bool AMDGPULegalizerInfo::legalizeAddrSpaceCast(
MachineInstr &MI, MachineRegisterInfo &MRI,
MachineIRBuilder &MIRBuilder) const {
MachineFunction &MF = MIRBuilder.getMF();
MIRBuilder.setInstr(MI);
unsigned Dst = MI.getOperand(0).getReg();
unsigned Src = MI.getOperand(1).getReg();
LLT DstTy = MRI.getType(Dst);
LLT SrcTy = MRI.getType(Src);
unsigned DestAS = DstTy.getAddressSpace();
unsigned SrcAS = SrcTy.getAddressSpace();
// TODO: Avoid reloading from the queue ptr for each cast, or at least each
// vector element.
assert(!DstTy.isVector());
const AMDGPUTargetMachine &TM
= static_cast<const AMDGPUTargetMachine &>(MF.getTarget());
const GCNSubtarget &ST = MF.getSubtarget<GCNSubtarget>();
if (ST.getTargetLowering()->isNoopAddrSpaceCast(SrcAS, DestAS)) {
MI.setDesc(MIRBuilder.getTII().get(TargetOpcode::G_BITCAST));
return true;
}
if (SrcAS == AMDGPUAS::FLAT_ADDRESS) {
assert(DestAS == AMDGPUAS::LOCAL_ADDRESS ||
DestAS == AMDGPUAS::PRIVATE_ADDRESS);
unsigned NullVal = TM.getNullPointerValue(DestAS);
auto SegmentNull = MIRBuilder.buildConstant(DstTy, NullVal);
auto FlatNull = MIRBuilder.buildConstant(SrcTy, 0);
unsigned PtrLo32 = MRI.createGenericVirtualRegister(DstTy);
// Extract low 32-bits of the pointer.
MIRBuilder.buildExtract(PtrLo32, Src, 0);
unsigned CmpRes = MRI.createGenericVirtualRegister(LLT::scalar(1));
MIRBuilder.buildICmp(CmpInst::ICMP_NE, CmpRes, Src, FlatNull.getReg(0));
MIRBuilder.buildSelect(Dst, CmpRes, PtrLo32, SegmentNull.getReg(0));
MI.eraseFromParent();
return true;
}
assert(SrcAS == AMDGPUAS::LOCAL_ADDRESS ||
SrcAS == AMDGPUAS::PRIVATE_ADDRESS);
auto SegmentNull =
MIRBuilder.buildConstant(SrcTy, TM.getNullPointerValue(SrcAS));
auto FlatNull =
MIRBuilder.buildConstant(DstTy, TM.getNullPointerValue(DestAS));
unsigned ApertureReg = getSegmentAperture(DestAS, MRI, MIRBuilder);
unsigned CmpRes = MRI.createGenericVirtualRegister(LLT::scalar(1));
MIRBuilder.buildICmp(CmpInst::ICMP_NE, CmpRes, Src, SegmentNull.getReg(0));
unsigned BuildPtr = MRI.createGenericVirtualRegister(DstTy);
// Coerce the type of the low half of the result so we can use merge_values.
unsigned SrcAsInt = MRI.createGenericVirtualRegister(LLT::scalar(32));
MIRBuilder.buildInstr(TargetOpcode::G_PTRTOINT)
.addDef(SrcAsInt)
.addUse(Src);
// TODO: Should we allow mismatched types but matching sizes in merges to
// avoid the ptrtoint?
MIRBuilder.buildMerge(BuildPtr, {SrcAsInt, ApertureReg});
MIRBuilder.buildSelect(Dst, CmpRes, BuildPtr, FlatNull.getReg(0));
MI.eraseFromParent();
return true;
}
void LegalizerInfo::computeTables() {
assert(TablesInitialized == false);
for (unsigned OpcodeIdx = 0; OpcodeIdx <= LastOp - FirstOp; ++OpcodeIdx) {
const unsigned Opcode = FirstOp + OpcodeIdx;
for (unsigned TypeIdx = 0; TypeIdx != SpecifiedActions[OpcodeIdx].size();
++TypeIdx) {
// 0. Collect information specified through the setAction API, i.e.
