re PR tree-optimization/14752 ([tree-ssa] "~a" should be changed to "a" if used in the condition of an if statement)

	PR middle-end/14752
	* c-common.c (c_common_truthvalue_conversion) <MINUS_EXPR,
	BIT_XOR_EXPR, BIT_AND_EXPR>: Delete.  Let fold optimize these
	cases via the construction of "expr != 0".

	* gcc.dg/fold-eqandshift-2.c: New test case.

From-SVN: r111575

4 files changed, 34 insertions, 31 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 2b678ab..7b11e7b 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,10 @@
+2006-02-28  Roger Sayle  <roger@eyesopen.com>
+
+	PR middle-end/14752
+	* c-common.c (c_common_truthvalue_conversion) <MINUS_EXPR,
+	BIT_XOR_EXPR, BIT_AND_EXPR>: Delete.  Let fold optimize these
+	cases via the construction of "expr != 0".
+
 2006-02-28  Steven Bosscher  <stevenb.gcc@gmail.com>
 
 	* alias.c (alias_invariant, alias_invariant_size): Remove.
diff --git a/gcc/c-common.c b/gcc/c-common.c
index 4f8ab8e..1a11c3b 100644
--- a/gcc/c-common.c
+++ b/gcc/c-common.c
@@ -2537,37 +2537,6 @@ c_common_truthvalue_conversion (tree expr)
 	return c_common_truthvalue_conversion (TREE_OPERAND (expr, 0));
       break;
 
-    case MINUS_EXPR:
-      /* Perhaps reduce (x - y) != 0 to (x != y).  The expressions
-	 aren't guaranteed to the be same for modes that can represent
-	 infinity, since if x and y are both +infinity, or both
-	 -infinity, then x - y is not a number.
-
-	 Note that this transformation is safe when x or y is NaN.
-	 (x - y) is then NaN, and both (x - y) != 0 and x != y will
-	 be false.  */
-      if (HONOR_INFINITIES (TYPE_MODE (TREE_TYPE (TREE_OPERAND (expr, 0)))))
-	break;
-      /* Fall through....  */
-    case BIT_XOR_EXPR:
-      /* This and MINUS_EXPR can be changed into a comparison of the
-	 two objects.  */
-      if (TREE_TYPE (TREE_OPERAND (expr, 0))
-	  == TREE_TYPE (TREE_OPERAND (expr, 1)))
-	return fold_build2 (NE_EXPR, truthvalue_type_node,
-			    TREE_OPERAND (expr, 0), TREE_OPERAND (expr, 1));
-      return fold_build2 (NE_EXPR, truthvalue_type_node,
-			  TREE_OPERAND (expr, 0),
-			  fold_convert (TREE_TYPE (TREE_OPERAND (expr, 0)),
-					TREE_OPERAND (expr, 1)));
-
-    case BIT_AND_EXPR:
-      if (integer_onep (TREE_OPERAND (expr, 1))
-	  && TREE_TYPE (expr) != truthvalue_type_node)
-	/* Using convert here would cause infinite recursion.  */
-	return build1 (NOP_EXPR, truthvalue_type_node, expr);
-      break;
-
     case MODIFY_EXPR:
       if (!TREE_NO_WARNING (expr))
 	warning (OPT_Wparentheses,
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index e0af455..5b2507c 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2006-02-28  Roger Sayle  <roger@eyesopen.com>
+
+	PR middle-end/14752
+	* gcc.dg/fold-eqandshift-2.c: New test case.
+
 2006-02-28  Richard Guenther  <rguenther@suse.de>
 
 	* gcc.dg/tree-ssa/pr26421.c: Fix testcase to force struct
diff --git a/gcc/testsuite/gcc.dg/fold-eqandshift-2.c b/gcc/testsuite/gcc.dg/fold-eqandshift-2.c
new file mode 100644
index 0000000..14ffb85
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/fold-eqandshift-2.c
@@ -0,0 +1,22 @@
+/* PR middle-end/14752 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-original" } */
+
+void bar (void);
+
+void foo (unsigned int a)
+{
+  if ((a >> 2) & 1)
+    bar ();
+}
+
+void baz (unsigned int b)
+{
+  if ((~b >> 2) & 1)
+    bar ();
+}
+
+/* { dg-final { scan-tree-dump-times "\\(a \& 4\\) != 0" 1 "original" } } */
+/* { dg-final { scan-tree-dump-times "\\(b \& 4\\) == 0" 1 "original" } } */
+/* { dg-final { cleanup-tree-dump "original" } } */
+