Serious code size regression from 3.0.2 to now

[Joern Rennecke]

tm wrote:
> > > I can see two possible solutions for this problem:
> > >
> > > 1) Tweak BBRO heuristics to prevent out-of-lining short code sequences
> > >    of less than n insns
> >
Geoff Keating:
> > That would be a significant de-optimisation.
tm wrote:
> Not necessarily. On the SH4 we can branch over single instructions
> with no penalty because it conditionally executes the one instruction on
> the inverse of the branch condition.

More to the point, putting short sequences out-of-line is a de-optimization
even for the path that does not use them, because it needs a long branch - i.e.
actually multiple instructions and a data entry in the text segment - to
reach these out-of-line instructions.  So we even blow up the size of the
likely path, and cause Icache / Dcache conflicts.
	
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