Enhance if-conversion for automatic arrays

Automatic arrays that are not address-taken should not be subject to
store data races.  This applies to OMP SIMD in-branch lowered
functions result array which for the testcase otherwise prevents
vectorization with SSE and for AVX and AVX512 ends up with spurious
.MASK_STORE to the stack surviving.

This inefficiency was noted in PR111793.

I've introduced ref_can_have_store_data_races, commonizing uses
of flag_store_data_races in if-conversion, cselim and store motion.

	PR tree-optimization/111793
	* tree-ssa-alias.h (ref_can_have_store_data_races): Declare.
	* tree-ssa-alias.cc (ref_can_have_store_data_races): New
	function.
	* tree-if-conv.cc (ifcvt_memrefs_wont_trap): Use
	ref_can_have_store_data_races to allow more unconditional
	stores.
	* tree-ssa-loop-im.cc (execute_sm): Likewise.
	* tree-ssa-phiopt.cc (cond_store_replacement): Likewise.

	* gcc.dg/vect/vect-simd-clone-21.c: New testcase.

1 files changed, 1 insertions, 3 deletions

diff --git a/gcc/tree-ssa-phiopt.cc b/gcc/tree-ssa-phiopt.cc
index 0ef42a1..f05ca72 100644
--- a/gcc/tree-ssa-phiopt.cc
+++ b/gcc/tree-ssa-phiopt.cc
@@ -3343,9 +3343,7 @@ cond_store_replacement (basic_block middle_bb, basic_block join_bb,
       /* If LHS is an access to a local variable without address-taken
 	 (or when we allow data races) and known not to trap, we could
 	 always safely move down the store.  */
-      tree base = get_base_address (lhs);
-      if (!auto_var_p (base)
-	  || (TREE_ADDRESSABLE (base) && !flag_store_data_races)
+      if (ref_can_have_store_data_races (lhs)
 	  || tree_could_trap_p (lhs))
 	return false;
     }