[dev.ssa] cmd/compile: refactor out CheckLoweredPhi

This will be used verbatim in other architectures.

Change-Id: I307891ae597d797fd45f296b6a38ffe9fac6b975
Reviewed-on: https://go-review.googlesource.com/24155
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/cmd/compile/internal/amd64/ssa.go

@@ -714,17 +714,7 @@ func ssaGenValue(s *gc.SSAGenState, v *ssa.Value) {
 			p.To.Name = obj.NAME_AUTO
 		}
 	case ssa.OpPhi:
-		// just check to make sure regalloc and stackalloc did it right
-		if v.Type.IsMemory() {
-			return
-		}
-		f := v.Block.Func
-		loc := f.RegAlloc[v.ID]
-		for _, a := range v.Args {
-			if aloc := f.RegAlloc[a.ID]; aloc != loc { // TODO: .Equal() instead?
-				v.Fatalf("phi arg at different location than phi: %v @ %v, but arg %v @ %v\n%s\n", v, loc, a, aloc, v.Block.Func)
-			}
-		}
+		gc.CheckLoweredPhi(v)
 	case ssa.OpInitMem:
 		// memory arg needs no code
 	case ssa.OpArg:

src/cmd/compile/internal/arm/ssa.go

@@ -158,17 +158,7 @@ func ssaGenValue(s *gc.SSAGenState, v *ssa.Value) {
 		p.To.Type = obj.TYPE_REG
 		p.To.Reg = gc.SSARegNum(v)
 	case ssa.OpPhi:
-		// just check to make sure regalloc and stackalloc did it right
-		if v.Type.IsMemory() {
-			return
-		}
-		f := v.Block.Func
-		loc := f.RegAlloc[v.ID]
-		for _, a := range v.Args {
-			if aloc := f.RegAlloc[a.ID]; aloc != loc { // TODO: .Equal() instead?
-				v.Fatalf("phi arg at different location than phi: %v @ %v, but arg %v @ %v\n%s\n", v, loc, a, aloc, v.Block.Func)
-			}
-		}
+		gc.CheckLoweredPhi(v)
 	case ssa.OpStoreReg:
 		if v.Type.IsFlags() {
 			v.Unimplementedf("store flags not implemented: %v", v.LongString())

src/cmd/compile/internal/gc/ssa.go

@@ -4245,6 +4245,24 @@ func SSARegNum(v *ssa.Value) int16 {
 	return Thearch.SSARegToReg[SSAReg(v).Num]
 }
 
+// CheckLoweredPhi checks that regalloc and stackalloc correctly handled phi values.
+// Called during ssaGenValue.
+func CheckLoweredPhi(v *ssa.Value) {
+	if v.Op != ssa.OpPhi {
+		v.Fatalf("CheckLoweredPhi called with non-phi value: %v", v.LongString())
+	}
+	if v.Type.IsMemory() {
+		return
+	}
+	f := v.Block.Func
+	loc := f.RegAlloc[v.ID]
+	for _, a := range v.Args {
+		if aloc := f.RegAlloc[a.ID]; aloc != loc { // TODO: .Equal() instead?
+			v.Fatalf("phi arg at different location than phi: %v @ %v, but arg %v @ %v\n%s\n", v, loc, a, aloc, v.Block.Func)
+		}
+	}
+}
+
 // AutoVar returns a *Node and int64 representing the auto variable and offset within it
 // where v should be spilled.
 func AutoVar(v *ssa.Value) (*Node, int64) {