u/pyler2

matrix_vector_product.cpp:408:30: warning: iteration 7158278 invokes undefined behavior [-Waggressive-loop-optimizations]

408 | yy[i] += zz[i*cols+j] * temp;

Win ^tm

https://llvm.org/docs/LinkTimeOptimization.html

Waiting for IDE support for this. Amazing!

P1144?

Try clang trunk :) it fully unrolled your C++ code :D

This is quite interesting. So we can generate gimple (like gcc IR?) and load it to gcc, to optimize it and generate binary? like LLVM IR we can optimize using opt, compile to asm with llc, etc..

​

Any examples/tutorials?

And try Clang even with -stdlib=libc++. Quite amazing numbers.

This will probably miss GCC 9.. no activity on the gcc / libstdc++ mailing list..

maybe you can also do same comparision for Chromium?

but the question is who should write a Rust GCC frontend? :D Mozilla? Too much effort..

Have Mozilla investigated a Facebook's BOLT tool to optimalize PGO binary builds even more?

post this request to his github repo

wow, libc++'s regex is very bad.

Clang vectorized his code, GCC did not.

Experimental internet =D

#include <experimental/internet>

Any libc++ folks here? Is there any ongoing work on Network TS for libc++?

If a passed in variable in a function call is unmodified, a warning to use a

const &

would be nice.

​

-> Also, almost done in LLVM. :)

Using magic numbers.

Development is in progress, it was almost done when I saw it on LLVM Phabricator.

Step Back is really cool feature... what about bring it to LLDB? /u/Teemperor

5x? wow.. this guy is a magician

Mailing list vs. Phabricator

LLVM has stricker rules to get patches in, I think.. Many devs will give you valuable feedback and with every feature/bugfix you need to provide set of new tests..

Sometimes you send a new feature (maybe just 20 lines of code) and a test file for it has 600 lines :D

struct A {
struct A *next;
int field;
};
int f(struct A *item) {
while (!item) {
// Not NULL check since invalid addr OK
__builtin_prefetch(item->next, 1, 1) ;
item->field++;
// more processing...
item++;
}
return 0;
}

GCC:

01 - prefetcht2

02 and higher - ud2 trap.

(gdb) py == (lldb) script