cmd/compile: splitload (CMPconst [0] x) into (TEST x x) on amd64

Provides minor widespread benefit to generated code.

Removes one source of random fluctuation when changing
other aspects of the compiler.

Change-Id: I16db6f5e240a97d27f05dc1ba5b8b729af3adb12
Reviewed-on: https://go-review.googlesource.com/c/go/+/229702
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

1 files changed, 271 insertions, 0 deletions

diff --git a/src/cmd/compile/internal/ssa/rewriteAMD64splitload.go b/src/cmd/compile/internal/ssa/rewriteAMD64splitload.go
index b04dcaf7fb..65bfec0f68 100644
--- a/src/cmd/compile/internal/ssa/rewriteAMD64splitload.go
+++ b/src/cmd/compile/internal/ssa/rewriteAMD64splitload.go
@@ -58,12 +58,35 @@ func rewriteValueAMD64splitload_OpAMD64CMPBconstload(v *Value) bool {
 	b := v.Block
 	typ := &b.Func.Config.Types
 	// match: (CMPBconstload {sym} [vo] ptr mem)
+	// cond: vo.Val() == 0
+	// result: (TESTB x:(MOVBload {sym} [vo.Off32()] ptr mem) x)
+	for {
+		vo := auxIntToValAndOff(v.AuxInt)
+		sym := auxToSym(v.Aux)
+		ptr := v_0
+		mem := v_1
+		if !(vo.Val() == 0) {
+			break
+		}
+		v.reset(OpAMD64TESTB)
+		x := b.NewValue0(v.Pos, OpAMD64MOVBload, typ.UInt8)
+		x.AuxInt = int32ToAuxInt(vo.Off32())
+		x.Aux = symToAux(sym)
+		x.AddArg2(ptr, mem)
+		v.AddArg2(x, x)
+		return true
+	}
+	// match: (CMPBconstload {sym} [vo] ptr mem)
+	// cond: vo.Val() != 0
 	// result: (CMPBconst (MOVBload {sym} [vo.Off32()] ptr mem) [vo.Val8()])
 	for {
 		vo := auxIntToValAndOff(v.AuxInt)
 		sym := auxToSym(v.Aux)
 		ptr := v_0
 		mem := v_1
+		if !(vo.Val() != 0) {
+			break
+		}
 		v.reset(OpAMD64CMPBconst)
 		v.AuxInt = int8ToAuxInt(vo.Val8())
 		v0 := b.NewValue0(v.Pos, OpAMD64MOVBload, typ.UInt8)
@@ -73,6 +96,7 @@ func rewriteValueAMD64splitload_OpAMD64CMPBconstload(v *Value) bool {
 		v.AddArg(v0)
 		return true
 	}
+	return false
 }
 func rewriteValueAMD64splitload_OpAMD64CMPBconstloadidx1(v *Value) bool {
 	v_2 := v.Args[2]
@@ -81,6 +105,27 @@ func rewriteValueAMD64splitload_OpAMD64CMPBconstloadidx1(v *Value) bool {
 	b := v.Block
 	typ := &b.Func.Config.Types
 	// match: (CMPBconstloadidx1 {sym} [vo] ptr idx mem)
+	// cond: vo.Val() == 0
+	// result: (TESTB x:(MOVBloadidx1 {sym} [vo.Off32()] ptr idx mem) x)
+	for {
+		vo := auxIntToValAndOff(v.AuxInt)
+		sym := auxToSym(v.Aux)
+		ptr := v_0
+		idx := v_1
+		mem := v_2
+		if !(vo.Val() == 0) {
+			break
+		}
+		v.reset(OpAMD64TESTB)
+		x := b.NewValue0(v.Pos, OpAMD64MOVBloadidx1, typ.UInt8)
+		x.AuxInt = int32ToAuxInt(vo.Off32())
+		x.Aux = symToAux(sym)
+		x.AddArg3(ptr, idx, mem)
+		v.AddArg2(x, x)
