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curve25519: eliminate unnecessary "callee save" prologues

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The assembly implementations of ladderstep and mul contain register
save prologues that are unnecessary in Go because there are no callee
save registers in the Go ABI. Remove these prologues, update all SP
offsets, and reduce the frame size accordingly.

The SP offsets were updated with:

python -c 'import sys, re; sys.stdout.write(re.sub(r"(\d+)\(SP\)", lambda m: "%d(SP)" % (int(m.group(1))-YYY), sys.stdin.read()))'

where YYY was 64 for mul_amd64.s and 56 for ladderstep_amd64.s.

Change-Id: I728948809f479b1c061cc65167dadad651efab31
Reviewed-on: https://go-review.googlesource.com/31580
Reviewed-by: Adam Langley <agl@golang.org>
Reviewed-by: Minux Ma <minux@golang.org>
This commit is contained in:
Austin Clements
2016-10-21 19:51:09 +00:00
parent 722a7b7827
commit f62085100e
2 changed files with 420 additions and 453 deletions
Download Patch File Download Diff File Expand all files Collapse all files
curve25519/ladderstep_amd64.s
+412 -428
View File
File diff suppressed because it is too large Load Diff
curve25519/mul_amd64.s
+8 -25
View File
@@ -8,29 +8,21 @@
// +build amd64,!gccgo,!appengine
// func mul(dest, a, b *[5]uint64)
TEXT ·mul(SB),0,$80-24
TEXT ·mul(SB),0,$16-24
MOVQ dest+0(FP), DI
MOVQ a+8(FP), SI
MOVQ b+16(FP), DX
MOVQ R11,0(SP)
MOVQ R12,8(SP)
MOVQ R13,16(SP)
MOVQ R14,24(SP)
MOVQ R15,32(SP)
MOVQ BX,40(SP)
MOVQ BP,48(SP)
MOVQ DI,56(SP)
MOVQ DX,CX
MOVQ 24(SI),DX
IMUL3Q $19,DX,AX
MOVQ AX,64(SP)
MOVQ AX,0(SP)
MULQ 16(CX)
MOVQ AX,R8
MOVQ DX,R9
MOVQ 32(SI),DX
IMUL3Q $19,DX,AX
MOVQ AX,72(SP)
MOVQ AX,8(SP)
MULQ 8(CX)
ADDQ AX,R8
ADCQ DX,R9
@@ -105,11 +97,11 @@ TEXT ·mul(SB),0,$80-24
MULQ 8(CX)
ADDQ AX,BX
ADCQ DX,BP
MOVQ 64(SP),AX
MOVQ 0(SP),AX
MULQ 24(CX)
ADDQ AX,R10
ADCQ DX,R11
MOVQ 64(SP),AX
MOVQ 0(SP),AX
MULQ 32(CX)
ADDQ AX,R12
ADCQ DX,R13
@@ -117,15 +109,15 @@ TEXT ·mul(SB),0,$80-24
MULQ 0(CX)
ADDQ AX,BX
ADCQ DX,BP
MOVQ 72(SP),AX
MOVQ 8(SP),AX
MULQ 16(CX)
ADDQ AX,R10
ADCQ DX,R11
MOVQ 72(SP),AX
MOVQ 8(SP),AX
MULQ 24(CX)
ADDQ AX,R12
ADCQ DX,R13
MOVQ 72(SP),AX
MOVQ 8(SP),AX
MULQ 32(CX)
ADDQ AX,R14
ADCQ DX,R15
@@ -172,13 +164,4 @@ TEXT ·mul(SB),0,$80-24
MOVQ R9,16(DI)
MOVQ AX,24(DI)
MOVQ R10,32(DI)
MOVQ 0(SP),R11
MOVQ 8(SP),R12
MOVQ 16(SP),R13
MOVQ 24(SP),R14
MOVQ 32(SP),R15
MOVQ 40(SP),BX
MOVQ 48(SP),BP
MOVQ DI,AX
MOVQ SI,DX
RET