//===-- HexagonISelLowering.cpp - Hexagon DAG Lowering Implementation -----===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the interfaces that Hexagon uses to lower LLVM code
// into a selection DAG.
//
//===----------------------------------------------------------------------===//
#include "HexagonISelLowering.h"
#include "HexagonMachineFunctionInfo.h"
#include "HexagonSubtarget.h"
#include "HexagonTargetMachine.h"
#include "HexagonTargetObjectFile.h"
#include "llvm/CodeGen/CallingConvLower.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineJumpTableInfo.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/SelectionDAGISel.h"
#include "llvm/CodeGen/ValueTypes.h"
#include "llvm/IR/CallingConv.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/GlobalAlias.h"
#include "llvm/IR/GlobalVariable.h"
#include "llvm/IR/InlineAsm.h"
#include "llvm/IR/Intrinsics.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
using namespace llvm;
#define DEBUG_TYPE "hexagon-lowering"
static cl::opt<bool>
EmitJumpTables("hexagon-emit-jump-tables", cl::init(true), cl::Hidden,
cl::desc("Control jump table emission on Hexagon target"));
namespace {
class HexagonCCState : public CCState {
int NumNamedVarArgParams;
public:
HexagonCCState(CallingConv::ID CC, bool isVarArg, MachineFunction &MF,
const TargetMachine &TM, SmallVectorImpl<CCValAssign> &locs,
LLVMContext &C, int NumNamedVarArgParams)
: CCState(CC, isVarArg, MF, TM, locs, C),
NumNamedVarArgParams(NumNamedVarArgParams) {}
int getNumNamedVarArgParams() const { return NumNamedVarArgParams; }
};
}
// Implement calling convention for Hexagon.
static bool
CC_Hexagon(unsigned ValNo, MVT ValVT,
MVT LocVT, CCValAssign::LocInfo LocInfo,
ISD::ArgFlagsTy ArgFlags, CCState &State);
static bool
CC_Hexagon32(unsigned ValNo, MVT ValVT,
MVT LocVT, CCValAssign::LocInfo LocInfo,
ISD::ArgFlagsTy ArgFlags, CCState &State);
static bool
CC_Hexagon64(unsigned ValNo, MVT ValVT,
MVT LocVT, CCValAssign::LocInfo LocInfo,
ISD::ArgFlagsTy ArgFlags, CCState &State);
static bool
RetCC_Hexagon(unsigned ValNo, MVT ValVT,
MVT LocVT, CCValAssign::LocInfo LocInfo,
ISD::ArgFlagsTy ArgFlags, CCState &State);
static bool
RetCC_Hexagon32(unsigned ValNo, MVT ValVT,
MVT LocVT, CCValAssign::LocInfo LocInfo,
ISD::ArgFlagsTy ArgFlags, CCState &State);
static bool
RetCC_Hexagon64(unsigned ValNo, MVT ValVT,
MVT LocVT, CCValAssign::LocInfo LocInfo,
ISD::ArgFlagsTy ArgFlags, CCState &State);
static bool
CC_Hexagon_VarArg (unsigned ValNo, MVT ValVT,
MVT LocVT, CCValAssign::LocInfo LocInfo,
ISD::ArgFlagsTy ArgFlags, CCState &State) {
HexagonCCState &HState = static_cast<HexagonCCState &>(State);
// NumNamedVarArgParams can not be zero for a VarArg function.
assert((HState.getNumNamedVarArgParams() > 0) &&
"NumNamedVarArgParams is not bigger than zero.");
if ((int)ValNo < HState.getNumNamedVarArgParams()) {
// Deal with named arguments.
return CC_Hexagon(ValNo, ValVT, LocVT, LocInfo, ArgFlags, State);
}
// Deal with un-named arguments.
unsigned ofst;
if (ArgFlags.isByVal()) {
// If pass-by-value, the size allocated on stack is decided
// by ArgFlags.getByValSize(), not by the size of LocVT.
