cmd/compile: remove memequal call from string compares in more cases

Add more rules to ensure that order doesn't matter. Add memequal 0 rule. Try to use a constant argument to memequal when one is available. Fixes #59684 Change-Id: I36e85ffbd949396ed700ed6e8ec2bc3ae013f5d2 Reviewed-on: https://go-review.googlesource.com/c/go/+/485535 Reviewed-by: Keith Randall <khr@google.com> Reviewed-by: Cherry Mui <cherryyz@google.com> Run-TryBot: Keith Randall <khr@golang.org> TryBot-Result: Gopher Robot <gobot@golang.org>
2024-09-15 22:20:06 +00:00 · 2023-04-17 15:51:29 -07:00 · 2023-04-17 15:51:29 -07:00 · 6b165577fe
parent 48a1dcb927
commit 6b165577fe
4 changed files with 251 additions and 11 deletions
--- a/src/cmd/compile/internal/compare/compare.go
+++ b/src/cmd/compile/internal/compare/compare.go
@ -259,9 +259,40 @@ func EqString(s, t ir.Node) (eqlen *ir.BinaryExpr, eqmem *ir.CallExpr) {
 	slen := typecheck.Conv(ir.NewUnaryExpr(base.Pos, ir.OLEN, s), types.Types[types.TUINTPTR])
 	tlen := typecheck.Conv(ir.NewUnaryExpr(base.Pos, ir.OLEN, t), types.Types[types.TUINTPTR])

+	// Pick the 3rd arg to memequal. Both slen and tlen are fine to use, because we short
+	// circuit the memequal call if they aren't the same. But if one is a constant some
+	// memequal optimizations are easier to apply.
+	probablyConstant := func(n ir.Node) bool {
+		if n.Op() == ir.OCONVNOP {
+			n = n.(*ir.ConvExpr).X
+		}
+		if n.Op() == ir.OLITERAL {
+			return true
+		}
+		if n.Op() != ir.ONAME {
+			return false
+		}
+		name := n.(*ir.Name)
+		if name.Class != ir.PAUTO {
+			return false
+		}
+		if def := name.Defn; def == nil {
+			// n starts out as the empty string
+			return true
+		} else if def.Op() == ir.OAS && (def.(*ir.AssignStmt).Y == nil || def.(*ir.AssignStmt).Y.Op() == ir.OLITERAL) {
+			// n starts out as a constant string
+			return true
+		}
+		return false
+	}
+	cmplen := slen
+	if probablyConstant(t) && !probablyConstant(s) {
+		cmplen = tlen
+	}
+
 	fn := typecheck.LookupRuntime("memequal")
 	fn = typecheck.SubstArgTypes(fn, types.Types[types.TUINT8], types.Types[types.TUINT8])
-	call := typecheck.Call(base.Pos, fn, []ir.Node{sptr, tptr, ir.Copy(slen)}, false).(*ir.CallExpr)
+	call := typecheck.Call(base.Pos, fn, []ir.Node{sptr, tptr, ir.Copy(cmplen)}, false).(*ir.CallExpr)

 	cmp := ir.NewBinaryExpr(base.Pos, ir.OEQ, slen, tlen)
 	cmp = typecheck.Expr(cmp).(*ir.BinaryExpr)
--- a/src/cmd/compile/internal/ssa/_gen/generic.rules
+++ b/src/cmd/compile/internal/ssa/_gen/generic.rules
@ -2068,24 +2068,51 @@
  && symIsRO(scon)
  => (MakeResult (Eq8 (Load <typ.Int8> sptr mem) (Const8 <typ.Int8> [int8(read8(scon,0))])) mem)

+(StaticLECall {callAux} (Addr {scon} (SB)) sptr (Const64 [1]) mem)
+  && isSameCall(callAux, "runtime.memequal")
+  && symIsRO(scon)
+  => (MakeResult (Eq8 (Load <typ.Int8> sptr mem) (Const8 <typ.Int8> [int8(read8(scon,0))])) mem)
+
 (StaticLECall {callAux} sptr (Addr {scon} (SB)) (Const64 [2]) mem)
  && isSameCall(callAux, "runtime.memequal")
  && symIsRO(scon)
  && canLoadUnaligned(config)
  => (MakeResult (Eq16 (Load <typ.Int16> sptr mem) (Const16 <typ.Int16> [int16(read16(scon,0,config.ctxt.Arch.ByteOrder))])) mem)

