Don't eliminate a partially redundant load if it's in a landing pad.

A landing pad can be jumped to only by the unwind edge of an invoke
instruction. If we eliminate a partially redundant load in a landing pad, it
will create a basic block that violates this constraint. It then leads to other
problems down the line if it tries to merge that basic block with the landing
pad. Avoid this by not eliminating the load in a landing pad.

PR17621

llvm-svn: 193064

1 files changed, 1 insertions, 14 deletions

diff --git a/llvm/lib/Transforms/Utils/Local.cpp b/llvm/lib/Transforms/Utils/Local.cpp
index 78217c8efa3..82b8da3a107 100644
--- a/llvm/lib/Transforms/Utils/Local.cpp
+++ b/llvm/lib/Transforms/Utils/Local.cpp
@@ -503,19 +503,7 @@ void llvm::MergeBasicBlockIntoOnlyPred(BasicBlock *DestBB, Pass *P) {
 
   // Splice all the instructions from PredBB to DestBB.
   PredBB->getTerminator()->eraseFromParent();
-
-  // First splice over the PHI nodes.
-  BasicBlock::iterator PI = PredBB->begin();
-  while (isa<PHINode>(PI))
-    ++PI;
-
-  if (PI != PredBB->begin())
-    DestBB->getInstList().splice(DestBB->begin(), PredBB->getInstList(),
-                                 PredBB->begin(), PI);
-
-  // Now splice over the rest of the instructions.
-  DestBB->getInstList().splice(DestBB->getFirstInsertionPt(),
-                               PredBB->getInstList(), PI, PredBB->end());
+  DestBB->getInstList().splice(DestBB->begin(), PredBB->getInstList());
 
   if (P) {
     DominatorTree *DT = P->getAnalysisIfAvailable<DominatorTree>();
@@ -525,7 +513,6 @@ void llvm::MergeBasicBlockIntoOnlyPred(BasicBlock *DestBB, Pass *P) {
       DT->eraseNode(PredBB);
     }
   }
-
   // Nuke BB.
   PredBB->eraseFromParent();
 }