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|
/*
* memcpy.c - optimized memcpy() routines for aclib
* Written by Andrew Church <achurch@achurch.org>
*
* This file is part of transcode, a video stream processing tool.
* transcode is free software, distributable under the terms of the GNU
* General Public License (version 2 or later). See the file COPYING
* for details.
*/
#include "ac.h"
#include "ac_internal.h"
#include <string.h>
/* Use memmove because memcpy isn't guaranteed to be ascending */
static void *(*memcpy_ptr)(void *, const void *, size_t) = memmove;
/*************************************************************************/
/* External interface */
void *ac_memcpy(void *dest, const void *src, size_t size)
{
return (*memcpy_ptr)(dest, src, size);
}
/*************************************************************************/
/*************************************************************************/
/* Note the check for ARCH_X86 here: this is to prevent compilation of this
* code on x86_64, since all x86_64 processors support SSE2, and because
* this code is not set up to use the 64-bit registers for addressing on
* x86_64. */
#if defined(HAVE_ASM_MMX) && defined(ARCH_X86)
/* MMX-optimized routine, intended for PMMX/PII processors.
* Nonstandard instructions used:
* (CPUID.MMX) MOVQ
*/
static void *memcpy_mmx(void *dest, const void *src, size_t bytes)
{
asm("\
PENTIUM_LINE_SIZE = 32 # PMMX/PII cache line size \n\
PENTIUM_CACHE_SIZE = 8192 # PMMX/PII total cache size \n\
# Use only half because writes may touch the cache too (PII) \n\
PENTIUM_CACHE_BLOCK = (PENTIUM_CACHE_SIZE/2 - PENTIUM_LINE_SIZE) \n\
\n\
push %%ebx # Save PIC register \n\
push %%edi # Save destination for return value \n\
cld # MOVS* should ascend \n\
\n\
mov $64, %%ebx # Constant \n\
\n\
cmp %%ebx, %%ecx \n\
jb mmx.memcpy_last # Just use movs if <64 bytes \n\
\n\
# First align destination address to a multiple of 8 bytes \n\
mov $8, %%eax # EAX <- (8-dest) & 7 \n\
sub %%edi, %%eax \n\
and $7, %%eax # ... which is the number of bytes to copy\n"
#ifdef ACLIB_DISABLE_X86_TEXTRELS // Because "lea 0f" requires a textrel
" xchg %%eax, %%ecx \n\
mov %%ecx, %%edx \n\
repz movsb \n\
mov %%eax, %%ecx \n\
mov %%edx, %%eax \n"
#else
" lea 0f, %%edx # Use a computed jump--faster than a loop\n\
sub %%eax, %%edx \n\
jmp *%%edx # Execute 0-7 MOVSB's \n\
movsb \n\
movsb \n\
movsb \n\
movsb \n\
movsb \n\
movsb \n\
movsb \n"
#endif
"0: sub %%eax, %%ecx # Update count \n\
\n\
# Now copy data in blocks \n\
0: mov %%ecx, %%edx # EDX <- ECX >> 6 (cache lines to copy) \n\
shr $6, %%edx \n\
jz mmx.memcpy_last # <64 bytes left? Skip to end \n\
cmp $PENTIUM_CACHE_BLOCK/64, %%edx \n\
jb 1f # Limit size of block \n\
mov $PENTIUM_CACHE_BLOCK/64, %%edx \n\
1: mov %%edx, %%eax # EAX <- EDX << 6 (bytes to copy) \n\
shl $6, %%eax \n\
sub %%eax, %%ecx # Update remaining count \n\
add %%eax, %%esi # Point to end of region to be block-copied\n\
2: test %%eax, -32(%%esi) # Touch each cache line in reverse order\n\
test %%eax, -64(%%esi) \n\
sub %%ebx, %%esi # Update pointer \n\
sub %%ebx, %%eax # And loop \n\
