[CallSiteSplitting] Report edge deletion to DomTreeUpdater

Summary:
When splitting musttail calls, the split blocks' original terminators
get removed; inform the DTU when this happens.

Also add a testcase that fails an assertion in the DTU without this fix.


Reviewers: fhahn, junbuml

Reviewed By: fhahn

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D55027

llvm-svn: 347872

1 files changed, 3 insertions, 1 deletions

diff --git a/llvm/lib/Transforms/Scalar/CallSiteSplitting.cpp b/llvm/lib/Transforms/Scalar/CallSiteSplitting.cpp
index 2be41605c98..a806d6faed6 100644
--- a/llvm/lib/Transforms/Scalar/CallSiteSplitting.cpp
+++ b/llvm/lib/Transforms/Scalar/CallSiteSplitting.cpp
@@ -365,8 +365,10 @@ static void splitCallSite(
     // attempting removal.
     SmallVector<BasicBlock *, 2> Splits(predecessors((TailBB)));
     assert(Splits.size() == 2 && "Expected exactly 2 splits!");
-    for (unsigned i = 0; i < Splits.size(); i++)
+    for (unsigned i = 0; i < Splits.size(); i++) {
       Splits[i]->getTerminator()->eraseFromParent();
+      DTU.deleteEdge(Splits[i], TailBB);
+    }
 
     // Erase the tail block once done with musttail patching
     DTU.deleteBB(TailBB);