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constant fold ptrtoint(inttoptr) with target data when available. This allows 

us to fold the entry block of PR1602 to false instead of:

br i1 icmp eq (i32 and (i32 ptrtoint (void (%struct.S*)* inttoptr (i64
1 to void (%struct.S*)*) to i32), i32 1), i32 0), label %cond_next, label
%cond_true

llvm-svn: 41023
This commit is contained in:
Chris Lattner 2007-08-11 23:49:01 +00:00
parent 99c8ee2977
commit 460e34afed
1 changed files with 17 additions and 2 deletions
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19
llvm/lib/Analysis/ConstantFolding.cpp
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@ -217,6 +217,23 @@ Constant *llvm::ConstantFoldInstOperands(const Instruction* I,
case Instruction::FCmp:
return ConstantExpr::getCompare(cast<CmpInst>(I)->getPredicate(), Ops[0],
Ops[1]);
case Instruction::PtrToInt:
// If the input is a inttoptr, eliminate the pair. This requires knowing
// the width of a pointer, so it can't be done in ConstantExpr::getCast.
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ops[0])) {
if (TD && CE->getOpcode() == Instruction::IntToPtr) {
Constant *Input = CE->getOperand(0);
unsigned InWidth = Input->getType()->getPrimitiveSizeInBits();
Constant *Mask =
ConstantInt::get(APInt::getLowBitsSet(InWidth,
TD->getPointerSizeInBits()));
Input = ConstantExpr::getAnd(Input, Mask);
// Do a zext or trunc to get to the dest size.
return ConstantExpr::getIntegerCast(Input, I->getType(), false);
}
}
// FALL THROUGH.
case Instruction::IntToPtr:
case Instruction::Trunc:
case Instruction::ZExt:
case Instruction::SExt:
@ -226,8 +243,6 @@ Constant *llvm::ConstantFoldInstOperands(const Instruction* I,
case Instruction::SIToFP:
case Instruction::FPToUI:
case Instruction::FPToSI:
case Instruction::PtrToInt:
case Instruction::IntToPtr:
case Instruction::BitCast:
return ConstantExpr::getCast(Opc, Ops[0], DestTy);
case Instruction::Select: