cmd/internal/gc, cmd/6g: generate boolean values without jumps
Use SETcc instructions instead of Jcc to generate boolean values.
This generates shorter, jump-free code, which may in turn enable other
peephole optimizations.
For example, given
func f(i, j int) bool {
return i == j
}
Before
"".f t=1 size=32 value=0 args=0x18 locals=0x0
0x0000 00000 (x.go:3) TEXT "".f(SB), $0-24
0x0000 00000 (x.go:3) FUNCDATA $0, gclocals·b4c25e9b09fd0cf9bb429dcefe91c353(SB)
0x0000 00000 (x.go:3) FUNCDATA $1, gclocals·33cdeccccebe80329f1fdbee7f5874cb(SB)
0x0000 00000 (x.go:4) MOVQ "".i+8(FP), BX
0x0005 00005 (x.go:4) MOVQ "".j+16(FP), BP
0x000a 00010 (x.go:4) CMPQ BX, BP
0x000d 00013 (x.go:4) JEQ 21
0x000f 00015 (x.go:4) MOVB $0, "".~r2+24(FP)
0x0014 00020 (x.go:4) RET
0x0015 00021 (x.go:4) MOVB $1, "".~r2+24(FP)
0x001a 00026 (x.go:4) JMP 20
After
"".f t=1 size=32 value=0 args=0x18 locals=0x0
0x0000 00000 (x.go:3) TEXT "".f(SB), $0-24
0x0000 00000 (x.go:3) FUNCDATA $0, gclocals·b4c25e9b09fd0cf9bb429dcefe91c353(SB)
0x0000 00000 (x.go:3) FUNCDATA $1, gclocals·33cdeccccebe80329f1fdbee7f5874cb(SB)
0x0000 00000 (x.go:4) MOVQ "".i+8(FP), BX
0x0005 00005 (x.go:4) MOVQ "".j+16(FP), BP
0x000a 00010 (x.go:4) CMPQ BX, BP
0x000d 00013 (x.go:4) SETEQ "".~r2+24(FP)
0x0012 00018 (x.go:4) RET
regexp benchmarks, best of 12 runs:
benchmark old ns/op new ns/op delta
BenchmarkNotOnePassShortB 782 733 -6.27%
BenchmarkLiteral 180 171 -5.00%
BenchmarkNotLiteral 2855 2721 -4.69%
BenchmarkMatchHard_32 2672 2557 -4.30%
BenchmarkMatchHard_1K 80182 76732 -4.30%
BenchmarkMatchEasy1_32M 76440180 73304748 -4.10%
BenchmarkMatchEasy1_32K 68798 66350 -3.56%
BenchmarkAnchoredLongMatch 482 465 -3.53%
BenchmarkMatchEasy1_1M 2373042 2292692 -3.39%
BenchmarkReplaceAll 2776 2690 -3.10%
BenchmarkNotOnePassShortA 1397 1360 -2.65%
BenchmarkMatchClass_InRange 3842 3742 -2.60%
BenchmarkMatchEasy0_32 125 122 -2.40%
BenchmarkMatchEasy0_32K 11414 11164 -2.19%
BenchmarkMatchEasy0_1K 668 654 -2.10%
BenchmarkAnchoredShortMatch 260 255 -1.92%
BenchmarkAnchoredLiteralShortNonMatch 164 161 -1.83%
BenchmarkOnePassShortB 623 612 -1.77%
BenchmarkOnePassShortA 801 788 -1.62%
BenchmarkMatchClass 4094 4033 -1.49%
BenchmarkMatchEasy0_32M 14078800 13890704 -1.34%
BenchmarkMatchHard_32K 4095844 4045820 -1.22%
BenchmarkMatchEasy1_1K 1663 1643 -1.20%
BenchmarkMatchHard_1M 131261708 129708215 -1.18%
BenchmarkMatchHard_32M 4210112412 4169292003 -0.97%
BenchmarkMatchMedium_32K 2460752 2438611 -0.90%
BenchmarkMatchEasy0_1M 422914 419672 -0.77%
BenchmarkMatchMedium_1M 78581121 78040160 -0.69%
BenchmarkMatchMedium_32M 2515287278 2498464906 -0.67%
BenchmarkMatchMedium_32 1754 1746 -0.46%
BenchmarkMatchMedium_1K 52105 52106 +0.00%
BenchmarkAnchoredLiteralLongNonMatch 185 185 +0.00%
BenchmarkMatchEasy1_32 107 107 +0.00%
BenchmarkOnePassLongNotPrefix 505 505 +0.00%
BenchmarkOnePassLongPrefix 147 147 +0.00%
The godoc binary is ~0.12% smaller after this CL.
Updates #5729.
toolstash -cmp passes for all architectures other than amd64 and amd64p32.
Other architectures can be done in follow-up CLs.
Change-Id: I0e167e259274b722958567fc0af83a17ca002da7
Reviewed-on: https://go-review.googlesource.com/2284
Reviewed-by: Russ Cox <rsc@golang.org>
diff --git a/src/cmd/internal/gc/go.go b/src/cmd/internal/gc/go.go
index c0ec7b5..d399ebb 100644
--- a/src/cmd/internal/gc/go.go
+++ b/src/cmd/internal/gc/go.go
@@ -791,6 +791,13 @@
Expandchecks func(*obj.Prog)
Getg func(*Node)
Gins func(int, *Node, *Node) *obj.Prog
+ // Ginsboolval inserts instructions to convert the result
+ // of a just-completed comparison to a boolean value.
+ // The first argument is the conditional jump instruction
+ // corresponding to the desired value.
+ // The second argument is the destination.
+ // If not present, Ginsboolval will be emulated with jumps.
+ Ginsboolval func(int, *Node)
Ginscon func(int, int64, *Node)
Ginsnop func()
Gmove func(*Node, *Node)
