g++ and aliasing bools

[Paolo Carlini]

Gabriel Dos Reis wrote:

>kenner@vlsi1.ultra.nyu.edu (Richard Kenner) writes:
>
>| I am very much against the idea of defining a change to be "correct" if
>| it doesn't cause any regression test failures.  You have to be able to make
>| an argument that a change is correct independently and the regression tests
>| serve as a debugger of (among other things) that proof.
>
>I completely agree with Kenner and Mark.  Given, current ABIs
>supported by g++, aliasing detection is a very subtle issue and we
>should resist from the temptation of not proving that our algorithms
>are correct; simply because correctness should come first, speed later.
>That doesn't mean I'm against any effort to improve alias analysis in
>g++, I'm simply against a change which doesn't consider correctness as
>serious issue.
>
In this connection I would like to clearly state that indeed I agree 
with all of you. By the way, I'm doing proofs myself daily in my 
research work and I *understand* the power of abstract reasoning!

My sympathy with Dan's message was due to the fact that in the last 
months I got the impression that C++-alias analysis may be really 
crucial in order to effectively optimize some codes whereas it looks 
like, for some reason nobody among the knowledgeable people is actively 
working on it... I took Dan's words as a spur for the C++ developers to 
start working again on that without being scared by the first technical 
difficulties!!

Cheers,
Paolo.