cmd/compile: fix uint<->float conversion on 386

The frontend rewriting lowers them to runtime calls on 386. It
matches explicitly uint32, but missed uint.

Fixes #16738.

Change-Id: Iece7a45edf74615baca052a53273c208f057636d
Reviewed-on: https://go-review.googlesource.com/27085
Run-TryBot: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

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

@@ -74,6 +74,27 @@ func cvt8(a float32) int32 {
 	return int32(a)
 }
 
+// make sure to cover int, uint cases (issue #16738)
+//go:noinline
+func cvt9(a float64) int {
+	return int(a)
+}
+
+//go:noinline
+func cvt10(a float64) uint {
+	return uint(a)
+}
+
+//go:noinline
+func cvt11(a float32) int {
+	return int(a)
+}
+
+//go:noinline
+func cvt12(a float32) uint {
+	return uint(a)
+}
+
 func TestFloatConvert(t *testing.T) {
 	if got := cvt1(3.5); got != 3 {
 		t.Errorf("cvt1 got %d, wanted 3", got)
@@ -99,4 +120,16 @@ func TestFloatConvert(t *testing.T) {
 	if got := cvt8(3.5); got != 3 {
 		t.Errorf("cvt8 got %d, wanted 3", got)
 	}
+	if got := cvt9(3.5); got != 3 {
+		t.Errorf("cvt9 got %d, wanted 3", got)
+	}
+	if got := cvt10(3.5); got != 3 {
+		t.Errorf("cvt10 got %d, wanted 3", got)
+	}
+	if got := cvt11(3.5); got != 3 {
+		t.Errorf("cvt11 got %d, wanted 3", got)
+	}
+	if got := cvt12(3.5); got != 3 {
+		t.Errorf("cvt12 got %d, wanted 3", got)
+	}
 }

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

@@ -1126,7 +1126,7 @@ opswitch:
 					n = mkcall("float64touint64", n.Type, init, conv(n.Left, Types[TFLOAT64]))
 					break
 				}
-				if n.Type.Etype == TUINT32 || n.Type.Etype == TUINTPTR {
+				if n.Type.Etype == TUINT32 || n.Type.Etype == TUINT || n.Type.Etype == TUINTPTR {
 					n = mkcall("float64touint32", n.Type, init, conv(n.Left, Types[TFLOAT64]))
 					break
 				}
@@ -1141,7 +1141,7 @@ opswitch:
 					n = conv(mkcall("uint64tofloat64", Types[TFLOAT64], init, conv(n.Left, Types[TUINT64])), n.Type)
 					break
 				}
-				if n.Left.Type.Etype == TUINT32 || n.Left.Type.Etype == TUINTPTR {
+				if n.Left.Type.Etype == TUINT32 || n.Left.Type.Etype == TUINT || n.Left.Type.Etype == TUINTPTR {
 					n = conv(mkcall("uint32tofloat64", Types[TFLOAT64], init, conv(n.Left, Types[TUINT32])), n.Type)
 					break
 				}