[all-commits] [llvm/llvm-project] d92e54: [libc] Use __builtin_clz to find leading 1 in hypot
Siva Chandra via All-commits
all-commits at lists.llvm.org
Thu Jan 20 15:33:04 PST 2022
Branch: refs/heads/main
Home: https://github.com/llvm/llvm-project
Commit: d92e5412ea571158b5b524855d19b5eafa0567ce
https://github.com/llvm/llvm-project/commit/d92e5412ea571158b5b524855d19b5eafa0567ce
Author: Clint Caywood <caywood at google.com>
Date: 2022-01-20 (Thu, 20 Jan 2022)
Changed paths:
M libc/src/__support/FPUtil/Hypot.h
Log Message:
-----------
[libc] Use __builtin_clz to find leading 1 in hypot
This is an optimization that using a single CPU instruction on supported
architectures (amd64 and aarch64, but possibly others) to replace what was
previously an iterative look-up-table algorithm.
Originally I suggested using inline assembly for this in
https://reviews.llvm.org/D117584.
Reviewed By: lntue, sivachandra
Differential Revision: https://reviews.llvm.org/D117684
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