tree 7e1c47c3f6d877272332322ba9b57f16753a9cf8
parent ef33a790c2df1cc7a18e1070107368ca036bfc39
author lntue <35648136+lntue@fuchsia.infra.roller.users.noreply.github.com> 1699320838 +0000
committer Copybara-Service <copybara-worker@google.com> 1699320977 -0800

[roll] Roll llvm-project/libc [libc][math] Implement powf function correctly rounded to all rounding modes. (#71188)

We compute `pow(x, y)` using the formula
```
  pow(x, y) = x^y = 2^(y * log2(x))
```
We follow similar steps as in `log2f(x)` and `exp2f(x)`, by breaking
down into `hi + mid + lo` parts, in which `hi` parts are computed using
the exponent field directly, `mid` parts will use look-up tables, and
`lo` parts are approximated by polynomials.

We add some speedup for common use-cases:
```
  pow(2, y) = exp2(y)
  pow(10, y) = exp10(y)
  pow(x, 2) = x * x
  pow(x, 1/2) = sqrt(x)
  pow(x, -1/2) = rsqrt(x) - to be added
```

GitOrigin-RevId: a8ab5682e0806b034ec59afafa79ea1358a54c81
Original-Revision: bfcf18edd8508218e352268d47beb679fc03deab
Change-Id: Ie8d198f3a1edf5e1cefa52a3a172ceab3ea3d4e2