Enabling gcc optimization pass

[Basile STARYNKEVITCH]

Rohit Arul Raj wrote:
> Hi all,
> 
> I have 3 functions- fun1, fun2, fun3 in the same source file and i
> want to enable one or any of the gcc optimization pass to code in fun2
> only,
> 
> 1. Is it possible to implement this using function attributes or #pragms's?


I believe that currently, tuning optimisation levels at a function granularity (or perhaps even smaller, like blocks) is 
impossible in current GCC. I heard at the GCC summit (18th july 2007 at Ottawa) that it would be a desirable feature, 
but I am not sure that someone is actively working on it.

So currently, the answer seems to be no.

> 
I believe that currently, tuning optimisation levels at a function granularity (or perhaps even smaller, like blocks) is 
impossible in current GCC. I heard at the GCC summit (18th july 2007 at Ottawa) that it would be a desirable feature, 
but I am not sure that someone is actively working on it.

> 2. What will be its side-effects?

Apparently, one of the issues is that some optimising passes (or their combination) rely on some global variable, so it 
is not a trivial job to tune optimisations at the function level.

But I may be wrong on both points.

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