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Commit c8b148e7 authored by Todd Neal's avatar Todd Neal
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cmd/compile: fold constants from lsh/rsh/lsh and rsh/lsh/rsh 

Fixes #14825

Change-Id: Ib44d80579a55c15d75ea2ad1ef54efa6ca66a9a6
Reviewed-on: https://go-review.googlesource.com/20745
Run-TryBot: Todd Neal <todd@tneal.org>
Reviewed-by: default avatarKeith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
parent 42cd69f5
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src/cmd/compile/internal/gc/testdata/arith_ssa.go
View file @ c8b148e7
......@@ -14,6 +14,84 @@ const (
y = 0x0fffFFFF
)
//go:noinline
func lshNop1(x uint64) uint64 {
// two outer shifts should be removed
return (((x << 5) >> 2) << 2)
}
//go:noinline
func lshNop2(x uint64) uint64 {
return (((x << 5) >> 2) << 3)
}
//go:noinline
func lshNop3(x uint64) uint64 {
return (((x << 5) >> 2) << 6)
}
//go:noinline
func lshNotNop(x uint64) uint64 {
// outer shift can't be removed
return (((x << 5) >> 2) << 1)
}
//go:noinline
func rshNop1(x uint64) uint64 {
return (((x >> 5) << 2) >> 2)
}
//go:noinline
func rshNop2(x uint64) uint64 {
return (((x >> 5) << 2) >> 3)
}
//go:noinline
func rshNop3(x uint64) uint64 {
return (((x >> 5) << 2) >> 6)
}
//go:noinline
func rshNotNop(x uint64) uint64 {
return (((x >> 5) << 2) >> 1)
}
func testShiftRemoval() {
allSet := ^uint64(0)
if want, got := uint64(0x7ffffffffffffff), rshNop1(allSet); want != got {
println("testShiftRemoval rshNop1 failed, wanted", want, "got", got)
failed = true
}
if want, got := uint64(0x3ffffffffffffff), rshNop2(allSet); want != got {
println("testShiftRemoval rshNop2 failed, wanted", want, "got", got)
failed = true
}
if want, got := uint64(0x7fffffffffffff), rshNop3(allSet); want != got {
println("testShiftRemoval rshNop3 failed, wanted", want, "got", got)
failed = true
}
if want, got := uint64(0xffffffffffffffe), rshNotNop(allSet); want != got {
println("testShiftRemoval rshNotNop failed, wanted", want, "got", got)
failed = true
}
if want, got := uint64(0xffffffffffffffe0), lshNop1(allSet); want != got {
println("testShiftRemoval lshNop1 failed, wanted", want, "got", got)
failed = true
}
if want, got := uint64(0xffffffffffffffc0), lshNop2(allSet); want != got {
println("testShiftRemoval lshNop2 failed, wanted", want, "got", got)
failed = true
}
if want, got := uint64(0xfffffffffffffe00), lshNop3(allSet); want != got {
println("testShiftRemoval lshNop3 failed, wanted", want, "got", got)
failed = true
}
if want, got := uint64(0x7ffffffffffffff0), lshNotNop(allSet); want != got {
println("testShiftRemoval lshNotNop failed, wanted", want, "got", got)
failed = true
}
}
//go:noinline
func parseLE64(b []byte) uint64 {
// skip the first two bytes, and parse the remaining 8 as a uint64
......@@ -494,6 +572,7 @@ func main() {
testLargeConst()
testLoadCombine()
testLoadSymCombine()
testShiftRemoval()
if failed {
panic("failed")
......