// for specific bit sizes.
// For scalar types:
SizeAndActionsVec ScalarSpecifiedActions;
// For pointer types:
std::map<uint16_t, SizeAndActionsVec> AddressSpace2SpecifiedActions;
// For vector types:
std::map<uint16_t, SizeAndActionsVec> ElemSize2SpecifiedActions;
for (auto LLT2Action : SpecifiedActions[OpcodeIdx][TypeIdx]) {
const LLT Type = LLT2Action.first;
const LegalizeAction Action = LLT2Action.second;
auto SizeAction = std::make_pair(Type.getSizeInBits(), Action);
if (Type.isPointer())
AddressSpace2SpecifiedActions[Type.getAddressSpace()].push_back(
SizeAction);
else if (Type.isVector())
ElemSize2SpecifiedActions[Type.getElementType().getSizeInBits()]
.push_back(SizeAction);
else
ScalarSpecifiedActions.push_back(SizeAction);
}
// 1. Handle scalar types
{
// Decide how to handle bit sizes for which no explicit specification
// was given.
SizeChangeStrategy S = &unsupportedForDifferentSizes;
if (TypeIdx < ScalarSizeChangeStrategies[OpcodeIdx].size() &&
ScalarSizeChangeStrategies[OpcodeIdx][TypeIdx] != nullptr)
S = ScalarSizeChangeStrategies[OpcodeIdx][TypeIdx];
std::sort(ScalarSpecifiedActions.begin(), ScalarSpecifiedActions.end());
checkPartialSizeAndActionsVector(ScalarSpecifiedActions);
setScalarAction(Opcode, TypeIdx, S(ScalarSpecifiedActions));
}
// 2. Handle pointer types
for (auto PointerSpecifiedActions : AddressSpace2SpecifiedActions) {
std::sort(PointerSpecifiedActions.second.begin(),
PointerSpecifiedActions.second.end());
checkPartialSizeAndActionsVector(PointerSpecifiedActions.second);
// For pointer types, we assume that there isn't a meaningfull way
// to change the number of bits used in the pointer.
setPointerAction(
Opcode, TypeIdx, PointerSpecifiedActions.first,
unsupportedForDifferentSizes(PointerSpecifiedActions.second));
}
// 3. Handle vector types
SizeAndActionsVec ElementSizesSeen;
for (auto VectorSpecifiedActions : ElemSize2SpecifiedActions) {
std::sort(VectorSpecifiedActions.second.begin(),
VectorSpecifiedActions.second.end());
const uint16_t ElementSize = VectorSpecifiedActions.first;
ElementSizesSeen.push_back({ElementSize, Legal});
checkPartialSizeAndActionsVector(VectorSpecifiedActions.second);
// For vector types, we assume that the best way to adapt the number
// of elements is to the next larger number of elements type for which
// the vector type is legal, unless there is no such type. In that case,
// legalize towards a vector type with a smaller number of elements.
SizeAndActionsVec NumElementsActions;
for (SizeAndAction BitsizeAndAction : VectorSpecifiedActions.second) {
assert(BitsizeAndAction.first % ElementSize == 0);
const uint16_t NumElements = BitsizeAndAction.first / ElementSize;
NumElementsActions.push_back({NumElements, BitsizeAndAction.second});
}
setVectorNumElementAction(
Opcode, TypeIdx, ElementSize,
moreToWiderTypesAndLessToWidest(NumElementsActions));
}
std::sort(ElementSizesSeen.begin(), ElementSizesSeen.end());
SizeChangeStrategy VectorElementSizeChangeStrategy =
&unsupportedForDifferentSizes;
if (TypeIdx < VectorElementSizeChangeStrategies[OpcodeIdx].size() &&
VectorElementSizeChangeStrategies[OpcodeIdx][TypeIdx] != nullptr)
VectorElementSizeChangeStrategy =
VectorElementSizeChangeStrategies[OpcodeIdx][TypeIdx];
setScalarInVectorAction(
Opcode, TypeIdx, VectorElementSizeChangeStrategy(ElementSizesSeen));
}
}
TablesInitialized = true;
}