| Title | Asssertion "ring->next != NULL" in ztfm test |
| Status | closed |
| Priority | nice |
| Assigned user | Gareth Rees |
| Organization | Ravenbrook |
| Description | The ztfm test case fails on OS X in the COOL (Debug) variety with the following output: /Users/gdr/info.ravenbrook.com/project/mps/branch/2013-10-21/cet-addr-to-obj/code/xc/Debug/ztfm: randomize(): choosing initial state (v3): 2113482590. Create arena, size = 500000000. Transform INT_DYI(1): 5; DYI_INT(5): 1 Will make and transform sets of old nodes into new nodes. Set sizes: 1000, 10, 1, 1000, 10, 1, total: 4044. perset: 1000, first: 0 Transform [260..574) to [1260..1574). /Users/gdr/info.ravenbrook.com/project/mps/branch/2013-10-21/cet-addr-to-obj/code/ring.c:32: MPS ASSERTION FAILED: ring->next != NULL GDR 2014-01-10: It also fails on w3i6mv with seed 10479569. |
| Analysis | Running the failing test case under lldb shows that the assertion goes off in TransformCreate(). Here's the relevant part of the backtrace: frame #7: 0x000000010004e767 ztfm`RingCheck(ring=0x000000010fffdb50) + 487 at ring.c:32 frame #8: 0x000000010012bc5f ztfm`TransformCheck(transform=0x000000010fffdb40) + 1455 at trans.c:58 frame #9: 0x000000010012c144 ztfm`TransformCreate(transformReturn=0x00007fff5fbff2e0, arena=0x0000000100b91000) + 708 at trans.c:110 Reading the code shows that the RingCheck() fails because arenaRing is never initialized! In fact, this ring not used at all in trans.c [1], so it seems simpler to remove it rather than initialize it pointlessly. (Note also that if a Ring had a signature this mistake could not have happened.) |
| How found | automated_test |
| Evidence | [1] //info.ravenbrook.com/project/mps/custom/cet/main/code/trans.c |
| Created by | Gareth Rees |
| Created on | 2014-01-09 14:53:18 |
| Last modified by | Gareth Rees |
| Last modified on | 2014-01-11 22:06:09 |
| History | 2014-01-09 GDR Created. 2014-01-10 GDR Add assertion failure on w3i6mv. |
| Change | Effect | Date | User | Description |
|---|---|---|---|---|
| 183944 | closed | 2014-01-11 22:06:09 | Gareth Rees | Remove arenaRing from struct mps_transform_s: it was not used. |