src/cmd/compile/internal/ssa/gen/generic.rules
View file @ c8b148e7
......@@ -91,6 +91,18 @@
(Rsh8x64 (Const8 [0]) _) -> (Const8 [0])
(Rsh8Ux64 (Const8 [0]) _) -> (Const8 [0])
// ((x >> c1) << c2) >> c3
(Rsh64Ux64 (Lsh64x64 (Rsh64Ux64 x (Const64 [c1])) (Const64 [c2])) (Const64 [c3])) && c1 >= c2 && c3 >= c2 -> (Rsh64Ux64 x (Const64 <config.fe.TypeUInt64()> [c1-c2+c3]))
(Rsh32Ux32 (Lsh32x32 (Rsh32Ux32 x (Const32 [c1])) (Const32 [c2])) (Const32 [c3])) && c1 >= c2 && c3 >= c2 -> (Rsh32Ux32 x (Const32 <config.fe.TypeUInt32()> [c1-c2+c3]))
(Rsh16Ux16 (Lsh16x16 (Rsh16Ux16 x (Const16 [c1])) (Const16 [c2])) (Const16 [c3])) && c1 >= c2 && c3 >= c2 -> (Rsh16Ux16 x (Const16 <config.fe.TypeUInt16()> [c1-c2+c3]))
(Rsh8Ux8 (Lsh8x8 (Rsh8Ux8 x (Const8 [c1])) (Const8 [c2])) (Const8 [c3])) && c1 >= c2 && c3 >= c2 -> (Rsh8Ux8 x (Const8 <config.fe.TypeUInt8()> [c1-c2+c3]))
// ((x << c1) >> c2) << c3
(Lsh64x64 (Rsh64Ux64 (Lsh64x64 x (Const64 [c1])) (Const64 [c2])) (Const64 [c3])) && c1 >= c2 && c3 >= c2 -> (Lsh64x64 x (Const64 <config.fe.TypeUInt64()> [c1-c2+c3]))
(Lsh32x32 (Rsh32Ux32 (Lsh32x32 x (Const32 [c1])) (Const32 [c2])) (Const32 [c3])) && c1 >= c2 && c3 >= c2 -> (Lsh32x32 x (Const32 <config.fe.TypeUInt32()> [c1-c2+c3]))
(Lsh16x16 (Rsh16Ux16 (Lsh16x16 x (Const16 [c1])) (Const16 [c2])) (Const16 [c3])) && c1 >= c2 && c3 >= c2 -> (Lsh16x16 x (Const16 <config.fe.TypeUInt16()> [c1-c2+c3]))
(Lsh8x8 (Rsh8Ux8 (Lsh8x8 x (Const8 [c1])) (Const8 [c2])) (Const8 [c3])) && c1 >= c2 && c3 >= c2 -> (Lsh8x8 x (Const8 <config.fe.TypeUInt8()> [c1-c2+c3]))
(IsInBounds x x) -> (ConstBool [0])
(IsInBounds (And32 (Const32 [c]) _) (Const32 [d])) && inBounds32(c, d) -> (ConstBool [1])
(IsInBounds (And64 (Const64 [c]) _) (Const64 [d])) && inBounds64(c, d) -> (ConstBool [1])
......
