cmd/compile: fold negation into multiplication

goos: linux
goarch: riscv64
pkg: cmd/compile/internal/test
cpu: Spacemit(R) X60
        │ /root/mul.base.log │          /root/mul.new.log          │
        │       sec/op       │   sec/op     vs base                │
MulNeg           6.426µ ± 0%   4.501µ ± 0%  -29.96% (p=0.000 n=10)
Mul2Neg          9.000µ ± 0%   6.431µ ± 0%  -28.54% (p=0.000 n=10)
Mul2             1.263µ ± 0%   1.263µ ± 0%        ~ (p=1.000 n=10)
MulNeg2          1.577µ ± 0%   1.577µ ± 0%        ~ (p=0.211 n=10)
geomean          3.276µ        2.756µ       -15.89%

goos: linux
goarch: amd64
pkg: cmd/compile/internal/test
cpu: AMD EPYC 7532 32-Core Processor
        │ /root/base  │              /root/new              │
        │   sec/op    │   sec/op     vs base                │
MulNeg    691.9n ± 1%   319.4n ± 0%  -53.83% (p=0.000 n=10)
Mul2Neg   630.0n ± 0%   629.6n ± 0%   -0.07% (p=0.000 n=10)
Mul2      438.1n ± 0%   438.1n ± 0%        ~ (p=0.728 n=10)
MulNeg2   439.3n ± 0%   439.4n ± 0%        ~ (p=0.656 n=10)
geomean   538.2n        443.6n       -17.58%

Change-Id: Ice8e6c8d1e8e3009ba8a0b1b689205174e199019
Reviewed-on: https://go-review.googlesource.com/c/go/+/720180
Reviewed-by: abner chenc <chenguoqi@loongson.cn>
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Junyang Shao <shaojunyang@google.com>
Reviewed-by: Joel Sing <joel@sing.id.au>
Reviewed-by: Keith Randall <khr@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Keith Randall <khr@golang.org>

