A faster way to calculate the day-of-the-week (benjoffe.com)lobsters
75 points by benjoffe in lobste.rs · 36h ago · 7 lobsters
Tech / everything · hot matching “c++”
2 shown · updated 8s ago · read only-
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Why is rep movsb slow for overlapping forward memmove, and why does libc use it? (stackoverflow.com)stack
12 points by Alex Guteniev in stackoverflow.com · 15mo ago · stack
TL;DR: memmove that uses rep movsb is magnitudes slow on overlapping array of 8193 bytes compared to memmove for 8191 elements that doesn't use rep movsb . I'm asking why. Consider the following benchmark: #include <benchmark/benchmark.h> #include <cstring> using namespace std;…