1 /* -----------------------------------------------------------------------------
2 * $Id: Sanity.c,v 1.10 1999/02/11 17:40:28 simonm Exp $
4 * (c) The GHC Team, 1998-1999
6 * Sanity checking code for the heap and stack.
8 * Used when debugging: check that the stack looks reasonable.
10 * - All things that are supposed to be pointers look like pointers.
12 * - Objects in text space are marked as static closures, those
13 * in the heap are dynamic.
15 * ---------------------------------------------------------------------------*/
23 #include "BlockAlloc.h"
26 #define LOOKS_LIKE_PTR(r) \
27 (IS_DATA_PTR(r) || ((IS_USER_PTR(r) && Bdescr((P_)r)->free != (void *)-1)))
29 /* -----------------------------------------------------------------------------
31 -------------------------------------------------------------------------- */
33 StgOffset checkStackClosure( StgClosure* c );
35 StgOffset checkStackObject( StgPtr sp );
37 void checkStackChunk( StgPtr sp, StgPtr stack_end );
39 static StgOffset checkSmallBitmap( StgPtr payload, StgNat32 bitmap );
41 static StgOffset checkLargeBitmap( StgPtr payload,
42 StgLargeBitmap* large_bitmap );
44 void checkClosureShallow( StgClosure* p );
47 checkSmallBitmap( StgPtr payload, StgNat32 bitmap )
52 for(; bitmap != 0; ++i, bitmap >>= 1 ) {
53 if ((bitmap & 1) == 0) {
54 checkClosure(stgCast(StgClosure*,payload[i]));
62 checkLargeBitmap( StgPtr payload, StgLargeBitmap* large_bitmap )
68 for (bmp=0; bmp<large_bitmap->size; bmp++) {
69 StgNat32 bitmap = large_bitmap->bitmap[bmp];
70 for(; bitmap != 0; ++i, bitmap >>= 1 ) {
71 if ((bitmap & 1) == 0) {
72 checkClosure(stgCast(StgClosure*,payload[i]));
80 checkStackClosure( StgClosure* c )
82 const StgInfoTable* info = get_itbl(c);
84 /* All activation records have 'bitmap' style layout info. */
86 case RET_DYN: /* Dynamic bitmap: the mask is stored on the stack */
88 StgRetDyn* r = stgCast(StgRetDyn*,c);
89 return sizeofW(StgRetDyn) +
90 checkSmallBitmap(r->payload,r->liveness);
92 case RET_BCO: /* small bitmap (<= 32 entries) */
99 return sizeofW(StgClosure) +
100 checkSmallBitmap((StgPtr)c->payload,info->layout.bitmap);
101 case RET_BIG: /* large bitmap (> 32 entries) */
103 return sizeofW(StgClosure) +
104 checkLargeBitmap((StgPtr)c->payload,
105 info->layout.large_bitmap);
107 case FUN_STATIC: /* probably a slow-entry point return address: */
110 /* if none of the above, maybe it's a closure which looks a
111 * little like an infotable
113 checkClosureShallow(*stgCast(StgClosure**,c));
115 /* barf("checkStackClosure: weird activation record found on stack (%p).",c); */
120 * check that it looks like a valid closure - without checking its payload
121 * used to avoid recursion between checking PAPs and checking stack
126 checkClosureShallow( StgClosure* p )
128 ASSERT(LOOKS_LIKE_GHC_INFO(p->header.info));
130 /* Is it a static closure (i.e. in the data segment)? */
131 if (LOOKS_LIKE_STATIC(p)) {
132 ASSERT(closure_STATIC(p));
134 ASSERT(!closure_STATIC(p));
135 ASSERT(LOOKS_LIKE_PTR(p));
139 /* check an individual stack object */
141 checkStackObject( StgPtr sp )
143 if (IS_ARG_TAG(*sp)) {
144 /* Tagged words might be "stubbed" pointers, so there's no
145 * point checking to see whether they look like pointers or
146 * not (some of them will).
148 return ARG_SIZE(*sp) + 1;
149 } else if (LOOKS_LIKE_GHC_INFO(*stgCast(StgPtr*,sp))) {
150 return checkStackClosure(stgCast(StgClosure*,sp));
151 } else { /* must be an untagged closure pointer in the stack */
152 checkClosureShallow(*stgCast(StgClosure**,sp));
157 /* check sections of stack between update frames */
159 checkStackChunk( StgPtr sp, StgPtr stack_end )
164 while (p < stack_end) {
165 p += checkStackObject( p );
167 ASSERT( p == stack_end );
171 checkClosure( StgClosure* p )
173 const StgInfoTable *info;
176 ASSERT(LOOKS_LIKE_GHC_INFO(p->header.info));
179 /* Is it a static closure (i.e. in the data segment)? */
180 if (LOOKS_LIKE_STATIC(p)) {
181 ASSERT(closure_STATIC(p));
183 ASSERT(!closure_STATIC(p));
184 ASSERT(LOOKS_LIKE_PTR(p));
188 switch (info->type) {
191 StgBCO* bco = stgCast(StgBCO*,p);
193 for(i=0; i < bco->n_ptrs; ++i) {
194 ASSERT(LOOKS_LIKE_PTR(bcoConstPtr(bco,i)));
196 return bco_sizeW(bco);
201 StgMVar *mvar = (StgMVar *)p;
202 ASSERT(LOOKS_LIKE_PTR(mvar->head));
203 ASSERT(LOOKS_LIKE_PTR(mvar->tail));
204 ASSERT(LOOKS_LIKE_PTR(mvar->value));
205 return sizeofW(StgMVar);
216 for (i = 0; i < info->layout.payload.ptrs; i++) {
217 ASSERT(LOOKS_LIKE_PTR(payloadPtr(p,i)));
219 return stg_max(sizeW_fromITBL(info), sizeofW(StgHeader) + MIN_UPD_SIZE);
236 case IND_OLDGEN_PERM:
246 case CONSTR_CHARLIKE:
248 case CONSTR_NOCAF_STATIC:
254 for (i = 0; i < info->layout.payload.ptrs; i++) {
255 ASSERT(LOOKS_LIKE_PTR(payloadPtr(p,i)));
257 return sizeW_fromITBL(info);
261 /* deal with these specially - the info table isn't
262 * representative of the actual layout.
