MATCH: Add ABSU<a> == 0 to a == 0 simplification

There is already an `ABS<a> == 0` to `a == 0` pattern,
this just extends that to ABSU too.

OK? Bootstrapped and tested on x86_64-linux-gnu with no regressions.

	PR tree-optimization/109722

gcc/ChangeLog:

	* match.pd: Extend the `ABS<a> == 0` pattern
	to cover `ABSU<a> == 0` too.

gcc/testsuite/ChangeLog:

	* gcc.dg/tree-ssa/abs-1.c: New test.

diff --git a/gcc/match.pd b/gcc/match.pd
index 08a4f8ebdc1e8fb82bebd27f0ca3bae539ce5bdd..ceae1c34abc121a43dbad560e1a8b47c8139fbd0 100644 (file)
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -5807,11 +5807,12 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
     (if (tem && !TREE_OVERFLOW (tem))
      (scmp @0 { tem; }))))))
 
-/* Convert ABS_EXPR<x> == 0 or ABS_EXPR<x> != 0 to x == 0 or x != 0.  */
-(for op (eq ne)
- (simplify
-  (op (abs @0) zerop@1)
-  (op @0 @1)))
+/* Convert ABS[U]_EXPR<x> == 0 or ABS[U]_EXPR<x> != 0 to x == 0 or x != 0.  */
+(for op (abs absu)
+ (for eqne (eq ne)
+  (simplify
+   (eqne (op @0) zerop@1)
+   (eqne @0 { build_zero_cst (TREE_TYPE (@0)); }))))
 
 /* From fold_sign_changed_comparison and fold_widened_comparison.
    FIXME: the lack of symmetry is disturbing.  */

diff --git a/gcc/testsuite/gcc.dg/tree-ssa/abs-1.c b/gcc/testsuite/gcc.dg/tree-ssa/abs-1.c
new file mode 100644 (file)
index 0000000..ce40411
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/abs-1.c
@@ -0,0 +1,12 @@
+/* PR tree-optimization/109722 */
+/* { dg-do compile } */
+/* { dg-options "-O -fdump-tree-gimple -fdump-tree-optimized" } */
+
+int g(signed char x){
+    x = x < 0 ? -x : x;
+    return x == 0;
+}
+
+/* This should work even if int is 16bits. */
+/* { dg-final { scan-tree-dump "ABSU_EXPR" "gimple"} } */
+/* { dg-final { scan-tree-dump-not "ABSU_EXPR" "optimized"} } */