* fold-const.c (invert_tree_comparison): Always invert EQ_EXPR/NE_EXPR.

	PR tree-optimization/44683
	* tree-ssa-dom.c (record_edge_info): Record simple equivalences only if
	we can be sure that there are no signed zeros involved.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@180340 138bc75d-0d04-0410-961f-82ee72b054a4

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 2602f76..e9b48cb 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,11 @@
+2011-10-23  Eric Botcazou  <ebotcazou@adacore.com>
+
+       * fold-const.c (invert_tree_comparison): Always invert EQ_EXPR/NE_EXPR.
+
+       PR tree-optimization/44683
+       * tree-ssa-dom.c (record_edge_info): Record simple equivalences only if
+       we can be sure that there are no signed zeros involved.
+
 2011-10-23  Jan Hubicka  <jh@suse.cz>
 
        * ipa-inline.c (estimate_badness): Scale up and handle overflows.

diff --git a/gcc/fold-const.c b/gcc/fold-const.c
index a838c34..e4c2589 100644 (file)
--- a/gcc/fold-const.c
+++ b/gcc/fold-const.c
@@ -2100,15 +2100,14 @@ pedantic_non_lvalue_loc (location_t loc, tree x)
   return protected_set_expr_location_unshare (x, loc);
 }
 \f
-/* Given a tree comparison code, return the code that is the logical inverse
-   of the given code.  It is not safe to do this for floating-point
-   comparisons, except for NE_EXPR and EQ_EXPR, so we receive a machine mode
-   as well: if reversing the comparison is unsafe, return ERROR_MARK.  */
+/* Given a tree comparison code, return the code that is the logical inverse.
+   It is generally not safe to do this for floating-point comparisons, except
+   for EQ_EXPR and NE_EXPR, so we return ERROR_MARK in this case.  */
 
 enum tree_code
 invert_tree_comparison (enum tree_code code, bool honor_nans)
 {
-  if (honor_nans && flag_trapping_math)
+  if (honor_nans && flag_trapping_math && code != EQ_EXPR && code != NE_EXPR)
     return ERROR_MARK;
 
   switch (code)

diff --git a/gcc/tree-ssa-dom.c b/gcc/tree-ssa-dom.c
index 8bfc91a..949acf1 100644 (file)
--- a/gcc/tree-ssa-dom.c
+++ b/gcc/tree-ssa-dom.c
@@ -1610,12 +1610,15 @@ record_edge_info (basic_block bb)
             {
               tree cond = build2 (code, boolean_type_node, op0, op1);
               tree inverted = invert_truthvalue_loc (loc, cond);
+              bool can_infer_simple_equiv
+                = !(HONOR_SIGNED_ZEROS (TYPE_MODE (TREE_TYPE (op0)))
+                    && real_zerop (op0));
               struct edge_info *edge_info;
 
               edge_info = allocate_edge_info (true_edge);
               record_conditions (edge_info, cond, inverted);
 
-              if (code == EQ_EXPR)
+              if (can_infer_simple_equiv && code == EQ_EXPR)
                 {
                   edge_info->lhs = op1;
                   edge_info->rhs = op0;
@@ -1624,7 +1627,7 @@ record_edge_info (basic_block bb)
               edge_info = allocate_edge_info (false_edge);
               record_conditions (edge_info, inverted, cond);
 
-              if (TREE_CODE (inverted) == EQ_EXPR)
+              if (can_infer_simple_equiv && TREE_CODE (inverted) == EQ_EXPR)
                 {
                   edge_info->lhs = op1;
                   edge_info->rhs = op0;
@@ -1632,17 +1635,20 @@ record_edge_info (basic_block bb)
             }
 
           else if (TREE_CODE (op0) == SSA_NAME
-                   && (is_gimple_min_invariant (op1)
-                       || TREE_CODE (op1) == SSA_NAME))
+                   && (TREE_CODE (op1) == SSA_NAME
+                       || is_gimple_min_invariant (op1)))
             {
               tree cond = build2 (code, boolean_type_node, op0, op1);
               tree inverted = invert_truthvalue_loc (loc, cond);
+              bool can_infer_simple_equiv
+                = !(HONOR_SIGNED_ZEROS (TYPE_MODE (TREE_TYPE (op1)))
+                    && (TREE_CODE (op1) == SSA_NAME || real_zerop (op1)));
               struct edge_info *edge_info;
 
               edge_info = allocate_edge_info (true_edge);
               record_conditions (edge_info, cond, inverted);
 
-              if (code == EQ_EXPR)
+              if (can_infer_simple_equiv && code == EQ_EXPR)
                 {
                   edge_info->lhs = op0;
                   edge_info->rhs = op1;
@@ -1651,7 +1657,7 @@ record_edge_info (basic_block bb)
               edge_info = allocate_edge_info (false_edge);
               record_conditions (edge_info, inverted, cond);
 
-              if (TREE_CODE (inverted) == EQ_EXPR)
+              if (can_infer_simple_equiv && TREE_CODE (inverted) == EQ_EXPR)
                 {
                   edge_info->lhs = op0;
                   edge_info->rhs = op1;