On 07/09/2011 04:57 PM, Justin Ruggles wrote:

> This is about 75% faster on Athlon64.


I think my previous tests were not correct. I don't remember how I
performed them.  Here are some more thorough tests.

gcc: gcc-4.5 (Ubuntu/Linaro 4.5.1-7ubuntu2) 4.5.1
--cpu=host (k8-sse3)
arch=x86_64

benchmarks for ac3dsp.extract_exponents() with nb_coefs=4608

av_log2() LUT version:                        53821
av_log2() built-in version:                   73185
patched version using float/int type punning: 49864

So the patched version is only 8% faster than the current default on
Athlon64 (which is the LUT version since the gcc built-in version is not
selected when HAVE_FAST_CLZ is 0).

-Justin
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