re PR tree-optimization/56355 (abs and multiplication)

2013-03-20  Marc Glisse  <marc.glisse@inria.fr>

	PR tree-optimization/56355
gcc/
	* fold-const.c (tree_binary_nonnegative_warnv_p) <MULT_EXPR>:
	Also handle integers with undefined overflow.

gcc/testsuite/
	* gcc.dg/pr56355-1.c: New file.

From-SVN: r196829

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 9873aca..1f4bb6d 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2013-03-20  Marc Glisse  <marc.glisse@inria.fr>
+
+       PR tree-optimization/56355
+       * fold-const.c (tree_binary_nonnegative_warnv_p) <MULT_EXPR>:
+       Also handle integers with undefined overflow.
+
 2013-03-20  Catherine Moore  <clm@codesourcery.com>
            Maciej W. Rozycki  <macro@codesourcery.com>
            Tom de Vries  <tom@codesourcery.com>

diff --git a/gcc/fold-const.c b/gcc/fold-const.c
index de7117e..ae03938 100644 (file)
--- a/gcc/fold-const.c
+++ b/gcc/fold-const.c
@@ -15294,15 +15294,18 @@ tree_binary_nonnegative_warnv_p (enum tree_code code, tree type, tree op0,
       break;
 
     case MULT_EXPR:
-      if (FLOAT_TYPE_P (type))
+      if (FLOAT_TYPE_P (type) || TYPE_OVERFLOW_UNDEFINED (type))
        {
-         /* x * x for floating point x is always non-negative.  */
-         if (operand_equal_p (op0, op1, 0))
-           return true;
-         return (tree_expr_nonnegative_warnv_p (op0,
-                                                strict_overflow_p)
-                 && tree_expr_nonnegative_warnv_p (op1,
-                                                   strict_overflow_p));
+         /* x * x is always non-negative for floating point x
+            or without overflow.  */
+         if (operand_equal_p (op0, op1, 0)
+             || (tree_expr_nonnegative_warnv_p (op0, strict_overflow_p)
+                 && tree_expr_nonnegative_warnv_p (op1, strict_overflow_p)))
+           {
+             if (TYPE_OVERFLOW_UNDEFINED (type))
+               *strict_overflow_p = true;
+             return true;
+           }
        }
 
       /* zero_extend(x) * zero_extend(y) is non-negative if x and y are

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index a3f78a7..ef7bdd6 100644 (file)
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2013-03-20  Marc Glisse  <marc.glisse@inria.fr>
+
+       PR tree-optimization/56355
+       * gcc.dg/pr56355-1.c: New file.
+
 2013-03-20  Catherine Moore  <clm@codesourcery.com>
            Richard Sandiford <rdsandiford@googlemail.com>
 

diff --git a/gcc/testsuite/gcc.dg/pr56355-1.c b/gcc/testsuite/gcc.dg/pr56355-1.c
new file mode 100644 (file)
index 0000000..08b9c2e
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr56355-1.c
@@ -0,0 +1,8 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -Wstrict-overflow=4" } */
+
+int
+f (int i)
+{
+  return __builtin_abs (i * i); /* { dg-warning "assuming signed overflow" } */
+}