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Implement SimplifyCFG/InvokeEliminate.ll
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@8126 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -6,7 +6,10 @@
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#include "llvm/Transforms/Utils/Local.h"
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#include "llvm/Constant.h"
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#include "llvm/Intrinsics.h"
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#include "llvm/iPHINode.h"
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#include "llvm/iTerminators.h"
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#include "llvm/iOther.h"
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#include "llvm/Support/CFG.h"
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#include <algorithm>
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#include <functional>
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@ -87,12 +90,44 @@ static bool PropagatePredecessorsForPHIs(BasicBlock *BB, BasicBlock *Succ) {
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// WARNING: The entry node of a function may not be simplified.
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//
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bool SimplifyCFG(BasicBlock *BB) {
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bool Changed = false;
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Function *M = BB->getParent();
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assert(BB && BB->getParent() && "Block not embedded in function!");
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assert(BB->getTerminator() && "Degenerate basic block encountered!");
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assert(&BB->getParent()->front() != BB && "Can't Simplify entry block!");
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// Check to see if the first instruction in this block is just an
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// 'llvm.unwind'. If so, replace any invoke instructions which use this as an
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// exception destination with call instructions.
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//
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if (CallInst *CI = dyn_cast<CallInst>(&BB->front()))
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if (Function *F = CI->getCalledFunction())
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if (F->getIntrinsicID() == LLVMIntrinsic::unwind) {
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std::vector<BasicBlock*> Preds(pred_begin(BB), pred_end(BB));
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while (!Preds.empty()) {
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BasicBlock *Pred = Preds.back();
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if (InvokeInst *II = dyn_cast<InvokeInst>(Pred->getTerminator()))
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if (II->getExceptionalDest() == BB) {
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// Insert a new branch instruction before the invoke, because this
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// is now a fall through...
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BranchInst *BI = new BranchInst(II->getNormalDest(), II);
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Pred->getInstList().remove(II); // Take out of symbol table
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// Insert the call now...
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std::vector<Value*> Args(II->op_begin()+3, II->op_end());
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CallInst *CI = new CallInst(II->getCalledValue(), Args,
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II->getName(), BI);
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// If the invoke produced a value, the Call now does instead
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II->replaceAllUsesWith(CI);
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delete II;
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Changed = true;
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}
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Preds.pop_back();
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}
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}
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// Remove basic blocks that have no predecessors... which are unreachable.
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if (pred_begin(BB) == pred_end(BB) &&
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!BB->hasConstantReferences()) {
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@ -123,7 +158,7 @@ bool SimplifyCFG(BasicBlock *BB) {
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// Check to see if we can constant propagate this terminator instruction
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// away...
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bool Changed = ConstantFoldTerminator(BB);
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Changed |= ConstantFoldTerminator(BB);
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// Check to see if this block has no non-phi instructions and only a single
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// successor. If so, replace references to this basic block with references
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