[Bug tree-optimization/121595] fabs(a+0.0) -> fabs(a) for non trapping case

[matteo.nicoli001 at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121595

Matteo Nicoli <matteo.nicoli001 at gmail dot com> changed:

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  Attachment #62175|0                           |1
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--- Comment #7 from Matteo Nicoli <matteo.nicoli001 at gmail dot com> ---
Created attachment 62178
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=62178&action=edit
Patch for 121595 updated

Thank you Andrew for your review.
Patch updated. I simplified the expression in `gcc/match.pd` and modified
`gcc.dg/fabs-plus-zero-2.c` by adding those cases:

+double f1(double a) { return __builtin_fabs(a + 0.0); }
+double f2(double a) { return __builtin_fabs(a + -0.0); }
+double f3(double a) { return __builtin_fabs(a - 0.0); }
+double f4(double a) { return __builtin_fabs(a - -0.0); }