Re: [RFC] Fix PR19401: always completely peel loops

[Gabriel Dos Reis <gdr at integrable-solutions dot net>]

Andrew Pinski <pinskia@physics.uc.edu> writes:

| On Jan 13, 2005, at 4:44 PM, Richard Guenther wrote:
| 
| > On Thu, 13 Jan 2005 13:51:27 -0500, Paul Schlie <schlie@comcast.net>
| > wrote:
| >
| > Sure.  I guess maybe we should do this for the C++ frontend only - it
| > is not only for loop optimization itself, but also would expose more
| > variables to scalarization (if only complete loop peeling was run
| > before scalarization).  I should probably file another bug wrt the
| > lack of scalarization for
| 
| No it should not do it only for the C++ front-end because most
| of the time it is a win for all front-ends.  No optimization
| should be dependent on what front-end you used.

I disagree.  Optimizations should support language usages/patterns and
language idioms.  Not all languages have the same idioms or usage
patterns.  There are optimizations that can benefits to set of
languages; but not all of them fall into that observation.
We've been through this many times.

My usual rant is about basing C++ optimizations on C APIs and usage,
which often leads to severe pessimizations. 

-- Gaby