From ec080e7b221889a3b1b2616a19e4019295509627 Mon Sep 17 00:00:00 2001 From: Chris Lattner Date: Fri, 30 Oct 2009 22:39:36 +0000 Subject: if basic blocks are destroyed while there are *just* BlockAddress' hanging around, then zap them. This is analogous to dangling constantexprs hanging off functions. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@85627 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/VMCore/BasicBlock.cpp | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) (limited to 'lib/VMCore') diff --git a/lib/VMCore/BasicBlock.cpp b/lib/VMCore/BasicBlock.cpp index e8069c0..23d0557 100644 --- a/lib/VMCore/BasicBlock.cpp +++ b/lib/VMCore/BasicBlock.cpp @@ -58,6 +58,24 @@ BasicBlock::BasicBlock(LLVMContext &C, const Twine &Name, Function *NewParent, BasicBlock::~BasicBlock() { + // If the address of the block is taken and it is being deleted (e.g. because + // it is dead), this means that there is either a dangling constant expr + // hanging off the block, or an undefined use of the block (source code + // expecting the address of a label to keep the block alive even though there + // is no indirect branch). Handle these cases by zapping the BlockAddress + // nodes. There are no other possible uses at this point. + if (hasAddressTaken()) { + assert(!use_empty() && "There should be at least one blockaddress!"); + Constant *Replacement = + ConstantInt::get(llvm::Type::getInt32Ty(getContext()), 1); + while (!use_empty()) { + BlockAddress *BA = cast(use_back()); + BA->replaceAllUsesWith(ConstantExpr::getIntToPtr(Replacement, + BA->getType())); + BA->destroyConstant(); + } + } + assert(getParent() == 0 && "BasicBlock still linked into the program!"); dropAllReferences(); InstList.clear(); -- cgit v1.1