PR tree-optimization/67953

	* match.pd (X - (X / Y) * Y): Don't change signedness of @0.

	* gcc.dg/fold-minus-6.c (fn4): Change the type of A to
	unsigned.
	* gcc.dg/torture/pr67953.c: New test.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@228839 138bc75d-0d04-0410-961f-82ee72b054a4

5 files changed, 51 insertions, 2 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 5a0fde82ca7..6dec962d283 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2015-10-15  Marek Polacek  <polacek@redhat.com>
+
+	PR tree-optimization/67953
+	* match.pd (X - (X / Y) * Y): Don't change signedness of @0.
+
 2015-10-15  Jiong Wang  <jiong.wang@arm.com>
 
 	* config.gcc: Recognize "." in architecture base name for AArch64.
diff --git a/gcc/match.pd b/gcc/match.pd
index 655c9ffcf26..24e19a96472 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -267,7 +267,8 @@ along with GCC; see the file COPYING3.  If not see
 /* X - (X / Y) * Y is the same as X % Y.  */
 (simplify
  (minus (convert1? @0) (convert2? (mult (trunc_div @0 @1) @1)))
- (if (INTEGRAL_TYPE_P (type) || VECTOR_INTEGER_TYPE_P (type))
+ (if ((INTEGRAL_TYPE_P (type) || VECTOR_INTEGER_TYPE_P (type))
+      && TYPE_UNSIGNED (TREE_TYPE (@0)) == TYPE_UNSIGNED (type))
   (trunc_mod (convert @0) (convert @1))))
 
 /* Optimize TRUNC_MOD_EXPR by a power of two into a BIT_AND_EXPR,
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index f45ab81e5ca..631d8a7b613 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,10 @@
+2015-10-15  Marek Polacek  <polacek@redhat.com>
+
+	PR tree-optimization/67953
+	* gcc.dg/fold-minus-6.c (fn4): Change the type of A to
+	unsigned.
+	* gcc.dg/torture/pr67953.c: New test.
+
 2015-10-14  Jeff Law  <law@redhat.com>
 
 	* gcc.dg/tree-ssa/ssa-dom-thread-2.c: Deleted.  The six functions
diff --git a/gcc/testsuite/gcc.dg/fold-minus-6.c b/gcc/testsuite/gcc.dg/fold-minus-6.c
index 1c22c252f72..153545266d8 100644
--- a/gcc/testsuite/gcc.dg/fold-minus-6.c
+++ b/gcc/testsuite/gcc.dg/fold-minus-6.c
@@ -20,7 +20,7 @@ fn3 (long int x)
 }
 
 int
-fn4 (int a, int b)
+fn4 (unsigned int a, int b)
 {
   return a - (unsigned) ((a / b) * b);
 }
diff --git a/gcc/testsuite/gcc.dg/torture/pr67953.c b/gcc/testsuite/gcc.dg/torture/pr67953.c
new file mode 100644
index 00000000000..68ff0132425
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr67953.c
@@ -0,0 +1,36 @@
+/* PR tree-optimization/67953 */
+/* { dg-do run } */
+
+unsigned int
+fn1 (signed int a)
+{
+  return (unsigned int) a - ((a / 3) * 3);
+}
+
+unsigned int
+fn2 (signed int a)
+{
+  return a - ((a / 3) * 3);
+}
+
+unsigned int
+fn3 (int a)
+{
+  return a - (unsigned) ((a / 3) * 3);
+}
+
+signed int
+fn4 (int a)
+{
+  return (unsigned) a - (unsigned) ((a / 3) * 3);
+}
+
+int
+main ()
+{
+  if (fn1 (-5) != -2
+      || fn2 (-5) != -2
+      || fn3 (-5) != -2
+      || fn4 (-5) != -2)
+    __builtin_abort ();
+}