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. --- gcc/match.pd | 10 ++++++++++ gcc/testsuite/gcc.dg/tree-ssa/abs-3.c | 13 +++++++++++++ gcc/testsuite/gcc.dg/tree-ssa/abs-4.c | 13 +++++++++++++ 3 files changed, 36 insertions(+) create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/abs-3.c create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/abs-4.c diff --git a/gcc/match.pd b/gcc/match.pd index 26395880047..b025fb8facf 100644 --- 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 index 00000000000..d2638e8f4c5 --- /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 index 00000000000..6197519faf7 --- /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"} } */ -- 2.31.1