Transform (x / y) != 0 to x >=y and (x / y) == 0 to x < y if x, y are unsigned

[Prathamesh Kulkarni]

Hi,
This patch adds the transforms mentioned in $subject.
Bootstrap+test in progress on x86_64-unknown-linux-gnu.
OK to commit if passes ?

Thanks,
Prathamesh

2017-09-15  Prathamesh Kulkarni  <prathamesh.kulka...@linaro.org>

        * match.pd ((X / Y) == 0 -> X < Y): New pattern.
        ((X / Y) != 0 -> X >= Y): Likewise.

testsuite/
        * gcc.dg/tree-ssa/cmpdiv.c: New test.

diff --git a/gcc/match.pd b/gcc/match.pd
index dbfceaf10a5..0e1b59c9c10 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -1266,6 +1266,18 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
           || TYPE_OVERFLOW_WRAPS (TREE_TYPE (@0))))
    (op @1 @0))))
 
+/* (X / Y) == 0 -> X < Y if X, Y are unsigned.  */
+(simplify
+  (eq (trunc_div @0 @1) integer_zerop)
+  (if (TYPE_UNSIGNED (TREE_TYPE(@0)) && TYPE_UNSIGNED (TREE_TYPE (@1)))
+    (lt @0 @1)))
+
+/* (X / Y) != 0 -> X >= Y, if X, Y are unsigned.  */
+(simplify
+  (ne (trunc_div @0 @1) integer_zerop)
+  (if (TYPE_UNSIGNED (TREE_TYPE(@0)) && TYPE_UNSIGNED (TREE_TYPE (@1)))
+    (ge @0 @1)))
+
 /* X == C - X can never be true if C is odd.  */
 (for cmp (eq ne)
  (simplify
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/cmpdiv.c 
b/gcc/testsuite/gcc.dg/tree-ssa/cmpdiv.c
new file mode 100644
index 00000000000..14161f5ea6f
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/cmpdiv.c
@@ -0,0 +1,18 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-optimized-raw" } */
+
+_Bool f1(unsigned x, unsigned y)
+{
+  unsigned t1 = x / y;
+  _Bool t2 = (t1 != 0);
+  return t2;
+}
+
+_Bool f2(unsigned x, unsigned y)
+{
+  unsigned t1 = x / y;
+  _Bool t2 = (t1 == 0);
+  return t2;
+}
+
+/* { dg-final { scan-tree-dump-not "trunc_div_expr" "optimized" } } */