On 25/02/16 18:00, Alan Lawrence wrote:
On 22/02/16 12:03, Jakub Jelinek wrote:
(f) A global command-line option, which we check alongside DECL_COMMON and
further tests (basically, we want only DECL_COMMON decls that either have
ARRAY_TYPE, or some other aggregate type with flexible array member or some
other trailing array in the struct), and use the resulting predicate in
places where we optimize based on DECL_SIZE{,_UNIT} of the decl - if that
predicate returns true, we assume the DECL_SIZE is
"variable"/"unlimited"/whatever.
The two spots known to me that would need to use this new predicate would
be:
tree.c (array_at_struct_end_p):
[...]
tree-dfa.c (get_ref_base_and_extent):
[...]
Close enough to what I meant by (a)/(b), but never mind that, and I hadn't
looked at where the change for aggressive loop opts needed to be. However...
Well you are essentially writing the patch for me at this point (so, thanks!),
but here's a patch that puts that under a global -funknown-commons flag.
Testcase as before.
Bootstrapped (with flag overridden to true) on x86_64 and aarch64, check-gcc,
check-fortran, and tested 416.gamess on AArch64, where this patch enables
running *without* the -fno-aggressive-loop-opts previously required.
In the gcc testsuite, these fail with the option turned on:
gcc.dg/pr53265.c (test for warnings, line 137)
gcc.dg/pr53265.c (test for warnings, line 138)
gcc.dg/pr64277.c scan-tree-dump cunroll ... (*2)
gcc.dg/tree-ssa/cunroll-{1,2,3,4,9,10,11}.c scan-tree-dump
cunroll/cunrolli/ivcanon (various)
gcc.dg/tree-ssa/loop-38.c scan-tree-dump cunrolli "Loop 1 iterates at most 11
times"
...which all appear harmless.
Thomas Koenig suggests (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69368#c80)
that this be combined with some flag fiddling and warnings in the Fortran
front-end; this patch doesn't do that, as I'm not very familiar with the
frontends, but that can follow in a separate patch. (Thomas?)
OK for trunk?
Cheers, Alan
gcc/ChangeLog:
DATE Alan Lawrence <alan.lawre...@arm.com>
Jakub Jelinek <ja...@redhat.com>
* common.opt (funknown-commons, flag_unknown_commons): New.
* tree.c (array_at_struct_end_p): Do not limit to size of decl for
DECL_COMMONS if flag_unknown_commons is set.
* tree-dfa.c (get_ref_base_and_extent): Likewise.
gcc/testsuite/ChangeLog:
* gfortran.dg/unknown_commons.f: New.
Ping.
(Besides my original patch
https://gcc.gnu.org/ml/gcc-patches/2016-02/msg01356.html which we decided was
too fragile, I believe this is the only patch proposed that actually fixes the
miscompare in 416.gamess.)
Thanks, Alan
