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Remove code designed to compensate for a bug in GCC. The bug has since 

been fixed.

llvm-svn: 1881
This commit is contained in:
Chris Lattner 2002-03-15 20:35:21 +00:00
parent fbf5be52c3
commit 205373ff74
1 changed files with 5 additions and 57 deletions
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62
llvm/lib/Transforms/IPO/DeadTypeElimination.cpp
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@ -393,7 +393,6 @@ static inline bool FixCastsAndPHIs(BasicBlock *BB) {
} }
} }
return Changed; return Changed;
} }
@ -436,33 +435,10 @@ static inline void RefactorPredecessor(BasicBlock *BB, BasicBlock *Pred) {
} }
// CheckIncomingValueFor - Make sure that the specified PHI node has an entry
// for the provided basic block. If it doesn't, add one and return true.
//
static inline void CheckIncomingValueFor(PHINode *PN, BasicBlock *BB) {
if (PN->getBasicBlockIndex(BB) != -1) return; // Already has value
Value *NewVal = 0;
const Type *Ty = PN->getType();
if (const PointerType *PT = dyn_cast<PointerType>(Ty))
NewVal = ConstantPointerNull::get(PT);
else if (Ty == Type::BoolTy)
NewVal = ConstantBool::True;
else if (Ty == Type::FloatTy || Ty == Type::DoubleTy)
NewVal = ConstantFP::get(Ty, 42);
else if (Ty->isIntegral())
NewVal = ConstantInt::get(Ty, 42);
assert(NewVal && "Unknown PHI node type!");
PN->addIncoming(NewVal, BB);
}
// fixLocalProblems - Loop through the method and fix problems with the PHI // fixLocalProblems - Loop through the method and fix problems with the PHI
// nodes in the current method. The two problems that are handled are: // nodes in the current method. The problem is that PHI nodes might exist with
// // multiple entries for the same predecessor. GCC sometimes generates code
// 1. PHI nodes with multiple entries for the same predecessor. GCC sometimes // that looks like this:
// generates code that looks like this:
// //
// bb7: br bool %cond1004, label %bb8, label %bb8 // bb7: br bool %cond1004, label %bb8, label %bb8
// bb8: %reg119 = phi uint [ 0, %bb7 ], [ 1, %bb7 ] // bb8: %reg119 = phi uint [ 0, %bb7 ], [ 1, %bb7 ]
@ -475,18 +451,6 @@ static inline void CheckIncomingValueFor(PHINode *PN, BasicBlock *BB) {
// bb8: %reg119 = phi uint [ 0, %bbX ], [ 1, %bb7 ] // bb8: %reg119 = phi uint [ 0, %bbX ], [ 1, %bb7 ]
// //
// //
// 2. PHI nodes with fewer arguments than predecessors.
// These can be generated by GCC if a variable is uninitalized over a path
// in the CFG. We fix this by adding an entry for the missing predecessors
// that is initialized to either 42 for a numeric/FP value, or null if it's
// a pointer value. This problem can be generated by code that looks like
// this:
// int foo(int y) {
// int X;
// if (y) X = 1;
// return X;
// }
//
static bool fixLocalProblems(Method *M) { static bool fixLocalProblems(Method *M) {
bool Changed = false; bool Changed = false;
// Don't use iterators because invalidation gets messy... // Don't use iterators because invalidation gets messy...
@ -498,8 +462,8 @@ static bool fixLocalProblems(Method *M) {
if (isa<PHINode>(BB->front())) { if (isa<PHINode>(BB->front())) {
const vector<BasicBlock*> Preds(pred_begin(BB), pred_end(BB)); const vector<BasicBlock*> Preds(pred_begin(BB), pred_end(BB));
// Handle Problem #1. Sort the list of predecessors so that it is easy to // Handle the problem. Sort the list of predecessors so that it is easy
// decide whether or not duplicate predecessors exist. // to decide whether or not duplicate predecessors exist.
vector<BasicBlock*> SortedPreds(Preds); vector<BasicBlock*> SortedPreds(Preds);
sort(SortedPreds.begin(), SortedPreds.end()); sort(SortedPreds.begin(), SortedPreds.end());
@ -512,22 +476,6 @@ static bool fixLocalProblems(Method *M) {
} }
LastOne = SortedPreds[i]; LastOne = SortedPreds[i];
} }
// Loop over all of the PHI nodes in the current BB. These PHI nodes are
// guaranteed to be at the beginning of the basic block.
//
for (BasicBlock::iterator I = BB->begin();
PHINode *PN = dyn_cast<PHINode>(*I); ++I) {
// Handle problem #2.
if (PN->getNumIncomingValues() != Preds.size()) {
assert(PN->getNumIncomingValues() <= Preds.size() &&
"Can't handle extra arguments to PHI nodes!");
for (unsigned i = 0; i < Preds.size(); ++i)
CheckIncomingValueFor(PN, Preds[i]);
Changed = true;
}
}
} }
} }
return Changed; return Changed;