Re: intermodule optimisation patch

[Geoffrey Keating <geoffk at apple dot com>]

On Tuesday, May 20, 2003, at 02:40  PM, Richard Henderson wrote:

> On Mon, May 19, 2003 at 04:59:39PM -0500, Chris Lattner wrote:
> > But what happens if you modify one of the source
> > files?  With your approach you have to recompile and reoptimize the 
> > entire
> > program.  With my approach you need to redo only the interprocedural
> > optimizations and code generation phases.
>
> Eh?  "Only" the interprocedural optimizations?
>
> Given that information should be used during the high-level
> optimization phases (in particular for noticing what memory
> is read/written by a function), this does in fact mean
> starting over from near-scratch.  The only thing you get to
> skip is parsing and semantic analysis, which ought to be
> near the bottom of the profile during optimization anyway.

For those cases when parsing *isn't* near the bottom of the profile, 
it's most likely due to header files, and one plan (this is part of 
Per's idea that he'll be presenting at the conference) is to re-use 
information from previous parsings of header files to reduce compile 
time.

--
Geoff Keating <geoffk@apple.com>