src/cmd/compile/internal/ssa/rewritegeneric.go
View file @ c8b148e7
......@@ -3420,6 +3420,39 @@ func rewriteValuegeneric_OpLoad(v *Value, config *Config) bool {
func rewriteValuegeneric_OpLsh16x16(v *Value, config *Config) bool {
b := v.Block
_ = b
// match: (Lsh16x16 (Rsh16Ux16 (Lsh16x16 x (Const16 [c1])) (Const16 [c2])) (Const16 [c3]))
// cond: c1 >= c2 && c3 >= c2
// result: (Lsh16x16 x (Const16 <config.fe.TypeUInt16()> [c1-c2+c3]))
for {
if v.Args[0].Op != OpRsh16Ux16 {
break
}
if v.Args[0].Args[0].Op != OpLsh16x16 {
break
}
x := v.Args[0].Args[0].Args[0]
if v.Args[0].Args[0].Args[1].Op != OpConst16 {
break
}
c1 := v.Args[0].Args[0].Args[1].AuxInt
if v.Args[0].Args[1].Op != OpConst16 {
break
}
c2 := v.Args[0].Args[1].AuxInt
if v.Args[1].Op != OpConst16 {
break
}
c3 := v.Args[1].AuxInt
if !(c1 >= c2 && c3 >= c2) {
break
}
v.reset(OpLsh16x16)
v.AddArg(x)
v0 := b.NewValue0(v.Line, OpConst16, config.fe.TypeUInt16())
v0.AuxInt = c1 - c2 + c3
v.AddArg(v0)
return true
}
// match: (Lsh16x16 <t> x (Const16 [c]))
// cond:
// result: (Lsh16x64 x (Const64 <t> [int64(uint16(c))]))
......@@ -3601,6 +3634,39 @@ func rewriteValuegeneric_OpLsh32x16(v *Value, config *Config) bool {
func rewriteValuegeneric_OpLsh32x32(v *Value, config *Config) bool {
b := v.Block
_ = b
// match: (Lsh32x32 (Rsh32Ux32 (Lsh32x32 x (Const32 [c1])) (Const32 [c2])) (Const32 [c3]))
// cond: c1 >= c2 && c3 >= c2
// result: (Lsh32x32 x (Const32 <config.fe.TypeUInt32()> [c1-c2+c3]))
for {
if v.Args[0].Op != OpRsh32Ux32 {
break
}
if v.Args[0].Args[0].Op != OpLsh32x32 {
break
}
x := v.Args[0].Args[0].Args[0]
if v.Args[0].Args[0].Args[1].Op != OpConst32 {
break
}
c1 := v.Args[0].Args[0].Args[1].AuxInt
if v.Args[0].Args[1].Op != OpConst32 {
break
}
c2 := v.Args[0].Args[1].AuxInt
if v.Args[1].Op != OpConst32 {
break
}
c3 := v.Args[1].AuxInt
if !(c1 >= c2 && c3 >= c2) {
break
}
v.reset(OpLsh32x32)
v.AddArg(x)
v0 := b.NewValue0(v.Line, OpConst32, config.fe.TypeUInt32())
v0.AuxInt = c1 - c2 + c3
v.AddArg(v0)
return true
}
// match: (Lsh32x32 <t> x (Const32 [c]))
// cond:
// result: (Lsh32x64 x (Const64 <t> [int64(uint32(c))]))
......@@ -3840,6 +3906,39 @@ func rewriteValuegeneric_OpLsh64x64(v *Value, config *Config) bool {
v.AuxInt = 0
return true
}
// match: (Lsh64x64 (Rsh64Ux64 (Lsh64x64 x (Const64 [c1])) (Const64 [c2])) (Const64 [c3]))
// cond: c1 >= c2 && c3 >= c2
// result: (Lsh64x64 x (Const64 <config.fe.TypeUInt64()> [c1-c2+c3]))
for {
if v.Args[0].Op != OpRsh64Ux64 {
break
}
if v.Args[0].Args[0].Op != OpLsh64x64 {
break
}
x := v.Args[0].Args[0].Args[0]
if v.Args[0].Args[0].Args[1].Op != OpConst64 {
break
}
c1 := v.Args[0].Args[0].Args[1].AuxInt
if v.Args[0].Args[1].Op != OpConst64 {
