/*
* Copyright (c) 2005-2006 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,
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*/
#include <machine/cpu_capabilities.h>
#include <platfunc.h>
/*
* The bcopy/memcpy loops, tuned for Pentium-M class processors with SSE2
* and 64-byte cache lines, such as Core and Core 2.
*
* The following #defines are tightly coupled to the u-architecture:
*/
#define kShort 80 // too short to bother with SSE (must be >=80)
#define kVeryLong (500*1024) // large enough for non-temporal stores (must be >= 8192)
#define kBigChunk (256*1024) // outer loop chunk size for kVeryLong sized operands
#define kFastUCode (16*1024) // cutoff for microcode fastpath for "rep/movsl"
// void bcopy(const void *src, void *dst, size_t len)PLATFUNC_FUNCTION_START(bcopy, sse2, 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
jmp Ljoin
//
// void *memcpy(void *dst, const void *src, size_t len)//
PLATFUNC_FUNCTION_START(memcpy, sse2, 32, 0) // void *memcpy(void *dst, const void *src, size_t len)
PLATFUNC_FUNCTION_START(memmove, sse2, 32, 0) // void *memmove(void *dst, const void *src, size_t len)
Lmemcpy_sse2:
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
Ljoin: // here from bcopy() with esi and edi loaded
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
Lrejoin: // here from very-long-operand copies
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 LLeftovers
2: // loop copying doublewords
movl (%esi),%eax
addl $4,%esi
movl %eax,(%edi)
addl $4,%edi
dec %ecx
jnz 2b
LLeftovers: // handle leftover bytes (0..3) in last word
andl $3,%edx // any leftover bytes?
jz 5f
4: // loop copying bytes
movb (%esi),%al
inc %esi
movb %al,(%edi)
inc %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
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 SSE3.
// First, 16-byte align the destination.
// ecx = length (> kShort)
// esi = source ptr
// edi = dest ptr
LNotShort:
cmpl $(kVeryLong),%ecx // long enough to justify heavyweight loops?
movl %edi,%edx // copy destination
jae LVeryLong // use very-long-operand path
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. Prepare for forward loops over 64-byte chunks.
// Since kShort>=80 and we've moved at most 15 bytes already, there is at least one chunk.
LDestAligned:
movl %ecx,%edx // copy length
movl %ecx,%eax // twice
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 // is source aligned too?
jnz LUnalignedLoop // no
cmpl $(kFastUCode),%eax // long enough for the fastpath in microcode?
jb LAlignedLoop // no, use SSE
cld // we'll move forward
movl %eax,%ecx // copy length again
shrl $2,%ecx // compute #words to move
addl %edx,%esi // restore ptrs to 1st byte of source and dest
addl %edx,%edi
rep // the u-code will optimize this
movsl
movl %eax,%edx // original length
jmp LLeftovers // handle 0..3 leftover bytes
// Forward aligned loop for medium length operands (kShort < n < kVeryLong).
.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..15 bytes and done
// Forward unaligned loop for medium length operands (kShort < n < kVeryLong).
// Note that LDDQU==MOVDQU on these machines, ie we don't care when we cross
// source cache lines.
.align 4,0x90 // 16-byte align inner loops
LUnalignedLoop: // loop over 64-byte chunks
movdqu (%esi,%edx),%xmm0 // the loads are unaligned
movdqu 16(%esi,%edx),%xmm1
movdqu 32(%esi,%edx),%xmm2
movdqu 48(%esi,%edx),%xmm3
movdqa %xmm0,(%edi,%edx) // we can use aligned stores
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
// Very long forward moves. These are at least several pages, so we loop over big
// chunks of memory (kBigChunk in size.) We first prefetch the chunk, and then copy
// it using non-temporal stores. Hopefully all the reads occur in the prefetch loop,
// so the copy loop reads from L2 and writes directly to memory (with write combining.)
// This minimizes bus turnaround and maintains good DRAM page locality.
// Note that for this scheme to work, kVeryLong must be a large fraction of L2 cache
// size. Otherwise, it is counter-productive to bypass L2 on the stores.
// ecx = length (>= kVeryLong bytes)
// edi = dest (aligned)
// esi = source
LVeryLong:
pushl %ebx // we'll need to use this
movl %edi,%ebx // copy dest ptr
negl %ebx
andl $63,%ebx // get #bytes to cache line align destination
jz LBigChunkLoop // already aligned
// Cache line align destination, so temporal stores in copy loops work right.
pushl %ecx // save total length remaining
pushl %ebx // arg3 - #bytes to align destination (1..63)
pushl %esi // arg2 - source
pushl %edi // arg1 - dest
call Lmemcpy_sse2 // align the destination
movl 12(%esp),%ecx // recover total length
addl $16,%esp
addl %ebx,%esi // adjust ptrs and lengths past copy
addl %ebx,%edi
subl %ebx,%ecx
// Loop over big chunks.
// ecx = length remaining (>= 4096)
// edi = dest (64-byte aligned)
// esi = source (may be unaligned)
LBigChunkLoop:
movl $(kBigChunk),%edx // assume we can do a full chunk
cmpl %edx,%ecx // do we have a full chunk left to do?
cmovbl %ecx,%edx // if not, only move what we have left
andl $-4096,%edx // we work in page multiples
xor %eax,%eax // initialize chunk offset
jmp LTouchLoop
// Because the source may be unaligned, we use byte loads to touch.
