match: X % Y < Y -> Y >= 0 and X % Y >= Y -> Y < 0 [PR125737]

We had a pattern for `X % Y < Y` when X and Y where non-negative but
this can be generalized for all values. And also we can handle `>=` too.

Bootstrapped and tested on x86_64-pc-linux-gnu

	PR tree-optimization/125737

gcc:
	* match.pd: Optimize X % Y < Y -> Y >= 0 and X % Y >= Y -> Y < 0

gcc/testsuite:
	* gcc.dg/pr125737.c: Move test to pr125737-1.c.
	* gcc.dg/pr125737-1.c: Add test for (a % b) >= b when a and b are nonnegative.
	* gcc.dg/pr125737-2.c: New test for (a % b) {<,>=} b.

Signed-off-by: Kael Franco <kaelfandrew@gmail.com>

diff --git a/gcc/match.pd b/gcc/match.pd
index 5d589989bd1e977e3e438c1ac0a82406bee6ccf0..ddf3b61638ce0f89d84310b59e9925aaba541045 100644 (file)
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -1746,11 +1746,13 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
                    wi::max_value (TYPE_PRECISION (TREE_TYPE (@0)), SIGNED)))
    (resop @2 { build_zero_cst (TREE_TYPE (@2)); }))))
 
-/* X % Y is smaller than Y.  */
-(for cmp (lt ge)
+/* X % Y < Y -> Y >= 0
+   X % Y >= Y -> Y < 0  */
+(for ltge (lt ge)
+     gelt (ge lt)
  (simplify
-  (cmp:c (trunc_mod tree_expr_nonnegative_p@0 tree_expr_nonnegative_p@1) @1)
-  { constant_boolean_node (cmp == LT_EXPR, type); }))
+  (ltge:c (trunc_mod @0 @1) @1)
+  (gelt @1 { build_zero_cst (TREE_TYPE (@1)); })))
 
 /* x | ~0 -> ~0  */
 (simplify

diff --git a/gcc/testsuite/gcc.dg/pr125737.c b/gcc/testsuite/gcc.dg/pr125737-1.c
similarity index 51%
rename from gcc/testsuite/gcc.dg/pr125737.c
rename to gcc/testsuite/gcc.dg/pr125737-1.c
index 93d0fcd215afc09163460a059be100442ef2d93f..85347a63c7f2d1b916f13a8333ea06ff6d7d0f39 100644 (file)
--- a/gcc/testsuite/gcc.dg/pr125737.c
+++ b/gcc/testsuite/gcc.dg/pr125737-1.c
@@ -9,4 +9,12 @@ f (unsigned short a, unsigned short b) {
   return c < bb;
 }
 
-/* { dg-final { scan-tree-dump-times "return 1;" 1 "optimized" } } */
+int
+g (unsigned short a, unsigned short b) {
+  int aa = a;
+  int bb = b;
+  int c = aa % bb;
+  return (c >= bb) == 0;
+}
+
+/* { dg-final { scan-tree-dump-times "return 1;" 2 "optimized" } } */

diff --git a/gcc/testsuite/gcc.dg/pr125737-2.c b/gcc/testsuite/gcc.dg/pr125737-2.c
new file mode 100644 (file)
index 0000000..0090fa0
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr125737-2.c
@@ -0,0 +1,14 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+
+_Bool
+a_mod_b_lt_b (int a, int b) {
+  return ((a % b) < b) == (b >= 0);
+}
+
+_Bool
+a_mod_b_ge_b (int a, int b) {
+  return ((a % b) >= b) == (b < 0);
+}
+
+/* { dg-final { scan-tree-dump-times "return 1;" 2 "optimized" } } */