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Created attachment 30289 [details]
gzipped C source code
The attached source code causes the following crash
on gcc-4.9 trunk dated 20130605 on an AMD x86_64 box
when compiled with -O3.
Unable to coalesce ssa_names 45 and 3671 which are marked as MUST COALESCE.
sp_45(ab) and sp_3671(ab)
In file included from vm.c:661:0:
vm-engine.c: In function ‘vm_debug_engine’:
vm-engine.c:39:1: internal compiler error: SSA corruption
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <http://gcc.gnu.org/bugs.html> for instructions.
Created attachment 30291 [details]
It's the vectorizer, thus fails at -O -ftree-vectorize already.
niter analysis computes
(((unsigned long) sp_35(ab) - (unsigned long) (sp_3(ab) + 8)) + 7) / 8))
which the vectorizer inserts, obviously breaking coalescing of sp_35 and sp_3.
It's expand_simple_operations done in niter analysis that breaks this and
I have a patch to fix that.
Date: Thu Jun 20 10:22:33 2013
New Revision: 200237
2013-06-20 Richard Biener <firstname.lastname@example.org>
* tree-ssa-loop-niter.c (expand_simple_operations): Avoid including
SSA names into the expanded expression that take part in
* gcc.dg/torture/pr57584.c: New testcase.