runtime: fix heapdump bugs.

Iterate the right number of times in arrays and channels.
Handle channels with zero-sized objects in them.
Output longer type names if we have them.
Compute argument offset correctly.

LGTM=rsc
R=golang-codereviews, rsc
CC=golang-codereviews
https://golang.org/cl/82980043

diff --git a/src/pkg/runtime/heapdump.c b/src/pkg/runtime/heapdump.c
index f9bc4e559ff5d26bb9e664eff85348f869247afe..e66dd6a7aed999eabe5ff5c5eac3b571f82a6d5d 100644 (file)
--- a/src/pkg/runtime/heapdump.c
+++ b/src/pkg/runtime/heapdump.c
@@ -186,7 +186,14 @@ dumptype(Type *t)
        dumpint(TagType);
        dumpint((uintptr)t);
        dumpint(t->size);
-       dumpstr(*t->string);
+       if(t->x == nil || t->x->pkgPath == nil || t->x->name == nil) {
+               dumpstr(*t->string);
+       } else {
+               dumpint(t->x->pkgPath->len + 1 + t->x->name->len);
+               write(t->x->pkgPath->str, t->x->pkgPath->len);
+               write((byte*)".", 1);
+               write(t->x->name->str, t->x->name->len);
+       }
        dumpbool(t->size > PtrSize || (t->kind & KindNoPointers) == 0);
        dumpfields((uintptr*)t->gc + 1);
 }
@@ -375,7 +382,7 @@ dumpframe(Stkframe *s, void *arg)
        dumpint(FieldKindEol);
 
        // Record arg info for parent.
-       child->argoff = s->argp - (byte*)s->sp;
+       child->argoff = s->argp - (byte*)s->fp;
        child->arglen = s->arglen;
        child->sp = (byte*)s->sp;
        child->depth++;
@@ -853,11 +860,13 @@ dumpefacetypes(void *obj, uintptr size, Type *type, uintptr kind)
                playgcprog(0, (uintptr*)type->gc + 1, dumpeface_callback, obj);
                break;
        case TypeInfo_Array:
-               for(i = 0; i < size; i += type->size)
+               for(i = 0; i <= size - type->size; i += type->size)
                        playgcprog(i, (uintptr*)type->gc + 1, dumpeface_callback, obj);
                break;
        case TypeInfo_Chan:
-               for(i = runtime·Hchansize; i < size; i += type->size)
+               if(type->size == 0) // channels may have zero-sized objects in them
+                       break;
+               for(i = runtime·Hchansize; i <= size - type->size; i += type->size)
                        playgcprog(i, (uintptr*)type->gc + 1, dumpeface_callback, obj);
                break;
        }