jnz 2b \n\
# Note that ESI now points to the beginning of the block \n\
3: movq (%%esi), %%mm0 # Do the actual copy, 64 bytes at a time\n\
movq 8(%%esi), %%mm1 \n\
movq 16(%%esi), %%mm2 \n\
movq 24(%%esi), %%mm3 \n\
movq 32(%%esi), %%mm4 \n\
movq 40(%%esi), %%mm5 \n\
movq 48(%%esi), %%mm6 \n\
movq 56(%%esi), %%mm7 \n\
movq %%mm0, (%%edi) \n\
movq %%mm1, 8(%%edi) \n\
movq %%mm2, 16(%%edi) \n\
movq %%mm3, 24(%%edi) \n\
movq %%mm4, 32(%%edi) \n\
movq %%mm5, 40(%%edi) \n\
movq %%mm6, 48(%%edi) \n\
movq %%mm7, 56(%%edi) \n\
add %%ebx, %%esi # Update pointers \n\
add %%ebx, %%edi \n\
dec %%edx # And loop \n\
jnz 3b \n\
jmp 0b \n\
\n\
mmx.memcpy_last: \n\
# Copy last <64 bytes, using the computed jump trick \n\
mov %%ecx, %%eax # EAX <- ECX>>2 \n\
shr $2, %%eax \n"
#ifdef ACLIB_DISABLE_X86_TEXTRELS
" xchg %%eax, %%ecx \n\
repz movsd \n\
mov %%eax, %%ecx \n"
#else
" lea 0f, %%edx \n\
sub %%eax, %%edx \n\
jmp *%%edx # Execute 0-15 MOVSD's \n\
movsd \n\
movsd \n\
movsd \n\
movsd \n\
movsd \n\
movsd \n\
movsd \n\
movsd \n\
movsd \n\
movsd \n\
movsd \n\
movsd \n\
movsd \n\
movsd \n\
movsd \n"
#endif
"0: and $3, %%ecx # ECX <- ECX & 3 \n"
#ifdef ACLIB_DISABLE_X86_TEXTRELS
" repz movsb \n"
#else
" lea 0f, %%edx \n\
sub %%ecx, %%edx \n\
jmp *%%edx # Execute 0-3 MOVSB's \n\
movsb \n\
movsb \n\
movsb \n"
#endif
"0: \n\
# All done! \n\
emms # Clean up MMX state \n\
pop %%edi # Restore destination (return value) \n\
pop %%ebx # Restore PIC register \n\
" : /* no outputs */
: "D" (dest), "S" (src), "c" (bytes)
: "%eax", "%edx"
);
return dest;
}
#endif /* HAVE_ASM_MMX && ARCH_X86 */
/*************************************************************************/
#if defined(HAVE_ASM_SSE) && defined(ARCH_X86)
/* SSE-optimized routine. Backported from AMD64 routine below.
* Nonstandard instructions used:
* (CPUID.CMOVE) CMOVA
* (CPUID.MMX) MOVQ
* (CPUID.SSE) MOVNTQ
*/
static void *memcpy_sse(void *dest, const void *src, size_t bytes)
{
asm("\
push %%ebx # Save PIC register \n\
push %%edi # Save destination for return value \n\
cld # MOVS* should ascend \n\
\n\
cmp $64, %%ecx # Skip block copy for small blocks \n\
jb sse.memcpy_last \n\
\n\
mov $128, %%ebx # Constant used later \n\
\n\
# First align destination address to a multiple of 8 bytes \n\
mov $8, %%eax # EAX <- (8-dest) & 7 \n\
sub %%edi, %%eax \n\
and $7, %%eax # ... which is the number of bytes to copy\n"
#ifdef ACLIB_DISABLE_X86_TEXTRELS
" xchg %%eax, %%ecx \n\
mov %%ecx, %%edx \n\
repz movsb \n\
mov %%eax, %%ecx \n\
mov %%edx, %%eax \n"
#else
" lea 0f, %%edx # Use a computed jump--faster than a loop\n\
sub %%eax, %%edx \n\
jmp *%%edx # Execute 0-7 MOVSB's \n\
movsb \n\
movsb \n\
movsb \n\
movsb \n\
movsb \n\
movsb \n\
movsb \n"
#endif
"0: sub %%eax, %%ecx # Update count \n\
\n\
cmp $0x10040, %%ecx # Is this a large block? (0x10040 is an \n\
# arbitrary value where prefetching and \n\
# write combining seem to start becoming\n\
# faster) \n\
jae sse.memcpy_bp # Yup, use prefetch copy \n\
\n\
sse.memcpy_small: # Small block copy routine--no prefetch \n"
#if 0
" mov %%ecx, %%edx # EDX <- bytes to copy / 8 \n\
shr $3, %%edx \n\
