Re: Which optimization levels affect gimple?

[Diego Novillo <dnovillo at redhat dot com>]

Paulo J. Matos wrote on 01/28/07 18:08:
> On 1/26/07, Diego Novillo <dnovillo@redhat.com> wrote:
> > Richard Guenther wrote on 01/26/07 07:28:
> >
> > > It's after doing TER, so the statements are no longer valid GIMPLE statements.
> > Silly me.  Richard's right.  You want the output of -fdump-tree-uncprop.
> >   That's the last GIMPLE dump (if my memory doesn't fail me again).
>
> Ok, so, I guess that being GIMPLE a language, there's somewhere a
> specification of possible constructs, right? Where can I find it? I
> tried to search in the inside gcc manual but there seems to be nothing
> like a formal specification of the nodes in the GIMPLE AST.
The GIMPLE grammar is documented in the internals manual.  In the tree 
ssa sections.  Search for "GIMPLE grammar" or something along those lines.

> Moreover, is there anything referencing which optimizations are
> performed between fdump-tree-gimple and fdump-tree-uncprop (being
> those, afaik, the first and last gimple dumps)?
-fdump-tree-all gives you all the dumps by the high-level optimizers. 
-fdump-all-all gives you all the dumps by both GIMPLE and RTL optimizers.

> If reading source code could help me understand GIMPLE, could please
> someone tell me where to start looking at it. I've svn'ed gcc and it's
> huge so I'm quite lost. Where is the output of fdump-tree-gimple done?
Start with passes.c:init_optimization_passes.  That's the pass sequencer.