Differential D28994

riscv: Add a soft-float implementation of fabs()
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Authored by arichardson on Mar 1 2021, 11:30 AM.

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dim
jrtc27

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rG524b018d2004: riscv: Add a soft-float implementation of fabs()

Summary

We could just use a C implementation using __builtin_fabs(), but using
this assembly version guarantees that there is no additional prolog/epilog
code. Additionally, clang generates worse code for masking off the top bit
than GCC: https://bugs.llvm.org/show_bug.cgi?id=49377.

Test Plan

Should fix RISCV64 softfloat world build

Diff Detail

Repository

rG FreeBSD src repository

Lint

Automatic diff as part of commit; lint not applicable.

Unit

Automatic diff as part of commit; unit tests not applicable.

Event Timeline

arichardson created this revision.Mar 1 2021, 11:30 AM

Herald added a subscriber: imp. · View Herald TranscriptMar 1 2021, 11:30 AM

arichardson requested review of this revision.Mar 1 2021, 11:30 AM

Harbormaster completed remote builds in B37471: Diff 84888.Mar 1 2021, 11:31 AM

arichardson edited the test plan for this revision. (Show Details)Mar 1 2021, 11:31 AM

arichardson added a reviewer: jrtc27.

LGTM

This revision is now accepted and ready to land.Mar 1 2021, 11:32 AM

Closed by commit rG524b018d2004: riscv: Add a soft-float implementation of fabs() (authored by arichardson). · Explain WhyMar 1 2021, 12:57 PM

This revision was automatically updated to reflect the committed changes.

arichardson added a commit: rG524b018d2004: riscv: Add a soft-float implementation of fabs().

dim mentioned this in rG27e68baf24f1: Build lib/msun tests with compiler builtins disabled.Mar 9 2021, 8:22 PM

dim mentioned this in rGe91ff79b2811: Build lib/msun tests with compiler builtins disabled.

dim mentioned this in rG7ee9798bad0b: Build lib/msun tests with compiler builtins disabled.

Revision Contents
Changeset List

Path

Size

lib/

libc/

riscv/

gen/

11 lines

Diff 84894

lib/libc/riscv/gen/fabs.S

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