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Remove code designed to compensate for a bug in GCC. The bug has since
been fixed. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@1881 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -393,7 +393,6 @@ static inline bool FixCastsAndPHIs(BasicBlock *BB) {
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}
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}
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return Changed;
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}
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@ -436,33 +435,10 @@ static inline void RefactorPredecessor(BasicBlock *BB, BasicBlock *Pred) {
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}
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// CheckIncomingValueFor - Make sure that the specified PHI node has an entry
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// for the provided basic block. If it doesn't, add one and return true.
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//
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static inline void CheckIncomingValueFor(PHINode *PN, BasicBlock *BB) {
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if (PN->getBasicBlockIndex(BB) != -1) return; // Already has value
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Value *NewVal = 0;
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const Type *Ty = PN->getType();
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if (const PointerType *PT = dyn_cast<PointerType>(Ty))
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NewVal = ConstantPointerNull::get(PT);
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else if (Ty == Type::BoolTy)
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NewVal = ConstantBool::True;
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else if (Ty == Type::FloatTy || Ty == Type::DoubleTy)
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NewVal = ConstantFP::get(Ty, 42);
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else if (Ty->isIntegral())
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NewVal = ConstantInt::get(Ty, 42);
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assert(NewVal && "Unknown PHI node type!");
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PN->addIncoming(NewVal, BB);
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}
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// fixLocalProblems - Loop through the method and fix problems with the PHI
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// nodes in the current method. The two problems that are handled are:
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//
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// 1. PHI nodes with multiple entries for the same predecessor. GCC sometimes
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// generates code that looks like this:
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// nodes in the current method. The problem is that PHI nodes might exist with
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// multiple entries for the same predecessor. GCC sometimes generates code
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// that looks like this:
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//
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// bb7: br bool %cond1004, label %bb8, label %bb8
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// bb8: %reg119 = phi uint [ 0, %bb7 ], [ 1, %bb7 ]
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@ -475,18 +451,6 @@ static inline void CheckIncomingValueFor(PHINode *PN, BasicBlock *BB) {
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// bb8: %reg119 = phi uint [ 0, %bbX ], [ 1, %bb7 ]
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//
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//
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// 2. PHI nodes with fewer arguments than predecessors.
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// These can be generated by GCC if a variable is uninitalized over a path
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// in the CFG. We fix this by adding an entry for the missing predecessors
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// that is initialized to either 42 for a numeric/FP value, or null if it's
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// a pointer value. This problem can be generated by code that looks like
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// this:
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// int foo(int y) {
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// int X;
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// if (y) X = 1;
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// return X;
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// }
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//
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static bool fixLocalProblems(Method *M) {
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bool Changed = false;
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// Don't use iterators because invalidation gets messy...
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@ -498,8 +462,8 @@ static bool fixLocalProblems(Method *M) {
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if (isa<PHINode>(BB->front())) {
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const vector<BasicBlock*> Preds(pred_begin(BB), pred_end(BB));
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// Handle Problem #1. Sort the list of predecessors so that it is easy to
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// decide whether or not duplicate predecessors exist.
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// Handle the problem. Sort the list of predecessors so that it is easy
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// to decide whether or not duplicate predecessors exist.
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vector<BasicBlock*> SortedPreds(Preds);
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sort(SortedPreds.begin(), SortedPreds.end());
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@ -512,22 +476,6 @@ static bool fixLocalProblems(Method *M) {
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}
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LastOne = SortedPreds[i];
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}
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// Loop over all of the PHI nodes in the current BB. These PHI nodes are
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// guaranteed to be at the beginning of the basic block.
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//
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for (BasicBlock::iterator I = BB->begin();
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PHINode *PN = dyn_cast<PHINode>(*I); ++I) {
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// Handle problem #2.
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if (PN->getNumIncomingValues() != Preds.size()) {
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assert(PN->getNumIncomingValues() <= Preds.size() &&
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"Can't handle extra arguments to PHI nodes!");
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for (unsigned i = 0; i < Preds.size(); ++i)
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CheckIncomingValueFor(PN, Preds[i]);
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Changed = true;
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}
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}
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}
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}
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return Changed;
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