re PR tree-optimization/68583 (Missed if-conversion)

2015-12-09  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/68583
	* tree-if-conv.c (if_convertible_phi_p): Drop
	flag_tree_loop_if_convert_stores check in favor of the
	existing any_mask_load_store check.
	(insert_gimplified_predicates): Likewise.
	(combine_blocks): Likewise.
	(tree_if_conversion): Likewise.
	(ifcvt_memrefs_wont_trap): Properly check
	flag_tree_loop_if_convert_stores in all places that can end
	up introducing store-data-races.
	(if_convertible_gimple_assign_stmt_p): Remove restriction
	on flag_tree_loop_if_convert_stores for stores we can if-convert
	without introducing store-data-races.  Force versioning for
	all if-converted stores.

	* gcc.dg/tree-ssa/ifc-pr68583.c: New testcase.
	* gcc.dg/vect/vect-72.c: Adjust.
	* gcc.dg/vect/vect-cselim-2.c: Likewise.
	* gcc.dg/vect/vect-strided-store-a-u8-i2.c: Likewise.

From-SVN: r231453

gcc/ChangeLog

@@ -1,3 +1,20 @@
+2015-12-09  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/68583
+	* tree-if-conv.c (if_convertible_phi_p): Drop
+	flag_tree_loop_if_convert_stores check in favor of the
+	existing any_mask_load_store check.
+	(insert_gimplified_predicates): Likewise.
+	(combine_blocks): Likewise.
+	(tree_if_conversion): Likewise.
+	(ifcvt_memrefs_wont_trap): Properly check
+	flag_tree_loop_if_convert_stores in all places that can end
+	up introducing store-data-races.
+	(if_convertible_gimple_assign_stmt_p): Remove restriction
+	on flag_tree_loop_if_convert_stores for stores we can if-convert
+	without introducing store-data-races.  Force versioning for
+	all if-converted stores.
+
 2015-12-09  Tom de Vries  <tom@codesourcery.com>
 
 	PR tree-optimization/68716

gcc/testsuite/ChangeLog

@@ -1,3 +1,11 @@
+2015-12-09  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/68583
+	* gcc.dg/tree-ssa/ifc-pr68583.c: New testcase.
+	* gcc.dg/vect/vect-72.c: Adjust.
+	* gcc.dg/vect/vect-cselim-2.c: Likewise.
+	* gcc.dg/vect/vect-strided-store-a-u8-i2.c: Likewise.
+
 2015-12-09  Richard Biener  <rguenther@suse.de>
 
 	PR tree-optimization/68417

gcc/testsuite/gcc.dg/tree-ssa/ifc-pr68583.c

@@ -0,0 +1,23 @@
+/* { dg-do compile } */
+/* { dg-options "-O3 -fdump-tree-ifcvt" } */
+
+void foo (long *a)
+{
+  int i;
+  for (i = 0; i < 100; i+=2)
+    {
+      long *p = &a[i+1];
+      if (a[i] == 0)
+	{
+	  *p = 2;
+	  a[i] = 3;
+	}
+      else
+	{
+	  *p = 3;
+	  a[i] = 4;
+	}
+    }
+}
+
+/* { dg-final { scan-tree-dump "Applying if-conversion" "ifcvt" } } */

gcc/testsuite/gcc.dg/vect/vect-72.c

@@ -19,9 +19,10 @@ int main1 ()
   for (i=0; i < N+1; i++)
     {
       ib[i] = i;
-      /* Avoid vectorization.  */
       if (i%3 == 0)
         ib[i] = 5;
+      /* Avoid vectorization.  */
+      __asm__ volatile ("" : : : "memory");
     }
 
   for (i = 1; i < N+1; i++)

gcc/testsuite/gcc.dg/vect/vect-cselim-2.c

@@ -1,4 +1,7 @@
 /* { dg-require-effective-target vect_int } */
+/* We now if-convert the loop unconditonally as the memory locations
+   are always stored to.  */
+/* { dg-additional-options "-fno-tree-loop-if-convert" } */
 
 #include <stdarg.h>
 #include "tree-vect.h"

gcc/testsuite/gcc.dg/vect/vect-strided-store-a-u8-i2.c

@@ -26,6 +26,8 @@ main1 ()
       b[i] = i * 2;
       if (i%3 == 0)
         a[i] = 10; 
+      /* Prevent vectorization.  */
+      __asm__ volatile ("" : : : "memory");
     }
 
   for (i = 0; i < N; i++)

gcc/tree-if-conv.c

@@ -517,7 +517,7 @@ bb_with_exit_edge_p (struct loop *loop, basic_block bb)
    PHI is not if-convertible if:
    - it has more than 2 arguments.
 
