cmd/gc, runtime: refactor interface inlining decision into compiler

We need to change the interface value representation for
concurrent garbage collection, so that there is no ambiguity
about whether the data word holds a pointer or scalar.

This CL does NOT make any representation changes.

Instead, it removes representation assumptions from
various pieces of code throughout the tree.
The isdirectiface function in cmd/gc/subr.c is now
the only place that decides that policy.
The policy propagates out from there in the reflect
metadata, as a new flag in the internal kind value.

A follow-up CL will change the representation by
changing the isdirectiface function. If that CL causes
problems, it will be easy to roll back.

Update #8405.

LGTM=iant
R=golang-codereviews, iant
CC=golang-codereviews, r
https://golang.org/cl/129090043

1 files changed, 2 insertions, 2 deletions

diff --git a/src/pkg/runtime/stack.c b/src/pkg/runtime/stack.c
index 772080af55..b4e992e658 100644
--- a/src/pkg/runtime/stack.c
+++ b/src/pkg/runtime/stack.c
@@ -585,7 +585,7 @@ adjustpointers(byte **scanp, BitVector *bv, AdjustInfo *adjinfo, Func *f)
 				break;
 			case BitsEface:
 				t = (Type*)scanp[i];
-				if(t != nil && (t->size > PtrSize || (t->kind & KindNoPointers) == 0)) {
+				if(t != nil && ((t->kind & KindDirectIface) == 0 || (t->kind & KindNoPointers) == 0)) {
 					p = scanp[i+1];
 					if(minp <= p && p < maxp) {
 						if(StackDebug >= 3)
@@ -602,7 +602,7 @@ adjustpointers(byte **scanp, BitVector *bv, AdjustInfo *adjinfo, Func *f)
 				if(tab != nil) {
 					t = tab->type;
 					//runtime·printf("          type=%p\n", t);
-					if(t->size > PtrSize || (t->kind & KindNoPointers) == 0) {
+					if((t->kind & KindDirectIface) == 0 || (t->kind & KindNoPointers) == 0) {
 						p = scanp[i+1];
 						if(minp <= p && p < maxp) {
 							if(StackDebug >= 3)