mov %%edx, %%eax # Leave remainder in ECX for later \n\
shl $3, %%eax \n\
sub %%eax, %%ecx \n\
.balign 16 \n\
0: movq (%%esi), %%mm0 # Copy 8 bytes of data \n\
movq %%mm0, (%%edi) \n\
add $8, %%esi # Update pointers \n\
add $8, %%edi \n\
dec %%edx # And loop \n\
jg 0b \n\
jmp sse.memcpy_last # Copy any remaining bytes \n\
\n\
nop # Align loops below \n"
#else
" # It appears that a simple rep movs is faster than cleverness \n\
# with movq... \n\
mov %%ecx, %%edx # EDX <- ECX & 3 \n\
and $3, %%edx \n\
shr $2, %%ecx # ECX <- ECX >> 2 \n\
rep movsl # Copy away! \n\
mov %%edx, %%ecx # Take care of last 0-3 bytes \n\
rep movsb \n\
jmp sse.memcpy_end # And exit \n\
\n\
.balign 16 \n\
nop \n\
nop \n"
#endif
"sse.memcpy_bp: # Block prefetch copy routine \n\
0: mov %%ecx, %%edx # EDX: temp counter \n\
shr $6, %%edx # Divide by cache line size (64 bytes) \n\
cmp %%ebx, %%edx # ... and cap at 128 (8192 bytes) \n\
cmova %%ebx, %%edx \n\
shl $3, %%edx # EDX <- cache lines to copy * 8 \n\
mov %%edx, %%eax # EAX <- cache lines to preload * 8 \n\
# (also used as memory offset) \n\
1: test %%eax, -64(%%esi,%%eax,8) # Preload cache lines in pairs \n\
test %%eax, -128(%%esi,%%eax,8) # (going backwards) \n\
# (note that test %%eax,... seems to be faster than prefetchnta \n\
# on x86) \n\
sub $16, %%eax # And loop \n\
jg 1b \n\
\n\
# Then copy--forward, which seems to be faster than reverse for \n\
# certain alignments \n\
xor %%eax, %%eax \n\
2: movq (%%esi,%%eax,8), %%mm0 # Copy 8 bytes and loop \n\
movntq %%mm0, (%%edi,%%eax,8) \n\
inc %%eax \n\
cmp %%edx, %%eax \n\
jb 2b \n\
\n\
# Finally, update pointers and count, and loop \n\
shl $3, %%edx # EDX <- bytes copied \n\
add %%edx, %%esi \n\
add %%edx, %%edi \n\
sub %%edx, %%ecx \n\
cmp $64, %%ecx # At least one cache line left? \n\
jae 0b # Yup, loop \n\
\n\
sse.memcpy_last: \n\
# Copy last <64 bytes, using the computed jump trick \n\
mov %%ecx, %%eax # EAX <- ECX>>2 \n\
shr $2, %%eax \n"
#ifdef ACLIB_DISABLE_X86_TEXTRELS
" xchg %%eax, %%ecx \n\
repz movsd \n\
mov %%eax, %%ecx \n"
#else
" lea 0f, %%edx \n\
sub %%eax, %%edx \n\
jmp *%%edx # Execute 0-15 MOVSD's \n\
movsd \n\
movsd \n\
movsd \n\
movsd \n\
movsd \n\
movsd \n\
movsd \n\
movsd \n\
movsd \n\
movsd \n\
movsd \n\
movsd \n\
movsd \n\
movsd \n\
movsd \n"
#endif
"0: and $3, %%ecx # ECX <- ECX & 3 \n"
#ifdef ACLIB_DISABLE_X86_TEXTRELS
" repz movsb \n"
#else
" lea sse.memcpy_end, %%edx \n\
sub %%ecx, %%edx \n\
jmp *%%edx # Execute 0-3 MOVSB's \n\
movsb \n\
movsb \n\
movsb \n"
#endif
" \n\
sse.memcpy_end: \n\
# All done! \n\
emms # Clean up after MMX instructions \n\
sfence # Flush the write buffer \n\
pop %%edi # Restore destination (return value) \n\
pop %%ebx # Restore PIC register \n\
" : /* no outputs */
: "D" (dest), "S" (src), "c" (bytes)
: "%eax", "%edx"
);
return dest;
}
#endif /* HAVE_ASM_SSE && ARCH_X86 */
/*************************************************************************/
#if defined(HAVE_ASM_SSE2) && defined(ARCH_X86_64)
/* AMD64-optimized routine, using SSE2. Derived from AMD64 optimization
* guide section 5.13: Appropriate Memory Copying Routines.
