[PATCH] D60617: MSan: handle llvm.lifetime.start intrinsic

[Alexander Potapenko via Phabricator via llvm-commits]

glider added a comment.

In D60617#1464971 <https://reviews.llvm.org/D60617#1464971>, @eugenis wrote:

> Please test the case when alloca can not be found.
>  See https://bugs.llvm.org/show_bug.cgi?id=41481 for the reference.


Ok, will do. The repro in the bug doesn't produce IR containing a select statement for me, but the idea is clear.

> With this change msan will start detecting new bugs, ex.:
>  for (int i = 0; ...; ++i) {
> 
>   int x;
>   if (i == 0) x=0;
>   read(x);
> 
> }
> 
> It can also slow down some programs a lot.

Agreed. This also makes less sense without origins - do you think we shall hide it behind track-origins>0 ?

> Do you plan to remove SanitizeMemory condition from shouldEmitLifetimeMarkers ?

Sorry, I don't get it. We won't see any lifetime markers with that condition removed, right?
What's the point of this fix then?


Repository:
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  https://reviews.llvm.org/D60617/new/

https://reviews.llvm.org/D60617