[PATCH] D37460: [GVN] Prevent LoadPRE from hoisting across instructions that don't pass control flow to successors

[Philip Reames via Phabricator via llvm-commits]

reames added inline comments.


================
Comment at: lib/Transforms/Scalar/GVN.cpp:2312
   if (MD)
     MD->removeInstruction(CurInst);
   DEBUG(verifyRemoved(CurInst));
----------------
reames wrote:
> It just occurred to me, are you sure loads - which are the only instruction type in use here - every have implicit control flow?  If not, this piece is dead code and should be replaced with an assertion instead.
> 
> In particular:
> assert(!MayNotTransferExecutionToSuccessor(CurInst), "loads don't have implicit control flow");
Talking to Max, we realized my comment here is wrong.  This is the *Scalar* PRE block, not the *Load* PRE block I thought I was looking at.


https://reviews.llvm.org/D37460