[all-commits] [llvm/llvm-project] 9af8dc: [libc][math] Update range reduction step for log10...

[lntue via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 9af8dca70fce1538675a857e3a053f6d35b18aea
      https://github.com/llvm/llvm-project/commit/9af8dca70fce1538675a857e3a053f6d35b18aea
  Author: Tue Ly <lntue.h at gmail.com>
  Date:   2023-04-07 (Fri, 07 Apr 2023)

  Changed paths:
    M libc/docs/math/index.rst
    M libc/src/math/generic/common_constants.cpp
    M libc/src/math/generic/common_constants.h
    M libc/src/math/generic/log10f.cpp
    M libc/test/src/math/log10f_test.cpp

  Log Message:
  -----------
  [libc][math] Update range reduction step for log10f and reduce its latency.

Simplify the range reduction steps by choosing the reduction constants
carefully so that the reduced arguments v = r*m_x - 1 and v^2 are exact in double
precision, even without FMA instructions, and -2^-8 <= v < 2^-7.  This allows the
polynomial evaluations to be parallelized more efficiently.

Reviewed By: zimmermann6

Differential Revision: https://reviews.llvm.org/D147676