+		return true
+	}
+	// match: (CMPBconstloadidx1 {sym} [vo] ptr idx mem)
+	// cond: vo.Val() != 0
 	// result: (CMPBconst (MOVBloadidx1 {sym} [vo.Off32()] ptr idx mem) [vo.Val8()])
 	for {
 		vo := auxIntToValAndOff(v.AuxInt)
@@ -88,6 +133,9 @@ func rewriteValueAMD64splitload_OpAMD64CMPBconstloadidx1(v *Value) bool {
 		ptr := v_0
 		idx := v_1
 		mem := v_2
+		if !(vo.Val() != 0) {
+			break
+		}
 		v.reset(OpAMD64CMPBconst)
 		v.AuxInt = int8ToAuxInt(vo.Val8())
 		v0 := b.NewValue0(v.Pos, OpAMD64MOVBloadidx1, typ.UInt8)
@@ -97,6 +145,7 @@ func rewriteValueAMD64splitload_OpAMD64CMPBconstloadidx1(v *Value) bool {
 		v.AddArg(v0)
 		return true
 	}
+	return false
 }
 func rewriteValueAMD64splitload_OpAMD64CMPBload(v *Value) bool {
 	v_2 := v.Args[2]
@@ -152,12 +201,35 @@ func rewriteValueAMD64splitload_OpAMD64CMPLconstload(v *Value) bool {
 	b := v.Block
 	typ := &b.Func.Config.Types
 	// match: (CMPLconstload {sym} [vo] ptr mem)
+	// cond: vo.Val() == 0
+	// result: (TESTL x:(MOVLload {sym} [vo.Off32()] ptr mem) x)
+	for {
+		vo := auxIntToValAndOff(v.AuxInt)
+		sym := auxToSym(v.Aux)
+		ptr := v_0
+		mem := v_1
+		if !(vo.Val() == 0) {
+			break
+		}
+		v.reset(OpAMD64TESTL)
+		x := b.NewValue0(v.Pos, OpAMD64MOVLload, typ.UInt32)
+		x.AuxInt = int32ToAuxInt(vo.Off32())
+		x.Aux = symToAux(sym)
+		x.AddArg2(ptr, mem)
+		v.AddArg2(x, x)
+		return true
+	}
+	// match: (CMPLconstload {sym} [vo] ptr mem)
+	// cond: vo.Val() != 0
 	// result: (CMPLconst (MOVLload {sym} [vo.Off32()] ptr mem) [vo.Val32()])
 	for {
 		vo := auxIntToValAndOff(v.AuxInt)
 		sym := auxToSym(v.Aux)
 		ptr := v_0
 		mem := v_1
+		if !(vo.Val() != 0) {
+			break
+		}
 		v.reset(OpAMD64CMPLconst)
 		v.AuxInt = int32ToAuxInt(vo.Val32())
 		v0 := b.NewValue0(v.Pos, OpAMD64MOVLload, typ.UInt32)
@@ -167,6 +239,7 @@ func rewriteValueAMD64splitload_OpAMD64CMPLconstload(v *Value) bool {
 		v.AddArg(v0)
 		return true
 	}
+	return false
 }
 func rewriteValueAMD64splitload_OpAMD64CMPLconstloadidx1(v *Value) bool {
 	v_2 := v.Args[2]
@@ -175,6 +248,27 @@ func rewriteValueAMD64splitload_OpAMD64CMPLconstloadidx1(v *Value) bool {
 	b := v.Block
 	typ := &b.Func.Config.Types
 	// match: (CMPLconstloadidx1 {sym} [vo] ptr idx mem)
+	// cond: vo.Val() == 0
+	// result: (TESTL x:(MOVLloadidx1 {sym} [vo.Off32()] ptr idx mem) x)
+	for {
+		vo := auxIntToValAndOff(v.AuxInt)
+		sym := auxToSym(v.Aux)
+		ptr := v_0
+		idx := v_1
+		mem := v_2
+		if !(vo.Val() == 0) {
+			break
+		}
+		v.reset(OpAMD64TESTL)
+		x := b.NewValue0(v.Pos, OpAMD64MOVLloadidx1, typ.UInt32)
+		x.AuxInt = int32ToAuxInt(vo.Off32())
+		x.Aux = symToAux(sym)
