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Re: (i386-linux x sh-elf) More weak stack addressing
- To: Toshiyasu Morita <tm at netcom dot com>
- Subject: Re: (i386-linux x sh-elf) More weak stack addressing
- From: Joern Rennecke <amylaar at cygnus dot co dot uk>
- Date: Thu, 20 Jul 2000 23:55:21 +0100 (BST)
- CC: gcc at gcc dot gnu dot org
> On Thu, Jul 20, 2000 at 03:06:35PM -0700, Toshiyasu Morita wrote:
>
> > Maybe I'm missing something, but it seems peeking beyond labels is
> > extremely important for the Hitachi SH. Forgive me for overexplaining
> > a bit - I'm basically explaining my assumptions to see if people
> > can spot any glaring oversights.
> >
> > Consider:
> >
> > The SH uses pc-relative addressing to load large constants,
> > therefore it generates literal pools in the .text segment. These
> > literal pools must be "jumped around" to continue execution.
But they don't exist yet at reload time. They are generated in a later
pass.
> > >From a code analysis perspective, these jumps aren't really jumps
> > since they jump to a label accessed by only a single jump. Therefore
> > the jump destination can be considered in the same block as the jump
> > source.
> >
> > If an optimization pass assumes a jump ends a basic block, it will miss
> > many potential optimiations.
My test doesn't consider jumps - only labels.