assert ((ArgFlags.getByValSize() > 8) &&
"ByValSize must be bigger than 8 bytes");
ofst = State.AllocateStack(ArgFlags.getByValSize(), 4);
State.addLoc(CCValAssign::getMem(ValNo, ValVT, ofst, LocVT, LocInfo));
return false;
}
if (LocVT == MVT::i1 || LocVT == MVT::i8 || LocVT == MVT::i16) {
LocVT = MVT::i32;
ValVT = MVT::i32;
if (ArgFlags.isSExt())
LocInfo = CCValAssign::SExt;
else if (ArgFlags.isZExt())
LocInfo = CCValAssign::ZExt;
else
LocInfo = CCValAssign::AExt;
}
if (LocVT == MVT::i32 || LocVT == MVT::f32) {
ofst = State.AllocateStack(4, 4);
State.addLoc(CCValAssign::getMem(ValNo, ValVT, ofst, LocVT, LocInfo));
return false;
}
if (LocVT == MVT::i64 || LocVT == MVT::f64) {
ofst = State.AllocateStack(8, 8);
State.addLoc(CCValAssign::getMem(ValNo, ValVT, ofst, LocVT, LocInfo));
return false;
}
llvm_unreachable(nullptr);
}
static bool
CC_Hexagon (unsigned ValNo, MVT ValVT,
MVT LocVT, CCValAssign::LocInfo LocInfo,
ISD::ArgFlagsTy ArgFlags, CCState &State) {
if (ArgFlags.isByVal()) {
// Passed on stack.
assert ((ArgFlags.getByValSize() > 8) &&
"ByValSize must be bigger than 8 bytes");
unsigned Offset = State.AllocateStack(ArgFlags.getByValSize(), 4);
State.addLoc(CCValAssign::getMem(ValNo, ValVT, Offset, LocVT, LocInfo));
return false;
}
if (LocVT == MVT::i1 || LocVT == MVT::i8 || LocVT == MVT::i16) {
LocVT = MVT::i32;
ValVT = MVT::i32;
if (ArgFlags.isSExt())
LocInfo = CCValAssign::SExt;
else if (ArgFlags.isZExt())
LocInfo = CCValAssign::ZExt;
else
LocInfo = CCValAssign::AExt;
}
if (LocVT == MVT::i32 || LocVT == MVT::f32) {
if (!CC_Hexagon32(ValNo, ValVT, LocVT, LocInfo, ArgFlags, State))
return false;
}
if (LocVT == MVT::i64 || LocVT == MVT::f64) {
if (!CC_Hexagon64(ValNo, ValVT, LocVT, LocInfo, ArgFlags, State))
return false;
}
return true; // CC didn't match.
}
static bool CC_Hexagon32(unsigned ValNo, MVT ValVT,
MVT LocVT, CCValAssign::LocInfo LocInfo,
ISD::ArgFlagsTy ArgFlags, CCState &State) {
static const MCPhysReg RegList[] = {
Hexagon::R0, Hexagon::R1, Hexagon::R2, Hexagon::R3, Hexagon::R4,
Hexagon::R5
};
if (unsigned Reg = State.AllocateReg(RegList, 6)) {
State.addLoc(CCValAssign::getReg(ValNo, ValVT, Reg, LocVT, LocInfo));
return false;
}
unsigned Offset = State.AllocateStack(4, 4);
State.addLoc(CCValAssign::getMem(ValNo, ValVT, Offset, LocVT, LocInfo));
return false;
}
static bool CC_Hexagon64(unsigned ValNo, MVT ValVT,
MVT LocVT, CCValAssign::LocInfo LocInfo,
ISD::ArgFlagsTy ArgFlags, CCState &State) {
if (unsigned Reg = State.AllocateReg(Hexagon::D0)) {
State.addLoc(CCValAssign::getReg(ValNo, ValVT, Reg, LocVT, LocInfo));
return false;
}
static const MCPhysReg RegList1[] = {
Hexagon::D1, Hexagon::D2
};
static const MCPhysReg RegList2[] = {
Hexagon::R1, Hexagon::R3
};
if (unsigned Reg = State.AllocateReg(RegList1, RegList2, 2)) {
State.addLoc(CCValAssign::getReg(ValNo, ValVT, Reg, LocVT, LocInfo));
return false;
}
unsigned Offset = State.AllocateStack(8, 8, Hexagon::D2);
State.addLoc(CCValAssign::getMem(ValNo, ValVT, Offset, LocVT, LocInfo));
return false;
}
static bool RetCC_Hexagon(unsigned ValNo, MVT ValVT,
MVT LocVT, CCValAssign::LocInfo LocInfo,
ISD::ArgFlagsTy ArgFlags, CCState &State) {
if (LocVT == MVT::i1 ||
LocVT == MVT::i8 ||
LocVT == MVT::i16) {
LocVT = MVT::i32;
ValVT = MVT::i32;
if (ArgFlags.isSExt())
LocInfo = CCValAssign::SExt;
else if (ArgFlags.isZExt())
LocInfo = CCValAssign::ZExt;
else
LocInfo = CCValAssign::AExt;
}
if (LocVT == MVT::i32 || LocVT == MVT::f32) {
if (!RetCC_Hexagon32(ValNo, ValVT, LocVT, LocInfo, ArgFlags, State))
return false;
}
if (LocVT == MVT::i64 || LocVT == MVT::f64) {
if (!RetCC_Hexagon64(ValNo, ValVT, LocVT, LocInfo, ArgFlags, State))
return false;
}
return true; // CC didn't match.
}
static bool RetCC_Hexagon32(unsigned ValNo, MVT ValVT,
MVT LocVT, CCValAssign::LocInfo LocInfo,
ISD::ArgFlagsTy ArgFlags, CCState &State) {
if (LocVT == MVT::i32 || LocVT == MVT::f32) {
if (unsigned Reg = State.AllocateReg(Hexagon::R0)) {
State.addLoc(CCValAssign::getReg(ValNo, ValVT, Reg, LocVT, LocInfo));
return false;
}
}
unsigned Offset = State.AllocateStack(4, 4);
State.addLoc(CCValAssign::getMem(ValNo, ValVT, Offset, LocVT, LocInfo));
return false;
}
static bool RetCC_Hexagon64(unsigned ValNo, MVT ValVT,
MVT LocVT, CCValAssign::LocInfo LocInfo,
ISD::ArgFlagsTy ArgFlags, CCState &State) {
if (LocVT == MVT::i64 || LocVT == MVT::f64) {
if (unsigned Reg = State.AllocateReg(Hexagon::D0)) {
State.addLoc(CCValAssign::getReg(ValNo, ValVT, Reg, LocVT, LocInfo));
return false;
}
}
unsigned Offset = State.AllocateStack(8, 8);
State.addLoc(CCValAssign::getMem(ValNo, ValVT, Offset, LocVT, LocInfo));
return false;
}
SDValue
HexagonTargetLowering::LowerINTRINSIC_WO_CHAIN(SDValue Op, SelectionDAG &DAG)
const {
return SDValue();
}
/// CreateCopyOfByValArgument - Make a copy of an aggregate at address specified
/// by "Src" to address "Dst" of size "Size". Alignment information is
/// specified by the specific parameter attribute. The copy will be passed as
/// a byval function parameter. Sometimes what we are copying is the end of a
/// larger object, the part that does not fit in registers.
static SDValue
CreateCopyOfByValArgument(SDValue Src, SDValue Dst, SDValue Chain,
ISD::ArgFlagsTy Flags, SelectionDAG &DAG,
SDLoc dl) {
SDValue SizeNode = DAG.getConstant(Flags.getByValSize(), MVT::i32);
return DAG.getMemcpy(Chain, dl, Dst, Src, SizeNode, Flags.getByValAlign(),
/*isVolatile=*/false, /*AlwaysInline=*/false,
MachinePointerInfo(), MachinePointerInfo());
}
// LowerReturn - Lower ISD::RET. If a struct is larger than 8 bytes and is
// passed by value, the function prototype is modified to return void and
// the value is stored in memory pointed by a pointer passed by caller.
SDValue
HexagonTargetLowering::LowerReturn(SDValue Chain,
CallingConv::ID CallConv, bool isVarArg,
const SmallVectorImpl<ISD::OutputArg> &Outs,
const SmallVectorImpl<SDValue> &OutVals,
SDLoc dl, SelectionDAG &DAG) const {
// CCValAssign - represent the assignment of the return value to locations.
SmallVector<CCValAssign, 16> RVLocs;
// CCState - Info about the registers and stack slot.
