re PR tree-optimization/71437 (Performance regression after r235817)

	PR tree-optimization/71437
	* tree-ssa-dom.c (derive_equivalences_from_bit_ior): New function.
	(record_temporary_equivalences): Use it.

From-SVN: r246187

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 23a611236b940667bb99d76d83f43f43db74a557..82ab3d749c9fc7e03b2e1b3009ddf755f41fac38 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,5 +1,9 @@
 2017-03-15  Jeff Law  <law@redhat.com>
-       
+
+       PR tree-optimization/71437
+       * tree-ssa-dom.c (derive_equivalences_from_bit_ior): New function.
+       (record_temporary_equivalences): Use it.
+
        PR tree-optimization/71437
        * tree-ssa-dom.c (struct cond_equivalence): Moved from here into
        tree-ssa-scopedtables.

diff --git a/gcc/tree-ssa-dom.c b/gcc/tree-ssa-dom.c
index ad71269ce3d624089e65b3ffcc384e478cd14350..0ebe892977d6cc3ab7310a083451e622a1c8f903 100644 (file)
--- a/gcc/tree-ssa-dom.c
+++ b/gcc/tree-ssa-dom.c
@@ -691,6 +691,33 @@ back_propagate_equivalences (tree lhs, edge e,
     BITMAP_FREE (domby);
 }
 
+/* Record NAME has the value zero and if NAME was set from a BIT_IOR_EXPR
+   recurse into both operands recording their values as zero too.  */
+
+static void
+derive_equivalencs_from_bit_ior (tree name, const_and_copies *const_and_copies)
+{
+  if (TREE_CODE (name) == SSA_NAME)
+    {
+      tree value = fold_convert (TREE_TYPE (name), integer_zero_node);
+
+      /* This records the equivalence for the toplevel object.  */
+      record_equality (name, value, const_and_copies);
+
+      /* And we can recurse into each operand to potentially find more
+        equivalences.  */
+      gimple *def_stmt = SSA_NAME_DEF_STMT (name);
+      if (is_gimple_assign (def_stmt)
+         && gimple_assign_rhs_code (def_stmt) == BIT_IOR_EXPR)
+       {
+         derive_equivalencs_from_bit_ior (gimple_assign_rhs1 (def_stmt),
+                                          const_and_copies);
+         derive_equivalencs_from_bit_ior (gimple_assign_rhs2 (def_stmt),
+                                          const_and_copies);
+       }
+    }
+}
+
 /* Record into CONST_AND_COPIES and AVAIL_EXPRS_STACK any equivalences implied
    by traversing edge E (which are cached in E->aux).
 
@@ -711,7 +738,28 @@ record_temporary_equivalences (edge e,
       /* If we have 0 = COND or 1 = COND equivalences, record them
         into our expression hash tables.  */
       for (i = 0; edge_info->cond_equivalences.iterate (i, &eq); ++i)
-       avail_exprs_stack->record_cond (eq);
+       {
+         avail_exprs_stack->record_cond (eq);
+
+         /* If the condition is testing that X == 0 is true or X != 0 is false
+            and X is set from a BIT_IOR_EXPR, then we can record equivalences
+            for the operands of the BIT_IOR_EXPR (and recurse on those).  */
+         tree op0 = eq->cond.ops.binary.opnd0;
+         tree op1 = eq->cond.ops.binary.opnd1;
+         if (TREE_CODE (op0) == SSA_NAME && integer_zerop (op1))
+           {
+             enum tree_code code = eq->cond.ops.binary.op;
+             if ((code == EQ_EXPR && eq->value == boolean_true_node)
+                 || (code == NE_EXPR && eq->value == boolean_false_node))
+               derive_equivalencs_from_bit_ior (op0, const_and_copies);
+
+             /* TODO: We could handle BIT_AND_EXPR in a similar fashion
+                recording that the operands have a nonzero value.  */
+
+             /* TODO: We can handle more cases here, particularly when OP0 is
+                known to have a boolean range.  */
+           }
+       }
 
       tree lhs = edge_info->lhs;
       if (!lhs || TREE_CODE (lhs) != SSA_NAME)