-   When the flag_tree_loop_if_convert_stores is not set, PHI is not
+   When we didn't see if-convertible stores, PHI is not
    if-convertible if:
    - a virtual PHI is immediately used in another PHI node,
    - there is a virtual PHI in a BB other than the loop->header.
@@ -545,10 +545,10 @@ if_convertible_phi_p (struct loop *loop, basic_block bb, gphi *phi,
         }
     }
 
-  if (flag_tree_loop_if_convert_stores || any_mask_load_store)
+  if (any_mask_load_store)
     return true;
 
-  /* When the flag_tree_loop_if_convert_stores is not set, check
+  /* When there were no if-convertible stores, check
      that there are no memory writes in the branches of the loop to be
      if-converted.  */
   if (virtual_operand_p (gimple_phi_result (phi)))
@@ -713,16 +713,15 @@ ifcvt_memrefs_wont_trap (gimple *stmt, vec<data_reference_p> drs)
          to unconditionally.  */
       if (base_master_dr
 	  && DR_BASE_W_UNCONDITIONALLY (*base_master_dr))
-	return true;
+	return flag_tree_loop_if_convert_stores;
       else
 	{
 	  /* or the base is know to be not readonly.  */
 	  tree base_tree = get_base_address (DR_REF (a));
 	  if (DECL_P (base_tree)
 	      && decl_binds_to_current_def_p (base_tree)
-	      && flag_tree_loop_if_convert_stores
-	      && !TREE_READONLY (base_tree))
-	    return true;
+	      && ! TREE_READONLY (base_tree))
+	    return flag_tree_loop_if_convert_stores;
 	}
     }
   return false;
@@ -791,7 +790,6 @@ if_convertible_gimple_assign_stmt_p (gimple *stmt,
 				     bool *any_mask_load_store)
 {
   tree lhs = gimple_assign_lhs (stmt);
-  basic_block bb;
 
   if (dump_file && (dump_flags & TDF_DETAILS))
     {
@@ -835,28 +833,10 @@ if_convertible_gimple_assign_stmt_p (gimple *stmt,
       return false;
     }
 
-  if (flag_tree_loop_if_convert_stores)
-    return true;
-
-  bb = gimple_bb (stmt);
-
-  if (TREE_CODE (lhs) != SSA_NAME
-      && bb != bb->loop_father->header
-      && !bb_with_exit_edge_p (bb->loop_father, bb))
-    {
-      if (ifcvt_can_use_mask_load_store (stmt))
-	{
-	  gimple_set_plf (stmt, GF_PLF_2, true);
-	  *any_mask_load_store = true;
-	  return true;
-	}
-      if (dump_file && (dump_flags & TDF_DETAILS))
-	{
-	  fprintf (dump_file, "LHS is not var\n");
-	  print_gimple_stmt (dump_file, stmt, 0, TDF_SLIM);
-	}
-      return false;
-    }
+  /* When if-converting stores force versioning, likewise if we
+     ended up generating store data races.  */
+  if (gimple_vdef (stmt))
+    *any_mask_load_store = true;
 
   return true;
 }
@@ -1851,8 +1831,7 @@ insert_gimplified_predicates (loop_p loop, bool any_mask_load_store)
       stmts = bb_predicate_gimplified_stmts (bb);
       if (stmts)
 	{
-	  if (flag_tree_loop_if_convert_stores
-	      || any_mask_load_store)
+	  if (any_mask_load_store)
 	    {
 	      /* Insert the predicate of the BB just after the label,
 		 as the if-conversion of memory writes will use this
@@ -2174,7 +2153,7 @@ combine_blocks (struct loop *loop, bool any_mask_load_store)
   insert_gimplified_predicates (loop, any_mask_load_store);
   predicate_all_scalar_phis (loop);
 
-  if (flag_tree_loop_if_convert_stores || any_mask_load_store)
+  if (any_mask_load_store)
     predicate_mem_writes (loop);
 
   /* Merge basic blocks: first remove all the edges in the loop,
@@ -2691,7 +2670,7 @@ tree_if_conversion (struct loop *loop)
     }
 
   todo |= TODO_cleanup_cfg;
-  if (flag_tree_loop_if_convert_stores || any_mask_load_store)
+  if (any_mask_load_store)
     {
       mark_virtual_operands_for_renaming (cfun);
       todo |= TODO_update_ssa_only_virtuals;