prog: remove Dir from Type

Having Dir is Type is handy, but forces us to duplicate lots of types.
E.g. if a struct is referenced as both in and out, then we need to
have 2 copies and 2 copies of structs/types it includes.
If also prevents us from having the struct type as struct identity
(because we can have up to 3 of them).

Revert to the old way we used to do it: propagate Dir as we walk
syscall arguments. This moves lots of dir passing from pkg/compiler
to prog package.
Now Arg contains the dir, so once we build the tree, we can use dirs
as before.

Reduces size of sys/linux/gen/amd64.go from 6058336 to 5661150 (-6.6%).

Update #1580

1 files changed, 3 insertions, 4 deletions

diff --git a/pkg/compiler/compiler.go b/pkg/compiler/compiler.go
index 7316b4d4c..8e5afddde 100644
--- a/pkg/compiler/compiler.go
+++ b/pkg/compiler/compiler.go
@@ -249,14 +249,13 @@ func (comp *compiler) getTypeDesc(t *ast.Type) *typeDesc {
 	return nil
 }
 
-func (comp *compiler) getArgsBase(t *ast.Type, field string, dir prog.Dir, isArg bool) (
-	*typeDesc, []*ast.Type, prog.IntTypeCommon) {
+func (comp *compiler) getArgsBase(t *ast.Type, field string, isArg bool) (*typeDesc, []*ast.Type, prog.IntTypeCommon) {
 	desc := comp.getTypeDesc(t)
 	if desc == nil {
 		panic(fmt.Sprintf("no type desc for %#v", *t))
 	}
 	args, opt := removeOpt(t)
-	com := genCommon(t.Ident, field, sizeUnassigned, dir, opt != nil)
+	com := genCommon(t.Ident, field, sizeUnassigned, opt != nil)
 	base := genIntCommon(com, 0, false)
 	if desc.NeedBase {
 		base.TypeSize = comp.ptrSize
@@ -306,7 +305,7 @@ func (comp *compiler) foreachType(n0 ast.Node,
 
 func (comp *compiler) foreachSubType(t *ast.Type, isArg bool,
 	cb func(*ast.Type, *typeDesc, []*ast.Type, prog.IntTypeCommon)) {
-	desc, args, base := comp.getArgsBase(t, "", prog.DirIn, isArg)
+	desc, args, base := comp.getArgsBase(t, "", isArg)
 	cb(t, desc, args, base)
 	for i, arg := range args {
 		if desc.Args[i].Type == typeArgType {