// ecx = length remaining (including this chunk)
// edi = ptr to start of dest chunk
// esi = ptr to start of source chunk
// edx = chunk length (multiples of pages)
// ebx = scratch reg used to read a byte of each cache line
// eax = chunk offset
.align 4,0x90 // 16-byte align inner loops
LTouchLoop:
movzb (%esi,%eax),%ebx // touch line 0, 2, 4, or 6 of page
movzb 1*64(%esi,%eax),%ebx // touch line 1, 3, 5, or 7
movzb 8*64(%esi,%eax),%ebx // touch line 8, 10, 12, or 14
movzb 9*64(%esi,%eax),%ebx // etc
movzb 16*64(%esi,%eax),%ebx
movzb 17*64(%esi,%eax),%ebx
movzb 24*64(%esi,%eax),%ebx
movzb 25*64(%esi,%eax),%ebx
movzb 32*64(%esi,%eax),%ebx
movzb 33*64(%esi,%eax),%ebx
movzb 40*64(%esi,%eax),%ebx
movzb 41*64(%esi,%eax),%ebx
movzb 48*64(%esi,%eax),%ebx
movzb 49*64(%esi,%eax),%ebx
movzb 56*64(%esi,%eax),%ebx
movzb 57*64(%esi,%eax),%ebx
subl $-128,%eax // next slice of page (adding 128 w 8-bit immediate)
testl $512,%eax // done with this page?
jz LTouchLoop // no, next of four slices
addl $(4096-512),%eax // move on to next page
cmpl %eax,%edx // done with this chunk?
jnz LTouchLoop // no, do next page
// The chunk has been pre-fetched, now copy it using non-temporal stores.
// There are two copy loops, depending on whether the source is 16-byte aligned
// or not.
addl %edx,%esi // increment ptrs by chunk length
addl %edx,%edi
subl %edx,%ecx // adjust remaining length
negl %edx // prepare loop index (counts up to 0)
testl $15,%esi // is source 16-byte aligned?
jnz LVeryLongUnaligned // source is not aligned
jmp LVeryLongAligned
.align 4,0x90 // 16-byte align inner loops
LVeryLongAligned: // aligned loop over 128-bytes
movdqa (%esi,%edx),%xmm0
movdqa 16(%esi,%edx),%xmm1
movdqa 32(%esi,%edx),%xmm2
movdqa 48(%esi,%edx),%xmm3
movdqa 64(%esi,%edx),%xmm4
movdqa 80(%esi,%edx),%xmm5
movdqa 96(%esi,%edx),%xmm6
movdqa 112(%esi,%edx),%xmm7
movntdq %xmm0,(%edi,%edx)
movntdq %xmm1,16(%edi,%edx)
movntdq %xmm2,32(%edi,%edx)
movntdq %xmm3,48(%edi,%edx)
movntdq %xmm4,64(%edi,%edx)
movntdq %xmm5,80(%edi,%edx)
movntdq %xmm6,96(%edi,%edx)
movntdq %xmm7,112(%edi,%edx)
subl $-128,%edx // add 128 with an 8-bit immediate
jnz LVeryLongAligned
jmp LVeryLongChunkEnd
.align 4,0x90 // 16-byte align inner loops
LVeryLongUnaligned: // unaligned loop over 128-bytes
movdqu (%esi,%edx),%xmm0
movdqu 16(%esi,%edx),%xmm1
movdqu 32(%esi,%edx),%xmm2
movdqu 48(%esi,%edx),%xmm3
movdqu 64(%esi,%edx),%xmm4
movdqu 80(%esi,%edx),%xmm5
movdqu 96(%esi,%edx),%xmm6
movdqu 112(%esi,%edx),%xmm7
movntdq %xmm0,(%edi,%edx)
movntdq %xmm1,16(%edi,%edx)
movntdq %xmm2,32(%edi,%edx)
movntdq %xmm3,48(%edi,%edx)
movntdq %xmm4,64(%edi,%edx)
movntdq %xmm5,80(%edi,%edx)
movntdq %xmm6,96(%edi,%edx)
movntdq %xmm7,112(%edi,%edx)
subl $-128,%edx // add 128 with an 8-bit immediate
jnz LVeryLongUnaligned
LVeryLongChunkEnd:
cmpl $4096,%ecx // at least another page to go?
jae LBigChunkLoop // yes
sfence // required by non-temporal stores
popl %ebx
jmp Lrejoin // handle remaining (0..4095) bytes
// Reverse moves.
// 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
jmp LReverseAlignedLoop // use aligned loop
.align 4,0x90 // 16-byte align inner loops
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.
.align 4,0x90 // 16-byte align inner loops
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,sse2,kHasSSE2|kCache64,kHasSupplementalSSE3)
PLATFUNC_DESCRIPTOR(memcpy,sse2,kHasSSE2|kCache64,kHasSupplementalSSE3)
PLATFUNC_DESCRIPTOR(memmove,sse2,kHasSSE2|kCache64,kHasSupplementalSSE3)