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From: "joseph at codesourcery dot com" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug libgcc/102017] libgcc ieee754-df.S for arm does not support
 exceptions
Date: Mon, 23 Aug 2021 19:51:15 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D102017

--- Comment #2 from joseph at codesourcery dot com <joseph at codesourcery =
dot com> ---
If you want to support exceptions and rounding modes for double precision=20
on processors with hardware support for single-precision only=20
floating-point arithmetic, I suggest using soft-fp instead of this=20
Arm-specific code; lots of configurations use soft-fp integrated with=20
hardware exceptions and rounding modes like that (e.g. for binary128=20
TFmode arithmetic on architectures without hardware support for it but=20
with hardware SFmode and DFmode support).

If you want to support exceptions, rounding modes or both on processors=20
with no hardware floating-point, you have the complication of needing=20
working TLS support from the runtime environment (if the floating-point=20
code might ever be used in an environment with threads), because=20
exceptions and rounding modes are thread-local (not global) state.=