[Bug tree-optimization/63660] -Wmaybe-uninitialized false positive (uninit pass limits)

["manu at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63660

--- Comment #3 from Manuel López-Ibáñez <manu at gcc dot gnu.org> ---
(In reply to Edward-san from comment #2)
> Isn't it possible to bailout if the limit is reached?

I guess the analysis is trying to prove that the variable is indeed initialized
(or that it is never used uninitialized). It bails out trying to prove that,
thus the warning. The warning code could be conservative and never warn if the
limit is reached, but then we will have the other problem: false-negatives.

A way to advance with this (if you want to help) is to check which limit is
actually hit by your code. Then see by how much you would need to change the
limit to warn (by for example adding a --param to control it). Then, with this
information at hand, the GCC maintainers can decide whether to increase the
limit a bit or perhaps to never warn if the limit is hit (people that want all
potential warnings not matter the compile-time cost can use the --param for a
deeper analysis).
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From: "dmalcolm at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug jit/64166] New: JIT does not provide a way for verifying dumpfiles from testcases
Date: Wed, 03 Dec 2014 14:55:00 -0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?idd166

            Bug ID: 64166
           Summary: JIT does not provide a way for verifying dumpfiles
                    from testcases
           Product: gcc
           Version: 5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: jit
          Assignee: dmalcolm at gcc dot gnu.org
          Reporter: dmalcolm at gcc dot gnu.org
            Blocks: 64020

In PR jit/64020 I found that there isn't currently a good way for a jit
testcase to get at a specific dumpfile and to assert properties about it (e.g.
that a particular string or regex is found).

I'm opening this bug to track this.

I'm not yet sure to what extent to expose this in the API to end-users.