[Bug tree-optimization/60165] "may be used uninitialized" warning with -O3 but not with -O2

["vincent-gcc at vinc17 dot net" <gcc-bugzilla@gcc.gnu.org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60165

--- Comment #14 from Vincent Lefèvre <vincent-gcc at vinc17 dot net> ---
(In reply to Marc Glisse from comment #9)
> The definition of a function changes with inlining ;-)

It shouldn't: what happens at run time isn't changed by inlining.

> f(&i) is considered as an initialization of i. This heuristic is necessary,
> otherwise the number of false positives would make the warning useless.

Perhaps, but this isn't documented.

> I don't know why you think warnings should be so well defined.

According to the gcc man page, it is well-defined: the rule is given
explicitly.

(In reply to Jakub Jelinek from comment #12)
> In your testcase, if fn1 isn't inlined, it is the same thing for GCC, a
> function call as a black box which could do anything to the memory pointed
> to by the escaped pointer (unless the function is say pure or const, at
> which point it couldn't store to it).

Here you assume that the function can do anything, while Marc said that GCC
assumes that i is initialized. There's a contradiction.

Moreover in the case of MPFR, the called function is in the same preprocessed
source file, so that it is not obvious for the user that GCC will see it as a
black box (when not inlined).
>From gcc-bugs-return-443468-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org Thu Feb 13 13:35:46 2014
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Subject: [Bug bootstrap/59878] [4.9 Regression] ISL from cloog does not work with trunk
Date: Thu, 13 Feb 2014 13:35:00 -0000
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http://gcc.gnu.org/bugzilla/show_bug.cgi?idY878

--- Comment #5 from Richard Biener <rguenth at gcc dot gnu.org> ---
Author: rguenth
Date: Thu Feb 13 13:35:10 2014
New Revision: 207758

URL: http://gcc.gnu.org/viewcvs?rev 7758&root=gcc&view=rev
Log:
2014-02-13  Richard Biener  <rguenther@suse.de>

    PR bootstrap/59878
    * doc/install.texi (ISL): Update recommended version to 0.12.2,
    mention the possibility of an in-tree build.
    (CLooG): Update recommended version to 0.18.1, mention the
    possibility of an in-tree build and clarify that the ISL
    bundled with CLooG does not work.

Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/doc/install.texi