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From: "adhemerval.zanella at linaro dot org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/94194] x86: Provide feraiseexcept builtins
Date: Mon, 16 Mar 2020 19:28:28 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D94194

--- Comment #2 from Adhemerval Zanella <adhemerval.zanella at linaro dot or=
g> ---
Afaik the libc implementation is free to set any macro value for FE_*, alth=
ough
glibc and other implementations I am awre of try to make is related to
architecture values when it does make sense (and it also tend to simplify t=
he
implementation).

So I would expect that the compiler either would need to export a
system-neutral value (GCC_FE_* or something related) with the drawback it w=
ould
not be a direct replacement for the system library call (as other builtins =
tend
to be) or define functions that does not use input arguments (something lik=
e=20
__builtin_feraiseexcept_div_by_zero). For -fno-trapping-math I would expect=
 to
be a nop in such a scenario, although I haven't given much thought about it.

However, I opened this bug more to check if this optimization would be worth
implementing. My take is to remove it from glibc installed headers [1], and=
 my
impression is this should not add much from the compiler side of view as we=
ll.

[1] https://sourceware.org/pipermail/libc-alpha/2020-March/111775.html=