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Re: Missing _BitScanReverse64()

From: Paul Eggert
Subject: Re: Missing _BitScanReverse64()
Date: Mon, 05 Jan 2015 20:40:32 -0800
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.3.0

Pádraig Brady wrote:
I noticed that count_one_bits() branches on the popcount_support
variable on each call, which might negate much of the gain from using this 

Could be. As far as I know it's never been benchmarked. I stole that code from Emacs without investigating its performance (requires MS-Windows to test, which I don't have). It'd be nice to simplify the code by removing it if it doesn't help performance significantly on MS-Windows.

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