Teach SplitBlockPredecessors how to handle landingpad blocks.
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
llvm-svn: 227390
diff --git a/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp b/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp
index efd5eff..b455257 100644
--- a/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp
+++ b/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp
@@ -454,11 +454,15 @@
}
}
-/// 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 @@
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);