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tile: optimize and clean up string functions

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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@tilera.com>
This commit is contained in:
Chris Metcalf 2013-08-01 15:52:17 -04:00
parent dd78bc11fb
commit c53c70a90f
8 changed files with 209 additions and 81 deletions
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2
arch/tile/lib/memchr_64.c
View file

@ -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.

255
arch/tile/lib/memcpy_64.c
View file

@ -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;
dst8 = (op_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.
*/
if (__builtin_expect((uintptr_t)src1 & (sizeof(op_t) - 1), 0)) {
/* Unaligned copy. */
/* Create an aligned src8. */
const word_t *__restrict src8 =
(const word_t *)((uintptr_t)src1 & -sizeof(word_t));
word_t b;
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;
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;
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++);
dst8 += CHIP_L2_LINE_SIZE() / sizeof(word_t);
src8 += CHIP_L2_LINE_SIZE() / sizeof(word_t);
/* wh64 and wait for tmp7 load completion. */
__asm__ ("move %0, %0; wh64 %1\n"
: : "r"(tmp7), "r"(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);
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))

5
arch/tile/lib/memset_32.c
View file

@ -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)
{

9
arch/tile/lib/memset_64.c
View file

@ -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)

2
arch/tile/lib/strchr_32.c
View file

@ -16,8 +16,6 @@
#include <linux/string.h>
#include <linux/module.h>
#undef strchr
char *strchr(const char *s, int c)
{
int z, g;

2
arch/tile/lib/strchr_64.c
View file

@ -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

13
arch/tile/lib/string-endian.h
View file

@ -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);
}

2
arch/tile/lib/strlen_32.c
View file

@ -16,8 +16,6 @@
#include <linux/string.h>
#include <linux/module.h>
#undef strlen
size_t strlen(const char *s)
{
/* Get an aligned pointer. */