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Implement expansion of unsigned i64 -> FP. 

Note that this probably only works for little endian targets, but is enough
to get siod working :)

llvm-svn: 21280
This commit is contained in:
Chris Lattner 2005-04-13 05:09:42 +00:00
parent e7ef27bcfe
commit e69ad5fd12
1 changed files with 31 additions and 2 deletions
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33
llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
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@ -1822,7 +1822,37 @@ ExpandIntToFP(bool isSigned, MVT::ValueType DestTy, SDOperand Source) {
// signed, then adjust the result if the sign bit is set.
SDOperand SignedConv = ExpandIntToFP(true, DestTy, Source);
assert(0 && "Unsigned casts not supported yet!");
assert(Source.getValueType() == MVT::i64 &&
"This only works for 64-bit -> FP");
// The 64-bit value loaded will be incorrectly if the 'sign bit' of the
// incoming integer is set. To handle this, we dynamically test to see if
// it is set, and, if so, add a fudge factor.
SDOperand Lo, Hi;
ExpandOp(Source, Lo, Hi);
SDOperand SignSet = DAG.getSetCC(ISD::SETLT, TLI.getSetCCResultTy(), Hi,
DAG.getConstant(0, Hi.getValueType()));
SDOperand Zero = getIntPtrConstant(0), Four = getIntPtrConstant(4);
SDOperand CstOffset = DAG.getNode(ISD::SELECT, Zero.getValueType(),
SignSet, Four, Zero);
// FIXME: This is almost certainly broken for big-endian systems. Should
// this just put the fudge factor in the low bits of the uint64 constant or?
static Constant *FudgeFactor =
ConstantUInt::get(Type::ULongTy, 0x5f800000ULL << 32);
MachineConstantPool *CP = DAG.getMachineFunction().getConstantPool();
SDOperand CPIdx = DAG.getConstantPool(CP->getConstantPoolIndex(FudgeFactor),
TLI.getPointerTy());
CPIdx = DAG.getNode(ISD::ADD, TLI.getPointerTy(), CPIdx, CstOffset);
SDOperand FudgeInReg;
if (DestTy == MVT::f32)
FudgeInReg = DAG.getLoad(MVT::f32, DAG.getEntryNode(), CPIdx);
else {
assert(DestTy == MVT::f64 && "Unexpected conversion");
FudgeInReg = DAG.getNode(ISD::EXTLOAD, MVT::f64, DAG.getEntryNode(),
CPIdx, MVT::f32);
}
return DAG.getNode(ISD::ADD, DestTy, SignedConv, FudgeInReg);
}
SDOperand Callee = DAG.getExternalSymbol(FnName, TLI.getPointerTy());
@ -1835,7 +1865,6 @@ ExpandIntToFP(bool isSigned, MVT::ValueType DestTy, SDOperand Source) {
// calls wherever we need them to satisfy data dependences.
const Type *RetTy = MVT::getTypeForValueType(DestTy);
return TLI.LowerCallTo(InChain, RetTy, false, Callee, Args, DAG).first;
}