From 8b0bea993d452ef7861642a9c04bae213246ded1 Mon Sep 17 00:00:00 2001 From: Lynn Boger Date: Thu, 14 Oct 2021 12:55:43 -0500 Subject: [PATCH] cmd/compile/internal/ssa/gen: eliminate unnecessary neg and xori on PPC64 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 Reviewed-by: Cherry Mui --- src/cmd/compile/internal/ssa/gen/PPC64.rules | 6 +- src/cmd/compile/internal/ssa/gen/PPC64Ops.go | 2 +- src/cmd/compile/internal/ssa/rewritePPC64.go | 68 ++++++++++++++++++++ 3 files changed, 74 insertions(+), 2 deletions(-) diff --git a/src/cmd/compile/internal/ssa/gen/PPC64.rules b/src/cmd/compile/internal/ssa/gen/PPC64.rules index 8e42bae215..ccca72a416 100644 --- a/src/cmd/compile/internal/ssa/gen/PPC64.rules +++ b/src/cmd/compile/internal/ssa/gen/PPC64.rules @@ -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) diff --git a/src/cmd/compile/internal/ssa/gen/PPC64Ops.go b/src/cmd/compile/internal/ssa/gen/PPC64Ops.go index ff9ce64e18..42775fa3c2 100644 --- a/src/cmd/compile/internal/ssa/gen/PPC64Ops.go +++ b/src/cmd/compile/internal/ssa/gen/PPC64Ops.go @@ -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 diff --git a/src/cmd/compile/internal/ssa/rewritePPC64.go b/src/cmd/compile/internal/ssa/rewritePPC64.go index 1e6624e906..ea1c1fa60a 100644 --- a/src/cmd/compile/internal/ssa/rewritePPC64.go +++ b/src/cmd/compile/internal/ssa/rewritePPC64.go @@ -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 {