[LLVMdev] FYI: Phoronix GCC vs. LLVM-GCC benchmarks
clattner at apple.com
Wed Sep 16 10:11:05 PDT 2009
On Sep 16, 2009, at 10:05 AM, Stefano Delli Ponti wrote:
> Chris Lattner:
>> 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.
> My thinking was that, for instance, -02 for GCC and -02 for LLVM(-
> GCC) do not necessarily mean the same thing, they may be not /
> But perhaps, my ignorance, you are saying that they _are_, that LLVM
> assigns the same types of optimizations as GCC to the different
Right, we want them to be roughly comparable.
O0 -> best debug experience, fastest compile times.
O2 -> optimize without bloating the code too much and without burning
*too* many cycles.
O3 -> take more time and produce fatter code to get faster code.
O1 is something of a wasteland with no clear purpose :)
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