1 files changed, 156 insertions, 0 deletions

diff --git a/src/cmd/compile/internal/ssa/rewritegeneric.go b/src/cmd/compile/internal/ssa/rewritegeneric.go
index 2428f17947..1621153b43 100644
--- a/src/cmd/compile/internal/ssa/rewritegeneric.go
+++ b/src/cmd/compile/internal/ssa/rewritegeneric.go
@@ -16786,6 +16786,45 @@ func rewriteValuegeneric_OpMul16(v *Value) bool {
 		}
 		break
 	}
+	// match: (Mul16 (Const16 <t> [c]) (Neg16 x))
+	// result: (Mul16 x (Const16 <t> [-c]))
+	for {
+		for _i0 := 0; _i0 <= 1; _i0, v_0, v_1 = _i0+1, v_1, v_0 {
+			if v_0.Op != OpConst16 {
+				continue
+			}
+			t := v_0.Type
+			c := auxIntToInt16(v_0.AuxInt)
+			if v_1.Op != OpNeg16 {
+				continue
+			}
+			x := v_1.Args[0]
+			v.reset(OpMul16)
+			v0 := b.NewValue0(v.Pos, OpConst16, t)
+			v0.AuxInt = int16ToAuxInt(-c)
+			v.AddArg2(x, v0)
+			return true
+		}
+		break
+	}
+	// match: (Mul16 (Neg16 x) (Neg16 y))
+	// result: (Mul16 x y)
+	for {
+		for _i0 := 0; _i0 <= 1; _i0, v_0, v_1 = _i0+1, v_1, v_0 {
+			if v_0.Op != OpNeg16 {
+				continue
+			}
+			x := v_0.Args[0]
+			if v_1.Op != OpNeg16 {
+				continue
+			}
+			y := v_1.Args[0]
+			v.reset(OpMul16)
+			v.AddArg2(x, y)
+			return true
+		}
+		break
+	}
 	// match: (Mul16 (Const16 <t> [c]) (Add16 <t> (Const16 <t> [d]) x))
 	// cond: !isPowerOfTwo(c)
 	// result: (Add16 (Const16 <t> [c*d]) (Mul16 <t> (Const16 <t> [c]) x))
@@ -16997,6 +17036,45 @@ func rewriteValuegeneric_OpMul32(v *Value) bool {
 		}
 		break
 	}
+	// match: (Mul32 (Const32 <t> [c]) (Neg32 x))
+	// result: (Mul32 x (Const32 <t> [-c]))
+	for {
+		for _i0 := 0; _i0 <= 1; _i0, v_0, v_1 = _i0+1, v_1, v_0 {
+			if v_0.Op != OpConst32 {
+				continue
+			}
+			t := v_0.Type
+			c := auxIntToInt32(v_0.AuxInt)
+			if v_1.Op != OpNeg32 {
+				continue
+			}
+			x := v_1.Args[0]
+			v.reset(OpMul32)
+			v0 := b.NewValue0(v.Pos, OpConst32, t)
+			v0.AuxInt = int32ToAuxInt(-c)
+			v.AddArg2(x, v0)
+			return true
+		}
+		break
+	}
+	// match: (Mul32 (Neg32 x) (Neg32 y))
+	// result: (Mul32 x y)
+	for {
+		for _i0 := 0; _i0 <= 1; _i0, v_0, v_1 = _i0+1, v_1, v_0 {
+			if v_0.Op != OpNeg32 {
+				continue
+			}
+			x := v_0.Args[0]
+			if v_1.Op != OpNeg32 {
+				continue
+			}
+			y := v_1.Args[0]
+			v.reset(OpMul32)
+			v.AddArg2(x, y)
+			return true
+		}
+		break
+	}
 	// match: (Mul32 (Const32 <t> [c]) (Add32 <t> (Const32 <t> [d]) x))
 	// cond: !isPowerOfTwo(c)
 	// result: (Add32 (Const32 <t> [c*d]) (Mul32 <t> (Const32 <t> [c]) x))
@@ -17369,6 +17447,45 @@ func rewriteValuegeneric_OpMul64(v *Value) bool {
 		}
 		break
 	}
+	// match: (Mul64 (Const64 <t> [c]) (Neg64 x))
+	// result: (Mul64 x (Const64 <t> [-c]))
+	for {
+		for _i0 := 0; _i0 <= 1; _i0, v_0, v_1 = _i0+1, v_1, v_0 {
+			if v_0.Op != OpConst64 {
+				continue
+			}
+			t := v_0.Type
+			c := auxIntToInt64(v_0.AuxInt)
+			if v_1.Op != OpNeg64 {
+				continue
+			}
+			x := v_1.Args[0]
+			v.reset(OpMul64)
+			v0 := b.NewValue0(v.Pos, OpConst64, t)
+			v0.AuxInt = int64ToAuxInt(-c)
+			v.AddArg2(x, v0)
+			return true
+		}
+		break
+	}
+	// match: (Mul64 (Neg64 x) (Neg64 y))
+	// result: (Mul64 x y)
+	for {
+		for _i0 := 0; _i0 <= 1; _i0, v_0, v_1 = _i0+1, v_1, v_0 {
+			if v_0.Op != OpNeg64 {
+				continue
+			}
+			x := v_0.Args[0]
+			if v_1.Op != OpNeg64 {
+				continue
+			}
+			y := v_1.Args[0]
+			v.reset(OpMul64)
+			v.AddArg2(x, y)
+			return true
+		}
+		break
+	}
 	// match: (Mul64 (Const64 <t> [c]) (Add64 <t> (Const64 <t> [d]) x))
 	// cond: !isPowerOfTwo(c)
 	// result: (Add64 (Const64 <t> [c*d]) (Mul64 <t> (Const64 <t> [c]) x))
@@ -17741,6 +17858,45 @@ func rewriteValuegeneric_OpMul8(v *Value) bool {
 		}
 		break
 	}
+	// match: (Mul8 (Const8 <t> [c]) (Neg8 x))
+	// result: (Mul8 x (Const8 <t> [-c]))
+	for {
+		for _i0 := 0; _i0 <= 1; _i0, v_0, v_1 = _i0+1, v_1, v_0 {
+			if v_0.Op != OpConst8 {
+				continue
+			}
+			t := v_0.Type
+			c := auxIntToInt8(v_0.AuxInt)
+			if v_1.Op != OpNeg8 {
+				continue
+			}
+			x := v_1.Args[0]
+			v.reset(OpMul8)
+			v0 := b.NewValue0(v.Pos, OpConst8, t)
+			v0.AuxInt = int8ToAuxInt(-c)
+			v.AddArg2(x, v0)
+			return true
+		}
+		break
+	}
+	// match: (Mul8 (Neg8 x) (Neg8 y))
+	// result: (Mul8 x y)
+	for {
+		for _i0 := 0; _i0 <= 1; _i0, v_0, v_1 = _i0+1, v_1, v_0 {
+			if v_0.Op != OpNeg8 {
+				continue
+			}
+			x := v_0.Args[0]
+			if v_1.Op != OpNeg8 {
+				continue
+			}
+			y := v_1.Args[0]
+			v.reset(OpMul8)
+			v.AddArg2(x, y)
+			return true
+		}
+		break
+	}
 	// match: (Mul8 (Const8 <t> [c]) (Add8 <t> (Const8 <t> [d]) x))
 	// cond: !isPowerOfTwo(c)
 	// result: (Add8 (Const8 <t> [c*d]) (Mul8 <t> (Const8 <t> [c]) x))