* Nonstandard instructions used:
* (CPUID.CMOVE) CMOVA
* (CPUID.SSE2) MOVDQA, MOVDQU, MOVNTDQ
*
* Note that this routine will also run more or less as-is (modulo register
* names and label(%%rip) references) on x86 CPUs, but tests have shown the
* SSE1 version above to be faster.
*/
/* The block copying code--macroized because we use two versions of it
* depending on whether the source is 16-byte-aligned or not. Pass either
* movdqa or movdqu (unquoted) for the parameter. */
#define AMD64_BLOCK_MEMCPY(movdq) \
" # First prefetch (note that if we end on an odd number of cache \n\
# lines, we skip prefetching the last one--faster that way than \n\
# prefetching line by line or treating it as a special case) \n\
0: mov %%ecx, %%edx # EDX: temp counter (always <32 bits) \n\
shr $6, %%edx # Divide by cache line size (64 bytes) \n\
cmp %%ebx, %%edx # ... and cap at 128 (8192 bytes) \n\
cmova %%ebx, %%edx \n\
shl $3, %%edx # EDX <- cache lines to copy * 8 \n\
mov %%edx, %%eax # EAX <- cache lines to preload * 8 \n\
# (also used as memory offset) \n\
1: prefetchnta -64(%%rsi,%%rax,8) # Preload cache lines in pairs \n\
prefetchnta -128(%%rsi,%%rax,8) # (going backwards) \n\
sub $16, %%eax # And loop \n\
jg 1b \n\
\n\
# Then copy--forward, which seems to be faster than reverse for \n\
# certain alignments \n\
xor %%eax, %%eax \n\
2: " #movdq " (%%rsi,%%rax,8), %%xmm0 # Copy 16 bytes and loop \n\
movntdq %%xmm0, (%%rdi,%%rax,8) \n\
add $2, %%eax \n\
cmp %%edx, %%eax \n\
jb 2b \n\
\n\
# Finally, update pointers and count, and loop \n\
shl $3, %%edx # EDX <- bytes copied \n\
add %%rdx, %%rsi \n\
add %%rdx, %%rdi \n\
sub %%rdx, %%rcx \n\
cmp $64, %%rcx # At least one cache line left? \n\
jae 0b # Yup, loop \n"
static void *memcpy_amd64(void *dest, const void *src, size_t bytes)
{
asm("\
push %%rdi # Save destination for return value \n\
cld # MOVS* should ascend \n\
\n\
cmp $64, %%rcx # Skip block copy for small blocks \n\
jb amd64.memcpy_last \n\
\n\
mov $128, %%ebx # Constant used later \n\
\n\
# First align destination address to a multiple of 16 bytes \n\
mov $8, %%eax # EAX <- (8-dest) & 7 \n\
sub %%edi, %%eax # (we don't care about the top 32 bits) \n\
and $7, %%eax # ... which is the number of bytes to copy\n\
lea 0f(%%rip), %%rdx # Use a computed jump--faster than a loop\n\
sub %%rax, %%rdx \n\
jmp *%%rdx # Execute 0-7 MOVSB's \n\
movsb \n\
movsb \n\
movsb \n\
movsb \n\
movsb \n\
movsb \n\
movsb \n\
0: sub %%rax, %%rcx # Update count \n\
test $8, %%edi # Is destination not 16-byte aligned? \n\
je 1f \n\
movsq # Then move 8 bytes to align it \n\
sub $8, %%rcx \n\
\n\
1: cmp $0x38000, %%rcx # Is this a large block? (0x38000 is an \n\
