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cmd/compile: optimize (ZeroExt (Const [c]))
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These rules trigger 116 times while running make.bash.
And at least for the sample code at
golang/go#18906 (comment)
they are providing optimizations not already present
in amd64.

Updates #18906

Change-Id: I410a480f566f5ab176fc573fb5ac74f9cffec225
Reviewed-on: https://go-review.googlesource.com/36217
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
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@josharian
josharian committed Feb 3, 2017
1 parent c46a438 commit 3025c70
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Showing 2 changed files with 169 additions and 0 deletions.
13 changes: 13 additions & 0 deletions gen/generic.rules
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Original file line number Diff line number Diff line change
Expand Up @@ -68,6 +68,19 @@
(Trunc64to32 (SignExt16to64 x)) -> (SignExt16to32 x)
(Trunc64to32 (SignExt32to64 x)) -> x

(ZeroExt8to16 (Const8 [c])) -> (Const16 [int64( uint8(c))])
(ZeroExt8to32 (Const8 [c])) -> (Const32 [int64( uint8(c))])
(ZeroExt8to64 (Const8 [c])) -> (Const64 [int64( uint8(c))])
(ZeroExt16to32 (Const16 [c])) -> (Const32 [int64(uint16(c))])
(ZeroExt16to64 (Const16 [c])) -> (Const64 [int64(uint16(c))])
(ZeroExt32to64 (Const32 [c])) -> (Const64 [int64(uint32(c))])
(SignExt8to16 (Const8 [c])) -> (Const16 [int64( int8(c))])
(SignExt8to32 (Const8 [c])) -> (Const32 [int64( int8(c))])
(SignExt8to64 (Const8 [c])) -> (Const64 [int64( int8(c))])
(SignExt16to32 (Const16 [c])) -> (Const32 [int64( int16(c))])
(SignExt16to64 (Const16 [c])) -> (Const64 [int64( int16(c))])
(SignExt32to64 (Const32 [c])) -> (Const64 [int64( int32(c))])

