cmd/compile: use MakeResult in empty MakeSlice elimination

This gets eliminated by thoses rules above:
  // for rewriting results of some late-expanded rewrites (below)
  (SelectN [0] (MakeResult x ___)) => x
  (SelectN [1] (MakeResult x y ___)) => y
  (SelectN [2] (MakeResult x y z ___)) => z

Fixes #58161

Change-Id: I4fbfd52c72c06b6b3db906bd9910b6dbb7fe8975
Reviewed-on: https://go-review.googlesource.com/c/go/+/463846
Reviewed-by: Cherry Mui <cherryyz@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Run-TryBot: Keith Randall <khr@golang.org>
Reviewed-by: Keith Randall <khr@google.com>

3 files changed, 68 insertions, 108 deletions

diff --git a/src/cmd/compile/internal/ssa/_gen/generic.rules b/src/cmd/compile/internal/ssa/_gen/generic.rules
index 0cbde1ee45..10da571988 100644
--- a/src/cmd/compile/internal/ssa/_gen/generic.rules
+++ b/src/cmd/compile/internal/ssa/_gen/generic.rules
@@ -2077,15 +2077,9 @@
   => (Zero {types.Types[types.TUINT8]} [int64(c)] sptr mem)
 
 // Recognise make([]T, 0) and replace it with a pointer to the zerobase
-(SelectN [0] call:(StaticLECall _ (Const(64|32) [0]) (Const(64|32) [0]) _))
-	&& isSameCall(call.Aux, "runtime.makeslice")
-	&& clobberIfDead(call)
-	=> (Addr {ir.Syms.Zerobase} (SB))
-
-(SelectN [1] call:(StaticLECall _ (Const(64|32) [0]) (Const(64|32) [0]) mem))
-	&& isSameCall(call.Aux, "runtime.makeslice")
-	&& clobberIfDead(call)
-	=> mem
+(StaticLECall {callAux} _ (Const(64|32) [0]) (Const(64|32) [0]) mem)
+	&& isSameCall(callAux, "runtime.makeslice")
+	=> (MakeResult (Addr <v.Type.FieldType(0)> {ir.Syms.Zerobase} (SB)) mem)
 
