https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103247
Bug ID: 103247
Summary: graphite: Wrong code when at -O1 or higher and
-floop-nest-optimize is given without an earlier
tree-cunrolli pass
Product: gcc
Version: 12.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: stammark at gcc dot gnu.org
Target Milestone: ---
Hi all,
I'm coming across a strange optimisation bug that happens if I try to combine
-O1 with the Graphite -floop-nest-optimize on test interchange-8
I initially spotted the symptom when compiling as:
./bin/aarch64-none-elf-gcc
../src/gcc/gcc/testsuite/gcc.dg/graphite/interchange-8.c -march=armv8-a
-specs=aem-validation.specs -o test.out -O1 -floop-nest-optimize
And then running on a simulator resulted in the abort () function being called.
and then replicated on x86 as:
gcc ../src/gcc/gcc/testsuite/gcc.dg/graphite/interchange-8.c -o test.out -O1
-floop-nest-optimize ; ./test.out
Which gives an `Aborted (core dumped)`
Some further digging showed that the execution failure seems to be something in
the graphite/loop-nest-optimize pass that requires a tree-cunrolli pass to have
been done earlier, for this test's source code, so:
# The test always runs with -floop-nest-optimize
# O2 and O3 constain tree-cunrolli
# O0 and O1 don't contain tree-cunrolli
-O0 -floop-nest-optimize: works (no abort () was called)
-O0 -fenable-tree-cunrolli -floop-nest-optimize: works
-O1 -floop-nest-optimize: broken
-O1 -fenable-tree-cunrolli -floop-nest-optimize: works
-O2 -floop-nest-optimize: works
-O2 -fdisable-tree-cunrolli -floop-nest-optimize: broken
-O3 -floop-nest-optimize: works
-O3 -fdisable-tree-cunrolli -floop-nest-optimize: broken
Is anyone aware of such a dependency between these passes and/or is this a real
bug or am I missing something?
Replicated on latest trunk and GCC-11.
Thanks!
