[LLVMdev] getnode(BB) = 0; block already in dominator tree

[Sumesh Udayakumaran]

Oh...its machine LICM ...in the following lines...

  CurPreheader = Pred->SplitCriticalEdge(CurLoop->getHeader(), this);
01463       if (!CurPreheader) {
01464         CurPreheader = reinterpret_cast<MachineBasicBlock *>(-1);
01465         return nullptr;
01466       }





On Thu, May 14, 2015 at 1:57 PM, Philip Reames
<listmail at philipreames.com> wrote:
> Er, LICM currently does not modify the CFG at all.  Are you proposing to
> change that?  And if so, why?  What's the motivating case?
>
> Philip
>
>
> On 05/14/2015 11:55 AM, Shreyas Krishnan wrote:
>
> Hi
>    I run into an issue as part of splitting a critical edge during LICM.
> When a new basic block is created and needs to be added into the dominator
> tree, the block is already in the dominator tree. I print the dominator tree
> and I see it is added into the tree as child of node it is supposed to
> dominate.
>
> How do I debug to find out why/when its getting added into the tree. ?
> Tips/suggestions on how to debug to find out how the densemap involved is
> getting updated will be great.
>
> thanks
> Shrey
>
>
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