CCState CCInfo(CallConv, isVarArg, DAG.getMachineFunction(),
getTargetMachine(), RVLocs, *DAG.getContext());
// Analyze return values of ISD::RET
CCInfo.AnalyzeReturn(Outs, RetCC_Hexagon);
SDValue Flag;
SmallVector<SDValue, 4> RetOps(1, Chain);
// Copy the result values into the output registers.
for (unsigned i = 0; i != RVLocs.size(); ++i) {
CCValAssign &VA = RVLocs[i];
Chain = DAG.getCopyToReg(Chain, dl, VA.getLocReg(), OutVals[i], Flag);
// Guarantee that all emitted copies are stuck together with flags.
Flag = Chain.getValue(1);
RetOps.push_back(DAG.getRegister(VA.getLocReg(), VA.getLocVT()));
}
RetOps[0] = Chain; // Update chain.
// Add the flag if we have it.
if (Flag.getNode())
RetOps.push_back(Flag);
return DAG.getNode(HexagonISD::RET_FLAG, dl, MVT::Other, RetOps);
}
/// LowerCallResult - Lower the result values of an ISD::CALL into the
/// appropriate copies out of appropriate physical registers. This assumes that
/// Chain/InFlag are the input chain/flag to use, and that TheCall is the call
/// being lowered. Returns a SDNode with the same number of values as the
/// ISD::CALL.
SDValue
HexagonTargetLowering::LowerCallResult(SDValue Chain, SDValue InFlag,
CallingConv::ID CallConv, bool isVarArg,
const
SmallVectorImpl<ISD::InputArg> &Ins,
SDLoc dl, SelectionDAG &DAG,
SmallVectorImpl<SDValue> &InVals,
const SmallVectorImpl<SDValue> &OutVals,
SDValue Callee) const {
// Assign locations to each value returned by this call.
SmallVector<CCValAssign, 16> RVLocs;
CCState CCInfo(CallConv, isVarArg, DAG.getMachineFunction(),
getTargetMachine(), RVLocs, *DAG.getContext());
CCInfo.AnalyzeCallResult(Ins, RetCC_Hexagon);
// Copy all of the result registers out of their specified physreg.
for (unsigned i = 0; i != RVLocs.size(); ++i) {
Chain = DAG.getCopyFromReg(Chain, dl,
RVLocs[i].getLocReg(),
RVLocs[i].getValVT(), InFlag).getValue(1);
InFlag = Chain.getValue(2);
InVals.push_back(Chain.getValue(0));
}
return Chain;
}
/// LowerCall - Functions arguments are copied from virtual regs to
/// (physical regs)/(stack frame), CALLSEQ_START and CALLSEQ_END are emitted.
SDValue
HexagonTargetLowering::LowerCall(TargetLowering::CallLoweringInfo &CLI,
SmallVectorImpl<SDValue> &InVals) const {
SelectionDAG &DAG = CLI.DAG;
SDLoc &dl = CLI.DL;
SmallVectorImpl<ISD::OutputArg> &Outs = CLI.Outs;
SmallVectorImpl<SDValue> &OutVals = CLI.OutVals;
SmallVectorImpl<ISD::InputArg> &Ins = CLI.Ins;
SDValue Chain = CLI.Chain;
SDValue Callee = CLI.Callee;
bool &isTailCall = CLI.IsTailCall;
CallingConv::ID CallConv = CLI.CallConv;
bool isVarArg = CLI.IsVarArg;
bool IsStructRet = (Outs.empty()) ? false : Outs[0].Flags.isSRet();
// Check for varargs.
int NumNamedVarArgParams = -1;
if (GlobalAddressSDNode *GA = dyn_cast<GlobalAddressSDNode>(Callee))
{
const Function* CalleeFn = nullptr;
Callee = DAG.getTargetGlobalAddress(GA->getGlobal(), dl, MVT::i32);
if ((CalleeFn = dyn_cast<Function>(GA->getGlobal())))
{
// If a function has zero args and is a vararg function, that's
// disallowed so it must be an undeclared function. Do not assume
// varargs if the callee is undefined.
if (CalleeFn->isVarArg() &&
CalleeFn->getFunctionType()->getNumParams() != 0) {
NumNamedVarArgParams = CalleeFn->getFunctionType()->getNumParams();
}
}
}
// Analyze operands of the call, assigning locations to each operand.
