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https://github.com/golang/go
synced 2024-11-19 16:24:45 -07:00
45c06b27a4
Replace the confusing game where a frame size of $-8 would suppress the implicit setting up of a stack frame with a nice explicit flag. The code to set up the function prologue is still a little confusing but better than it was. Change-Id: I1d49278ff42c6bc734ebfb079998b32bc53f8d9a Reviewed-on: https://go-review.googlesource.com/15670 Reviewed-by: Minux Ma <minux@golang.org>
89 lines
1.9 KiB
ArmAsm
89 lines
1.9 KiB
ArmAsm
// Copyright 2014 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// +build ppc64 ppc64le
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#include "textflag.h"
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// void runtime·memmove(void*, void*, uintptr)
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TEXT runtime·memmove(SB), NOSPLIT|NOFRAME, $0-24
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MOVD to+0(FP), R3
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MOVD from+8(FP), R4
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MOVD n+16(FP), R5
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CMP R5, $0
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BNE check
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RET
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check:
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ANDCC $7, R5, R7 // R7 is the number of bytes to copy and CR0[EQ] is set if there are none.
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SRAD $3, R5, R6 // R6 is the number of words to copy
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CMP R6, $0, CR1 // CR1[EQ] is set if there are no words to copy.
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CMP R3, R4, CR2
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BC 12, 9, backward // I think you should be able to write this as "BGT CR2, backward"
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// Copying forward proceeds by copying R6 words then copying R7 bytes.
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// R3 and R4 are advanced as we copy. Becuase PPC64 lacks post-increment
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// load/store, R3 and R4 point before the bytes that are to be copied.
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BC 12, 6, noforwardlarge // "BEQ CR1, noforwardlarge"
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MOVD R6, CTR
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SUB $8, R3
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SUB $8, R4
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forwardlargeloop:
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MOVDU 8(R4), R8
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MOVDU R8, 8(R3)
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BC 16, 0, forwardlargeloop // "BDNZ"
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ADD $8, R3
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ADD $8, R4
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noforwardlarge:
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BNE forwardtail // Tests the bit set by ANDCC above
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RET
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forwardtail:
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SUB $1, R3
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SUB $1, R4
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MOVD R7, CTR
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forwardtailloop:
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MOVBZU 1(R4), R8
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MOVBZU R8, 1(R3)
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BC 16, 0, forwardtailloop
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RET
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backward:
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// Copying backwards proceeds by copying R7 bytes then copying R6 words.
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// R3 and R4 are advanced to the end of the destination/source buffers
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// respectively and moved back as we copy.
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ADD R5, R4, R4
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ADD R3, R5, R3
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BEQ nobackwardtail
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MOVD R7, CTR
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backwardtailloop:
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MOVBZU -1(R4), R8
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MOVBZU R8, -1(R3)
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BC 16, 0, backwardtailloop
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nobackwardtail:
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BC 4, 6, backwardlarge // "BNE CR1"
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RET
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backwardlarge:
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MOVD R6, CTR
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backwardlargeloop:
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MOVDU -8(R4), R8
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MOVDU R8, -8(R3)
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BC 16, 0, backwardlargeloop // "BDNZ"
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RET
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