+		x.AddArg3(ptr, idx, mem)
+		v.AddArg2(x, x)
+		return true
+	}
+	// match: (CMPLconstloadidx1 {sym} [vo] ptr idx mem)
+	// cond: vo.Val() != 0
 	// result: (CMPLconst (MOVLloadidx1 {sym} [vo.Off32()] ptr idx mem) [vo.Val32()])
 	for {
 		vo := auxIntToValAndOff(v.AuxInt)
@@ -182,6 +276,9 @@ func rewriteValueAMD64splitload_OpAMD64CMPLconstloadidx1(v *Value) bool {
 		ptr := v_0
 		idx := v_1
 		mem := v_2
+		if !(vo.Val() != 0) {
+			break
+		}
 		v.reset(OpAMD64CMPLconst)
 		v.AuxInt = int32ToAuxInt(vo.Val32())
 		v0 := b.NewValue0(v.Pos, OpAMD64MOVLloadidx1, typ.UInt32)
@@ -191,6 +288,7 @@ func rewriteValueAMD64splitload_OpAMD64CMPLconstloadidx1(v *Value) bool {
 		v.AddArg(v0)
 		return true
 	}
+	return false
 }
 func rewriteValueAMD64splitload_OpAMD64CMPLconstloadidx4(v *Value) bool {
 	v_2 := v.Args[2]
@@ -199,6 +297,27 @@ func rewriteValueAMD64splitload_OpAMD64CMPLconstloadidx4(v *Value) bool {
 	b := v.Block
 	typ := &b.Func.Config.Types
 	// match: (CMPLconstloadidx4 {sym} [vo] ptr idx mem)
+	// cond: vo.Val() == 0
+	// result: (TESTL x:(MOVLloadidx4 {sym} [vo.Off32()] ptr idx mem) x)
+	for {
+		vo := auxIntToValAndOff(v.AuxInt)
+		sym := auxToSym(v.Aux)
+		ptr := v_0
+		idx := v_1
+		mem := v_2
+		if !(vo.Val() == 0) {
+			break
+		}
+		v.reset(OpAMD64TESTL)
+		x := b.NewValue0(v.Pos, OpAMD64MOVLloadidx4, typ.UInt32)
+		x.AuxInt = int32ToAuxInt(vo.Off32())
+		x.Aux = symToAux(sym)
+		x.AddArg3(ptr, idx, mem)
+		v.AddArg2(x, x)
+		return true
+	}
+	// match: (CMPLconstloadidx4 {sym} [vo] ptr idx mem)
+	// cond: vo.Val() != 0
 	// result: (CMPLconst (MOVLloadidx4 {sym} [vo.Off32()] ptr idx mem) [vo.Val32()])
 	for {
 		vo := auxIntToValAndOff(v.AuxInt)
@@ -206,6 +325,9 @@ func rewriteValueAMD64splitload_OpAMD64CMPLconstloadidx4(v *Value) bool {
 		ptr := v_0
 		idx := v_1
 		mem := v_2
+		if !(vo.Val() != 0) {
+			break
+		}
 		v.reset(OpAMD64CMPLconst)
 		v.AuxInt = int32ToAuxInt(vo.Val32())
 		v0 := b.NewValue0(v.Pos, OpAMD64MOVLloadidx4, typ.UInt32)
@@ -215,6 +337,7 @@ func rewriteValueAMD64splitload_OpAMD64CMPLconstloadidx4(v *Value) bool {
 		v.AddArg(v0)
 		return true
 	}
+	return false
 }
 func rewriteValueAMD64splitload_OpAMD64CMPLload(v *Value) bool {
 	v_2 := v.Args[2]
@@ -295,12 +418,35 @@ func rewriteValueAMD64splitload_OpAMD64CMPQconstload(v *Value) bool {
 	b := v.Block
 	typ := &b.Func.Config.Types
 	// match: (CMPQconstload {sym} [vo] ptr mem)
+	// cond: vo.Val() == 0
+	// result: (TESTQ x:(MOVQload {sym} [vo.Off32()] ptr mem) x)
+	for {
+		vo := auxIntToValAndOff(v.AuxInt)
+		sym := auxToSym(v.Aux)
+		ptr := v_0
+		mem := v_1