// const negation is currently handled by frontend
//(Neg8 (Const8 [c])) -> (Const8 [-c])
//(Neg16 (Const16 [c])) -> (Const16 [-c])
Expand Down
156 changes: 156 additions & 0 deletions rewritegeneric.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -9801,6 +9801,19 @@ func rewriteValuegeneric_OpRsh8x8(v *Value, config *Config) bool {
func rewriteValuegeneric_OpSignExt16to32(v *Value, config *Config) bool {
b := v.Block
_ = b
// match: (SignExt16to32 (Const16 [c]))
// cond:
// result: (Const32 [int64( int16(c))])
for {
v_0 := v.Args[0]
if v_0.Op != OpConst16 {
break
}
c := v_0.AuxInt
v.reset(OpConst32)
v.AuxInt = int64(int16(c))
return true
}
// match: (SignExt16to32 (Trunc32to16 x:(Rsh32x64 _ (Const64 [s]))))
// cond: s >= 16
// result: x
Expand Down Expand Up @@ -9831,6 +9844,19 @@ func rewriteValuegeneric_OpSignExt16to32(v *Value, config *Config) bool {
func rewriteValuegeneric_OpSignExt16to64(v *Value, config *Config) bool {
b := v.Block
_ = b
// match: (SignExt16to64 (Const16 [c]))
// cond:
// result: (Const64 [int64( int16(c))])
for {
v_0 := v.Args[0]
if v_0.Op != OpConst16 {
break
}
c := v_0.AuxInt
v.reset(OpConst64)
v.AuxInt = int64(int16(c))
return true
}
// match: (SignExt16to64 (Trunc64to16 x:(Rsh64x64 _ (Const64 [s]))))
// cond: s >= 48
// result: x
Expand Down Expand Up @@ -9861,6 +9887,19 @@ func rewriteValuegeneric_OpSignExt16to64(v *Value, config *Config) bool {
func rewriteValuegeneric_OpSignExt32to64(v *Value, config *Config) bool {
b := v.Block
_ = b
// match: (SignExt32to64 (Const32 [c]))
// cond:
// result: (Const64 [int64( int32(c))])
for {
v_0 := v.Args[0]
if v_0.Op != OpConst32 {
break
}
c := v_0.AuxInt
v.reset(OpConst64)
v.AuxInt = int64(int32(c))
return true
}
// match: (SignExt32to64 (Trunc64to32 x:(Rsh64x64 _ (Const64 [s]))))
// cond: s >= 32
// result: x
Expand Down Expand Up @@ -9891,6 +9930,19 @@ func rewriteValuegeneric_OpSignExt32to64(v *Value, config *Config) bool {
func rewriteValuegeneric_OpSignExt8to16(v *Value, config *Config) bool {
b := v.Block
_ = b
// match: (SignExt8to16 (Const8 [c]))
// cond:
// result: (Const16 [int64( int8(c))])
for {
v_0 := v.Args[0]
if v_0.Op != OpConst8 {
break
}
c := v_0.AuxInt
v.reset(OpConst16)
v.AuxInt = int64(int8(c))
return true
}
// match: (SignExt8to16 (Trunc16to8 x:(Rsh16x64 _ (Const64 [s]))))
// cond: s >= 8
// result: x
Expand Down Expand Up @@ -9921,6 +9973,19 @@ func rewriteValuegeneric_OpSignExt8to16(v *Value, config *Config) bool {
func rewriteValuegeneric_OpSignExt8to32(v *Value, config *Config) bool {
b := v.Block
_ = b
// match: (SignExt8to32 (Const8 [c]))
// cond:
// result: (Const32 [int64( int8(c))])
for {
v_0 := v.Args[0]
if v_0.Op != OpConst8 {
break
}
c := v_0.AuxInt
v.reset(OpConst32)
v.AuxInt = int64(int8(c))
return true
}
// match: (SignExt8to32 (Trunc32to8 x:(Rsh32x64 _ (Const64 [s]))))
// cond: s >= 24
// result: x
Expand Down Expand Up @@ -9951,6 +10016,19 @@ func rewriteValuegeneric_OpSignExt8to32(v *Value, config *Config) bool {
func rewriteValuegeneric_OpSignExt8to64(v *Value, config *Config) bool {
b := v.Block
_ = b
// match: (SignExt8to64 (Const8 [c]))
// cond:
// result: (Const64 [int64( int8(c))])
for {
v_0 := v.Args[0]
if v_0.Op != OpConst8 {
break
}
c := v_0.AuxInt
v.reset(OpConst64)
v.AuxInt = int64(int8(c))
return true
}
// match: (SignExt8to64 (Trunc64to8 x:(Rsh64x64 _ (Const64 [s]))))
// cond: s >= 56
// result: x
Expand Down Expand Up @@ -12225,6 +12303,19 @@ func rewriteValuegeneric_OpZero(v *Value, config *Config) bool {
func rewriteValuegeneric_OpZeroExt16to32(v *Value, config *Config) bool {
b := v.Block
_ = b
// match: (ZeroExt16to32 (Const16 [c]))
// cond:
// result: (Const32 [int64(uint16(c))])
for {
v_0 := v.Args[0]
if v_0.Op != OpConst16 {
break
}
c := v_0.AuxInt
v.reset(OpConst32)
v.AuxInt = int64(uint16(c))
return true
}
// match: (ZeroExt16to32 (Trunc32to16 x:(Rsh32Ux64 _ (Const64 [s]))))
// cond: s >= 16
// result: x
Expand Down Expand Up @@ -12255,6 +12346,19 @@ func rewriteValuegeneric_OpZeroExt16to32(v *Value, config *Config) bool {
func rewriteValuegeneric_OpZeroExt16to64(v *Value, config *Config) bool {
b := v.Block
_ = b
// match: (ZeroExt16to64 (Const16 [c]))
// cond:
// result: (Const64 [int64(uint16(c))])
for {
v_0 := v.Args[0]
if v_0.Op != OpConst16 {
break
}
c := v_0.AuxInt
v.reset(OpConst64)
v.AuxInt = int64(uint16(c))
return true
}
// match: (ZeroExt16to64 (Trunc64to16 x:(Rsh64Ux64 _ (Const64 [s]))))
// cond: s >= 48
// result: x
Expand Down Expand Up @@ -12285,6 +12389,19 @@ func rewriteValuegeneric_OpZeroExt16to64(v *Value, config *Config) bool {
func rewriteValuegeneric_OpZeroExt32to64(v *Value, config *Config) bool {
b := v.Block
_ = b
// match: (ZeroExt32to64 (Const32 [c]))
// cond:
// result: (Const64 [int64(uint32(c))])
for {
v_0 := v.Args[0]
if v_0.Op != OpConst32 {
break
}
c := v_0.AuxInt
v.reset(OpConst64)
v.AuxInt = int64(uint32(c))
return true
}
// match: (ZeroExt32to64 (Trunc64to32 x:(Rsh64Ux64 _ (Const64 [s]))))
// cond: s >= 32
// result: x
Expand Down Expand Up @@ -12315,6 +12432,19 @@ func rewriteValuegeneric_OpZeroExt32to64(v *Value, config *Config) bool {
func rewriteValuegeneric_OpZeroExt8to16(v *Value, config *Config) bool {
b := v.Block
_ = b
// match: (ZeroExt8to16 (Const8 [c]))
// cond:
// result: (Const16 [int64( uint8(c))])
for {
v_0 := v.Args[0]
if v_0.Op != OpConst8 {
break
}
c := v_0.AuxInt
v.reset(OpConst16)
v.AuxInt = int64(uint8(c))
return true
}
// match: (ZeroExt8to16 (Trunc16to8 x:(Rsh16Ux64 _ (Const64 [s]))))
// cond: s >= 8
// result: x
Expand Down Expand Up @@ -12345,6 +12475,19 @@ func rewriteValuegeneric_OpZeroExt8to16(v *Value, config *Config) bool {
func rewriteValuegeneric_OpZeroExt8to32(v *Value, config *Config) bool {
b := v.Block
_ = b
// match: (ZeroExt8to32 (Const8 [c]))
// cond:
// result: (Const32 [int64( uint8(c))])
for {
v_0 := v.Args[0]
if v_0.Op != OpConst8 {
break
}
c := v_0.AuxInt
v.reset(OpConst32)
v.AuxInt = int64(uint8(c))
return true
}
// match: (ZeroExt8to32 (Trunc32to8 x:(Rsh32Ux64 _ (Const64 [s]))))
// cond: s >= 24
// result: x
Expand Down Expand Up @@ -12375,6 +12518,19 @@ func rewriteValuegeneric_OpZeroExt8to32(v *Value, config *Config) bool {
func rewriteValuegeneric_OpZeroExt8to64(v *Value, config *Config) bool {
b := v.Block
_ = b
// match: (ZeroExt8to64 (Const8 [c]))
// cond:
// result: (Const64 [int64( uint8(c))])
for {
v_0 := v.Args[0]
if v_0.Op != OpConst8 {
break
}
c := v_0.AuxInt
v.reset(OpConst64)
v.AuxInt = int64(uint8(c))
return true
}
// match: (ZeroExt8to64 (Trunc64to8 x:(Rsh64Ux64 _ (Const64 [s]))))
// cond: s >= 56
// result: x
Expand Down

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