diff options
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/Transforms/Utils/SimplifyCFG.cpp | 37 |
1 files changed, 36 insertions, 1 deletions
diff --git a/lib/Transforms/Utils/SimplifyCFG.cpp b/lib/Transforms/Utils/SimplifyCFG.cpp index ed0d45b..f47c840 100644 --- a/lib/Transforms/Utils/SimplifyCFG.cpp +++ b/lib/Transforms/Utils/SimplifyCFG.cpp @@ -6,7 +6,10 @@ #include "llvm/Transforms/Utils/Local.h" #include "llvm/Constant.h" +#include "llvm/Intrinsics.h" #include "llvm/iPHINode.h" +#include "llvm/iTerminators.h" +#include "llvm/iOther.h" #include "llvm/Support/CFG.h" #include <algorithm> #include <functional> @@ -87,12 +90,44 @@ static bool PropagatePredecessorsForPHIs(BasicBlock *BB, BasicBlock *Succ) { // WARNING: The entry node of a function may not be simplified. // bool SimplifyCFG(BasicBlock *BB) { + bool Changed = false; Function *M = BB->getParent(); assert(BB && BB->getParent() && "Block not embedded in function!"); assert(BB->getTerminator() && "Degenerate basic block encountered!"); assert(&BB->getParent()->front() != BB && "Can't Simplify entry block!"); + // Check to see if the first instruction in this block is just an + // 'llvm.unwind'. If so, replace any invoke instructions which use this as an + // exception destination with call instructions. + // + if (CallInst *CI = dyn_cast<CallInst>(&BB->front())) + if (Function *F = CI->getCalledFunction()) + if (F->getIntrinsicID() == LLVMIntrinsic::unwind) { + std::vector<BasicBlock*> Preds(pred_begin(BB), pred_end(BB)); + while (!Preds.empty()) { + BasicBlock *Pred = Preds.back(); + if (InvokeInst *II = dyn_cast<InvokeInst>(Pred->getTerminator())) + if (II->getExceptionalDest() == BB) { + // Insert a new branch instruction before the invoke, because this + // is now a fall through... + BranchInst *BI = new BranchInst(II->getNormalDest(), II); + Pred->getInstList().remove(II); // Take out of symbol table + + // Insert the call now... + std::vector<Value*> Args(II->op_begin()+3, II->op_end()); + CallInst *CI = new CallInst(II->getCalledValue(), Args, + II->getName(), BI); + // If the invoke produced a value, the Call now does instead + II->replaceAllUsesWith(CI); + delete II; + Changed = true; + } + + Preds.pop_back(); + } + } + // Remove basic blocks that have no predecessors... which are unreachable. if (pred_begin(BB) == pred_end(BB) && !BB->hasConstantReferences()) { @@ -123,7 +158,7 @@ bool SimplifyCFG(BasicBlock *BB) { // Check to see if we can constant propagate this terminator instruction // away... - bool Changed = ConstantFoldTerminator(BB); + Changed |= ConstantFoldTerminator(BB); // Check to see if this block has no non-phi instructions and only a single // successor. If so, replace references to this basic block with references |