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* [Bug tree-optimization/66975] New: parloops to handle signed int reductions @ 2015-07-23 12:35 vries at gcc dot gnu.org 2015-07-26 17:54 ` [Bug tree-optimization/66975] " vries at gcc dot gnu.org ` (3 more replies) 0 siblings, 4 replies; 5+ messages in thread From: vries at gcc dot gnu.org @ 2015-07-23 12:35 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66975 Bug ID: 66975 Summary: parloops to handle signed int reductions Product: gcc Version: 6.0 Status: UNCONFIRMED Severity: enhancement Priority: P3 Component: tree-optimization Assignee: unassigned at gcc dot gnu.org Reporter: vries at gcc dot gnu.org Target Milestone: --- With this ( https://gcc.gnu.org/ml/gcc-cvs/2015-07/msg00896.html ) fix we introduce xfails for signed int reductions: ... * gcc.dg/autopar/outer-4.c: Add xfail. * gcc.dg/autopar/outer-5.c: Same. * gcc.dg/autopar/outer-6.c: Same. * gcc.dg/autopar/reduc-2.c: Same. * gcc.dg/autopar/reduc-2char.c: Same. * gcc.dg/autopar/reduc-2short.c: Same. * gcc.dg/autopar/reduc-8.c: Same. ... The problem is that when parallelizing reductions in parloops, we change the order of evaluation, which can mean that we introduce an overflow, where there was none before. This only yields the same result if the overflow behaviour can be assumed to wrap. The fix adds this missing check. However, we can convert the signed reduction to an unsigned one, correctly parallelize it, and cast the result back to signed. ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/66975] parloops to handle signed int reductions 2015-07-23 12:35 [Bug tree-optimization/66975] New: parloops to handle signed int reductions vries at gcc dot gnu.org @ 2015-07-26 17:54 ` vries at gcc dot gnu.org 2015-07-29 11:42 ` vries at gcc dot gnu.org ` (2 subsequent siblings) 3 siblings, 0 replies; 5+ messages in thread From: vries at gcc dot gnu.org @ 2015-07-26 17:54 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66975 --- Comment #1 from vries at gcc dot gnu.org --- This ( https://gcc.gnu.org/ml/gcc-patches/2015-07/msg02064.html ) patches fixes the problem for operations that do not overflow, f.i. min and max. ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/66975] parloops to handle signed int reductions 2015-07-23 12:35 [Bug tree-optimization/66975] New: parloops to handle signed int reductions vries at gcc dot gnu.org 2015-07-26 17:54 ` [Bug tree-optimization/66975] " vries at gcc dot gnu.org @ 2015-07-29 11:42 ` vries at gcc dot gnu.org 2015-08-01 8:34 ` vries at gcc dot gnu.org 2015-08-01 8:36 ` vries at gcc dot gnu.org 3 siblings, 0 replies; 5+ messages in thread From: vries at gcc dot gnu.org @ 2015-07-29 11:42 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66975 --- Comment #2 from vries at gcc dot gnu.org --- (In reply to vries from comment #1) > This ( https://gcc.gnu.org/ml/gcc-patches/2015-07/msg02064.html ) patches > fixes the problem for operations that do not overflow, f.i. min and max. Updated patch: https://gcc.gnu.org/ml/gcc-patches/2015-07/msg02450.html ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/66975] parloops to handle signed int reductions 2015-07-23 12:35 [Bug tree-optimization/66975] New: parloops to handle signed int reductions vries at gcc dot gnu.org 2015-07-26 17:54 ` [Bug tree-optimization/66975] " vries at gcc dot gnu.org 2015-07-29 11:42 ` vries at gcc dot gnu.org @ 2015-08-01 8:34 ` vries at gcc dot gnu.org 2015-08-01 8:36 ` vries at gcc dot gnu.org 3 siblings, 0 replies; 5+ messages in thread From: vries at gcc dot gnu.org @ 2015-08-01 8:34 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66975 --- Comment #3 from vries at gcc dot gnu.org --- https://gcc.gnu.org/ml/gcc-cvs/2015-08/msg00003.html : Author: vries Date: Sat Aug 1 08:29:29 2015 New Revision: 226463 URL: https://gcc.gnu.org/viewcvs?rev=226463&root=gcc&view=rev Log: Allow non-overflow ops in reductions 2015-08-01 Tom de Vries <tom@codesourcery.com> * tree.c (operation_can_overflow, operation_no_trapping_overflow): New function. * tree.h (operation_can_overflow, operation_no_trapping_overflow): Declare. * tree-vect-loop.c (vect_is_simple_reduction_1): Use operation_no_trapping_overflow. Allow non-overflow operations. * graphite-sese-to-poly.c (is_reduction_operation_p): Allow non-overflow operations. * gcc.dg/autopar/reduc-2char.c (init_arrays): Mark with attribute optimize ("-ftree-parallelize-loops=0"). Add successful scans for 2 detected reductions. Add xfail scans for 3 detected reductions. * gcc.dg/autopar/reduc-2short.c: Same. * gcc.dg/autopar/reduc-8.c (init_arrays): Mark with attribute optimize ("-ftree-parallelize-loops=0"). Add successful scans for 2 detected reductions. * gcc.dg/vect/trapv-vect-reduc-4.c: Update scan to match vectorized min and max reductions. Modified: trunk/gcc/ChangeLog trunk/gcc/graphite-sese-to-poly.c trunk/gcc/testsuite/ChangeLog trunk/gcc/testsuite/gcc.dg/autopar/reduc-2char.c trunk/gcc/testsuite/gcc.dg/autopar/reduc-2short.c trunk/gcc/testsuite/gcc.dg/autopar/reduc-8.c trunk/gcc/testsuite/gcc.dg/vect/trapv-vect-reduc-4.c trunk/gcc/tree-vect-loop.c trunk/gcc/tree.c trunk/gcc/tree.h ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/66975] parloops to handle signed int reductions 2015-07-23 12:35 [Bug tree-optimization/66975] New: parloops to handle signed int reductions vries at gcc dot gnu.org ` (2 preceding siblings ...) 2015-08-01 8:34 ` vries at gcc dot gnu.org @ 2015-08-01 8:36 ` vries at gcc dot gnu.org 3 siblings, 0 replies; 5+ messages in thread From: vries at gcc dot gnu.org @ 2015-08-01 8:36 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66975 vries at gcc dot gnu.org changed: What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |NEW Last reconfirmed| |2015-08-01 Ever confirmed|0 |1 --- Comment #4 from vries at gcc dot gnu.org --- https://gcc.gnu.org/ml/gcc-patches/2015-07/msg01817.html : ... The "proper" solution (see other passes) is to rewrite the reduction to a wrapping one (cast to unsigned for the reduction op). ... ^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2015-08-01 8:36 UTC | newest] Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2015-07-23 12:35 [Bug tree-optimization/66975] New: parloops to handle signed int reductions vries at gcc dot gnu.org 2015-07-26 17:54 ` [Bug tree-optimization/66975] " vries at gcc dot gnu.org 2015-07-29 11:42 ` vries at gcc dot gnu.org 2015-08-01 8:34 ` vries at gcc dot gnu.org 2015-08-01 8:36 ` vries at gcc dot gnu.org
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