From 794e7d1ab2d7afe70fe0dd87ca8174ac860413e4 Mon Sep 17 00:00:00 2001
From: Niklas Fiekas <niklas.fiekas@backscattering.de>
Date: Mon, 15 Jun 2020 14:33:48 +0200
Subject: bpo-29782: Consolidate _Py_Bit_Length() (GH-20739)

In GH-2866, _Py_Bit_Length() was added to pymath.h for lack of a better
location. GH-20518 added a more appropriate header file for bit utilities. It
also shows how to properly use intrinsics. This allows reconsidering bpo-29782.

* Move the function to the new header.
* Changed return type to match __builtin_clzl() and reviewed usage.
* Use intrinsics where available.
* Pick a fallback implementation suitable for inlining.
---
 Python/pymath.c | 15 ---------------
 1 file changed, 15 deletions(-)

(limited to 'Python/pymath.c')

diff --git a/Python/pymath.c b/Python/pymath.c
index a08a0e7961..24b804223e 100644
--- a/Python/pymath.c
+++ b/Python/pymath.c
@@ -79,18 +79,3 @@ round(double x)
     return copysign(y, x);
 }
 #endif /* HAVE_ROUND */
-
-static const unsigned int BitLengthTable[32] = {
-    0, 1, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4,
-    5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5
-};
-
-unsigned int _Py_bit_length(unsigned long d) {
-   unsigned int d_bits = 0;
-   while (d >= 32) {
-       d_bits += 6;
-       d >>= 6;
-   }
-   d_bits += BitLengthTable[d];
-   return d_bits;
-}
-- 
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