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Why is unsigned integer overflow defined behavior but signed integer overflow isn't?
...t used. C implementations usually used the same representation used by the CPU - so the overflow behavior followed from the integer representation used by the CPU.
In practice, it is only the representations for signed values that may differ according to the implementation: one's complement, two's c...
How dangerous is it to access an array out of bounds?
...user privileges, a malfunctioning program can consume excessive resources (CPU, memory, disk), possibly bringing down the entire system. A lot of malware (viruses, etc.) exploits buffer overruns to gain unauthorized access to the system.
(One historical example: I've heard that on some old systems ...
Check synchronously if file/directory exists in Node.js
...nchronous calls. Calls into the I/O subsystem take significant time from a CPU's point of view. Note how easy it is to call lstat rather than lstatSync:
// Is it a directory?
lstat('/the/path', function(err, stats) {
if (!err && stats.isDirectory()) {
// Yes it is
}
});
Bu...
Why is f(i = -1, i = -1) undefined behavior?
...signment cannot be interleaved. It might be optimal to do so, depending on CPU architecture. The referenced page states this:
If A is not sequenced before B and B is not sequenced before A, then
two possibilities exist:
evaluations of A and B are unsequenced: they may be performed in ...
Fastest sort of fixed length 6 int array
... are single cycle instructions like add/subtract), but for a normal scalar CPU your method looks better.
– Paul R
May 8 '10 at 16:13
2
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Measure time in Linux - time vs clock vs getrusage vs clock_gettime vs gettimeofday vs timespec_get?
...e. It is present in C89 and later. At one time this was supposed to be the CPU time in cycles, but modern standards like POSIX require CLOCKS_PER_SEC to be 1000000, giving a maximum possible precision of 1 µs. The precision on my system is indeed 1 µs. This clock wraps around once it tops out (th...
Why aren't programs written in Assembly more often? [closed]
...ur old code can easily make use of the new instructions.
What if the next CPU has twice as many registers?
The converse of this question would be: What functionality do compilers provide?
I doubt you can/want to/should optimize your ASM better than gcc -O3 can.
...
Why are elementwise additions much faster in separate loops than in a combined loop?
...
OK, the right answer definitely has to do something with the CPU cache. But to use the cache argument can be quite difficult, especially without data.
There are many answers, that led to a lot of discussion, but let's face it: Cache issues can be very complex and are not one dimension...
Custom CSS Scrollbar for Firefox
...and has loads of parameters you can tweak, but it ended up being a bit too CPU intensive for me (and it adds a fair amount to the DOM).
Now I'm giving Perfect Scrollbar a go. It's simple and lightweight (6KB) and it's doing a decent job so far. It's not CPU intensive at all (as far as I can tell) a...
Why shouldn't I use PyPy over CPython if PyPy is 6.3 times faster?
... relevant, hardly anyone would run raytracing in a scripting language on a CPU these days. I did find pybenchmarks.org
– smci
Apr 23 '17 at 1:15
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