+		if !(vo.Val() == 0) {
+			break
+		}
+		v.reset(OpAMD64TESTQ)
+		x := b.NewValue0(v.Pos, OpAMD64MOVQload, typ.UInt64)
+		x.AuxInt = int32ToAuxInt(vo.Off32())
+		x.Aux = symToAux(sym)
+		x.AddArg2(ptr, mem)
+		v.AddArg2(x, x)
+		return true
+	}
+	// match: (CMPQconstload {sym} [vo] ptr mem)
+	// cond: vo.Val() != 0
 	// result: (CMPQconst (MOVQload {sym} [vo.Off32()] ptr mem) [vo.Val32()])
 	for {
 		vo := auxIntToValAndOff(v.AuxInt)
 		sym := auxToSym(v.Aux)
 		ptr := v_0
 		mem := v_1
+		if !(vo.Val() != 0) {
+			break
+		}
 		v.reset(OpAMD64CMPQconst)
 		v.AuxInt = int32ToAuxInt(vo.Val32())
 		v0 := b.NewValue0(v.Pos, OpAMD64MOVQload, typ.UInt64)
@@ -310,6 +456,7 @@ func rewriteValueAMD64splitload_OpAMD64CMPQconstload(v *Value) bool {
 		v.AddArg(v0)
 		return true
 	}
+	return false
 }
 func rewriteValueAMD64splitload_OpAMD64CMPQconstloadidx1(v *Value) bool {
 	v_2 := v.Args[2]
@@ -318,6 +465,27 @@ func rewriteValueAMD64splitload_OpAMD64CMPQconstloadidx1(v *Value) bool {
 	b := v.Block
 	typ := &b.Func.Config.Types
 	// match: (CMPQconstloadidx1 {sym} [vo] ptr idx mem)
+	// cond: vo.Val() == 0
+	// result: (TESTQ x:(MOVQloadidx1 {sym} [vo.Off32()] ptr idx mem) x)
+	for {
+		vo := auxIntToValAndOff(v.AuxInt)
+		sym := auxToSym(v.Aux)
+		ptr := v_0
+		idx := v_1
+		mem := v_2
+		if !(vo.Val() == 0) {
+			break
+		}
+		v.reset(OpAMD64TESTQ)
+		x := b.NewValue0(v.Pos, OpAMD64MOVQloadidx1, typ.UInt64)
+		x.AuxInt = int32ToAuxInt(vo.Off32())
+		x.Aux = symToAux(sym)
+		x.AddArg3(ptr, idx, mem)
+		v.AddArg2(x, x)
+		return true
+	}
+	// match: (CMPQconstloadidx1 {sym} [vo] ptr idx mem)
+	// cond: vo.Val() != 0
 	// result: (CMPQconst (MOVQloadidx1 {sym} [vo.Off32()] ptr idx mem) [vo.Val32()])
 	for {
 		vo := auxIntToValAndOff(v.AuxInt)
@@ -325,6 +493,9 @@ func rewriteValueAMD64splitload_OpAMD64CMPQconstloadidx1(v *Value) bool {
 		ptr := v_0
 		idx := v_1
 		mem := v_2
+		if !(vo.Val() != 0) {
+			break
+		}
 		v.reset(OpAMD64CMPQconst)
 		v.AuxInt = int32ToAuxInt(vo.Val32())
 		v0 := b.NewValue0(v.Pos, OpAMD64MOVQloadidx1, typ.UInt64)
@@ -334,6 +505,7 @@ func rewriteValueAMD64splitload_OpAMD64CMPQconstloadidx1(v *Value) bool {
 		v.AddArg(v0)
 		return true
 	}
+	return false
 }
 func rewriteValueAMD64splitload_OpAMD64CMPQconstloadidx8(v *Value) bool {
 	v_2 := v.Args[2]
@@ -342,6 +514,27 @@ func rewriteValueAMD64splitload_OpAMD64CMPQconstloadidx8(v *Value) bool {
 	b := v.Block
 	typ := &b.Func.Config.Types
 	// match: (CMPQconstloadidx8 {sym} [vo] ptr idx mem)
+	// cond: vo.Val() == 0
+	// result: (TESTQ x:(MOVQloadidx8 {sym} [vo.Off32()] ptr idx mem) x)
