[LLVMdev] FYI: Phoronix GCC vs. LLVM-GCC benchmarks

Chris Lattner clattner at apple.com
Wed Sep 16 09:02:09 PDT 2009

On Sep 16, 2009, at 6:46 AM, Stefano Delli Ponti wrote:

> Olivier Meurant:
>> I have run the john the ripper test.
>> I have used the official archive (same version as phoronix) from
>> http://www.openwall.com/john/g/john-
>> To build with llvm-gcc, replace the line CC = gcc with CC = llvm-gcc.
>> I have used the following command to build : make clean linux-x86- 
>> sse2
>> (seems to be the best on x86-32)
>> The makefile invocation is "gcc -c -Wall -O2 -fomit-frame-pointer
>> -funroll-loops src.c" and "llvm-gcc -c -Wall -O2 -fomit-frame-pointer
>> -funroll-loops src.c".
> I don't know what you think about this, but shouldn't it be more
> meaningful to make these tests with -O3? I mean, we ought to make the
> comparisons with the highest level of optimization available for  
> both of
> the compilers. It is difficult to compare an intermediate level.

Comparing -O3 (and even -O4) is interesting, but we want all  
optimization levels to perform better than GCC :).  Lots of people use  
-O2 and -Os, so comparing against other compiler's -O2 and -Os levels  
is just as interesting as comparing -O3 vs -O3.


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