[PATCH] Improve if-conversion of loads

[Richard Biener]

The following improves if-conversion of loads by enabling the analysis
code of -ftree-loop-if-convert-stores and using its
ifcvt_could_trap_p predicate which uses information about decls
being accessed unconditionally to prove the conditional accessed one
cannot trap.

This depends on the fix for PR66313.

Bootstrapped on x86_64-unknown-linux-gnu, testing in progress.

Richard.

2015-07-09  Richard Biener  <rguent...@suse.de>

        * tree-if-conv.c (if_convertible_gimple_assign_stmt_p):
        Use ifcvt_could_trap_p also when not flag_tree_loop_if_convert_stores.
        (if_convertible_loop_p_1): For this always compute bb predicates.
        (if_convertible_loop_p): And free them.

        * gcc.dg/vect/pr61194.c: Remove no longer required
        -ftree-loop-if-convert-stores.

Index: gcc/tree-if-conv.c
===================================================================
--- gcc/tree-if-conv.c  (revision 225599)
+++ gcc/tree-if-conv.c  (working copy)
@@ -874,7 +874,7 @@ if_convertible_gimple_assign_stmt_p (gim
       return true;
     }
 
-  if (gimple_assign_rhs_could_trap_p (stmt))
+  if (ifcvt_could_trap_p (stmt, refs))
     {
       if (ifcvt_can_use_mask_load_store (stmt))
        {
@@ -1297,18 +1297,15 @@ if_convertible_loop_p_1 (struct loop *lo
          }
     }
 
-  if (flag_tree_loop_if_convert_stores)
-    {
-      data_reference_p dr;
+  data_reference_p dr;
 
-      for (i = 0; refs->iterate (i, &dr); i++)
-       {
-         dr->aux = XNEW (struct ifc_dr);
-         DR_WRITTEN_AT_LEAST_ONCE (dr) = -1;
-         DR_RW_UNCONDITIONALLY (dr) = -1;
-       }
-      predicate_bbs (loop);
+  for (i = 0; refs->iterate (i, &dr); i++)
+    {
+      dr->aux = XNEW (struct ifc_dr);
+      DR_WRITTEN_AT_LEAST_ONCE (dr) = -1;
+      DR_RW_UNCONDITIONALLY (dr) = -1;
     }
+  predicate_bbs (loop);
 
   for (i = 0; i < loop->num_nodes; i++)
     {
@@ -1323,9 +1320,8 @@ if_convertible_loop_p_1 (struct loop *lo
            return false;
     }
 
-  if (flag_tree_loop_if_convert_stores)
-    for (i = 0; i < loop->num_nodes; i++)
-      free_bb_predicate (ifc_bbs[i]);
+  for (i = 0; i < loop->num_nodes; i++)
+    free_bb_predicate (ifc_bbs[i]);
 
   /* Checking PHIs needs to be done after stmts, as the fact whether there
      are any masked loads or stores affects the tests.  */
@@ -1399,14 +1395,10 @@ if_convertible_loop_p (struct loop *loop
   res = if_convertible_loop_p_1 (loop, &loop_nest, &refs, &ddrs,
                                 any_mask_load_store);
 
-  if (flag_tree_loop_if_convert_stores)
-    {
-      data_reference_p dr;
-      unsigned int i;
-
-      for (i = 0; refs.iterate (i, &dr); i++)
-       free (dr->aux);
-    }
+  data_reference_p dr;
+  unsigned int i;
+  for (i = 0; refs.iterate (i, &dr); i++)
+    free (dr->aux);
 
   free_data_refs (refs);
   free_dependence_relations (ddrs);
Index: gcc/testsuite/gcc.dg/vect/pr61194.c
===================================================================
--- gcc/testsuite/gcc.dg/vect/pr61194.c (revision 225599)
+++ gcc/testsuite/gcc.dg/vect/pr61194.c (working copy)
@@ -1,5 +1,4 @@
 /* { dg-require-effective-target vect_cond_mixed } */
-/* { dg-additional-options "-ftree-loop-if-convert-stores" } */
 
 #include "tree-vect.h"