Linked by ebasconp on Fri 10th Jun 2011 22:22 UTC
Benchmarks "Google has released a research paper that suggests C++ is the best-performing programming language in the market. The internet giant implemented a compact algorithm in four languages - C++, Java, Scala and its own programming language Go - and then benchmarked results to find 'factors of difference'."
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RE[4]: GCC isn't all that great
by Timmmm on Mon 13th Jun 2011 10:56 UTC in reply to "RE[3]: GCC isn't all that great"
Timmmm
Member since:
2006-07-25

for (i = a_len < b_len ? a_len : b_len ; i > 0 ; ) {
i--;
a[i] += b[i];
}


I'm pretty sure this is a terrible idea because it will mess up all the cache lines and pre-fetching if you walk through memory backwards.

Reply Parent Score: 2

RE[5]: GCC isn't all that great
by Megol on Tue 14th Jun 2011 14:26 in reply to "RE[4]: GCC isn't all that great"
Megol Member since:
2011-04-11

"for (i = a_len < b_len ? a_len : b_len ; i > 0 ; ) {
i--;
a[i] += b[i];
}


I'm pretty sure this is a terrible idea because it will mess up all the cache lines and pre-fetching if you walk through memory backwards.
"

No. Prefetchers (in every processor I've touched) support negative strides and working backwards have no performance problems.

Reply Parent Score: 1