Jeffrey A Law - Re: -Wuninitialized issues (original) (raw)

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• From: Jeffrey A Law
• To: Daniel Jacobowitz
• Cc: Mark Mitchell , gcc at gcc dot gnu dot org
• Date: Mon, 31 Oct 2005 18:37:14 -0700
• Subject: Re: -Wuninitialized issues
• References: 4365CA5E.3070401@codesourcery.com 1130802583.19967.122.camel@localhost.localdomain 20051031235227.GA10103@nevyn.them.org
• Reply-to: law at redhat dot com

On Mon, 2005-10-31 at 18:52 -0500, Daniel Jacobowitz wrote:

On Mon, Oct 31, 2005 at 04:49:43PM -0700, Jeffrey A Law wrote:

On Sun, 2005-10-30 at 23:40 -0800, Mark Mitchell wrote:

In reviewing the PR list, I saw several (maybe 5?) PRs about problems with -Wuninitialized. [ ... ] After pondering this some more I almost wonder if what we need is a separate warning for variables which were potentially uninitialized but which optimization passes somehow proved were unused or the paths in which the variable was uninitialized were unexecutable.

So the early pass would catch unconditionally uninitialized variables; it would also record (but not warn for) maybe uninitialized variables (by detecting default definitions appearing in PHI nodes).

Thoughts?

I think that sounds very clever... I just cobbled up some proof of concept code... It wasn't terribly difficult. I think the question we need to answer is whether or not we want to distinguish between potentially uninitialized uses remaining after optimization and those which were either optimized away or the object was proven always initialized. jeff