[LLVMdev] Can simplifycfg kill llvm.lifetime intrinsics?

Krzysztof Parzyszek kparzysz at codeaurora.org
Fri Dec 28 07:23:22 PST 2012

On 12/28/2012 1:51 AM, Alexey Samsonov wrote:
> On Fri, Dec 28, 2012 at 12:35 AM, Rafael EspĂ­ndola
> <rafael.espindola at gmail.com <mailto:rafael.espindola at gmail.com>> wrote:
>     What about calling
>     llvm.lifetime.start in one function and llvm.lifetime.end in another?
> I don't see how this can happen, assuming that arguments of llvm.lifetime
> can only come from allocas.

It could happen after a cold section of a function was outlined, for 
example.  Informational intrinsics should not prohibit optimizations, 
and barring provably wrong cases, we need to assume that an optimization 
(possibly a future one) can transform code in a way that is not 
predictable up front.


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