/*
* Copyright (c) 2008 Apple Computer, Inc. All rights reserved.
*
* @APPLE_OSREFERENCE_LICENSE_HEADER_START@
*
* This file contains Original Code and/or Modifications of Original Code
* as defined in and that are subject to the Apple Public Source License
* Version 2.0 (the 'License'). You may not use this file except in
* compliance with the License. The rights granted to you under the License
* may not be used to create, or enable the creation or redistribution of,
* unlawful or unlicensed copies of an Apple operating system, or to
* circumvent, violate, or enable the circumvention or violation of, any
* terms of an Apple operating system software license agreement.
*
* Please obtain a copy of the License at
* http://www.opensource.apple.com/apsl/ and read it before using this file.
*
* The Original Code and all software distributed under the License are
* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
* Please see the License for the specific language governing rights and
* limitations under the License.
*
* @APPLE_OSREFERENCE_LICENSE_HEADER_END@
*/
#include <machine/cpu_capabilities.h>
#include <platfunc.h>
/*
* The bcopy/memcpy loops, tuned for Nehalem.
*
* The following #defines are tightly coupled to the u-architecture:
*/
#define kShort 80 // too short to bother with SSE (must be >=80)
// void bcopy(const void *src, void *dst, size_t len)PLATFUNC_FUNCTION_START(bcopy, sse42, 32, 5)
pushl %ebp // set up a frame for backtraces
movl %esp,%ebp
pushl %esi
pushl %edi
movl 8(%ebp),%esi // get source ptr
movl 12(%ebp),%edi // get dest ptr
movl 16(%ebp),%ecx // get length
movl %edi,%edx
subl %esi,%edx // (dest - source)
cmpl %ecx,%edx // must move in reverse if (dest - source) < length
jb LReverseIsland
cmpl $(kShort),%ecx // long enough to bother with SSE?
jbe Lshort // no
jmp LNotShort
//
// void *memcpy(void *dst, const void *src, size_t len)//
PLATFUNC_FUNCTION_START(memcpy, sse42, 32, 0) // void *memcpy(void *dst, const void *src, size_t len)
PLATFUNC_FUNCTION_START(memmove, sse42, 32, 0) // void *memmove(void *dst, const void *src, size_t len)
pushl %ebp // set up a frame for backtraces
movl %esp,%ebp
pushl %esi
pushl %edi
movl 8(%ebp),%edi // get dest ptr
movl 12(%ebp),%esi // get source ptr
movl 16(%ebp),%ecx // get length
movl %edi,%edx
subl %esi,%edx // (dest - source)
cmpl %ecx,%edx // must move in reverse if (dest - source) < length
jb LReverseIsland
cmpl $(kShort),%ecx // long enough to bother with SSE?
ja LNotShort // yes
// Handle short forward copies. As the most common case, this is the fall-through path.
// ecx = length (<= kShort)
// esi = source ptr
// edi = dest ptr
Lshort:
movl %ecx,%edx // copy length
shrl $2,%ecx // get #doublewords
jz 3f
2: // loop copying doublewords
movl (%esi),%eax
addl $4,%esi
movl %eax,(%edi)
addl $4,%edi
dec %ecx
jnz 2b
3: // handle leftover bytes (0..3) in last word
andl $3,%edx // any leftover bytes?
jz Lexit
4: // loop copying bytes
movb (%esi),%al
inc %esi
movb %al,(%edi)
inc %edi
dec %edx
jnz 4b
Lexit:
movl 8(%ebp),%eax // get return value (dst ptr) for memcpy/memmove
popl %edi
popl %esi
popl %ebp
ret
LReverseIsland: // keep the "jb" above a short branch...
jmp LReverse // ...because reverse moves are uncommon
// Handle forward moves that are long enough to justify use of SSE.
// First, 16-byte align the destination.
// ecx = length (> kShort)
// esi = source ptr
// edi = dest ptr
LNotShort:
movl %edi,%edx // copy destination
negl %edx
andl $15,%edx // get #bytes to align destination
jz LDestAligned // already aligned
subl %edx,%ecx // decrement length
1: // loop copying 1..15 bytes
movb (%esi),%al
inc %esi
movb %al,(%edi)
inc %edi
dec %edx
jnz 1b
// Destination is now aligned. Nehalem does a great job with unaligned SSE loads,
// so we use MOVDQU rather than aligned loads and shifts. Since kShort>=80, we
// know there is at least one 64-byte chunk to move.
// When we enter the copy loops, the following registers are set up:
// ecx = residual length (0..63)
// edx = -(length to move), a multiple of 64
// esi = ptr to 1st source byte not to move (unaligned)
// edi = ptr to 1st dest byte not to move (aligned)
LDestAligned:
movl %ecx,%edx // copy length
andl $63,%ecx // get remaining bytes for Lshort
andl $-64,%edx // get number of bytes we will copy in inner loop
addl %edx,%esi // point to 1st byte not copied
addl %edx,%edi
negl %edx // now generate offset to 1st byte to be copied
testl $15,%esi // source also aligned?
jnz LUnalignedLoop
jmp LAlignedLoop
// Forward loop for aligned operands.
