[libc-commits] [libc] 6638cee - [libc] Remove redundant and incorrect comments in `logf.cpp` (#188236)

[via libc-commits]

Author: Zorojuro
Date: 2026-03-24T14:35:40Z
New Revision: 6638cee0d8db18cf19b9d832e8c5f0be12b4f1c8

URL: https://github.com/llvm/llvm-project/commit/6638cee0d8db18cf19b9d832e8c5f0be12b4f1c8
DIFF: https://github.com/llvm/llvm-project/commit/6638cee0d8db18cf19b9d832e8c5f0be12b4f1c8.diff

LOG: [libc] Remove redundant and incorrect comments in `logf.cpp` (#188236)

This PR intends to fix the nit (mostly caused during the refactor in
693a018dcf08e )

- During refactor we move the implementation along with the explanation
comments to header.
```CPP
// This is an algorithm for log(x) in single precision which is correctly
// rounded for all rounding modes, based on the implementation of log(x) from
// the RLIBM project at:
// https://people.cs.rutgers.edu/~sn349/rlibm

// Step 1 - Range reduction:
//   For x = 2^m * 1.mant, log(x) = m * log(2) + log(1.m)
//   If x is denormal, we normalize it by multiplying x by 2^23 and subtracting
.....
// Symposium on Principles of Programming Languages (POPL-2022), Philadelphia,
// USA, January 16-22, 2022.
// https://people.cs.rutgers.edu/~sn349/papers/rlibmall-popl-2022.pdf
```

Though the explanation comments were copied and moved to header in
d2492c1 . It wasn't deleted from the `cpp` file.
Along with this in the same,

`#include "src/__support/math/logf.h" // Lookup table for (1/f) and
log(f)`

is wrong as it is actually for 
`#include "src/__support/math/common_constants.h" // Lookup table for
(1/f) and log(f)`

Added: 
    

Modified: 
    libc/src/math/generic/logf.cpp

Removed: 
    


################################################################################
diff  --git a/libc/src/math/generic/logf.cpp b/libc/src/math/generic/logf.cpp
index 863a9378d3135..3c3676de6071f 100644
--- a/libc/src/math/generic/logf.cpp
+++ b/libc/src/math/generic/logf.cpp
@@ -7,39 +7,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "src/math/logf.h"
-#include "src/__support/math/logf.h" // Lookup table for (1/f) and log(f)
-
-// This is an algorithm for log(x) in single precision which is correctly
-// rounded for all rounding modes, based on the implementation of log(x) from
-// the RLIBM project at:
-// https://people.cs.rutgers.edu/~sn349/rlibm
-
-// Step 1 - Range reduction:
-//   For x = 2^m * 1.mant, log(x) = m * log(2) + log(1.m)
-//   If x is denormal, we normalize it by multiplying x by 2^23 and subtracting
-//   m by 23.
-
-// Step 2 - Another range reduction:
-//   To compute log(1.mant), let f be the highest 8 bits including the hidden
-// bit, and d be the 
diff erence (1.mant - f), i.e. the remaining 16 bits of the
-// mantissa. Then we have the following approximation formula:
-//   log(1.mant) = log(f) + log(1.mant / f)
-//               = log(f) + log(1 + d/f)
-//               ~ log(f) + P(d/f)
-// since d/f is sufficiently small.
-//   log(f) and 1/f are then stored in two 2^7 = 128 entries look-up tables.
-
-// Step 3 - Polynomial approximation:
-//   To compute P(d/f), we use a single degree-5 polynomial in double precision
-// which provides correct rounding for all but few exception values.
-//   For more detail about how this polynomial is obtained, please refer to the
-// paper:
-//   Lim, J. and Nagarakatte, S., "One Polynomial Approximation to Produce
-// Correctly Rounded Results of an Elementary Function for Multiple
-// Representations and Rounding Modes", Proceedings of the 49th ACM SIGPLAN
-// Symposium on Principles of Programming Languages (POPL-2022), Philadelphia,
-// USA, January 16-22, 2022.
-// https://people.cs.rutgers.edu/~sn349/papers/rlibmall-popl-2022.pdf
+#include "src/__support/math/logf.h"
 
 namespace LIBC_NAMESPACE_DECL {