Displaying 3 results from an estimated 3 matches for "9d9cf5".
2012 Jul 19
4
[LLVMdev] LLVM compile speed significantly slower than GCC (w/ test case)
...ng a relatively
data-intensive piece of code.
I compiled the file with both compilers for the arm-none-eabi triple.
The numbers I get are as follows:
GCC (4.5.2, Windows build from CodeSourcery) - With -O0: 110ms, with -O2: 215ms
Clang/LLVM (Release mode, LLVM git hash 7f5714f4..., clang git hash
9d9cf5...) - With -O0: 110ms, with -O2: 640ms
The compilers are essentially identical for the -O0 case, but when
compiling with -O2, LLVM takes almost three times as long as GCC.
I'm not sure whether this file is unusual in some way, such that
fixing whatever makes this slow wouldn't have much o...
2012 Jul 19
0
[LLVMdev] LLVM compile speed significantly slower than GCC (w/ test case)
...e of code.
>
> I compiled the file with both compilers for the arm-none-eabi triple.
> The numbers I get are as follows:
>
> GCC (4.5.2, Windows build from CodeSourcery) - With -O0: 110ms, with -O2: 215ms
> Clang/LLVM (Release mode, LLVM git hash 7f5714f4..., clang git hash
> 9d9cf5...) - With -O0: 110ms, with -O2: 640ms
>
> The compilers are essentially identical for the -O0 case, but when
> compiling with -O2, LLVM takes almost three times as long as GCC.
>
> I'm not sure whether this file is unusual in some way, such that
> fixing whatever makes this...
2012 Jul 20
1
[LLVMdev] LLVM compile speed significantly slower than GCC (w/ test case)
>> GCC (4.5.2, Windows build from CodeSourcery) - With -O0: 110ms, with -O2: 215ms
>> Clang/LLVM (Release mode, LLVM git hash 7f5714f4..., clang git hash
>> 9d9cf5...) - With -O0: 110ms, with -O2: 640ms
Hi Matt,
I only see 2x slowdown on my machine (consistently, O2 and O3), but
that's still bad.
If you compile to IR then pass "opt -time-passes" you can get a good
idea who the culprit is:
$ clang -O0 -S -emit-llvm sha1test.c
$ opt -time-pass...