go.tools/ssa: fix crash on (new)(T) due to missing unparen() call.

Audited codebase for other occurrences, found two more.
Added test coverage for all of them.

R=gri
CC=golang-dev
https://golang.org/cl/14698043

ssa/builder.go

@@ -457,7 +457,7 @@ func (b *builder) addr(fn *Function, e ast.Expr, escaping bool) lvalue {
 // in an addressable location.
 //
 func (b *builder) exprInPlace(fn *Function, loc lvalue, e ast.Expr) {
-	if e, ok := e.(*ast.CompositeLit); ok {
+	if e, ok := unparen(e).(*ast.CompositeLit); ok {
 		// A CompositeLit never evaluates to a pointer,
 		// so if the type of the location is a pointer,
 		// an &-operation is implied.
@@ -476,7 +476,9 @@ func (b *builder) exprInPlace(fn *Function, loc lvalue, e ast.Expr) {
 				// Can't in-place initialize an interface value.
 				// Fall back to copying.
 			} else {
-				b.compLit(fn, loc.address(fn), e, typ) // in place
+				addr := loc.address(fn)
+				b.compLit(fn, addr, e, typ) // in place
+				emitDebugRef(fn, e, addr, true)
 				return
 			}
 		}
@@ -551,7 +553,7 @@ func (b *builder) expr0(fn *Function, e ast.Expr) Value {
 			return y
 		}
 		// Call to "intrinsic" built-ins, e.g. new, make, panic.
-		if id, ok := e.Fun.(*ast.Ident); ok {
+		if id, ok := unparen(e.Fun).(*ast.Ident); ok {
 			if obj, ok := fn.Pkg.objectOf(id).(*types.Builtin); ok {
 				if v := b.builtin(fn, obj, e.Args, typ, e.Lparen); v != nil {
 					return v

ssa/emit.go

@@ -45,6 +45,7 @@ func emitDebugRef(f *Function, e ast.Expr, v Value, isAddr bool) {
 		panic("nil")
 	}
 	var obj types.Object
+	e = unparen(e)
 	if id, ok := e.(*ast.Ident); ok {
 		if isBlankIdent(id) {
 			return
@@ -57,7 +58,7 @@ func emitDebugRef(f *Function, e ast.Expr, v Value, isAddr bool) {
 	}
 	f.emit(&DebugRef{
 		X:      v,
-		Expr:   unparen(e),
+		Expr:   e,
 		IsAddr: isAddr,
 		object: obj,
 	})

ssa/interp/testdata/coverage.go

@@ -279,6 +279,13 @@ func main() {
 	_ = map[int]*struct{}{0: {}}
 }
 
+// Parens should not prevent intrinsic treatment of built-ins.
+// (Regression test for a crash.)
+func init() {
+	_ = (new)(int)
+	_ = (make)([]int, 0)
+}
+
 type mybool bool
 
 func (mybool) f() {}

ssa/ssa.go

@@ -99,7 +99,7 @@ type Value interface {
 	// Instruction.
 	//
 	// This is the same as the source name for Parameters,
-	// Builtins, Functions, Captures, Globals and some Allocs.
+	// Builtins, Functions, Captures, Globals.
 	// For constants, it is a representation of the constant's value
 	// and type.  For all other Values this is the name of the
 	// virtual register defined by the instruction.
@@ -115,7 +115,7 @@ type Value interface {
 	String() string
 
 	// Type returns the type of this value.  Many instructions
-	// (e.g. IndexAddr) change the behaviour depending on the
+	// (e.g. IndexAddr) change their behaviour depending on the
 	// types of their operands.
 	Type() types.Type
 
@@ -186,6 +186,7 @@ type Instruction interface {
 
 	// SetBlock sets the basic block to which this instruction
 	// belongs.
+	// TODO(adonovan): unexport this.
 	SetBlock(*BasicBlock)
 
