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Implement more aggressive folding of constant GEP instructions 

llvm-svn: 6913
This commit is contained in:
Chris Lattner 2003-06-26 05:22:45 +00:00
parent 0f1d8a3947
commit 4ede64e304
1 changed files with 25 additions and 6 deletions
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31
llvm/lib/VMCore/ConstantHandling.cpp
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@ -141,12 +141,30 @@ Constant *ConstantFoldGetElementPtr(const Constant *C,
// FIXME: Implement folding of GEP constant exprs the same as instcombine does
// Implement folding of:
// int* getelementptr ([2 x int]* cast ([3 x int]* %X to [2 x int]*),
// long 0, long 0)
// To: int* getelementptr ([3 x int]* %X, long 0, long 0)
//
if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(C))
if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
// Implement folding of:
// void ()** getelementptr (%struct..TorRec* getelementptr
// ([N x %struct..TorRec]* %llvm.global_dtors, long 0, long 0),
// long 0, ubyte 1)
// Into:
// %struct..TorRec* getelementptr ([N x %struct..TorRec]*
// %llvm.global_dtors, long 0, long 0, ubyte 1)
//
if (CE->getOpcode() == Instruction::GetElementPtr)
if (IdxList[0] == Constant::getNullValue(Type::LongTy)) {
std::vector<Constant*> NewIndices;
NewIndices.reserve(IdxList.size() + CE->getNumOperands());
for (unsigned i = 1, e = CE->getNumOperands(); i != e; ++i)
NewIndices.push_back(cast<Constant>(CE->getOperand(i)));
NewIndices.insert(NewIndices.end(), IdxList.begin()+1, IdxList.end());
return ConstantExpr::getGetElementPtr(CE->getOperand(0), NewIndices);
}
// Implement folding of:
// int* getelementptr ([2 x int]* cast ([3 x int]* %X to [2 x int]*),
// long 0, long 0)
// To: int* getelementptr ([3 x int]* %X, long 0, long 0)
//
if (CE->getOpcode() == Instruction::Cast && IdxList.size() > 1 &&
IdxList[0]->isNullValue())
if (const PointerType *SPT =
@ -157,6 +175,7 @@ Constant *ConstantFoldGetElementPtr(const Constant *C,
if (CAT->getElementType() == SAT->getElementType())
return ConstantExpr::getGetElementPtr(
(Constant*)CE->getOperand(0), IdxList);
}
return 0;
}