+	for {
+		vo := auxIntToValAndOff(v.AuxInt)
+		sym := auxToSym(v.Aux)
+		ptr := v_0
+		idx := v_1
+		mem := v_2
+		if !(vo.Val() == 0) {
+			break
+		}
+		v.reset(OpAMD64TESTQ)
+		x := b.NewValue0(v.Pos, OpAMD64MOVQloadidx8, typ.UInt64)
+		x.AuxInt = int32ToAuxInt(vo.Off32())
+		x.Aux = symToAux(sym)
+		x.AddArg3(ptr, idx, mem)
+		v.AddArg2(x, x)
+		return true
+	}
+	// match: (CMPQconstloadidx8 {sym} [vo] ptr idx mem)
+	// cond: vo.Val() != 0
 	// result: (CMPQconst (MOVQloadidx8 {sym} [vo.Off32()] ptr idx mem) [vo.Val32()])
 	for {
 		vo := auxIntToValAndOff(v.AuxInt)
@@ -349,6 +542,9 @@ func rewriteValueAMD64splitload_OpAMD64CMPQconstloadidx8(v *Value) bool {
 		ptr := v_0
 		idx := v_1
 		mem := v_2
+		if !(vo.Val() != 0) {
+			break
+		}
 		v.reset(OpAMD64CMPQconst)
 		v.AuxInt = int32ToAuxInt(vo.Val32())
 		v0 := b.NewValue0(v.Pos, OpAMD64MOVQloadidx8, typ.UInt64)
@@ -358,6 +554,7 @@ func rewriteValueAMD64splitload_OpAMD64CMPQconstloadidx8(v *Value) bool {
 		v.AddArg(v0)
 		return true
 	}
+	return false
 }
 func rewriteValueAMD64splitload_OpAMD64CMPQload(v *Value) bool {
 	v_2 := v.Args[2]
@@ -438,12 +635,35 @@ func rewriteValueAMD64splitload_OpAMD64CMPWconstload(v *Value) bool {
 	b := v.Block
 	typ := &b.Func.Config.Types
 	// match: (CMPWconstload {sym} [vo] ptr mem)
+	// cond: vo.Val() == 0
+	// result: (TESTW x:(MOVWload {sym} [vo.Off32()] ptr mem) x)
+	for {
+		vo := auxIntToValAndOff(v.AuxInt)
+		sym := auxToSym(v.Aux)
+		ptr := v_0
+		mem := v_1
+		if !(vo.Val() == 0) {
+			break
+		}
+		v.reset(OpAMD64TESTW)
+		x := b.NewValue0(v.Pos, OpAMD64MOVWload, typ.UInt16)
+		x.AuxInt = int32ToAuxInt(vo.Off32())
+		x.Aux = symToAux(sym)
+		x.AddArg2(ptr, mem)
+		v.AddArg2(x, x)
+		return true
+	}
+	// match: (CMPWconstload {sym} [vo] ptr mem)
+	// cond: vo.Val() != 0
 	// result: (CMPWconst (MOVWload {sym} [vo.Off32()] ptr mem) [vo.Val16()])
 	for {
 		vo := auxIntToValAndOff(v.AuxInt)
 		sym := auxToSym(v.Aux)
 		ptr := v_0
 		mem := v_1
+		if !(vo.Val() != 0) {
+			break
+		}
 		v.reset(OpAMD64CMPWconst)
 		v.AuxInt = int16ToAuxInt(vo.Val16())
 		v0 := b.NewValue0(v.Pos, OpAMD64MOVWload, typ.UInt16)
@@ -453,6 +673,7 @@ func rewriteValueAMD64splitload_OpAMD64CMPWconstload(v *Value) bool {
 		v.AddArg(v0)
 		return true
 	}
+	return false
 }
 func rewriteValueAMD64splitload_OpAMD64CMPWconstloadidx1(v *Value) bool {
 	v_2 := v.Args[2]
@@ -461,6 +682,27 @@ func rewriteValueAMD64splitload_OpAMD64CMPWconstloadidx1(v *Value) bool {
 	b := v.Block
 	typ := &b.Func.Config.Types
 	// match: (CMPWconstloadidx1 {sym} [vo] ptr idx mem)
+	// cond: vo.Val() == 0
