[llvm-dev] GVN Hoist moving a store across load

[Krzysztof Parzyszek via llvm-dev]

Opened https://llvm.org/bugs/show_bug.cgi?id=28874 for this.

-Krzysztof


On 8/5/2016 1:07 PM, Krzysztof Parzyszek via llvm-dev wrote:
> Hi,
>
> I have a scenario, roughly like this:
>
>   if (...) {
>     ... = *x
>     *x = 0
>   } else {
>     ... = *x
>     *x = 0
>   }
>
> The two sides are functionally different, but both load some value and
> then set it to 0.
>
> After GVN Hoist, I get:
>
>   *x = 0
>   if (...) {
>     ... = *x
>   } else {
>     ... = *x
>   }
>
> That is, the store was hoisted above the loads.
>
> The code is not exactly public, so I can't just attach it as a testcase,
> but it seems like some simple check is missing somewhere.
>
> Does this ring a bell?
>
> -Krzysztof
>

-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, 
hosted by The Linux Foundation