From 882029269e0cf4b497993b8e9a754429ef035fac Mon Sep 17 00:00:00 2001 From: Chris Lattner Date: Sun, 1 Nov 2009 04:57:33 +0000 Subject: change llvm::MergeBlockIntoPredecessor to not merge two blocks BB1->BB2 when BB2 has its address taken. Since it ends up doing BB2->rauw(BB1), this can cause the address of the entry block to be taken. Since it is generally undesirable to nuke blocks whose address is taken, even when we can, just unconditionally stop this xform. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@85708 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Transforms/Utils/BasicBlockUtils.cpp | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) (limited to 'lib/Transforms/Utils/BasicBlockUtils.cpp') diff --git a/lib/Transforms/Utils/BasicBlockUtils.cpp b/lib/Transforms/Utils/BasicBlockUtils.cpp index 1f9a2031f3..c728c0bd5f 100644 --- a/lib/Transforms/Utils/BasicBlockUtils.cpp +++ b/lib/Transforms/Utils/BasicBlockUtils.cpp @@ -94,10 +94,14 @@ void llvm::DeleteDeadPHIs(BasicBlock *BB) { /// MergeBlockIntoPredecessor - Attempts to merge a block into its predecessor, /// if possible. The return value indicates success or failure. -bool llvm::MergeBlockIntoPredecessor(BasicBlock* BB, Pass* P) { +bool llvm::MergeBlockIntoPredecessor(BasicBlock *BB, Pass *P) { pred_iterator PI(pred_begin(BB)), PE(pred_end(BB)); - // Can't merge the entry block. - if (pred_begin(BB) == pred_end(BB)) return false; + // Can't merge the entry block. Don't merge away blocks who have their + // address taken: this is a bug if the predecessor block is the entry node + // (because we'd end up taking the address of the entry) and undesirable in + // any case. + if (pred_begin(BB) == pred_end(BB) || + BB->hasAddressTaken()) return false; BasicBlock *PredBB = *PI++; for (; PI != PE; ++PI) // Search all predecessors, see if they are all same -- cgit v1.2.3-18-g5258