On 18.04.2005, at 11:51, Ian Rogers wrote:
I'm not sure if you can get GCC to generate code sequences like this,
but you probably at least need to use the -fprofile-generate and
-fprofile-use options
http://gcc.gnu.org/onlinedocs/gcc/Optimize-Options.html
Feedback optimisation (FDO) will not work for two reasons:
a) qemu itself is something like a realtime compiler so FDO
will only speed up the compiler but not the generated code
b) FDO will only provide speed boosts if the feedback phase
has a chance to analyse a representative work pattern that
is hopefully also repetitive
After all FDO is mostly about making a tradeoff size/speed
and rearranging code (mostly branches) to avoid branch
mispredictions of the CPU.
Servus,
Daniel