undo CL 12785045 / 71ce80dc4195

This has broken the 32-bit builds.

««« original CL description
cmd/gc, runtime: use type information to scan interface values

R=golang-dev, rsc, dvyukov
CC=golang-dev
https://golang.org/cl/12785045
»»»

R=khr, golang-dev, khr
CC=golang-dev
https://golang.org/cl/13010045

diff --git a/src/cmd/gc/pgen.c b/src/cmd/gc/pgen.c
index d649fc49daf805c9aaa6a0d2b6020ce7ce1c86b3..f39163406785d7d66b860202b212876539bb0ea2 100644 (file)
--- a/src/cmd/gc/pgen.c
+++ b/src/cmd/gc/pgen.c
@@ -257,6 +257,7 @@ walktype1(Type *t, vlong *xoffset, Bvec *bv)
                bvset(bv, ((*xoffset / widthptr) * BitsPerPointer) + 1);
                if(isnilinter(t))
                        bvset(bv, ((*xoffset / widthptr) * BitsPerPointer));
+               bvset(bv, ((*xoffset + widthptr) / widthptr) * BitsPerPointer);
                *xoffset += t->width;
                break;
 

diff --git a/src/pkg/runtime/mgc0.c b/src/pkg/runtime/mgc0.c
index 0084ca108b1ea4792885de660b1a10dd684c171c..459a980b96f139ead4b537c12544f5b5f25a99c9 100644 (file)
--- a/src/pkg/runtime/mgc0.c
+++ b/src/pkg/runtime/mgc0.c
@@ -36,10 +36,6 @@ enum {
 
        // Pointer map
        BitsPerPointer = 2,
-       BitsNoPointer = 0,
-       BitsPointer = 1,
-       BitsIface = 2,
-       BitsEface = 3,
 };
 
 // Bits in per-word bitmap.
@@ -1402,52 +1398,26 @@ struct BitVector
        uint32 data[];
 };
 
-// Scans an interface data value when the interface type indicates
-// that it is a pointer.
-static void
-scaninterfacedata(uintptr bits, byte *scanp, bool inprologue)
-{
-       Itab *tab;
-       Type *type;
-
-       if(!inprologue) {
-               if(bits == BitsIface) {
-                       tab = *(Itab**)scanp;
-                       if(tab->type->size <= sizeof(void*) && (tab->type->kind & KindNoPointers))
-                               return;
-               } else { // bits == BitsEface
-                       type = *(Type**)scanp;
-                       if(type->size <= sizeof(void*) && (type->kind & KindNoPointers))
-                               return;
-               }
-       }
-       addroot((Obj){scanp+PtrSize, PtrSize, 0});
-}
-
 // Starting from scanp, scans words corresponding to set bits.
 static void
-scanbitvector(byte *scanp, BitVector *bv, bool inprologue)
+scanbitvector(byte *scanp, BitVector *bv)
 {
-       uintptr word, bits;
-       uint32 *wordp;
+       uint32 *wp;
+       uint32 w;
        int32 i, remptrs;
 
-       wordp = bv->data;
+       wp = bv->data;
        for(remptrs = bv->n; remptrs > 0; remptrs -= 32) {
-               word = *wordp++;
+               w = *wp++;
                if(remptrs < 32)
                        i = remptrs;
                else
                        i = 32;
                i /= BitsPerPointer;
                for(; i > 0; i--) {
-                       bits = word & 3;
-                       if(bits != BitsNoPointer && *(void**)scanp != nil)
-                               if(bits == BitsPointer)
-                                       addroot((Obj){scanp, PtrSize, 0});
-                               else
-                                       scaninterfacedata(bits, scanp, inprologue);
-                       word >>= BitsPerPointer;
+                       if(w & 3)
+                               addroot((Obj){scanp, PtrSize, 0});
+                       w >>= BitsPerPointer;
                        scanp += PtrSize;
                }
        }
@@ -1460,14 +1430,12 @@ addframeroots(Stkframe *frame, void*)
        Func *f;
        BitVector *args, *locals;
        uintptr size;
-       bool afterprologue;
 
        f = frame->fn;
 
        // Scan local variables if stack frame has been allocated.
        // Use pointer information if known.
-       afterprologue = (frame->varp > (byte*)frame->sp);
-       if(afterprologue) {
+       if(frame->varp > (byte*)frame->sp) {
                locals = runtime·funcdata(f, FUNCDATA_GCLocals);
                if(locals == nil) {
                        // No locals information, scan everything.
@@ -1482,7 +1450,7 @@ addframeroots(Stkframe *frame, void*)
                        // Locals bitmap information, scan just the
                        // pointers in locals.
                        size = (locals->n*PtrSize) / BitsPerPointer;
-                       scanbitvector(frame->varp - size, locals, false);
+                       scanbitvector(frame->varp - size, locals);
                }
        }
 
@@ -1490,7 +1458,7 @@ addframeroots(Stkframe *frame, void*)
        // Use pointer information if known.
        args = runtime·funcdata(f, FUNCDATA_GCArgs);
        if(args != nil && args->n > 0)
-               scanbitvector(frame->argp, args, !afterprologue);
+               scanbitvector(frame->argp, args);
        else
                addroot((Obj){frame->argp, frame->arglen, 0});
 }