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cmd/compile/internal/ssa/gen: eliminate unnecessary neg and xori on PPC64

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This adds a few rules to PPC64 to eliminate some instructions:
- when an isel is used to generate a boolean value based on a
condition and followed by an xori to flip the result, it can
instead flip the operands in the isel and avoid the xori.
= when a neg follows a sub the operands to the sub can be
swapped and the neg avoided.

There are several opportunities in reflect.DeepEqual to omit
xori which improves some of its benchmarks by as much as
5%

Change-Id: I81bbc02c0f16995c65934b6f045867b731ab302b
Reviewed-on: https://go-review.googlesource.com/c/go/+/357509
Trust: Lynn Boger <laboger@linux.vnet.ibm.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
This commit is contained in:
Lynn Boger 2021-10-14 12:55:43 -05:00
parent 8b9c0d1a79
commit 8b0bea993d
3 changed files with 74 additions and 2 deletions
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6
src/cmd/compile/internal/ssa/gen/PPC64.rules
View File

@ -848,6 +848,7 @@
(ADDconst [c] (SUBFCconst [d] x)) && is32Bit(c+d) => (SUBFCconst [c+d] x)
(NEG (ADDconst [c] x)) && is32Bit(-c) => (SUBFCconst [-c] x)
(NEG (SUBFCconst [c] x)) && is32Bit(-c) => (ADDconst [-c] x)
(NEG (SUB x y)) => (SUB y x)
// Use register moves instead of stores and loads to move int<=>float values
// Common with math Float64bits, Float64frombits
@ -1087,7 +1088,7 @@
((CMP|CMPW|CMPU|CMPWU) x y) && canonLessThan(x,y) => (InvertFlags ((CMP|CMPW|CMPU|CMPWU) y x))
// ISEL auxInt values 0=LT 1=GT 2=EQ arg2 ? arg0 : arg1
// ISEL auxInt values 4=GE 5=LE 6=NE arg2 ? arg1 : arg0
// ISEL auxInt values 4=GE 5=LE 6=NE !arg2 ? arg1 : arg0
// ISELB special case where arg0, arg1 values are 0, 1
(Equal cmp) => (ISELB [2] (MOVDconst [1]) cmp)
@ -1138,6 +1139,9 @@
(ISEL [n] x y (InvertFlags bool)) && n%4 == 0 => (ISEL [n+1] x y bool)
(ISEL [n] x y (InvertFlags bool)) && n%4 == 1 => (ISEL [n-1] x y bool)
(ISEL [n] x y (InvertFlags bool)) && n%4 == 2 => (ISEL [n] x y bool)
(XORconst [1] (ISELB [6] (MOVDconst [1]) cmp)) => (ISELB [2] (MOVDconst [1]) cmp)
(XORconst [1] (ISELB [5] (MOVDconst [1]) cmp)) => (ISELB [1] (MOVDconst [1]) cmp)
(XORconst [1] (ISELB [4] (MOVDconst [1]) cmp)) => (ISELB [0] (MOVDconst [1]) cmp)
// A particular pattern seen in cgo code:
(AND (MOVDconst [c]) x:(MOVBZload _ _)) => (ANDconst [c&0xFF] x)

2
src/cmd/compile/internal/ssa/gen/PPC64Ops.go
View File

@ -396,7 +396,7 @@ func init() {
{name: "CMPWUconst", argLength: 1, reg: gp1cr, asm: "CMPWU", aux: "Int32", typ: "Flags"},
// ISEL auxInt values 0=LT 1=GT 2=EQ arg2 ? arg0 : arg1
// ISEL auxInt values 4=GE 5=LE 6=NE arg2 ? arg1 : arg0
// ISEL auxInt values 4=GE 5=LE 6=NE !arg2 ? arg1 : arg0
// ISELB special case where arg0, arg1 values are 0, 1 for boolean result
{name: "ISEL", argLength: 3, reg: crgp21, asm: "ISEL", aux: "Int32", typ: "Int32"}, // see above
{name: "ISELB", argLength: 2, reg: crgp11, asm: "ISEL", aux: "Int32", typ: "Int32"}, // see above