 // Evaluate constant address comparisons.
 (EqPtr  x x) => (ConstBool [true])
diff --git a/src/cmd/compile/internal/ssa/rewritegeneric.go b/src/cmd/compile/internal/ssa/rewritegeneric.go
index 5917d45505..b81d093119 100644
--- a/src/cmd/compile/internal/ssa/rewritegeneric.go
+++ b/src/cmd/compile/internal/ssa/rewritegeneric.go
@@ -26380,7 +26380,6 @@ func rewriteValuegeneric_OpSelectN(v *Value) bool {
 	v_0 := v.Args[0]
 	b := v.Block
 	config := b.Func.Config
-	typ := &b.Func.Config.Types
 	// match: (SelectN [0] (MakeResult x ___))
 	// result: x
 	for {
@@ -26467,104 +26466,6 @@ func rewriteValuegeneric_OpSelectN(v *Value) bool {
 		v.AddArg2(sptr, mem)
 		return true
 	}
-	// match: (SelectN [0] call:(StaticLECall _ (Const64 [0]) (Const64 [0]) _))
-	// cond: isSameCall(call.Aux, "runtime.makeslice") && clobberIfDead(call)
-	// result: (Addr {ir.Syms.Zerobase} (SB))
-	for {
-		if auxIntToInt64(v.AuxInt) != 0 {
-			break
-		}
-		call := v_0
-		if call.Op != OpStaticLECall || len(call.Args) != 4 {
-			break
-		}
-		_ = call.Args[2]
-		call_1 := call.Args[1]
-		if call_1.Op != OpConst64 || auxIntToInt64(call_1.AuxInt) != 0 {
-			break
-		}
-		call_2 := call.Args[2]
-		if call_2.Op != OpConst64 || auxIntToInt64(call_2.AuxInt) != 0 || !(isSameCall(call.Aux, "runtime.makeslice") && clobberIfDead(call)) {
-			break
-		}
-		v.reset(OpAddr)
-		v.Aux = symToAux(ir.Syms.Zerobase)
-		v0 := b.NewValue0(v.Pos, OpSB, typ.Uintptr)
-		v.AddArg(v0)
-		return true
-	}
-	// match: (SelectN [0] call:(StaticLECall _ (Const32 [0]) (Const32 [0]) _))
-	// cond: isSameCall(call.Aux, "runtime.makeslice") && clobberIfDead(call)
-	// result: (Addr {ir.Syms.Zerobase} (SB))
-	for {
-		if auxIntToInt64(v.AuxInt) != 0 {
-			break
-		}
-		call := v_0
-		if call.Op != OpStaticLECall || len(call.Args) != 4 {
-			break
-		}
-		_ = call.Args[2]
-		call_1 := call.Args[1]
-		if call_1.Op != OpConst32 || auxIntToInt32(call_1.AuxInt) != 0 {
-			break
-		}
-		call_2 := call.Args[2]
-		if call_2.Op != OpConst32 || auxIntToInt32(call_2.AuxInt) != 0 || !(isSameCall(call.Aux, "runtime.makeslice") && clobberIfDead(call)) {
-			break
-		}
-		v.reset(OpAddr)
-		v.Aux = symToAux(ir.Syms.Zerobase)
-		v0 := b.NewValue0(v.Pos, OpSB, typ.Uintptr)
-		v.AddArg(v0)
-		return true
-	}
-	// match: (SelectN [1] call:(StaticLECall _ (Const64 [0]) (Const64 [0]) mem))
-	// cond: isSameCall(call.Aux, "runtime.makeslice") && clobberIfDead(call)
-	// result: mem
-	for {
-		if auxIntToInt64(v.AuxInt) != 1 {
-			break
-		}
-		call := v_0
-		if call.Op != OpStaticLECall || len(call.Args) != 4 {
-			break
-		}
-		mem := call.Args[3]
-		call_1 := call.Args[1]
-		if call_1.Op != OpConst64 || auxIntToInt64(call_1.AuxInt) != 0 {
-			break
-		}
-		call_2 := call.Args[2]
-		if call_2.Op != OpConst64 || auxIntToInt64(call_2.AuxInt) != 0 || !(isSameCall(call.Aux, "runtime.makeslice") && clobberIfDead(call)) {
-			break
-		}
-		v.copyOf(mem)
-		return true
-	}
-	// match: (SelectN [1] call:(StaticLECall _ (Const32 [0]) (Const32 [0]) mem))
-	// cond: isSameCall(call.Aux, "runtime.makeslice") && clobberIfDead(call)
-	// result: mem
-	for {
-		if auxIntToInt64(v.AuxInt) != 1 {
-			break
-		}
-		call := v_0
-		if call.Op != OpStaticLECall || len(call.Args) != 4 {
-			break
-		}
-		mem := call.Args[3]
-		call_1 := call.Args[1]
-		if call_1.Op != OpConst32 || auxIntToInt32(call_1.AuxInt) != 0 {
-			break
-		}
-		call_2 := call.Args[2]
-		if call_2.Op != OpConst32 || auxIntToInt32(call_2.AuxInt) != 0 || !(isSameCall(call.Aux, "runtime.makeslice") && clobberIfDead(call)) {
-			break
-		}
-		v.copyOf(mem)
-		return true
-	}
 	// match: (SelectN [0] call:(StaticCall {sym} s1:(Store _ (Const64 [sz]) s2:(Store _ src s3:(Store {t} _ dst mem)))))
 	// cond: sz >= 0 && isSameCall(sym, "runtime.memmove") && s1.Uses == 1 && s2.Uses == 1 && s3.Uses == 1 && isInlinableMemmove(dst, src, int64(sz), config) && clobber(s1, s2, s3, call)
 	// result: (Move {types.Types[types.TUINT8]} [int64(sz)] dst src mem)
@@ -27463,6 +27364,56 @@ func rewriteValuegeneric_OpStaticLECall(v *Value) bool {
 		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)
+	for {
+		if len(v.Args) != 4 {
+			break
+		}
+		callAux := auxToCall(v.Aux)
+		mem := v.Args[3]
+		v_1 := v.Args[1]
+		if v_1.Op != OpConst64 || auxIntToInt64(v_1.AuxInt) != 0 {
+			break
+		}
+		v_2 := v.Args[2]
+		if v_2.Op != OpConst64 || auxIntToInt64(v_2.AuxInt) != 0 || !(isSameCall(callAux, "runtime.makeslice")) {
+			break
+		}
+		v.reset(OpMakeResult)
+		v0 := b.NewValue0(v.Pos, OpAddr, v.Type.FieldType(0))
+		v0.Aux = symToAux(ir.Syms.Zerobase)
+		v1 := b.NewValue0(v.Pos, OpSB, typ.Uintptr)
+		v0.AddArg(v1)
+		v.AddArg2(v0, mem)
+		return true
+	}
+	// match: (StaticLECall {callAux} _ (Const32 [0]) (Const32 [0]) mem)
+	// cond: isSameCall(callAux, "runtime.makeslice")
+	// result: (MakeResult (Addr <v.Type.FieldType(0)> {ir.Syms.Zerobase} (SB)) mem)
+	for {
+		if len(v.Args) != 4 {
+			break
+		}
+		callAux := auxToCall(v.Aux)
+		mem := v.Args[3]
+		v_1 := v.Args[1]
+		if v_1.Op != OpConst32 || auxIntToInt32(v_1.AuxInt) != 0 {
+			break
+		}
+		v_2 := v.Args[2]
+		if v_2.Op != OpConst32 || auxIntToInt32(v_2.AuxInt) != 0 || !(isSameCall(callAux, "runtime.makeslice")) {
+			break
+		}
+		v.reset(OpMakeResult)
+		v0 := b.NewValue0(v.Pos, OpAddr, v.Type.FieldType(0))
+		v0.Aux = symToAux(ir.Syms.Zerobase)
+		v1 := b.NewValue0(v.Pos, OpSB, typ.Uintptr)
+		v0.AddArg(v1)
+		v.AddArg2(v0, mem)
+		return true
+	}
 	return false
 }
 func rewriteValuegeneric_OpStore(v *Value) bool {
diff --git a/test/fixedbugs/issue58161.go b/test/fixedbugs/issue58161.go
new file mode 100644
index 0000000000..33113f6563
--- /dev/null
+++ b/test/fixedbugs/issue58161.go
@@ -0,0 +1,15 @@
+// compile -d=ssa/check/seed=1
+
+// Copyright 2023 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+func F[G int]() int {
+	return len(make([]int, copy([]G{}, []G{})))
+}
+
+func main() {
+	F[int]()
+}