SmallVector<CCValAssign, 16> ArgLocs;
HexagonCCState CCInfo(CallConv, isVarArg, DAG.getMachineFunction(),
getTargetMachine(), ArgLocs, *DAG.getContext(),
NumNamedVarArgParams);
if (NumNamedVarArgParams > 0)
CCInfo.AnalyzeCallOperands(Outs, CC_Hexagon_VarArg);
else
CCInfo.AnalyzeCallOperands(Outs, CC_Hexagon);
if(isTailCall) {
bool StructAttrFlag =
DAG.getMachineFunction().getFunction()->hasStructRetAttr();
isTailCall = IsEligibleForTailCallOptimization(Callee, CallConv,
isVarArg, IsStructRet,
StructAttrFlag,
Outs, OutVals, Ins, DAG);
for (unsigned i = 0, e = ArgLocs.size(); i != e; ++i){
CCValAssign &VA = ArgLocs[i];
if (VA.isMemLoc()) {
isTailCall = false;
break;
}
}
if (isTailCall) {
DEBUG(dbgs () << "Eligible for Tail Call\n");
} else {
DEBUG(dbgs () <<
"Argument must be passed on stack. Not eligible for Tail Call\n");
}
}
// Get a count of how many bytes are to be pushed on the stack.
unsigned NumBytes = CCInfo.getNextStackOffset();
SmallVector<std::pair<unsigned, SDValue>, 16> RegsToPass;
SmallVector<SDValue, 8> MemOpChains;
const HexagonRegisterInfo *QRI = static_cast<const HexagonRegisterInfo *>(
DAG.getTarget().getRegisterInfo());
SDValue StackPtr =
DAG.getCopyFromReg(Chain, dl, QRI->getStackRegister(), getPointerTy());
// Walk the register/memloc assignments, inserting copies/loads.
for (unsigned i = 0, e = ArgLocs.size(); i != e; ++i) {
CCValAssign &VA = ArgLocs[i];
SDValue Arg = OutVals[i];
ISD::ArgFlagsTy Flags = Outs[i].Flags;
// Promote the value if needed.
switch (VA.getLocInfo()) {
default:
// Loc info must be one of Full, SExt, ZExt, or AExt.
llvm_unreachable("Unknown loc info!");
case CCValAssign::Full:
break;
case CCValAssign::SExt:
Arg = DAG.getNode(ISD::SIGN_EXTEND, dl, VA.getLocVT(), Arg);
break;
case CCValAssign::ZExt:
Arg = DAG.getNode(ISD::ZERO_EXTEND, dl, VA.getLocVT(), Arg);
break;
case CCValAssign::AExt:
Arg = DAG.getNode(ISD::ANY_EXTEND, dl, VA.getLocVT(), Arg);
break;
}
if (VA.isMemLoc()) {
unsigned LocMemOffset = VA.getLocMemOffset();
SDValue PtrOff = DAG.getConstant(LocMemOffset, StackPtr.getValueType());
PtrOff = DAG.getNode(ISD::ADD, dl, MVT::i32, StackPtr, PtrOff);
if (Flags.isByVal()) {
// The argument is a struct passed by value. According to LLVM, "Arg"
// is is pointer.
MemOpChains.push_back(CreateCopyOfByValArgument(Arg, PtrOff, Chain,
Flags, DAG, dl));
} else {
// The argument is not passed by value. "Arg" is a buildin type. It is
// not a pointer.
MemOpChains.push_back(DAG.getStore(Chain, dl, Arg, PtrOff,
MachinePointerInfo(),false, false,
0));
}
continue;
}
// Arguments that can be passed on register must be kept at RegsToPass
// vector.
if (VA.isRegLoc()) {
RegsToPass.push_back(std::make_pair(VA.getLocReg(), Arg));
}
}
// Transform all store nodes into one single node because all store
// nodes are independent of each other.
if (!MemOpChains.empty()) {
Chain = DAG.getNode(ISD::TokenFactor, dl, MVT::Other, MemOpChains);
}
if (!isTailCall)
Chain = DAG.getCALLSEQ_START(Chain, DAG.getConstant(NumBytes,
getPointerTy(), true),
dl);
// Build a sequence of copy-to-reg nodes chained together with token
// chain and flag operands which copy the outgoing args into registers.
// The InFlag in necessary since all emitted instructions must be
// stuck together.