# arbitrary value where prefetching and \n\
# write combining seem to start becoming\n\
# faster) \n\
jb amd64.memcpy_small # Nope, use small copy (no prefetch/WC) \n\
test $15, %%esi # Is source also 16-byte aligned? \n\
# (use ESI to save a REX prefix byte) \n\
jnz amd64.memcpy_normal_bp # Nope, use slow copy \n\
jmp amd64.memcpy_fast_bp # Yup, use fast copy \n\
\n\
amd64.memcpy_small: # Small block copy routine--no prefetch \n\
mov %%ecx, %%edx # EDX <- bytes to copy / 16 \n\
shr $4, %%edx # (count known to fit in 32 bits) \n\
mov %%edx, %%eax # Leave remainder in ECX for later \n\
shl $4, %%eax \n\
sub %%eax, %%ecx \n\
.balign 16 \n\
0: movdqu (%%rsi), %%xmm0 # Copy 16 bytes of data \n\
movdqa %%xmm0, (%%rdi) \n\
add $16, %%rsi # Update pointers \n\
add $16, %%rdi \n\
dec %%edx # And loop \n\
jnz 0b \n\
jmp amd64.memcpy_last # Copy any remaining bytes \n\
\n\
.balign 16 \n\
nop \n\
nop \n\
amd64.memcpy_fast_bp: # Fast block prefetch loop \n"
AMD64_BLOCK_MEMCPY(movdqa)
" jmp amd64.memcpy_last # Copy any remaining bytes \n\
\n\
.balign 16 \n\
nop \n\
nop \n\
amd64.memcpy_normal_bp: # Normal (unaligned) block prefetch loop\n"
AMD64_BLOCK_MEMCPY(movdqu)
" \n\
amd64.memcpy_last: \n\
# Copy last <64 bytes, using the computed jump trick \n\
mov %%ecx, %%eax # EAX <- ECX>>3 \n\
shr $3, %%eax \n\
lea 0f(%%rip), %%rdx \n\
add %%eax, %%eax # Watch out, MOVSQ is 2 bytes! \n\
sub %%rax, %%rdx \n\
jmp *%%rdx # Execute 0-7 MOVSQ's \n\
movsq \n\
movsq \n\
movsq \n\
movsq \n\
movsq \n\
movsq \n\
movsq \n\
0: and $7, %%ecx # ECX <- ECX & 7 \n\
lea 0f(%%rip), %%rdx \n\
sub %%rcx, %%rdx \n\
jmp *%%rdx # Execute 0-7 MOVSB's \n\
movsb \n\
movsb \n\
movsb \n\
movsb \n\
movsb \n\
movsb \n\
movsb \n\
0: \n\
# All done! \n\
emms # Clean up after MMX instructions \n\
sfence # Flush the write buffer \n\
pop %%rdi # Restore destination (return value) \n\
" : /* no outputs */
: "D" (dest), "S" (src), "c" (bytes)
: "%rax", "%rbx", "%rdx"
);
return dest;
}
#endif /* HAVE_ASM_SSE2 && ARCH_X86_64 */
/*************************************************************************/
/* Initialization routine. */
int ac_memcpy_init(int accel)
{
memcpy_ptr = memmove;
#if defined(HAVE_ASM_MMX) && defined(ARCH_X86)
if (HAS_ACCEL(accel, AC_MMX))
memcpy_ptr = memcpy_mmx;
#endif
#if defined(HAVE_ASM_SSE) && defined(ARCH_X86)
if (HAS_ACCEL(accel, AC_CMOVE|AC_SSE))
memcpy_ptr = memcpy_sse;
#endif
#if defined(HAVE_ASM_SSE2) && defined(ARCH_X86_64)
if (HAS_ACCEL(accel, AC_CMOVE|AC_SSE2))
memcpy_ptr = memcpy_amd64;
#endif
return 1;
}
/*************************************************************************/
/*
* Local variables:
* c-file-style: "stroustrup"
* c-file-offsets: ((case-label . *) (statement-case-intro . *))
* indent-tabs-mode: nil
* End:
*
* vim: expandtab shiftwidth=4:
*/
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