break
}
c2 := v.Args[0].Args[1].AuxInt
if v.Args[1].Op != OpConst64 {
break
}
c3 := v.Args[1].AuxInt
if !(c1 >= c2 && c3 >= c2) {
break
}
v.reset(OpLsh64x64)
v.AddArg(x)
v0 := b.NewValue0(v.Line, OpConst64, config.fe.TypeUInt64())
v0.AuxInt = c1 - c2 + c3
v.AddArg(v0)
return true
}
// match: (Lsh64x64 x (Const64 [0]))
// cond:
// result: x
......@@ -4090,6 +4189,39 @@ func rewriteValuegeneric_OpLsh8x64(v *Value, config *Config) bool {
func rewriteValuegeneric_OpLsh8x8(v *Value, config *Config) bool {
b := v.Block
_ = b
// match: (Lsh8x8 (Rsh8Ux8 (Lsh8x8 x (Const8 [c1])) (Const8 [c2])) (Const8 [c3]))
// cond: c1 >= c2 && c3 >= c2
// result: (Lsh8x8 x (Const8 <config.fe.TypeUInt8()> [c1-c2+c3]))
for {
if v.Args[0].Op != OpRsh8Ux8 {
break
}
if v.Args[0].Args[0].Op != OpLsh8x8 {
break
}
x := v.Args[0].Args[0].Args[0]
if v.Args[0].Args[0].Args[1].Op != OpConst8 {
break
}
c1 := v.Args[0].Args[0].Args[1].AuxInt
if v.Args[0].Args[1].Op != OpConst8 {
break
}
c2 := v.Args[0].Args[1].AuxInt
if v.Args[1].Op != OpConst8 {
break
}
c3 := v.Args[1].AuxInt
if !(c1 >= c2 && c3 >= c2) {
break
}
v.reset(OpLsh8x8)
v.AddArg(x)
v0 := b.NewValue0(v.Line, OpConst8, config.fe.TypeUInt8())
v0.AuxInt = c1 - c2 + c3
v.AddArg(v0)
return true
}
// match: (Lsh8x8 <t> x (Const8 [c]))
// cond:
// result: (Lsh8x64 x (Const64 <t> [int64(uint8(c))]))
......@@ -5524,6 +5656,39 @@ func rewriteValuegeneric_OpPtrIndex(v *Value, config *Config) bool {
func rewriteValuegeneric_OpRsh16Ux16(v *Value, config *Config) bool {
b := v.Block
_ = b
// match: (Rsh16Ux16 (Lsh16x16 (Rsh16Ux16 x (Const16 [c1])) (Const16 [c2])) (Const16 [c3]))
// cond: c1 >= c2 && c3 >= c2
// result: (Rsh16Ux16 x (Const16 <config.fe.TypeUInt16()> [c1-c2+c3]))
for {
if v.Args[0].Op != OpLsh16x16 {
break
}
if v.Args[0].Args[0].Op != OpRsh16Ux16 {
break
}
x := v.Args[0].Args[0].Args[0]
if v.Args[0].Args[0].Args[1].Op != OpConst16 {
break
}
c1 := v.Args[0].Args[0].Args[1].AuxInt
if v.Args[0].Args[1].Op != OpConst16 {
break
}
c2 := v.Args[0].Args[1].AuxInt
if v.Args[1].Op != OpConst16 {
break
}
c3 := v.Args[1].AuxInt
if !(c1 >= c2 && c3 >= c2) {
break
}
v.reset(OpRsh16Ux16)
v.AddArg(x)
v0 := b.NewValue0(v.Line, OpConst16, config.fe.TypeUInt16())
v0.AuxInt = c1 - c2 + c3
v.AddArg(v0)
return true
}
// match: (Rsh16Ux16 <t> x (Const16 [c]))
// cond:
// result: (Rsh16Ux64 x (Const64 <t> [int64(uint16(c))]))
......@@ -5849,6 +6014,39 @@ func rewriteValuegeneric_OpRsh32Ux16(v *Value, config *Config) bool {
func rewriteValuegeneric_OpRsh32Ux32(v *Value, config *Config) bool {
b := v.Block
_ = b
// match: (Rsh32Ux32 (Lsh32x32 (Rsh32Ux32 x (Const32 [c1])) (Const32 [c2])) (Const32 [c3]))
// cond: c1 >= c2 && c3 >= c2
