50
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3
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1.8K
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Why does GCC generate such radically different assembly for nearly the same C code?
While writing an optimized ftol function I found some very odd behaviour in GCC 4.6.1. Let me show you the cod
64
votes
11
answers
1.9K
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Replacing a 32-bit loop counter with 64-bit introduces crazy performance deviations with _mm_popcnt_u64 on Intel CPUs
I was looking for the fastest way to popcount large arrays of data. I encountered a very weird effect: Changin
58
votes
12
answers
923
views
Why doesn't GCC optimize a*a*a*a*a*a to (a*a*a)*(a*a*a)?
I am doing some numerical optimization on a scientific application. One thing I noticed is that GCC will optim
51
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9
answers
2.7K
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Swift Beta performance: sorting arrays
I was implementing an algorithm in Swift Beta and noticed that the performance was very poor. After digging de
