[PATCH] Simplify abs (copysign (x, y))

[Richard Biener]

The following adds simplification of abs (copysign (x, y)) to abs (x).

Bootstrap & regtest in progress on x86_64-unknown-linux-gnu.

Richard.

        * match.pd (abs (copysign (x, y)) -> abs (x)): New pattern.

        * gcc.dg/fold-abs-6.c: New testcase.
---
 gcc/match.pd                      | 5 +++++
 gcc/testsuite/gcc.dg/fold-abs-6.c | 9 +++++++++
 2 files changed, 14 insertions(+)
 create mode 100644 gcc/testsuite/gcc.dg/fold-abs-6.c

diff --git a/gcc/match.pd b/gcc/match.pd
index a17778fbaa6..069d832decc 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -7429,6 +7429,11 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
  (COPYSIGN_ALL @0 tree_expr_nonnegative_p@1)
  (abs @0))
 
+(simplify
+ /* fabs (copysign(x, y)) -> fabs (x).  */
+ (abs (COPYSIGN_ALL @0 @1))
+ (abs @0))
+
 (for scale (LDEXP SCALBN SCALBLN)
  /* ldexp(0, x) -> 0.  */
  (simplify
diff --git a/gcc/testsuite/gcc.dg/fold-abs-6.c 
b/gcc/testsuite/gcc.dg/fold-abs-6.c
new file mode 100644
index 00000000000..42ef9230dfd
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/fold-abs-6.c
@@ -0,0 +1,9 @@
+/* { dg-do compile } */
+/* { dg-options "-O -fdump-tree-original" } */
+
+float foo (float x, float y)
+{
+  return __builtin_fabsf (__builtin_copysignf (x, y));
+}
+
+/* { dg-final { scan-tree-dump "return ABS_EXPR <x>;" "original" } } */
-- 
2.35.3