264 { StgWeak *w = (StgWeak *)p;
265 ASSERT(LOOKS_LIKE_PTR(w->key));
266 ASSERT(LOOKS_LIKE_PTR(w->value));
267 ASSERT(LOOKS_LIKE_PTR(w->finalizer));
269 ASSERT(LOOKS_LIKE_PTR(w->link));
271 return sizeW_fromITBL(info);
275 ASSERT(LOOKS_LIKE_PTR(stgCast(StgSelector*,p)->selectee));
276 return sizeofW(StgHeader) + MIN_UPD_SIZE;
280 /* we don't expect to see any of these after GC
281 * but they might appear during execution
284 StgInd *ind = stgCast(StgInd*,p);
285 ASSERT(LOOKS_LIKE_PTR(ind->indirectee));
286 q = (P_)p + sizeofW(StgInd);
287 while (!*q) { q++; }; /* skip padding words (see GC.c: evacuate())*/
301 barf("checkClosure: stack frame");
303 case AP_UPD: /* we can treat this as being the same as a PAP */
306 StgPAP *pap = stgCast(StgPAP*,p);
307 ASSERT(LOOKS_LIKE_PTR(pap->fun));
308 checkStackChunk((StgPtr)pap->payload,
309 (StgPtr)pap->payload + pap->n_args
311 return pap_sizeW(pap);
315 return arr_words_sizeW(stgCast(StgArrWords*,p));
318 case MUT_ARR_PTRS_FROZEN:
320 StgMutArrPtrs* a = stgCast(StgMutArrPtrs*,p);
322 for (i = 0; i < a->ptrs; i++) {
323 ASSERT(LOOKS_LIKE_PTR(a->payload[i]));
325 return mut_arr_ptrs_sizeW(a);
329 checkTSO((StgTSO *)p);
330 return tso_sizeW((StgTSO *)p);
335 barf("checkClosure: unimplemented/strange closure type");
337 barf("checkClosure");
339 #undef LOOKS_LIKE_PTR
342 /* -----------------------------------------------------------------------------
345 After garbage collection, the live heap is in a state where we can
346 run through and check that all the pointers point to the right
347 place. This function starts at a given position and sanity-checks
348 all the objects in the remainder of the chain.
349 -------------------------------------------------------------------------- */
352 checkHeap(bdescr *bd, StgPtr start)
363 while (p < bd->free) {
364 nat size = checkClosure(stgCast(StgClosure*,p));
365 /* This is the smallest size of closure that can live in the heap. */
366 ASSERT( size >= MIN_NONUPD_SIZE + sizeofW(StgHeader) );
370 while (p < bd->free &&
371 (*p == 0 || !LOOKS_LIKE_GHC_INFO(*p))) { p++; }
381 checkChain(bdescr *bd)
384 checkClosure((StgClosure *)bd->start);
389 /* check stack - making sure that update frames are linked correctly */
391 checkStack(StgPtr sp, StgPtr stack_end, StgUpdateFrame* su )
393 /* check everything down to the first update frame */
394 checkStackChunk( sp, stgCast(StgPtr,su) );
395 while ( stgCast(StgPtr,su) < stack_end) {
396 sp = stgCast(StgPtr,su);
397 switch (get_itbl(su)->type) {
402 su = stgCast(StgSeqFrame*,su)->link;
405 su = stgCast(StgCatchFrame*,su)->link;
408 /* not quite: ASSERT(stgCast(StgPtr,su) == stack_end); */
411 barf("checkStack: weird record found on update frame list.");
413 checkStackChunk( sp, stgCast(StgPtr,su) );
415 ASSERT(stgCast(StgPtr,su) == stack_end);
419 checkTSO(StgTSO *tso)
422 StgPtr stack = tso->stack;
423 StgUpdateFrame* su = tso->su;
424 StgOffset stack_size = tso->stack_size;
425 StgPtr stack_end = stack + stack_size;
427 if (tso->whatNext == ThreadComplete || tso->whatNext == ThreadKilled) {
428 /* The garbage collector doesn't bother following any pointers
429 * from dead threads, so don't check sanity here.
434 ASSERT(stack <= sp && sp < stack_end);
435 ASSERT(sp <= stgCast(StgPtr,su));
437 checkStack(sp, stack_end, su);
440 /* -----------------------------------------------------------------------------
441 Check Blackhole Sanity
443 Test whether an object is already on the update list.
444 It isn't necessarily an rts error if it is - it might be a programming
447 Future versions might be able to test for a blackhole without traversing
448 the update frame list.
450 -------------------------------------------------------------------------- */
451 rtsBool isBlackhole( StgTSO* tso, StgClosure* p )
453 StgUpdateFrame* su = tso->su;
455 switch (get_itbl(su)->type) {
457 if (su->updatee == p) {
464 su = stgCast(StgSeqFrame*,su)->link;
467 su = stgCast(StgCatchFrame*,su)->link;
472 barf("isBlackhole: weird record found on update frame list.");