[dev.typeparams] cmd/compile: directly set some simple expression types

This CL updates irgen to directly set the type for a bunch of basic
expressions that are easy to handle already. Trickier rewrites are
still handled with typecheck.Expr, but responsibility of calling that
is pushed down to the conversion of individual operations.

Change-Id: I774ac6ab4c72ad854860ab5c741867dd42a066b3
Reviewed-on: https://go-review.googlesource.com/c/go/+/285058
Trust: Matthew Dempsky <mdempsky@google.com>
Trust: Robert Griesemer <gri@golang.org>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Robert Griesemer <gri@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>

1 files changed, 35 insertions, 17 deletions

diff --git a/src/cmd/compile/internal/noder/helpers.go b/src/cmd/compile/internal/noder/helpers.go
index 2139f16a6c..3c20f74d8b 100644
--- a/src/cmd/compile/internal/noder/helpers.go
+++ b/src/cmd/compile/internal/noder/helpers.go
@@ -21,32 +21,41 @@ import (
 // results, rather than leaving the caller responsible for using
 // typecheck.Expr or typecheck.Stmt.
 
+// typed returns n after setting its type to typ.
+func typed(typ *types.Type, n ir.Node) ir.Node {
+	n.SetType(typ)
+	n.SetTypecheck(1)
+	return n
+}
+
 // Values
 
 func Const(pos src.XPos, typ *types.Type, val constant.Value) ir.Node {
-	n := ir.NewBasicLit(pos, val)
-	n.SetType(typ)
-	return n
+	return typed(typ, ir.NewBasicLit(pos, val))
 }
 
 func Nil(pos src.XPos, typ *types.Type) ir.Node {
-	n := ir.NewNilExpr(pos)
-	n.SetType(typ)
-	return n
+	return typed(typ, ir.NewNilExpr(pos))
 }
 
 // Expressions
 
 func Assert(pos src.XPos, x ir.Node, typ *types.Type) ir.Node {
-	return typecheck.Expr(ir.NewTypeAssertExpr(pos, x, ir.TypeNode(typ)))
+	return typed(typ, ir.NewTypeAssertExpr(pos, x, nil))
 }
 
 func Binary(pos src.XPos, op ir.Op, x, y ir.Node) ir.Node {
 	switch op {
 	case ir.OANDAND, ir.OOROR:
-		return ir.NewLogicalExpr(pos, op, x, y)
+		return typed(x.Type(), ir.NewLogicalExpr(pos, op, x, y))
+	case ir.OADD:
+		if x.Type().IsString() {
+			// TODO(mdempsky): Construct OADDSTR directly.
+			return typecheck.Expr(ir.NewBinaryExpr(pos, op, x, y))
+		}
+		fallthrough
 	default:
-		return ir.NewBinaryExpr(pos, op, x, y)
+		return typed(x.Type(), ir.NewBinaryExpr(pos, op, x, y))
 	}
 }
 
@@ -92,13 +101,17 @@ func Call(pos src.XPos, fun ir.Node, args []ir.Node, dots bool) ir.Node {
 }
 
 func Compare(pos src.XPos, typ *types.Type, op ir.Op, x, y ir.Node) ir.Node {
-	n := typecheck.Expr(ir.NewBinaryExpr(pos, op, x, y))
-	n.SetType(typ)
-	return n
+	n := ir.NewBinaryExpr(pos, op, x, y)
+	if !types.Identical(x.Type(), y.Type()) {
+		// TODO(mdempsky): Handle subtleties of constructing mixed-typed comparisons.
+		n = typecheck.Expr(n).(*ir.BinaryExpr)
+	}
+	return typed(typ, n)
 }
 
 func Index(pos src.XPos, x, index ir.Node) ir.Node {
-	return ir.NewIndexExpr(pos, x, index)
+	// TODO(mdempsky): Avoid typecheck.Expr.
+	return typecheck.Expr(ir.NewIndexExpr(pos, x, index))
 }
 
 func Slice(pos src.XPos, x, low, high, max ir.Node) ir.Node {
@@ -106,17 +119,22 @@ func Slice(pos src.XPos, x, low, high, max ir.Node) ir.Node {
 	if max != nil {
 		op = ir.OSLICE3
 	}
-	return ir.NewSliceExpr(pos, op, x, low, high, max)
+	// TODO(mdempsky): Avoid typecheck.Expr.
+	return typecheck.Expr(ir.NewSliceExpr(pos, op, x, low, high, max))
 }
 
 func Unary(pos src.XPos, op ir.Op, x ir.Node) ir.Node {
+	typ := x.Type()
 	switch op {
 	case ir.OADDR:
-		return typecheck.NodAddrAt(pos, x)
+		// TODO(mdempsky): Avoid typecheck.Expr. Probably just need to set OPTRLIT as needed.
+		return typed(types.NewPtr(typ), typecheck.Expr(typecheck.NodAddrAt(pos, x)))
 	case ir.ODEREF:
-		return ir.NewStarExpr(pos, x)
+		return typed(typ.Elem(), ir.NewStarExpr(pos, x))
+	case ir.ORECV:
+		return typed(typ.Elem(), ir.NewUnaryExpr(pos, op, x))
 	default:
-		return ir.NewUnaryExpr(pos, op, x)
+		return typed(typ, ir.NewUnaryExpr(pos, op, x))
 	}
 }