68
src/cmd/compile/internal/ssa/rewritePPC64.go
View File

@ -11372,6 +11372,18 @@ func rewriteValuePPC64_OpPPC64NEG(v *Value) bool {
v.AddArg(x)
return true
}
// match: (NEG (SUB x y))
// result: (SUB y x)
for {
if v_0.Op != OpPPC64SUB {
break
}
y := v_0.Args[1]
x := v_0.Args[0]
v.reset(OpPPC64SUB)
v.AddArg2(y, x)
return true
}
return false
}
func rewriteValuePPC64_OpPPC64NOR(v *Value) bool {
@ -13912,6 +13924,8 @@ func rewriteValuePPC64_OpPPC64XOR(v *Value) bool {
}
func rewriteValuePPC64_OpPPC64XORconst(v *Value) bool {
v_0 := v.Args[0]
b := v.Block
typ := &b.Func.Config.Types
// match: (XORconst [c] (XORconst [d] x))
// result: (XORconst [c^d] x)
for {
@ -13936,6 +13950,60 @@ func rewriteValuePPC64_OpPPC64XORconst(v *Value) bool {
v.copyOf(x)
return true
}
// match: (XORconst [1] (ISELB [6] (MOVDconst [1]) cmp))
// result: (ISELB [2] (MOVDconst [1]) cmp)
for {
if auxIntToInt64(v.AuxInt) != 1 || v_0.Op != OpPPC64ISELB || auxIntToInt32(v_0.AuxInt) != 6 {
break
}
cmp := v_0.Args[1]
v_0_0 := v_0.Args[0]
if v_0_0.Op != OpPPC64MOVDconst || auxIntToInt64(v_0_0.AuxInt) != 1 {
break
}
v.reset(OpPPC64ISELB)
v.AuxInt = int32ToAuxInt(2)
v0 := b.NewValue0(v.Pos, OpPPC64MOVDconst, typ.Int64)
v0.AuxInt = int64ToAuxInt(1)
v.AddArg2(v0, cmp)
return true
}
// match: (XORconst [1] (ISELB [5] (MOVDconst [1]) cmp))
// result: (ISELB [1] (MOVDconst [1]) cmp)
for {
if auxIntToInt64(v.AuxInt) != 1 || v_0.Op != OpPPC64ISELB || auxIntToInt32(v_0.AuxInt) != 5 {
break
}
cmp := v_0.Args[1]
v_0_0 := v_0.Args[0]
if v_0_0.Op != OpPPC64MOVDconst || auxIntToInt64(v_0_0.AuxInt) != 1 {
break
}
v.reset(OpPPC64ISELB)
v.AuxInt = int32ToAuxInt(1)
v0 := b.NewValue0(v.Pos, OpPPC64MOVDconst, typ.Int64)
v0.AuxInt = int64ToAuxInt(1)
v.AddArg2(v0, cmp)
return true
}
// match: (XORconst [1] (ISELB [4] (MOVDconst [1]) cmp))
// result: (ISELB [0] (MOVDconst [1]) cmp)
for {
if auxIntToInt64(v.AuxInt) != 1 || v_0.Op != OpPPC64ISELB || auxIntToInt32(v_0.AuxInt) != 4 {
break
}
cmp := v_0.Args[1]
v_0_0 := v_0.Args[0]
if v_0_0.Op != OpPPC64MOVDconst || auxIntToInt64(v_0_0.AuxInt) != 1 {
break
}
v.reset(OpPPC64ISELB)
v.AuxInt = int32ToAuxInt(0)
v0 := b.NewValue0(v.Pos, OpPPC64MOVDconst, typ.Int64)
v0.AuxInt = int64ToAuxInt(1)
v.AddArg2(v0, cmp)
return true
}
return false
}
func rewriteValuePPC64_OpPanicBounds(v *Value) bool {