a..9a7837d 100644
--- a/arch/tile/lib/memset_32.c
+++ b/arch/tile/lib/memset_32.c
@@ -12,13 +12,10 @@
* more details.
*/
-#include <arch/chip.h>
-
#include <linux/types.h>
#include <linux/string.h>
#include <linux/module.h>
-
-#undef memset
+#include <arch/chip.h>
void *memset(void *s, int c, size_t n)
{
diff --git a/arch/tile/lib/memset_64.c b/arch/tile/lib/memset_64.c
index 3873085..03ef69c 100644
--- a/arch/tile/lib/memset_64.c
+++ b/arch/tile/lib/memset_64.c
@@ -12,13 +12,11 @@
* more details.
*/
-#include <arch/chip.h>
-
#include <linux/types.h>
#include <linux/string.h>
#include <linux/module.h>
-
-#undef memset
+#include <arch/chip.h>
+#include "string-endian.h"
void *memset(void *s, int c, size_t n)
{
@@ -70,8 +68,7 @@ void *memset(void *s, int c, size_t n)
n64 = n >> 3;
/* Tile input byte out to 64 bits. */
- /* KLUDGE */
- v64 = 0x0101010101010101ULL * (uint8_t)c;
+ v64 = copy_byte(c);
/* This must be at least 8 or the following loop doesn't work. */
#define CACHE_LINE_SIZE_IN_DOUBLEWORDS (CHIP_L2_LINE_SIZE() / 8)
diff --git a/arch/tile/lib/strchr_32.c b/arch/tile/lib/strchr_32.c
index c94e6f7..841fe69 100644
--- a/arch/tile/lib/strchr_32.c
+++ b/arch/tile/lib/strchr_32.c
@@ -16,8 +16,6 @@
#include <linux/string.h>
#include <linux/module.h>
-#undef strchr
-
char *strchr(const char *s, int c)
{
int z, g;
diff --git a/arch/tile/lib/strchr_64.c b/arch/tile/lib/strchr_64.c
index f39f9dc..fe6e31c 100644
--- a/arch/tile/lib/strchr_64.c
+++ b/arch/tile/lib/strchr_64.c
@@ -26,7 +26,7 @@ char *strchr(const char *s, int c)
const uint64_t *p = (const uint64_t *)(s_int & -8);
/* Create eight copies of the byte for which we are looking. */
- const uint64_t goal = 0x0101010101010101ULL * (uint8_t) c;
+ const uint64_t goal = copy_byte(c);
/* Read the first aligned word, but force bytes before the string to
* match neither zero nor goal (we make sure the high bit of each
diff --git a/arch/tile/lib/string-endian.h b/arch/tile/lib/string-endian.h
index c0eed7c..2e49cbf 100644
--- a/arch/tile/lib/string-endian.h
+++ b/arch/tile/lib/string-endian.h
@@ -1,5 +1,5 @@
/*
- * Copyright 2011 Tilera Corporation. All Rights Reserved.
+ * Copyright 2013 Tilera Corporation. All Rights Reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
@@ -31,3 +31,14 @@
#define CFZ(x) __insn_clz(x)
#define REVCZ(x) __insn_ctz(x)
#endif
+
+/*
+ * Create eight copies of the byte in a uint64_t. Byte Shuffle uses
+ * the bytes of srcB as the index into the dest vector to select a
+ * byte. With all indices of zero, the first byte is copied into all
+ * the other bytes.
+ */
+static inline uint64_t copy_byte(uint8_t byte)
+{
+ return __insn_shufflebytes(byte, 0, 0);
+}
diff --git a/arch/tile/lib/strlen_32.c b/arch/tile/lib/strlen_32.c
index 4974292..f26f88e 100644
--- a/arch/tile/lib/strlen_32.c
+++ b/arch/tile/lib/strlen_32.c
@@ -16,8 +16,6 @@
#include <linux/string.h>
#include <linux/module.h>
-#undef strlen
-
size_t strlen(const char *s)
{
/* Get an aligned pointer. */
--
1.8.3.1
--
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