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Re: [PATCH] Further restrict TER replacing over calls (PR55752)
On Thu, 20 Dec 2012, Richard Biener wrote:
> On Thu, 20 Dec 2012, Jakub Jelinek wrote:
>
> > On Thu, Dec 20, 2012 at 02:51:55PM +0100, Richard Biener wrote:
> > > In the PR we perform expression replacement of an FP operation
> > > across a builtin call that sets the FP control register. This
> > > patch restricts replacement across calls further, from allowing
> > > all builtins to only allowing those without side-effects.
> > >
> > > Allowing replacement over calls at all was to not pessimize
> > > FP code generation for example for sqrt which is most often
> > > expanded to a single instruction.
> > >
> > > Bootstrap and regtest running on x86_64-unknown-linux-gnu.
> > >
> > > Comments?
> >
> > Wouldn't it be better to have there a list of known builtins over which it
> > is fine to do TER? I'd bet most of memory or string builtins that don't
> > call malloc/free should be still ok, but they surely have side-effects.
Btw, it would need to be a target specific list as most xmm intrinsic
builtins are fine to replace over.
Richard.