PR tree-optimization/90883
* tree-ssa-alias.c (stmt_kills_ref_p): Handle BUILT_IN_CALLOC.
* tree-ssa-dse.c: Update various comments to distinguish between
dead and redundant stores.
(initialize_ao_ref_for_dse): Handle BUILT_IN_CALLOC.
(dse_optimize_redundant_stores): New function.
(delete_dead_or_redundant_call): Renamed from delete_dead_call.
Distinguish between dead and redundant calls in dump output. All
callers updated.
(delete_dead_or_redundant_assignment): Similarly for assignments.
(dse_optimize_stmt): Handle _CHK variants. For statements which
store 0 into multiple memory locations, try to prove a subsequent
store is redundant.
PR tree-optimization/90883
* g++.dg/tree-ssa/pr90883.C: New test.
* gcc.dg/tree-ssa/ssa-dse-36.c: New test.
From-SVN: r272717
