MATCH: Add pattern for `signbit(x) ? x : -x` into abs (and swapped)

This adds a simple pattern to match.pd for `signbit(x) ? x : -x`
into abs<x>. This can be done for all types even ones that honor
signed zeros and NaNs because both signbit and - are considered
only looking at/touching the sign bit of those types and does
not trap either.

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

	PR tree-optimization/109829

gcc/ChangeLog:

	* match.pd: Add pattern for `signbit(x) !=/== 0 ? x : -x`.

gcc/testsuite/ChangeLog:

	* gcc.dg/tree-ssa/abs-3.c: New test.
	* gcc.dg/tree-ssa/abs-4.c: New test.

diff --git a/gcc/match.pd b/gcc/match.pd
index 26395880047b6da3af7f5c0f603792954f7bac52..b025fb8facf25b2ae304346cfbdd31986cd46418 100644 (file)
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -7439,6 +7439,16 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
        && TREE_CODE (@0) != INTEGER_CST)
    (op @0 (ext @1 @2)))))
 
+/* signbit(x) != 0 ? -x : x -> abs(x)
+   signbit(x) == 0 ? -x : x -> -abs(x) */
+(for sign (SIGNBIT)
+ (for neeq (ne eq)
+  (simplify
+   (cond (neeq (sign @0) integer_zerop) (negate @0) @0)
+    (if (neeq == NE_EXPR)
+     (abs @0)
+     (negate (abs @0))))))
+
 (simplify
  /* signbit(x) -> 0 if x is nonnegative.  */
  (SIGNBIT tree_expr_nonnegative_p@0)

diff --git a/gcc/testsuite/gcc.dg/tree-ssa/abs-3.c b/gcc/testsuite/gcc.dg/tree-ssa/abs-3.c
new file mode 100644 (file)
index 0000000..d2638e8
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/abs-3.c
@@ -0,0 +1,13 @@
+/* { dg-do compile } */
+/* { dg-options "-O1 -fdump-tree-optimized" } */
+/* PR tree-optimization/109829 */
+
+float abs_f(float x) { return __builtin_signbit(x) ? -x : x; }
+double abs_d(double x) { return __builtin_signbit(x) ? -x : x; }
+long double abs_ld(long double x) { return __builtin_signbit(x) ? -x : x; }
+
+
+/* __builtin_signbit(x) ? -x : x. Should be convert into ABS_EXP<x> */
+/* { dg-final { scan-tree-dump-not "signbit" "optimized"} } */
+/* { dg-final { scan-tree-dump-not "= -" "optimized"} } */
+/* { dg-final { scan-tree-dump-times "= ABS_EXPR" 3 "optimized"} } */

diff --git a/gcc/testsuite/gcc.dg/tree-ssa/abs-4.c b/gcc/testsuite/gcc.dg/tree-ssa/abs-4.c
new file mode 100644 (file)
index 0000000..6197519
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/abs-4.c
@@ -0,0 +1,13 @@
+/* { dg-do compile } */
+/* { dg-options "-O1 -fdump-tree-optimized" } */
+/* PR tree-optimization/109829 */
+
+float abs_f(float x) { return __builtin_signbit(x) ? x : -x; }
+double abs_d(double x) { return __builtin_signbit(x) ? x : -x; }
+long double abs_ld(long double x) { return __builtin_signbit(x) ? x : -x; }
+
+
+/* __builtin_signbit(x) ? x : -x. Should be convert into - ABS_EXP<x> */
+/* { dg-final { scan-tree-dump-not "signbit" "optimized"} } */
+/* { dg-final { scan-tree-dump-times "= ABS_EXPR" 3 "optimized"} } */
+/* { dg-final { scan-tree-dump-times "= -" 3 "optimized"} } */