SDValue InFlag;
if (!isTailCall) {
for (unsigned i = 0, e = RegsToPass.size(); i != e; ++i) {
Chain = DAG.getCopyToReg(Chain, dl, RegsToPass[i].first,
RegsToPass[i].second, InFlag);
InFlag = Chain.getValue(1);
}
}
// For tail calls lower the arguments to the 'real' stack slot.
if (isTailCall) {
// Force all the incoming stack arguments to be loaded from the stack
// before any new outgoing arguments are stored to the stack, because the
// outgoing stack slots may alias the incoming argument stack slots, and
// the alias isn't otherwise explicit. This is slightly more conservative
// than necessary, because it means that each store effectively depends
// on every argument instead of just those arguments it would clobber.
//
// Do not flag preceding copytoreg stuff together with the following stuff.
InFlag = SDValue();
for (unsigned i = 0, e = RegsToPass.size(); i != e; ++i) {
Chain = DAG.getCopyToReg(Chain, dl, RegsToPass[i].first,
RegsToPass[i].second, InFlag);
InFlag = Chain.getValue(1);
}
InFlag =SDValue();
}
// If the callee is a GlobalAddress/ExternalSymbol node (quite common, every
// direct call is) turn it into a TargetGlobalAddress/TargetExternalSymbol
// node so that legalize doesn't hack it.
if (flag_aligned_memcpy) {
const char *MemcpyName =
"__hexagon_memcpy_likely_aligned_min32bytes_mult8bytes";
Callee =
DAG.getTargetExternalSymbol(MemcpyName, getPointerTy());
flag_aligned_memcpy = false;
} else if (GlobalAddressSDNode *G = dyn_cast<GlobalAddressSDNode>(Callee)) {
Callee = DAG.getTargetGlobalAddress(G->getGlobal(), dl, getPointerTy());
} else if (ExternalSymbolSDNode *S =
dyn_cast<ExternalSymbolSDNode>(Callee)) {
Callee = DAG.getTargetExternalSymbol(S->getSymbol(), getPointerTy());
}
// Returns a chain & a flag for retval copy to use.
SDVTList NodeTys = DAG.getVTList(MVT::Other, MVT::Glue);
SmallVector<SDValue, 8> Ops;
Ops.push_back(Chain);
Ops.push_back(Callee);
// Add argument registers to the end of the list so that they are
// known live into the call.
for (unsigned i = 0, e = RegsToPass.size(); i != e; ++i) {
Ops.push_back(DAG.getRegister(RegsToPass[i].first,
RegsToPass[i].second.getValueType()));
}
if (InFlag.getNode()) {
Ops.push_back(InFlag);
}
if (isTailCall)
return DAG.getNode(HexagonISD::TC_RETURN, dl, NodeTys, Ops);
Chain = DAG.getNode(HexagonISD::CALL, dl, NodeTys, Ops);
InFlag = Chain.getValue(1);
// Create the CALLSEQ_END node.
Chain = DAG.getCALLSEQ_END(Chain, DAG.getIntPtrConstant(NumBytes, true),
DAG.getIntPtrConstant(0, true), InFlag, dl);
InFlag = Chain.getValue(1);
// Handle result values, copying them out of physregs into vregs that we
// return.
return LowerCallResult(Chain, InFlag, CallConv, isVarArg, Ins, dl, DAG,
InVals, OutVals, Callee);
}
static bool getIndexedAddressParts(SDNode *Ptr, EVT VT,
bool isSEXTLoad, SDValue &Base,
SDValue &Offset, bool &isInc,
SelectionDAG &DAG) {
if (Ptr->getOpcode() != ISD::ADD)
return false;
if (VT == MVT::i64 || VT == MVT::i32 || VT == MVT::i16 || VT == MVT::i8) {
isInc = (Ptr->getOpcode() == ISD::ADD);
Base = Ptr->getOperand(0);
Offset = Ptr->getOperand(1);
// Ensure that Offset is a constant.
return (isa<ConstantSDNode>(Offset));
}
return false;
}
// TODO: Put this function along with the other isS* functions in
// HexagonISelDAGToDAG.cpp into a common file. Or better still, use the
// functions defined in HexagonOperands.td.
static bool Is_PostInc_S4_Offset(SDNode * S, int ShiftAmount) {
ConstantSDNode *N = cast<ConstantSDNode>(S);
// immS4 predicate - True if the immediate fits in a 4-bit sign extended.