// result: (Rsh32Ux32 x (Const32 <config.fe.TypeUInt32()> [c1-c2+c3]))
for {
if v.Args[0].Op != OpLsh32x32 {
break
}
if v.Args[0].Args[0].Op != OpRsh32Ux32 {
break
}
x := v.Args[0].Args[0].Args[0]
if v.Args[0].Args[0].Args[1].Op != OpConst32 {
break
}
c1 := v.Args[0].Args[0].Args[1].AuxInt
if v.Args[0].Args[1].Op != OpConst32 {
break
}
c2 := v.Args[0].Args[1].AuxInt
if v.Args[1].Op != OpConst32 {
break
}
c3 := v.Args[1].AuxInt
if !(c1 >= c2 && c3 >= c2) {
break
}
v.reset(OpRsh32Ux32)
v.AddArg(x)
v0 := b.NewValue0(v.Line, OpConst32, config.fe.TypeUInt32())
v0.AuxInt = c1 - c2 + c3
v.AddArg(v0)
return true
}
// match: (Rsh32Ux32 <t> x (Const32 [c]))
// cond:
// result: (Rsh32Ux64 x (Const64 <t> [int64(uint32(c))]))
......@@ -6232,6 +6430,39 @@ func rewriteValuegeneric_OpRsh64Ux64(v *Value, config *Config) bool {
v.AuxInt = 0
return true
}
// match: (Rsh64Ux64 (Lsh64x64 (Rsh64Ux64 x (Const64 [c1])) (Const64 [c2])) (Const64 [c3]))
// cond: c1 >= c2 && c3 >= c2
// result: (Rsh64Ux64 x (Const64 <config.fe.TypeUInt64()> [c1-c2+c3]))
for {
if v.Args[0].Op != OpLsh64x64 {
break
}
if v.Args[0].Args[0].Op != OpRsh64Ux64 {
break
}
x := v.Args[0].Args[0].Args[0]
if v.Args[0].Args[0].Args[1].Op != OpConst64 {
break
}
c1 := v.Args[0].Args[0].Args[1].AuxInt
if v.Args[0].Args[1].Op != OpConst64 {
break
}
c2 := v.Args[0].Args[1].AuxInt
if v.Args[1].Op != OpConst64 {
break
}
c3 := v.Args[1].AuxInt
if !(c1 >= c2 && c3 >= c2) {
break
}
v.reset(OpRsh64Ux64)
v.AddArg(x)
v0 := b.NewValue0(v.Line, OpConst64, config.fe.TypeUInt64())
v0.AuxInt = c1 - c2 + c3
v.AddArg(v0)
return true
}
// match: (Rsh64Ux64 x (Const64 [0]))
// cond:
// result: x
......@@ -6682,6 +6913,39 @@ func rewriteValuegeneric_OpRsh8Ux64(v *Value, config *Config) bool {
func rewriteValuegeneric_OpRsh8Ux8(v *Value, config *Config) bool {
b := v.Block
_ = b
// match: (Rsh8Ux8 (Lsh8x8 (Rsh8Ux8 x (Const8 [c1])) (Const8 [c2])) (Const8 [c3]))
// cond: c1 >= c2 && c3 >= c2
// result: (Rsh8Ux8 x (Const8 <config.fe.TypeUInt8()> [c1-c2+c3]))
for {
if v.Args[0].Op != OpLsh8x8 {
break
}
if v.Args[0].Args[0].Op != OpRsh8Ux8 {
break
}
x := v.Args[0].Args[0].Args[0]
if v.Args[0].Args[0].Args[1].Op != OpConst8 {
break
}
c1 := v.Args[0].Args[0].Args[1].AuxInt
if v.Args[0].Args[1].Op != OpConst8 {
break
}
c2 := v.Args[0].Args[1].AuxInt
if v.Args[1].Op != OpConst8 {
break
}
c3 := v.Args[1].AuxInt
if !(c1 >= c2 && c3 >= c2) {
break
}
v.reset(OpRsh8Ux8)
v.AddArg(x)
v0 := b.NewValue0(v.Line, OpConst8, config.fe.TypeUInt8())
v0.AuxInt = c1 - c2 + c3
v.AddArg(v0)
return true
}
// match: (Rsh8Ux8 <t> x (Const8 [c]))
// cond:
// result: (Rsh8Ux64 x (Const64 <t> [int64(uint8(c))]))
......
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