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cmd/compile: constant fold SSA bool to int conversions

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Shaves off a few instructions here and there.

file                        before   after    Δ       %       
go/types.s                  322118   321851   -267    -0.083% 
go/internal/gcimporter.s    34937    34909    -28     -0.080% 
go/internal/gccgoimporter.s 56493    56474    -19     -0.034% 
cmd/compile/internal/ssa.s  3926994  3927177  +183    +0.005% 
total                       18862670 18862539 -131    -0.001% 

Change-Id: I724f32317b946b5138224808f85709d9c097a247
Reviewed-on: https://go-review.googlesource.com/c/go/+/221428
Reviewed-by: Keith Randall <khr@golang.org>
This commit is contained in:
Josh Bleecher Snyder 2020-02-29 07:07:56 -08:00
parent d889f0cb10
commit 74f898360d
2 changed files with 18 additions and 0 deletions
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1
src/cmd/compile/internal/ssa/gen/generic.rules
View File

@ -56,6 +56,7 @@
(Cvt64Fto64 (Const64F [c])) -> (Const64 [int64(auxTo64F(c))])
(Round32F x:(Const32F)) -> x
(Round64F x:(Const64F)) -> x
(CvtBoolToUint8 (ConstBool [c])) -> (Const8 [c])
(Trunc16to8 (ZeroExt8to16 x)) -> x
(Trunc32to8 (ZeroExt8to32 x)) -> x

17
src/cmd/compile/internal/ssa/rewritegeneric.go
View File

@ -68,6 +68,8 @@ func rewriteValuegeneric(v *Value) bool {
return rewriteValuegeneric_OpCvt64to32F(v)
case OpCvt64to64F:
return rewriteValuegeneric_OpCvt64to64F(v)
case OpCvtBoolToUint8:
return rewriteValuegeneric_OpCvtBoolToUint8(v)
case OpDiv16:
return rewriteValuegeneric_OpDiv16(v)
case OpDiv16u:
@ -2981,6 +2983,21 @@ func rewriteValuegeneric_OpCvt64to64F(v *Value) bool {
}
return false
}
func rewriteValuegeneric_OpCvtBoolToUint8(v *Value) bool {
v_0 := v.Args[0]
// match: (CvtBoolToUint8 (ConstBool [c]))
// result: (Const8 [c])
for {
if v_0.Op != OpConstBool {
break
}
c := v_0.AuxInt
v.reset(OpConst8)
v.AuxInt = c
return true
}
return false
}
func rewriteValuegeneric_OpDiv16(v *Value) bool {
v_1 := v.Args[1]
v_0 := v.Args[0]