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Re: criteria.html open issues
- To: dewar at gnat dot com
- Subject: Re: criteria.html open issues
- From: "Albert D. Cahalan" <acahalan at cs dot uml dot edu>
- Date: Mon, 28 May 2001 00:41:45 -0400 (EDT)
- Cc: acahalan at cs dot uml dot edu, gcc at gcc dot gnu dot org
> I do not understand the philosophy behind only enabling strict aliasing
> at -O3. Generally we often find -O3 to be a disadvantage because of the
> excessive inlining which can cause icache penalties. But strict aliasing
> seems like something that should come along with -O2.
Think about what the -O* levels are supposed to mean.
As the numbers go up:
1. the output gets better
2. the compile takes longer
3. non-standard code breaks
If -O3 is a disadvantage, then -O3 is broken. The excessive inlining
is a bug. Why have -O3 if it generally doesn't work?
Strict aliasing should not come along with -O2 because it breaks
lots of existing code. It looks like something that would make
compiles take longer too.
So -O3 should be changed to add one thing: strict aliasing.
The excessive inlining should be removed.