// field.
int64_t v = (int64_t)N->getSExtValue();
int64_t m = 0;
if (ShiftAmount > 0) {
m = v % ShiftAmount;
v = v >> ShiftAmount;
}
return (v <= 7) && (v >= -8) && (m == 0);
}
/// getPostIndexedAddressParts - returns true by value, base pointer and
/// offset pointer and addressing mode by reference if this node can be
/// combined with a load / store to form a post-indexed load / store.
bool HexagonTargetLowering::getPostIndexedAddressParts(SDNode *N, SDNode *Op,
SDValue &Base,
SDValue &Offset,
ISD::MemIndexedMode &AM,
SelectionDAG &DAG) const
{
EVT VT;
SDValue Ptr;
bool isSEXTLoad = false;
if (LoadSDNode *LD = dyn_cast<LoadSDNode>(N)) {
VT = LD->getMemoryVT();
isSEXTLoad = LD->getExtensionType() == ISD::SEXTLOAD;
} else if (StoreSDNode *ST = dyn_cast<StoreSDNode>(N)) {
VT = ST->getMemoryVT();
if (ST->getValue().getValueType() == MVT::i64 && ST->isTruncatingStore()) {
return false;
}
} else {
return false;
}
bool isInc = false;
bool isLegal = getIndexedAddressParts(Op, VT, isSEXTLoad, Base, Offset,
isInc, DAG);
// ShiftAmount = number of left-shifted bits in the Hexagon instruction.
int ShiftAmount = VT.getSizeInBits() / 16;
if (isLegal && Is_PostInc_S4_Offset(Offset.getNode(), ShiftAmount)) {
AM = isInc ? ISD::POST_INC : ISD::POST_DEC;
return true;
}
return false;
}
SDValue HexagonTargetLowering::LowerINLINEASM(SDValue Op,
SelectionDAG &DAG) const {
SDNode *Node = Op.getNode();
MachineFunction &MF = DAG.getMachineFunction();
HexagonMachineFunctionInfo *FuncInfo =
MF.getInfo<HexagonMachineFunctionInfo>();
switch (Node->getOpcode()) {
case ISD::INLINEASM: {
unsigned NumOps = Node->getNumOperands();
if (Node->getOperand(NumOps-1).getValueType() == MVT::Glue)
--NumOps; // Ignore the flag operand.
for (unsigned i = InlineAsm::Op_FirstOperand; i != NumOps;) {
if (FuncInfo->hasClobberLR())
break;
unsigned Flags =
cast<ConstantSDNode>(Node->getOperand(i))->getZExtValue();
unsigned NumVals = InlineAsm::getNumOperandRegisters(Flags);
++i; // Skip the ID value.
switch (InlineAsm::getKind(Flags)) {
default: llvm_unreachable("Bad flags!");
case InlineAsm::Kind_RegDef:
case InlineAsm::Kind_RegUse:
case InlineAsm::Kind_Imm:
case InlineAsm::Kind_Clobber:
case InlineAsm::Kind_Mem: {
for (; NumVals; --NumVals, ++i) {}
break;
}
case InlineAsm::Kind_RegDefEarlyClobber: {
for (; NumVals; --NumVals, ++i) {
unsigned Reg =
cast<RegisterSDNode>(Node->getOperand(i))->getReg();
// Check it to be lr
const HexagonRegisterInfo *QRI =
static_cast<const HexagonRegisterInfo *>(
DAG.getTarget().getRegisterInfo());
if (Reg == QRI->getRARegister()) {
FuncInfo->setHasClobberLR(true);
break;
}
}
break;
}
}
}
}
} // Node->getOpcode
return Op;
}
//
// Taken from the XCore backend.
