Always combine comparisons or conversions from booleans.

2014-11-16  Patrick Palka  <ppalka@gcc.gnu.org>

gcc/
	PR middle-end/63790
	* tree-ssa-forwprop.c (forward_propagate_into_comparison_1):
	Always combine comparisons or conversions from booleans.

gcc/testsuite/
	PR middle-end/63790
	* gcc.dg/tree-ssa/pr21031.c: Drop XFAIL.
	* gcc.dg/tree-ssa/forwprop-29.c: New test.

From-SVN: r217638

gcc/ChangeLog

+2014-11-16  Patrick Palka  <ppalka@gcc.gnu.org>
+
+	PR middle-end/63790
+	* tree-ssa-forwprop.c (forward_propagate_into_comparison_1):
+	Always combine comparisons or conversions from booleans.
+
 2014-11-16  Jan Hubicka  <hubicka@ucw.cz>
 
 	* ipa-polymorphic-call.c

gcc/testsuite/ChangeLog

+2014-11-16  Patrick Palka  <ppalka@gcc.gnu.org>
+
+	PR middle-end/63790
+	* gcc.dg/tree-ssa/pr21031.c: Drop XFAIL.
+	* gcc.dg/tree-ssa/forwprop-29.c: New test.
+
 2014-11-16  Andrew Pinski  <apinski@cavium.com>
 
 	* gcc.c-torture/execute/memset-4.c: New test.

gcc/testsuite/gcc.dg/tree-ssa/forwprop-29.c

+/* { dg-options "-O2" } */
+
+void runtime_error (void) __attribute__ ((noreturn));
+void compiletime_error (void) __attribute__ ((noreturn, error ("")));
+
+static void
+compiletime_check_equals_1 (int *x, int y)
+{
+  int __p = *x != y;
+  if (__builtin_constant_p (__p) && __p)
+    compiletime_error ();
+  if (__p)
+    runtime_error ();
+}
+
+static void
+compiletime_check_equals_2 (int *x, int y)
+{
+  int __p = *x != y;
+  if (__builtin_constant_p (__p) && __p)
+    compiletime_error (); /* { dg-error "call to" } */
+  if (__p)
+    runtime_error ();
+}
+
+void
+foo (int *x)
+{
+  compiletime_check_equals_1 (x, 5);
+  compiletime_check_equals_2 (x, 10);
+}

gcc/testsuite/gcc.dg/tree-ssa/pr21031.c

@@ -16,5 +16,5 @@ foo (int a)
     return 0;
 }
 
-/* { dg-final { scan-tree-dump-times "Replaced" 2 "forwprop1" { xfail *-*-* } } } */
+/* { dg-final { scan-tree-dump-times "Replaced" 2 "forwprop1" } } */
 /* { dg-final { cleanup-tree-dump "forwprop1" } } */

gcc/tree-ssa-forwprop.c

@@ -442,9 +442,21 @@ forward_propagate_into_comparison_1 (gimple stmt,
       gimple def_stmt = get_prop_source_stmt (op0, false, &single_use0_p);
       if (def_stmt && can_propagate_from (def_stmt))
 	{
+	  enum tree_code def_code = gimple_assign_rhs_code (def_stmt);
+	  bool invariant_only_p = !single_use0_p;
+
 	  rhs0 = rhs_to_tree (TREE_TYPE (op1), def_stmt);
+
+	  /* Always combine comparisons or conversions from booleans.  */
+	  if (TREE_CODE (op1) == INTEGER_CST
+	      && ((CONVERT_EXPR_CODE_P (def_code)
+		   && TREE_CODE (TREE_TYPE (TREE_OPERAND (rhs0, 0)))
+		      == BOOLEAN_TYPE)
+		  || TREE_CODE_CLASS (def_code) == tcc_comparison))
+	    invariant_only_p = false;
+
 	  tmp = combine_cond_expr_cond (stmt, code, type,
-					rhs0, op1, !single_use0_p);
+					rhs0, op1, invariant_only_p);
 	  if (tmp)
 	    return tmp;
 	}