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Re: intermodule optimisation patch

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 <>

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