cmd/compile: fold IsInBounds with small index
For the following example, but there are a few more in the stdlib:
func histogram(b []byte, h *[256]int32) {
for _, t := range b {
h[t]++
}
}
Change-Id: I56615f341ae52e02ef34025588dc6d1c52122295
Reviewed-on: https://go-review.googlesource.com/20924
Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: Alexandru Moșoi <alexandru@mosoi.ro>
TryBot-Result: Gobot Gobot <gobot@golang.org>
diff --git a/src/cmd/compile/internal/ssa/rewritegeneric.go b/src/cmd/compile/internal/ssa/rewritegeneric.go
index 9b304d8..ebc241e 100644
--- a/src/cmd/compile/internal/ssa/rewritegeneric.go
+++ b/src/cmd/compile/internal/ssa/rewritegeneric.go
@@ -2602,6 +2602,78 @@
func rewriteValuegeneric_OpIsInBounds(v *Value, config *Config) bool {
b := v.Block
_ = b
+ // match: (IsInBounds (ZeroExt8to32 _) (Const32 [c]))
+ // cond: (1 << 8) <= int32(c)
+ // result: (ConstBool [1])
+ for {
+ if v.Args[0].Op != OpZeroExt8to32 {
+ break
+ }
+ if v.Args[1].Op != OpConst32 {
+ break
+ }
+ c := v.Args[1].AuxInt
+ if !((1 << 8) <= int32(c)) {
+ break
+ }
+ v.reset(OpConstBool)
+ v.AuxInt = 1
+ return true
+ }
+ // match: (IsInBounds (ZeroExt8to64 _) (Const64 [c]))
+ // cond: (1 << 8) <= c
+ // result: (ConstBool [1])
+ for {
+ if v.Args[0].Op != OpZeroExt8to64 {
+ break
+ }
+ if v.Args[1].Op != OpConst64 {
+ break
+ }
+ c := v.Args[1].AuxInt
+ if !((1 << 8) <= c) {
+ break
+ }
+ v.reset(OpConstBool)
+ v.AuxInt = 1
+ return true
+ }
+ // match: (IsInBounds (ZeroExt16to32 _) (Const32 [c]))
+ // cond: (1 << 16) <= int32(c)
+ // result: (ConstBool [1])
+ for {
+ if v.Args[0].Op != OpZeroExt16to32 {
+ break
+ }
+ if v.Args[1].Op != OpConst32 {
+ break
+ }
+ c := v.Args[1].AuxInt
+ if !((1 << 16) <= int32(c)) {
+ break
+ }
+ v.reset(OpConstBool)
+ v.AuxInt = 1
+ return true
+ }
+ // match: (IsInBounds (ZeroExt16to64 _) (Const64 [c]))
+ // cond: (1 << 16) <= c
+ // result: (ConstBool [1])
+ for {
+ if v.Args[0].Op != OpZeroExt16to64 {
+ break
+ }
+ if v.Args[1].Op != OpConst64 {
+ break
+ }
+ c := v.Args[1].AuxInt
+ if !((1 << 16) <= c) {
+ break
+ }
+ v.reset(OpConstBool)
+ v.AuxInt = 1
+ return true
+ }
// match: (IsInBounds x x)
// cond:
// result: (ConstBool [0])