+(StaticLECall {callAux} (Addr {scon} (SB)) sptr (Const64 [2]) mem)
+  && isSameCall(callAux, "runtime.memequal")
+  && symIsRO(scon)
+  && canLoadUnaligned(config)
+  => (MakeResult (Eq16 (Load <typ.Int16> sptr mem) (Const16 <typ.Int16> [int16(read16(scon,0,config.ctxt.Arch.ByteOrder))])) mem)
+
 (StaticLECall {callAux} sptr (Addr {scon} (SB)) (Const64 [4]) mem)
  && isSameCall(callAux, "runtime.memequal")
  && symIsRO(scon)
  && canLoadUnaligned(config)
  => (MakeResult (Eq32 (Load <typ.Int32> sptr mem) (Const32 <typ.Int32> [int32(read32(scon,0,config.ctxt.Arch.ByteOrder))])) mem)

+(StaticLECall {callAux} (Addr {scon} (SB)) sptr (Const64 [4]) mem)
+  && isSameCall(callAux, "runtime.memequal")
+  && symIsRO(scon)
+  && canLoadUnaligned(config)
+  => (MakeResult (Eq32 (Load <typ.Int32> sptr mem) (Const32 <typ.Int32> [int32(read32(scon,0,config.ctxt.Arch.ByteOrder))])) mem)
+
 (StaticLECall {callAux} sptr (Addr {scon} (SB)) (Const64 [8]) mem)
  && isSameCall(callAux, "runtime.memequal")
  && symIsRO(scon)
  && canLoadUnaligned(config) && config.PtrSize == 8
  => (MakeResult (Eq64 (Load <typ.Int64> sptr mem) (Const64 <typ.Int64> [int64(read64(scon,0,config.ctxt.Arch.ByteOrder))])) mem)

