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Re: optimization/10862: [tree-ssa] Segfault for (essentially) empty function
- From: law at redhat dot com
- To: bangerth at dealii dot org
- Cc: gcc-gnats at gcc dot gnu dot org, gcc-patches at gcc dot gnu dot org
- Date: Mon, 19 May 2003 12:12:35 -0600
- Subject: Re: optimization/10862: [tree-ssa] Segfault for (essentially) empty function
- Reply-to: law at redhat dot com
In message <20030519144341.25098.qmail@sources.redhat.com>, bangerth@dealii.org
writes:
>
>>Number: 10862
>>Category: optimization
>>Synopsis: [tree-ssa] Segfault for (essentially) empty function
>>Confidential: no
>>Severity: serious
>>Priority: medium
>>Responsible: unassigned
>>State: open
>>Class: sw-bug
>>Submitter-Id: net
>>Arrival-Date: Mon May 19 14:46:01 UTC 2003
>>Closed-Date:
>>Last-Modified:
>>Originator: Wolfgang Bangerth
>>Release: unknown-1.0
>>Organization:
>>Environment:
>
>>Description:
>This one's rather funny (and was much simpler to reduce).
>We ICE on a function that's essentially empty:
>---------------------------------------template <int N> void foo () {
> int i;
> switch (i) {
> case 1:
> switch (N) {}
> default: ;
> }
>}
>
>template void foo<1> ();
>---------------------------
>
>g/x> /home/bangerth/bin/gcc-3.4-tree-ssa/bin/c++ -O2 -c a.cc
>a.cc: In function `void foo() [with int N = 1]':
>a.cc:10: instantiated from here
>a.cc:6: internal compiler error: Segmentation fault
>Please submit a full bug report,
>with preprocessed source if appropriate.
>See <URL:http://gcc.gnu.org/bugs.html> for instructions.
This patch ought to fix this problem.
* tree-ssa-dce.c (remove_conditional): If the conditional's block
has no post dominator in the CFG, then wire it to the exit node.
Avoid unnecessary check of bb->succ.
Index: tree-ssa-dce.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/Attic/tree-ssa-dce.c,v
retrieving revision 1.1.2.37
diff -c -3 -p -r1.1.2.37 tree-ssa-dce.c
*** tree-ssa-dce.c 16 May 2003 18:09:19 -0000 1.1.2.37
--- tree-ssa-dce.c 19 May 2003 16:50:25 -0000
*************** remove_conditional (basic_block bb)
*** 627,632 ****
--- 627,637 ----
if (bb->succ)
return;
+ /* If there is no post dominator, then this block is going to the
+ exit node. */
+ if (pdom_bb == NULL)
+ pdom_bb = EXIT_BLOCK_PTR;
+
/* If the post dominator has any PHI nodes in it at all, the
conditional has been marked as necessary. This means no PHI
node updating is required. If there are any PHI nodes, its a bug
*************** remove_conditional (basic_block bb)
*** 642,647 ****
#endif
/* Add an edge to BB's post dominator. */
! if (bb->succ == NULL)
! make_edge (bb, pdom_bb, EDGE_FALLTHRU);
}
--- 647,651 ----
#endif
/* Add an edge to BB's post dominator. */
! make_edge (bb, pdom_bb, EDGE_FALLTHRU);
}