[LLVMdev] -fplugin-arg-dragonegg-enable-gcc-optzns impact

[Duncan Sands]

Hi Jack,

>    Now that dragoneegg is robust in its default usage and the dragonegg svn
> is moderately stable with -fplugin-arg-dragonegg-enable-gcc-optzns, it is
> possible to gauge the impact of that feature. Comparing clang 2.9, FSF gcc 4.5.3svn,
> FSF gcc 4.6.0 and dragonegg svn with FSF gcc 4.5.3svn using the himenoBMTxpa benchmark,
> the enhancement to code performance from -fplugin-arg-dragonegg-enable-gcc-optzns is
> clear on x86_64-apple-darwin10 for -fomit-frame-pointer -O3 -ffast-math -funroll-loops...
>
> compiler                             MFLOPS
> clang 2.9                           230.529385
> gcc 4.5.3                           246.064891
> de-gcc 4.5.3                        204.845864
> de-gcc 4.5.3 optzns                 259.672855
> gcc 4.6.0                           260.344783
>
> Pretty impressive.

interesting results.  It needs some analysis to work out where the extra juice
is coming from though, in particular to distinguish between effects coming from
LLVM's IR level optimizations and those coming from its code generators.

Ciao, Duncan.