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Teach SplitBlockPredecessors how to handle landingpad blocks.

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Patch by: Igor Laevsky <igor@azulsystems.com>

"Currently SplitBlockPredecessors generates incorrect code in case if basic block we are going to split has a landingpad. Also seems like it is fairly common case among it's users to conditionally call either SplitBlockPredecessors or SplitLandingPadPredecessors. Because of this I think it is reasonable to add this condition directly into SplitBlockPredecessors."

Differential Revision: http://reviews.llvm.org/D7157



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@227390 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Philip Reames
2015-01-28 23:06:47 +00:00
parent 408796c672
commit 61a76b2d4a
6 changed files with 39 additions and 48 deletions
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25
lib/Transforms/Utils/BasicBlockUtils.cpp
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@ -454,11 +454,15 @@ static void UpdatePHINodes(BasicBlock *OrigBB, BasicBlock *NewBB,
}
}
/// SplitBlockPredecessors - This method transforms BB by introducing a new
/// basic block into the function, and moving some of the predecessors of BB to
/// be predecessors of the new block. The new predecessors are indicated by the
/// Preds array, which has NumPreds elements in it. The new block is given a
/// suffix of 'Suffix'.
/// SplitBlockPredecessors - This method introduces at least one new basic block
/// into the function and moves some of the predecessors of BB to be
/// predecessors of the new block. The new predecessors are indicated by the
/// Preds array. The new block is given a suffix of 'Suffix'. Returns new basic
/// block to which predecessors from Preds are now pointing.
///
/// If BB is a landingpad block then additional basicblock might be introduced.
/// It will have suffix of 'Suffix'+".split_lp".
/// See SplitLandingPadPredecessors for more details on this case.
///
/// This currently updates the LLVM IR, AliasAnalysis, DominatorTree,
/// LoopInfo, and LCCSA but no other analyses. In particular, it does not
@ -470,6 +474,17 @@ BasicBlock *llvm::SplitBlockPredecessors(BasicBlock *BB,
const char *Suffix, AliasAnalysis *AA,
DominatorTree *DT, LoopInfo *LI,
bool PreserveLCSSA) {
// For the landingpads we need to act a bit differently.
// Delegate this work to the SplitLandingPadPredecessors.
if (BB->isLandingPad()) {
SmallVector<BasicBlock*, 2> NewBBs;
std::string NewName = std::string(Suffix) + ".split-lp";
SplitLandingPadPredecessors(BB, Preds, Suffix, NewName.c_str(),
NewBBs, AA, DT, LI, PreserveLCSSA);
return NewBBs[0];
}
// Create new basic block, insert right before the original block.
BasicBlock *NewBB = BasicBlock::Create(BB->getContext(), BB->getName()+Suffix,
BB->getParent(), BB);