+(StaticLECall {callAux} (Addr {scon} (SB)) sptr (Const64 [8]) mem)
+  && isSameCall(callAux, "runtime.memequal")
+  && symIsRO(scon)
+  && canLoadUnaligned(config) && config.PtrSize == 8
+  => (MakeResult (Eq64 (Load <typ.Int64> sptr mem) (Const64 <typ.Int64> [int64(read64(scon,0,config.ctxt.Arch.ByteOrder))])) mem)
+
+(StaticLECall {callAux} _ _ (Const64 [0]) mem)
+  && isSameCall(callAux, "runtime.memequal")
+  => (MakeResult (ConstBool <typ.Bool> [true]) mem)
+
 // Turn known-size calls to memclrNoHeapPointers into a Zero.
 // Note that we are using types.Types[types.TUINT8] instead of sptr.Type.Elem() - see issue 55122 and CL 431496 for more details.
 (SelectN [0] call:(StaticCall {sym} sptr (Const(64|32) [c]) mem))
--- a/src/cmd/compile/internal/ssa/rewritegeneric.go
+++ b/src/cmd/compile/internal/ssa/rewritegeneric.go
@ -11096,16 +11096,6 @@ func rewriteValuegeneric_OpIsNonNil(v *Value) bool {
 		v.AuxInt = boolToAuxInt(true)
 		return true
 	}
-	// match: (IsNonNil (LocalAddr _ _))
-	// result: (ConstBool [true])
-	for {
-		if v_0.Op != OpLocalAddr {
-			break
-		}
-		v.reset(OpConstBool)
-		v.AuxInt = boolToAuxInt(true)
-		return true
-	}
 	return false
 }
 func rewriteValuegeneric_OpIsSliceInBounds(v *Value) bool {
@ -27793,6 +27783,39 @@ func rewriteValuegeneric_OpStaticLECall(v *Value) bool {
 		v.AddArg2(v0, mem)
 		return true
 	}
+	// match: (StaticLECall {callAux} (Addr {scon} (SB)) sptr (Const64 [1]) mem)
+	// cond: isSameCall(callAux, "runtime.memequal") && symIsRO(scon)
+	// result: (MakeResult (Eq8 (Load <typ.Int8> sptr mem) (Const8 <typ.Int8> [int8(read8(scon,0))])) mem)
+	for {
+		if len(v.Args) != 4 {
+			break
+		}
+		callAux := auxToCall(v.Aux)
+		mem := v.Args[3]
+		v_0 := v.Args[0]
+		if v_0.Op != OpAddr {
+			break
+		}
+		scon := auxToSym(v_0.Aux)
+		v_0_0 := v_0.Args[0]
+		if v_0_0.Op != OpSB {
+			break
+		}
+		sptr := v.Args[1]
+		v_2 := v.Args[2]
+		if v_2.Op != OpConst64 || auxIntToInt64(v_2.AuxInt) != 1 || !(isSameCall(callAux, "runtime.memequal") && symIsRO(scon)) {
+			break
+		}
+		v.reset(OpMakeResult)
+		v0 := b.NewValue0(v.Pos, OpEq8, typ.Bool)
+		v1 := b.NewValue0(v.Pos, OpLoad, typ.Int8)
+		v1.AddArg2(sptr, mem)
+		v2 := b.NewValue0(v.Pos, OpConst8, typ.Int8)
+		v2.AuxInt = int8ToAuxInt(int8(read8(scon, 0)))
+		v0.AddArg2(v1, v2)
+		v.AddArg2(v0, mem)
+		return true
+	}
 	// match: (StaticLECall {callAux} sptr (Addr {scon} (SB)) (Const64 [2]) mem)
 	// cond: isSameCall(callAux, "runtime.memequal") && symIsRO(scon) && canLoadUnaligned(config)
 	// result: (MakeResult (Eq16 (Load <typ.Int16> sptr mem) (Const16 <typ.Int16> [int16(read16(scon,0,config.ctxt.Arch.ByteOrder))])) mem)
@ -27826,6 +27849,39 @@ func rewriteValuegeneric_OpStaticLECall(v *Value) bool {
 		v.AddArg2(v0, mem)
 		return true
 	}
+	// match: (StaticLECall {callAux} (Addr {scon} (SB)) sptr (Const64 [2]) mem)
+	// cond: isSameCall(callAux, "runtime.memequal") && symIsRO(scon) && canLoadUnaligned(config)
+	// result: (MakeResult (Eq16 (Load <typ.Int16> sptr mem) (Const16 <typ.Int16> [int16(read16(scon,0,config.ctxt.Arch.ByteOrder))])) mem)
+	for {
+		if len(v.Args) != 4 {
+			break
+		}
+		callAux := auxToCall(v.Aux)
+		mem := v.Args[3]
+		v_0 := v.Args[0]
+		if v_0.Op != OpAddr {
+			break
+		}
+		scon := auxToSym(v_0.Aux)
+		v_0_0 := v_0.Args[0]
+		if v_0_0.Op != OpSB {
+			break
+		}
+		sptr := v.Args[1]
+		v_2 := v.Args[2]
+		if v_2.Op != OpConst64 || auxIntToInt64(v_2.AuxInt) != 2 || !(isSameCall(callAux, "runtime.memequal") && symIsRO(scon) && canLoadUnaligned(config)) {
+			break
+		}
+		v.reset(OpMakeResult)
+		v0 := b.NewValue0(v.Pos, OpEq16, typ.Bool)
+		v1 := b.NewValue0(v.Pos, OpLoad, typ.Int16)
+		v1.AddArg2(sptr, mem)
+		v2 := b.NewValue0(v.Pos, OpConst16, typ.Int16)
+		v2.AuxInt = int16ToAuxInt(int16(read16(scon, 0, config.ctxt.Arch.ByteOrder)))
+		v0.AddArg2(v1, v2)
+		v.AddArg2(v0, mem)
+		return true
+	}
 	// match: (StaticLECall {callAux} sptr (Addr {scon} (SB)) (Const64 [4]) mem)
 	// cond: isSameCall(callAux, "runtime.memequal") && symIsRO(scon) && canLoadUnaligned(config)
 	// result: (MakeResult (Eq32 (Load <typ.Int32> sptr mem) (Const32 <typ.Int32> [int32(read32(scon,0,config.ctxt.Arch.ByteOrder))])) mem)
@ -27859,6 +27915,39 @@ func rewriteValuegeneric_OpStaticLECall(v *Value) bool {
 		v.AddArg2(v0, mem)
 		return true
 	}
