On Mon, May 14, 2018 at 5:32 AM, Kugan Vivekanandarajah <kugan.vivekanandara...@linaro.org> wrote: > Hi Richard, > >>> Given the simple testcases you add I wonder if you want a cheaper >>> implementation, >>> namely check that when reaching a loop PHI the only aliasing stmt in >>> its use-chain >>> is the use_stmt you reached the PHI from. That would avoid this and the >>> tests >>> for the store being redundant and simplify the patch considerably. > > Tried implementing above in the attached patch. Bootstrapped on > x86_64-linux-gnu. Full testing is ongoing.
I think your phi_aliases_stmt_only is equal to has_single_use (PHI_RESULT (phi)) && PHI_RESULT (phi) == gimple_vuse (defvar_def) that is, we are sure we have phidef = PHI < , ... defvar> # defvar = VUSE <phidef> defvar_def stmt testing it this way is also more clearly matchign the intended structure. Maybe you can add the above IL picture as comment. OK with that changes. Richard. > Thanks, > Kugan > > gcc/ChangeLog: > > 2018-05-14 Kugan Vivekanandarajah <kug...@linaro.org> > > * tree-ssa-dse.c (phi_aliases_stmt_only): New. > (dse_classify_store): Use phi_aliases_stmt_only. > > gcc/testsuite/ChangeLog: > > 2018-05-14 Kugan Vivekanandarajah <kug...@linaro.org> > > * gcc.dg/tree-ssa/ssa-dse-31.c: New test. > * gcc.dg/tree-ssa/ssa-dse-32.c: New test.
