[PATCH] D17983: Eliminate many benign instances of "potentially uninitialized local variable" warnings

[David Blaikie via cfe-commits]

On Mar 9, 2016 8:18 AM, "Teresa Johnson" <tejohnson at google.com> wrote:
>
>
>
> On Wed, Mar 9, 2016 at 8:13 AM, David Blaikie <dblaikie at gmail.com> wrote:
>>
>>
>> On Mar 9, 2016 8:11 AM, "Teresa Johnson via llvm-commits" <
llvm-commits at lists.llvm.org> wrote:
>> >
>> > tejohnson added a subscriber: tejohnson.
>> > tejohnson added a comment.
>> >
>> > Thanks for doing this!
>> >
>> > I will fix these 3, which one of my changes would have provoked. It is
a benign case since we do have an assert at the use site checking the same
condition that the inits are guarded with, but there is no reason not to 0
init these to avoid the bogus warning.
>>
>> The reason not to is that it would silence msan catching the
unintentional codepath (eg: if you didn't have the assert there, and they
init and use conditions didn't match, msan would tell us - if we add what
we believe to be a dead init, then msan no longer helps us here)
>
>
> Hmm, ok. It's unfortunate that the warning and msan are at odds, although
I don't know how to reconcile them.

The approach we've taken so far, so far as I'm aware, is to disable
warnings like this that have such false positives.

> Will leave as is then. Is it worth a comment indicating why we are
leaving them uninitialized?

Not sure. If you think it helps readability. If it's fairly clear the
variable is only used under the same condition that it's initialized, I
think you could leave it.

>>
>> >
>> > Warning C4701   potentially uninitialized local variable
'FnEntry8BitAbbrev' used       LLVMBitWriter
 c:\llvm\llvm\lib\bitcode\writer\bitcodewriter.cpp       2353
>> > Warning C4701   potentially uninitialized local variable
'FnEntry7BitAbbrev' used       LLVMBitWriter
 c:\llvm\llvm\lib\bitcode\writer\bitcodewriter.cpp       2357
>> > Warning C4701   potentially uninitialized local variable
'FnEntry6BitAbbrev' used       LLVMBitWriter
 c:\llvm\llvm\lib\bitcode\writer\bitcodewriter.cpp       2355
>> >
>> >
>> > http://reviews.llvm.org/D17983
>> >
>> >
>> >
>> > _______________________________________________
>> > llvm-commits mailing list
>> > llvm-commits at lists.llvm.org
>> > http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-commits
>
>
>
>
> --
> Teresa Johnson |
>  Software Engineer |
>  tejohnson at google.com |
>  408-460-2413
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/cfe-commits/attachments/20160309/f2c95eac/attachment.html>