go/ssa: use core type for field accesses

Change Field and FieldAddr to consistently use the core type
instead of the underlying type to determine if the address is a pointer
or not.

Change-Id: I9a5e31497c1ff4ca733848d7f2a51e5e83ace7e8
Reviewed-on: https://go-review.googlesource.com/c/tools/+/496215
TryBot-Result: Gopher Robot <[email protected]>
Reviewed-by: Alan Donovan <[email protected]>
gopls-CI: kokoro <[email protected]>
Run-TryBot: Tim King <[email protected]>

Author: timothy-king

go/ssa/builder_generic_test.go

@@ -685,7 +685,7 @@ func TestInstructionString(t *testing.T) {
 	//@ instrs("f12", "*ssa.MakeMap", "make map[P]bool 1:int")
 	func f12[T any, P *struct{f T}](x T) map[P]bool { return map[P]bool{{}: true} }
 
-	//@ instrs("f13", "&v[0:int]")
+	//@ instrs("f13", "*ssa.IndexAddr", "&v[0:int]")
 	//@ instrs("f13", "*ssa.Store", "*t0 = 7:int", "*v = *new(A):A")
 	func f13[A [3]int, PA *A](v PA) {
 		*v = A{7}

go/ssa/emit.go

@@ -476,7 +476,7 @@ func emitTailCall(f *Function, call *Call) {
 // value of a field.
 func emitImplicitSelections(f *Function, v Value, indices []int, pos token.Pos) Value {
 	for _, index := range indices {
-		if st, vptr := deptr(v.Type()); vptr {
+		if st, vptr := deref(v.Type()); vptr {
 			fld := fieldOf(st, index)
 			instr := &FieldAddr{
 				X:     v,
@@ -486,7 +486,7 @@ func emitImplicitSelections(f *Function, v Value, indices []int, pos token.Pos)
 			instr.setType(types.NewPointer(fld.Type()))
 			v = f.emit(instr)
 			// Load the field's value iff indirectly embedded.
-			if _, fldptr := deptr(fld.Type()); fldptr {
+			if _, fldptr := deref(fld.Type()); fldptr {
 				v = emitLoad(f, v)
 			}
 		} else {
@@ -510,7 +510,7 @@ func emitImplicitSelections(f *Function, v Value, indices []int, pos token.Pos)
 // field's value.
 // Ident id is used for position and debug info.
 func emitFieldSelection(f *Function, v Value, index int, wantAddr bool, id *ast.Ident) Value {
-	if st, vptr := deptr(v.Type()); vptr {
+	if st, vptr := deref(v.Type()); vptr {
 		fld := fieldOf(st, index)
 		instr := &FieldAddr{
 			X:     v,

go/ssa/ssa.go

@@ -865,7 +865,7 @@ type Slice struct {
 type FieldAddr struct {
 	register
 	X     Value // *struct
-	Field int   // field is typeparams.CoreType(X.Type().Underlying().(*types.Pointer).Elem()).(*types.Struct).Field(Field)
+	Field int   // index into CoreType(CoreType(X.Type()).(*types.Pointer).Elem()).(*types.Struct).Fields
 }
 
 // The Field instruction yields the Field of struct X.
@@ -884,7 +884,7 @@ type FieldAddr struct {
 type Field struct {
 	register
 	X     Value // struct
-	Field int   // index into typeparams.CoreType(X.Type()).(*types.Struct).Fields
+	Field int   // index into CoreType(X.Type()).(*types.Struct).Fields
 }
 
 // The IndexAddr instruction yields the address of the element at