.align 4,0x90 // 16-byte align inner loops
LAlignedLoop: // loop over 64-byte chunks
movdqa (%esi,%edx),%xmm0
movdqa 16(%esi,%edx),%xmm1
movdqa 32(%esi,%edx),%xmm2
movdqa 48(%esi,%edx),%xmm3
movdqa %xmm0,(%edi,%edx)
movdqa %xmm1,16(%edi,%edx)
movdqa %xmm2,32(%edi,%edx)
movdqa %xmm3,48(%edi,%edx)
addl $64,%edx
jnz LAlignedLoop
jmp Lshort // copy remaining 0..63 bytes and done
// Forward loop for unaligned operands.
.align 4,0x90 // 16-byte align inner loops
LUnalignedLoop: // loop over 64-byte chunks
movdqu (%esi,%edx),%xmm0
movdqu 16(%esi,%edx),%xmm1
movdqu 32(%esi,%edx),%xmm2
movdqu 48(%esi,%edx),%xmm3
movdqa %xmm0,(%edi,%edx)
movdqa %xmm1,16(%edi,%edx)
movdqa %xmm2,32(%edi,%edx)
movdqa %xmm3,48(%edi,%edx)
addl $64,%edx
jnz LUnalignedLoop
jmp Lshort // copy remaining 0..63 bytes and done
// Reverse moves. They are only used with destructive overlap.
// ecx = length
// esi = source ptr
// edi = dest ptr
LReverse:
addl %ecx,%esi // point to end of strings
addl %ecx,%edi
cmpl $(kShort),%ecx // long enough to bother with SSE?
ja LReverseNotShort // yes
// Handle reverse short copies.
// ecx = length
// esi = one byte past end of source
// edi = one byte past end of dest
LReverseShort:
movl %ecx,%edx // copy length
shrl $2,%ecx // #words
jz 3f
1:
subl $4,%esi
movl (%esi),%eax
subl $4,%edi
movl %eax,(%edi)
dec %ecx
jnz 1b
3:
andl $3,%edx // bytes?
jz 5f
4:
dec %esi
movb (%esi),%al
dec %edi
movb %al,(%edi)
dec %edx
jnz 4b
5:
movl 8(%ebp),%eax // get return value (dst ptr) for memcpy/memmove
popl %edi
popl %esi
popl %ebp
ret
// Handle a reverse move long enough to justify using SSE.
// ecx = length
// esi = one byte past end of source
// edi = one byte past end of dest
LReverseNotShort:
movl %edi,%edx // copy destination
andl $15,%edx // get #bytes to align destination
je LReverseDestAligned // already aligned
subl %edx,%ecx // adjust length
1: // loop copying 1..15 bytes
dec %esi
movb (%esi),%al
dec %edi
movb %al,(%edi)
dec %edx
jnz 1b
// Destination is now aligned. Prepare for reverse loops.
LReverseDestAligned:
movl %ecx,%edx // copy length
andl $63,%ecx // get remaining bytes for Lshort
andl $-64,%edx // get number of bytes we will copy in inner loop
subl %edx,%esi // point to endpoint of copy
subl %edx,%edi
testl $15,%esi // is source aligned too?
jnz LReverseUnalignedLoop // no
LReverseAlignedLoop: // loop over 64-byte chunks
movdqa -16(%esi,%edx),%xmm0
movdqa -32(%esi,%edx),%xmm1
movdqa -48(%esi,%edx),%xmm2
movdqa -64(%esi,%edx),%xmm3
movdqa %xmm0,-16(%edi,%edx)
movdqa %xmm1,-32(%edi,%edx)
movdqa %xmm2,-48(%edi,%edx)
movdqa %xmm3,-64(%edi,%edx)
subl $64,%edx
jne LReverseAlignedLoop
jmp LReverseShort // copy remaining 0..63 bytes and done
// Reverse, unaligned loop. LDDQU==MOVDQU on these machines.
LReverseUnalignedLoop: // loop over 64-byte chunks
movdqu -16(%esi,%edx),%xmm0
movdqu -32(%esi,%edx),%xmm1
movdqu -48(%esi,%edx),%xmm2
movdqu -64(%esi,%edx),%xmm3
movdqa %xmm0,-16(%edi,%edx)
movdqa %xmm1,-32(%edi,%edx)
movdqa %xmm2,-48(%edi,%edx)
movdqa %xmm3,-64(%edi,%edx)
subl $64,%edx
jne LReverseUnalignedLoop
jmp LReverseShort // copy remaining 0..63 bytes and done
PLATFUNC_DESCRIPTOR(bcopy,sse42,kHasSSE4_2,0)
PLATFUNC_DESCRIPTOR(memcpy,sse42,kHasSSE4_2,0)
PLATFUNC_DESCRIPTOR(memmove,sse42,kHasSSE4_2,0)