f91ff1a509
Even this very simple, restricted initial implementation helps.
While running make.bash, it moves 84437 values
to new, closer homes.
As a concrete example:
func f_ssa(i, j int, b bool) int {
if !b {
return 0
}
return i + j
}
It cuts off one stack slot and two instructions:
Before:
"".f_ssa t=1 size=96 value=0 args=0x20 locals=0x18
0x0000 00000 (x.go:3) TEXT "".f_ssa(SB), $24-32
0x0000 00000 (x.go:3) SUBQ $24, SP
0x0004 00004 (x.go:3) FUNCDATA $0, "".gcargs·0(SB)
0x0004 00004 (x.go:3) FUNCDATA $1, "".gclocals·1(SB)
0x0004 00004 (x.go:5) MOVQ $0, AX
0x0006 00006 (x.go:3) MOVQ 32(SP), CX
0x000b 00011 (x.go:3) MOVQ 40(SP), DX
0x0010 00016 (x.go:3) LEAQ 48(SP), BX
0x0015 00021 (x.go:3) MOVB (BX), BPB
0x0018 00024 (x.go:3) MOVQ $0, SI
0x001a 00026 (x.go:3) MOVQ SI, 56(SP)
0x001f 00031 (x.go:3) TESTB BPB, BPB
0x0022 00034 (x.go:5) MOVQ AX, (SP)
0x0026 00038 (x.go:3) MOVQ CX, 8(SP)
0x002b 00043 (x.go:3) MOVQ DX, 16(SP)
0x0030 00048 (x.go:4) JEQ 74
0x0032 00050 (x.go:3) MOVQ 8(SP), AX
0x0037 00055 (x.go:3) MOVQ 16(SP), CX
0x003c 00060 (x.go:7) LEAQ (AX)(CX*1), DX
0x0040 00064 (x.go:7) MOVQ DX, 56(SP)
0x0045 00069 (x.go:3) ADDQ $24, SP
0x0049 00073 (x.go:3) RET
0x004a 00074 (x.go:5) MOVQ (SP), AX
0x004e 00078 (x.go:5) MOVQ AX, 56(SP)
0x0053 00083 (x.go:3) JMP 69
After:
"".f_ssa t=1 size=80 value=0 args=0x20 locals=0x10
0x0000 00000 (x.go:3) TEXT "".f_ssa(SB), $16-32
0x0000 00000 (x.go:3) SUBQ $16, SP
0x0004 00004 (x.go:3) FUNCDATA $0, "".gcargs·0(SB)
0x0004 00004 (x.go:3) FUNCDATA $1, "".gclocals·1(SB)
0x0004 00004 (x.go:3) MOVQ 32(SP), AX
0x0009 00009 (x.go:3) MOVQ 24(SP), CX
0x000e 00014 (x.go:3) LEAQ 40(SP), DX
0x0013 00019 (x.go:3) MOVB (DX), BL
0x0015 00021 (x.go:3) MOVQ $0, BP
0x0017 00023 (x.go:3) MOVQ BP, 48(SP)
0x001c 00028 (x.go:3) TESTB BL, BL
0x001e 00030 (x.go:3) MOVQ AX, (SP)
0x0022 00034 (x.go:3) MOVQ CX, 8(SP)
0x0027 00039 (x.go:4) JEQ 64
0x0029 00041 (x.go:3) MOVQ 8(SP), AX
0x002e 00046 (x.go:3) MOVQ (SP), CX
0x0032 00050 (x.go:7) LEAQ (AX)(CX*1), DX
0x0036 00054 (x.go:7) MOVQ DX, 48(SP)
0x003b 00059 (x.go:3) ADDQ $16, SP
0x003f 00063 (x.go:3) RET
0x0040 00064 (x.go:5) MOVQ $0, AX
0x0042 00066 (x.go:5) MOVQ AX, 48(SP)
0x0047 00071 (x.go:3) JMP 59
Of course, the old backend is still well ahead:
"".f_ssa t=1 size=48 value=0 args=0x20 locals=0x0
0x0000 00000 (x.go:3) TEXT "".f_ssa(SB), $0-32
0x0000 00000 (x.go:3) NOP
0x0000 00000 (x.go:3) NOP
0x0000 00000 (x.go:3) FUNCDATA $0, gclocals·a8eabfc4a4514ed6b3b0c61e9680e440(SB)
0x0000 00000 (x.go:3) FUNCDATA $1, gclocals·33cdeccccebe80329f1fdbee7f5874cb(SB)
0x0000 00000 (x.go:4) CMPB "".b+24(FP), $0
0x0005 00005 (x.go:4) JNE 17
0x0007 00007 (x.go:5) MOVQ $0, "".~r3+32(FP)
0x0010 00016 (x.go:5) RET
0x0011 00017 (x.go:7) MOVQ "".i+8(FP), BX
0x0016 00022 (x.go:7) MOVQ "".j+16(FP), BP
0x001b 00027 (x.go:7) ADDQ BP, BX
0x001e 00030 (x.go:7) MOVQ BX, "".~r3+32(FP)
0x0023 00035 (x.go:7) RET
Some regalloc improvements should help considerably.
Change-Id: I95bb5dd83e56afd70ae4e983f1d32dffd0c3d46a
Reviewed-on: https://go-review.googlesource.com/13142
Reviewed-by: Keith Randall <khr@golang.org>
|
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