llgo/ssa: PhisExpr

cl/compile.go

@@ -400,7 +400,7 @@ func (p *context) compileInstrOrValue(b llssa.Builder, iv instrOrValue, asValue
 			for i, pred := range preds {
 				bblks[i] = p.fn.Block(pred.Index)
 			}
-			phi.AddIncoming(vals, bblks)
+			phi.AddIncoming(b, vals, bblks)
 		})
 	case *ssa.ChangeType:
 		t := v.Type()

cl/compile_test.go

@@ -29,7 +29,7 @@ func testCompile(t *testing.T, src, expected string) {
 }
 
 func TestFromTestrt(t *testing.T) {
-	cltest.FromDir(t, "", "./_testrt", true)
+	cltest.FromDir(t, "concat", "./_testrt", true)
 }
 
 func TestFromTestdata(t *testing.T) {

ssa/expr.go

@@ -50,12 +50,17 @@ func (v Expr) TypeOf() types.Type {
 
 // Do evaluates the delay expression and returns the result.
 func (v Expr) Do() Expr {
-	if vt := v.Type; vt.kind == vkDelayExpr {
+	switch vt := v.Type; vt.kind {
+	case vkDelayExpr:
 		return vt.t.(delayExprTy)()
+	case vkPhisExpr:
+		panic("unreachable")
 	}
 	return v
 }
 
+// -----------------------------------------------------------------------------
+
 // DelayExpr returns a delay expression.
 func DelayExpr(f func() Expr) Expr {
 	return Expr{Type: &aType{t: delayExprTy(f), kind: vkDelayExpr}}
@@ -73,6 +78,24 @@ func (p delayExprTy) String() string {
 
 // -----------------------------------------------------------------------------
 
+type phisExprTy struct {
+	phis []llvm.Value
+}
+
+func (p phisExprTy) Underlying() types.Type {
+	panic("don't call")
+}
+
+func (p phisExprTy) String() string {
+	return "phisExpr"
+}
+
+func phisExpr(phis []llvm.Value) Expr {
+	return Expr{Type: &aType{t: &phisExprTy{phis}, kind: vkPhisExpr}}
+}
+
+// -----------------------------------------------------------------------------
+
 // Null returns a null constant expression.
 func (p Program) Null(t Type) Expr {
 	return Expr{llvm.ConstNull(t.ll), t}
@@ -337,6 +360,14 @@ func llvmValues(vals []Expr) []llvm.Value {
 	return ret
 }
 
+func fieldValues(b llvm.Builder, vals []Expr, fldIdx int) []llvm.Value {
+	ret := make([]llvm.Value, len(vals))
+	for i, v := range vals {
+		ret[i] = llvm.CreateExtractValue(b, v.impl, fldIdx)
+	}
+	return ret
+}
+
 func llvmBlocks(bblks []BasicBlock) []llvm.BasicBlock {
 	ret := make([]llvm.BasicBlock, len(bblks))
 	for i, v := range bblks {
@@ -351,15 +382,37 @@ type Phi struct {
 }
 
 // AddIncoming adds incoming values to a phi node.
-func (p Phi) AddIncoming(vals []Expr, bblks []BasicBlock) {
-	v := llvmValues(vals)
-	b := llvmBlocks(bblks)
-	p.impl.AddIncoming(v, b)
+func (p Phi) AddIncoming(b Builder, vals []Expr, bblks []BasicBlock) {
+	bs := llvmBlocks(bblks)
+	if p.kind != vkPhisExpr { // normal phi node
+		vs := llvmValues(vals)
+		p.impl.AddIncoming(vs, bs)
+		return
+	}
+	phis := p.t.(*phisExprTy).phis
+	for i, phi := range phis {
+		flds := fieldValues(b.impl, vals, i)
+		phi.AddIncoming(flds, bs)
+	}
 }
 
 // Phi returns a phi node.
 func (b Builder) Phi(t Type) Phi {
-	return Phi{Expr{llvm.CreatePHI(b.impl, t.ll), t}}
+	impl := b.impl
+	switch tund := t.t.Underlying().(type) {
+	case *types.Basic:
+		kind := tund.Kind()
+		switch kind {
+		case types.String:
+			prog := b.Prog
+			phis := make([]llvm.Value, 2)
+			phis[0] = llvm.CreatePHI(impl, prog.tyVoidPtr())
+			phis[1] = llvm.CreatePHI(impl, prog.tyInt())
+			return Phi{phisExpr(phis)}
+		}
+	}
+	phi := llvm.CreatePHI(impl, t.ll)
+	return Phi{Expr{phi, t}}
 }
 
 // -----------------------------------------------------------------------------

ssa/type.go

@@ -43,6 +43,7 @@ const (
 	vkFunc
 	vkTuple
 	vkDelayExpr = -1
+	vkPhisExpr  = -2
 )
 
 // -----------------------------------------------------------------------------