> likely/unlikely set the branch prediction values to 99% or 1%
> respectively. If this causes the code generated to perform less
> optimally than without, I'm sure the gcc guys would be -very- interested
> to hear that...
On some ppc64 the branch prediction is quite good and static prediction
will override the dynamic prediction. I think we avoid predicting a
branch unless we are quite sure (95%/5%).
So if likely/unlikely is overused (on more marginal conditionals) then
it could be a performance loss.
Anton
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This archive was generated by hypermail 2b29 : Wed Jan 23 2002 - 21:00:14 EST