[llvm-dev] Suspicious code in WholeProgramDevirt.cpp?

[Peter Collingbourne via llvm-dev]

Yes, this should have read:

if (Target.RetVal == (IsOne ? 1 : 0)) {

As it turns out, this evaluates to the same thing.

I've committed a fix in r262907.

Peter


On Mon, Mar 7, 2016 at 7:18 PM, <Alexander G. Riccio> via llvm-dev <
llvm-dev at lists.llvm.org> wrote:

> In DevirtModule::tryUniqueRetValOpt, there's a lambda that starts like
> this:
>
> // IsOne controls whether we look for a 0 or a 1.
>   auto tryUniqueRetValOptFor = [&](bool IsOne) {
>     const BitSetInfo *UniqueBitSet = 0;
>     for (const VirtualCallTarget &Target : TargetsForSlot) {
>       if (Target.RetVal == IsOne ? 1 : 0) {
>         if (UniqueBitSet)
>           return false;
>         UniqueBitSet = Target.BS;
>       }
>     }
>
> I'm working on a patch to turn up the warning levels that LLVM compiles
> at, and I got a new warning:
>
> C4805 '==': unsafe mix of type 'const uint64_t' and type 'bool' in
>> operation
>
>
> ...pointing at this line:
>
> if (Target.RetVal == IsOne ? 1 : 0) {
>
>
> It looks to me like that, instead of comparing Target.RetVal *to* 1 or 0,
> it's comparing Target.RetVal *to* IsOne, which I doubt is the intended
> outcome!
>
> What's up with that? Is that a bug?
>
> Sincerely,
> Alexander Riccio
> --
> "Change the world or go home."
> about.me/ariccio
>
> <http://about.me/ariccio>
> If left to my own devices, I will build more.
> ⁂
>
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>
>


-- 
-- 
Peter
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