+	// result: (TESTW x:(MOVWloadidx1 {sym} [vo.Off32()] ptr idx mem) x)
+	for {
+		vo := auxIntToValAndOff(v.AuxInt)
+		sym := auxToSym(v.Aux)
+		ptr := v_0
+		idx := v_1
+		mem := v_2
+		if !(vo.Val() == 0) {
+			break
+		}
+		v.reset(OpAMD64TESTW)
+		x := b.NewValue0(v.Pos, OpAMD64MOVWloadidx1, typ.UInt16)
+		x.AuxInt = int32ToAuxInt(vo.Off32())
+		x.Aux = symToAux(sym)
+		x.AddArg3(ptr, idx, mem)
+		v.AddArg2(x, x)
+		return true
+	}
+	// match: (CMPWconstloadidx1 {sym} [vo] ptr idx mem)
+	// cond: vo.Val() != 0
 	// result: (CMPWconst (MOVWloadidx1 {sym} [vo.Off32()] ptr idx mem) [vo.Val16()])
 	for {
 		vo := auxIntToValAndOff(v.AuxInt)
@@ -468,6 +710,9 @@ func rewriteValueAMD64splitload_OpAMD64CMPWconstloadidx1(v *Value) bool {
 		ptr := v_0
 		idx := v_1
 		mem := v_2
+		if !(vo.Val() != 0) {
+			break
+		}
 		v.reset(OpAMD64CMPWconst)
 		v.AuxInt = int16ToAuxInt(vo.Val16())
 		v0 := b.NewValue0(v.Pos, OpAMD64MOVWloadidx1, typ.UInt16)
@@ -477,6 +722,7 @@ func rewriteValueAMD64splitload_OpAMD64CMPWconstloadidx1(v *Value) bool {
 		v.AddArg(v0)
 		return true
 	}
+	return false
 }
 func rewriteValueAMD64splitload_OpAMD64CMPWconstloadidx2(v *Value) bool {
 	v_2 := v.Args[2]
@@ -485,6 +731,27 @@ func rewriteValueAMD64splitload_OpAMD64CMPWconstloadidx2(v *Value) bool {
 	b := v.Block
 	typ := &b.Func.Config.Types
 	// match: (CMPWconstloadidx2 {sym} [vo] ptr idx mem)
+	// cond: vo.Val() == 0
+	// result: (TESTW x:(MOVWloadidx2 {sym} [vo.Off32()] ptr idx mem) x)
+	for {
+		vo := auxIntToValAndOff(v.AuxInt)
+		sym := auxToSym(v.Aux)
+		ptr := v_0
+		idx := v_1
+		mem := v_2
+		if !(vo.Val() == 0) {
+			break
+		}
+		v.reset(OpAMD64TESTW)
+		x := b.NewValue0(v.Pos, OpAMD64MOVWloadidx2, typ.UInt16)
+		x.AuxInt = int32ToAuxInt(vo.Off32())
+		x.Aux = symToAux(sym)
+		x.AddArg3(ptr, idx, mem)
+		v.AddArg2(x, x)
+		return true
+	}
+	// match: (CMPWconstloadidx2 {sym} [vo] ptr idx mem)
+	// cond: vo.Val() != 0
 	// result: (CMPWconst (MOVWloadidx2 {sym} [vo.Off32()] ptr idx mem) [vo.Val16()])
 	for {
 		vo := auxIntToValAndOff(v.AuxInt)
@@ -492,6 +759,9 @@ func rewriteValueAMD64splitload_OpAMD64CMPWconstloadidx2(v *Value) bool {
 		ptr := v_0
 		idx := v_1
 		mem := v_2
+		if !(vo.Val() != 0) {
+			break
+		}
 		v.reset(OpAMD64CMPWconst)
 		v.AuxInt = int16ToAuxInt(vo.Val16())
 		v0 := b.NewValue0(v.Pos, OpAMD64MOVWloadidx2, typ.UInt16)
@@ -501,6 +771,7 @@ func rewriteValueAMD64splitload_OpAMD64CMPWconstloadidx2(v *Value) bool {
 		v.AddArg(v0)
 		return true
 	}
+	return false
 }
 func rewriteValueAMD64splitload_OpAMD64CMPWload(v *Value) bool {
 	v_2 := v.Args[2]