 	// Operands returns the operands of this instruction: the

ssa/testdata/valueforexpr.go

@@ -33,12 +33,12 @@ func f(spilled, unspilled int) {
 	_ = /*@Phi*/ (y)
 	map1 := /*@MakeMap*/ (make(map[string]string))
 	_ = map1
-	_ = /*@MakeMap*/ (map[string]string{"": ""})
 	_ = /*@MakeSlice*/ (make([]int, 0))
 	_ = /*@MakeClosure*/ (func() { print(spilled) })
-	sl := /*@Slice*/ ([]int{})
-	_ = /*@Alloc*/ (&struct{}{})
+
+	sl := []int{}
 	_ = /*@Slice*/ (sl[:0])
+
 	_ = /*@<nil>*/ (new(int)) // optimized away
 	tmp := /*@Alloc*/ (new(int))
 	_ = tmp
@@ -66,6 +66,71 @@ func f(spilled, unspilled int) {
 	/*@UnOp*/ (n) = /*@UnOp*/ (**n)
 }
 
+func complit() {
+	// Composite literals.
+	// We get different results for
+	// - composite literal as value (e.g. operand to print)
+	// - composite literal initializer for addressable value
+	// - composite literal value assigned to blank var
+
+	// 1. Slices
+	print( /*@Slice*/ ([]int{}))
+	print( /*@Alloc*/ (&[]int{}))
+	print(& /*@Alloc*/ ([]int{}))
+
+	sl1 := /*@Slice*/ ([]int{})
+	sl2 := /*@Alloc*/ (&[]int{})
+	sl3 := & /*@Alloc*/ ([]int{})
+	_, _, _ = sl1, sl2, sl3
+
+	_ = /*@Slice*/ ([]int{})
+	_ = /*@<nil>*/ (& /*@Slice*/ ([]int{})) // & optimized away
+	_ = & /*@Slice*/ ([]int{})
+
+	// 2. Arrays
+	print( /*@UnOp*/ ([1]int{}))
+	print( /*@Alloc*/ (&[1]int{}))
+	print(& /*@Alloc*/ ([1]int{}))
+
+	arr1 := /*@Alloc*/ ([1]int{})
+	arr2 := /*@Alloc*/ (&[1]int{})
+	arr3 := & /*@Alloc*/ ([1]int{})
+	_, _, _ = arr1, arr2, arr3
+
+	_ = /*@UnOp*/ ([1]int{})
+	_ = /*@Alloc*/ (& /*@Alloc*/ ([1]int{})) // & optimized away
+	_ = & /*@Alloc*/ ([1]int{})
+
+	// 3. Maps
+	type M map[int]int
+	print( /*@MakeMap*/ (M{}))
+	print( /*@Alloc*/ (&M{}))
+	print(& /*@Alloc*/ (M{}))
+
+	m1 := /*@MakeMap*/ (M{})
+	m2 := /*@Alloc*/ (&M{})
+	m3 := & /*@Alloc*/ (M{})
+	_, _, _ = m1, m2, m3
+
+	_ = /*@MakeMap*/ (M{})
+	_ = /*@<nil>*/ (& /*@MakeMap*/ (M{})) // & optimized away
+	_ = & /*@MakeMap*/ (M{})
+
+	// 4. Structs
+	print( /*@UnOp*/ (struct{}{}))
+	print( /*@Alloc*/ (&struct{}{}))
+	print(& /*@Alloc*/ (struct{}{}))
+
+	s1 := /*@Alloc*/ (struct{}{})
+	s2 := /*@Alloc*/ (&struct{}{})
+	s3 := & /*@Alloc*/ (struct{}{})
+	_, _, _ = s1, s2, s3
+
+	_ = /*@UnOp*/ (struct{}{})
+	_ = /*@Alloc*/ (& /*@Alloc*/ (struct{}{}))
+	_ = & /*@Alloc*/ (struct{}{})
+}
+
 type t struct{ x int }
 
 // Ensure we can locate methods of named types.