+	// match: (StaticLECall {callAux} (Addr {scon} (SB)) sptr (Const64 [4]) mem)
+	// cond: isSameCall(callAux, "runtime.memequal") && symIsRO(scon) && canLoadUnaligned(config)
+	// result: (MakeResult (Eq32 (Load <typ.Int32> sptr mem) (Const32 <typ.Int32> [int32(read32(scon,0,config.ctxt.Arch.ByteOrder))])) mem)
+	for {
+		if len(v.Args) != 4 {
+			break
+		}
+		callAux := auxToCall(v.Aux)
+		mem := v.Args[3]
+		v_0 := v.Args[0]
+		if v_0.Op != OpAddr {
+			break
+		}
+		scon := auxToSym(v_0.Aux)
+		v_0_0 := v_0.Args[0]
+		if v_0_0.Op != OpSB {
+			break
+		}
+		sptr := v.Args[1]
+		v_2 := v.Args[2]
+		if v_2.Op != OpConst64 || auxIntToInt64(v_2.AuxInt) != 4 || !(isSameCall(callAux, "runtime.memequal") && symIsRO(scon) && canLoadUnaligned(config)) {
+			break
+		}
+		v.reset(OpMakeResult)
+		v0 := b.NewValue0(v.Pos, OpEq32, typ.Bool)
+		v1 := b.NewValue0(v.Pos, OpLoad, typ.Int32)
+		v1.AddArg2(sptr, mem)
+		v2 := b.NewValue0(v.Pos, OpConst32, typ.Int32)
+		v2.AuxInt = int32ToAuxInt(int32(read32(scon, 0, config.ctxt.Arch.ByteOrder)))
+		v0.AddArg2(v1, v2)
+		v.AddArg2(v0, mem)
+		return true
+	}
 	// match: (StaticLECall {callAux} sptr (Addr {scon} (SB)) (Const64 [8]) mem)
 	// cond: isSameCall(callAux, "runtime.memequal") && symIsRO(scon) && canLoadUnaligned(config) && config.PtrSize == 8
 	// result: (MakeResult (Eq64 (Load <typ.Int64> sptr mem) (Const64 <typ.Int64> [int64(read64(scon,0,config.ctxt.Arch.ByteOrder))])) mem)
@ -27892,6 +27981,58 @@ func rewriteValuegeneric_OpStaticLECall(v *Value) bool {
 		v.AddArg2(v0, mem)
 		return true
 	}
+	// match: (StaticLECall {callAux} (Addr {scon} (SB)) sptr (Const64 [8]) mem)
+	// cond: isSameCall(callAux, "runtime.memequal") && symIsRO(scon) && canLoadUnaligned(config) && config.PtrSize == 8
+	// result: (MakeResult (Eq64 (Load <typ.Int64> sptr mem) (Const64 <typ.Int64> [int64(read64(scon,0,config.ctxt.Arch.ByteOrder))])) mem)
+	for {
+		if len(v.Args) != 4 {
+			break
+		}
+		callAux := auxToCall(v.Aux)
+		mem := v.Args[3]
+		v_0 := v.Args[0]
+		if v_0.Op != OpAddr {
+			break
+		}
+		scon := auxToSym(v_0.Aux)
+		v_0_0 := v_0.Args[0]
+		if v_0_0.Op != OpSB {
+			break
+		}
+		sptr := v.Args[1]
+		v_2 := v.Args[2]
+		if v_2.Op != OpConst64 || auxIntToInt64(v_2.AuxInt) != 8 || !(isSameCall(callAux, "runtime.memequal") && symIsRO(scon) && canLoadUnaligned(config) && config.PtrSize == 8) {
+			break
+		}
+		v.reset(OpMakeResult)
+		v0 := b.NewValue0(v.Pos, OpEq64, typ.Bool)
+		v1 := b.NewValue0(v.Pos, OpLoad, typ.Int64)
+		v1.AddArg2(sptr, mem)
+		v2 := b.NewValue0(v.Pos, OpConst64, typ.Int64)
+		v2.AuxInt = int64ToAuxInt(int64(read64(scon, 0, config.ctxt.Arch.ByteOrder)))
+		v0.AddArg2(v1, v2)
+		v.AddArg2(v0, mem)
+		return true
+	}
+	// match: (StaticLECall {callAux} _ _ (Const64 [0]) mem)
+	// cond: isSameCall(callAux, "runtime.memequal")
+	// result: (MakeResult (ConstBool <typ.Bool> [true]) mem)
+	for {
+		if len(v.Args) != 4 {
+			break
+		}
+		callAux := auxToCall(v.Aux)
+		mem := v.Args[3]
+		v_2 := v.Args[2]
+		if v_2.Op != OpConst64 || auxIntToInt64(v_2.AuxInt) != 0 || !(isSameCall(callAux, "runtime.memequal")) {
+			break
+		}
+		v.reset(OpMakeResult)
+		v0 := b.NewValue0(v.Pos, OpConstBool, typ.Bool)
+		v0.AuxInt = boolToAuxInt(true)
+		v.AddArg2(v0, mem)
+		return true
+	}
 	// match: (StaticLECall {callAux} _ (Const64 [0]) (Const64 [0]) mem)
 	// cond: isSameCall(callAux, "runtime.makeslice")
 	// result: (MakeResult (Addr <v.Type.FieldType(0)> {ir.Syms.Zerobase} (SB)) mem)
--- a/test/codegen/comparisons.go
+++ b/test/codegen/comparisons.go
@ -747,3 +747,44 @@ func cmpToCmnGreaterThanEqual(a, b, c, d int) int {
 	}
 	return c1 + c2 + c3 + c4
 }
+
+func cmp1(val string) bool {
+	var z string
+	// amd64:-".*memequal"
+	return z == val
+}
+
+func cmp2(val string) bool {
+	var z string
+	// amd64:-".*memequal"
+	return val == z
+}
+
+func cmp3(val string) bool {
+	z := "food"
+	// amd64:-".*memequal"
+	return z == val
+}
+
+func cmp4(val string) bool {
+	z := "food"
+	// amd64:-".*memequal"
+	return val == z
+}
+
+func cmp5[T comparable](val T) bool {
+	var z T
+	// amd64:-".*memequal"
+	return z == val
+}
+
+func cmp6[T comparable](val T) bool {
+	var z T
+	// amd64:-".*memequal"
+	return val == z
+}
+
+func cmp7() {
+	cmp5[string]("") // force instantiation
+	cmp6[string]("") // force instantiation
+}