Richard, Here is updated patch which includes (1) a test on exit proposed by you and (2) another test from PR68021 which is caught by new check on counted loop. Outer-loop unswitching is not performed for both new tests.
Bootstrapping and regression testing did not show any new failures. Is it OK for trunk. ChangeLog: 2014-12-16 Yuri Rumyantsev <ysrum...@gmail.com> PR tree-optimization/68021 PR tree-optimization/68906 * tree-ssa-loop-unswitch.c : Include couple header files. (tree_unswitch_outer_loop): Add check that an exit is not inside inner loop, use number_of_latch_executions to detect non-iterated loops. gcc/testsuite/ChangeLog * gcc.dg/torture/pr68021.c: New test. * gcc.dg/torture/pr68906.c: Likewise. 2015-12-16 15:51 GMT+03:00 Richard Biener <richard.guent...@gmail.com>: > On Wed, Dec 16, 2015 at 1:14 PM, Yuri Rumyantsev <ysrum...@gmail.com> wrote: >> Hi All, >> >> Here is simple patch which cures the issue with outer-loop unswitching >> - added invocation of number_of_latch_executions() to reject >> unswitching for non-iterated loops. >> >> Bootstrapping and regression testing did not show any new failures. >> Is it OK for trunk? > > No, that looks like just papering over the issue. > > The issue (with the 2nd testcase at least) is that single_exit () accepts > an exit from the inner loop. > > Index: gcc/tree-ssa-loop-unswitch.c > =================================================================== > --- gcc/tree-ssa-loop-unswitch.c (revision 231686) > +++ gcc/tree-ssa-loop-unswitch.c (working copy) > @@ -431,7 +431,7 @@ tree_unswitch_outer_loop (struct loop *l > return false; > /* Accept loops with single exit only. */ > exit = single_exit (loop); > - if (!exit) > + if (!exit || exit->src->loop_father != loop) > return false; > /* Check that phi argument of exit edge is not defined inside loop. */ > if (!check_exit_phi (loop)) > > fixes the runtime testcase for me (not suitable for the testsuite due > to the infinite > looping though). > > Can you please bootstrap/test the above with your testcase? The above patch > is > ok if it passes testing (no time myself right now) > > Thanks, > Richard. > >> ChangeLog: >> >> 2014-12-16 Yuri Rumyantsev <ysrum...@gmail.com> >> >> PR tree-optimization/68906 >> * tree-ssa-loop-unswitch.c : Include couple header files. >> (tree_unswitch_outer_loop): Use number_of_latch_executions >> to reject non-iterated loops. >> >> gcc/testsuite/ChangeLog >> * gcc.dg/torture/pr68906.c: New test.
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