https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113372
--- Comment #12 from Jakub Jelinek <jakub at gcc dot gnu.org> --- (In reply to Richard Biener from comment #11) > So the key would be to make the object live again after a CLOBBER when such > address SSA name is used (but before any other explicit mention appears)? > > The current algorithm relies on explitic mentions appearing, one original > idea was to turn those explicit mentions (or BLOCK starts) into > start-of-live CLOBBERs, but even that was shown to be not enough. > > But yes, if we want to try to mitigate the problems somewhat without > doing a full solution then possibly even just looking at SSA defs > when POINTER_TYPE and the def is an ADDR_EXPR might work (in the > visit_* callbacks of the walk_stmt_load_store_addr_ops), no propagation > needed at all (basically just undo CSE virtually here for the simple > cases). It couldn't be limited to just POINTER_TYPE, because it mostly is actually pointer-sized unsigned integer from IVOPTs, but yes, even without full propagation I think all the testcases I've mentioned could be solved by just doing the short walks in PHI arguments or other SSA_NAME uses (only PR111422 needs the latter). For this PR, we'd need to visit for ivtmp.40_3 uses in PHI args the def-stmt: ivtmp.40_3 = (unsigned long) &MEM <unsigned long[100]> [(void *)&bitint.6 + 8B]; for PR90348 ivtmp.32_28's def-stmt: ivtmp.32_28 = (unsigned long) ∈ for PR110115 ivtmp.27_2's def-stmt: ivtmp.27_2 = (unsigned long) &h; fpr PR111422 _44's def-stmt: _44 = &g + _43; So, if you think it is ok to use just a small hack rather than full propagation (which could even handle const/pure calls perhaps if they return pointer or pointer-sized integer), I can implement that too. Even the full propagation wouldn't handle everything of course, but could handle more than the small hack (which would need to be limited to just say 4 def-stmts and wouldn't try to look through PHIs).