//
SDValue HexagonTargetLowering::
LowerBR_JT(SDValue Op, SelectionDAG &DAG) const
{
SDValue Chain = Op.getOperand(0);
SDValue Table = Op.getOperand(1);
SDValue Index = Op.getOperand(2);
SDLoc dl(Op);
JumpTableSDNode *JT = cast<JumpTableSDNode>(Table);
unsigned JTI = JT->getIndex();
MachineFunction &MF = DAG.getMachineFunction();
const MachineJumpTableInfo *MJTI = MF.getJumpTableInfo();
SDValue TargetJT = DAG.getTargetJumpTable(JT->getIndex(), MVT::i32);
// Mark all jump table targets as address taken.
const std::vector<MachineJumpTableEntry> &JTE = MJTI->getJumpTables();
const std::vector<MachineBasicBlock*> &JTBBs = JTE[JTI].MBBs;
for (unsigned i = 0, e = JTBBs.size(); i != e; ++i) {
MachineBasicBlock *MBB = JTBBs[i];
MBB->setHasAddressTaken();
// This line is needed to set the hasAddressTaken flag on the BasicBlock
// object.
BlockAddress::get(const_cast<BasicBlock *>(MBB->getBasicBlock()));
}
SDValue JumpTableBase = DAG.getNode(HexagonISD::WrapperJT, dl,
getPointerTy(), TargetJT);
SDValue ShiftIndex = DAG.getNode(ISD::SHL, dl, MVT::i32, Index,
DAG.getConstant(2, MVT::i32));
SDValue JTAddress = DAG.getNode(ISD::ADD, dl, MVT::i32, JumpTableBase,
ShiftIndex);
SDValue LoadTarget = DAG.getLoad(MVT::i32, dl, Chain, JTAddress,
MachinePointerInfo(), false, false, false,
0);
return DAG.getNode(HexagonISD::BR_JT, dl, MVT::Other, Chain, LoadTarget);
}
SDValue
HexagonTargetLowering::LowerDYNAMIC_STACKALLOC(SDValue Op,
SelectionDAG &DAG) const {
SDValue Chain = Op.getOperand(0);
SDValue Size = Op.getOperand(1);
SDLoc dl(Op);
unsigned SPReg = getStackPointerRegisterToSaveRestore();
// Get a reference to the stack pointer.
SDValue StackPointer = DAG.getCopyFromReg(Chain, dl, SPReg, MVT::i32);
// Subtract the dynamic size from the actual stack size to
// obtain the new stack size.
SDValue Sub = DAG.getNode(ISD::SUB, dl, MVT::i32, StackPointer, Size);
//
// For Hexagon, the outgoing memory arguments area should be on top of the
// alloca area on the stack i.e., the outgoing memory arguments should be
// at a lower address than the alloca area. Move the alloca area down the
// stack by adding back the space reserved for outgoing arguments to SP
// here.
//
// We do not know what the size of the outgoing args is at this point.
// So, we add a pseudo instruction ADJDYNALLOC that will adjust the
// stack pointer. We patch this instruction with the correct, known
// offset in emitPrologue().
//
// Use a placeholder immediate (zero) for now. This will be patched up
// by emitPrologue().
SDValue ArgAdjust = DAG.getNode(HexagonISD::ADJDYNALLOC, dl,
MVT::i32,
Sub,
DAG.getConstant(0, MVT::i32));
// The Sub result contains the new stack start address, so it
// must be placed in the stack pointer register.
const HexagonRegisterInfo *QRI = static_cast<const HexagonRegisterInfo *>(
DAG.getTarget().getRegisterInfo());
SDValue CopyChain = DAG.getCopyToReg(Chain, dl, QRI->getStackRegister(), Sub);
SDValue Ops[2] = { ArgAdjust, CopyChain };
return DAG.getMergeValues(Ops, dl);
}
SDValue
HexagonTargetLowering::LowerFormalArguments(SDValue Chain,
CallingConv::ID CallConv,
bool isVarArg,
const
SmallVectorImpl<ISD::InputArg> &Ins,
SDLoc dl, SelectionDAG &DAG,
SmallVectorImpl<SDValue> &InVals)
const {
MachineFunction &MF = DAG.getMachineFunction();
MachineFrameInfo *MFI = MF.getFrameInfo();
MachineRegisterInfo &RegInfo = MF.getRegInfo();
HexagonMachineFunctionInfo *FuncInfo =
MF.getInfo<HexagonMachineFunctionInfo>();
// Assign locations to all of the incoming arguments.
SmallVector<CCValAssign, 16> ArgLocs;
CCState CCInfo(CallConv, isVarArg, DAG.getMachineFunction(),
getTargetMachine(), ArgLocs, *DAG.getContext());
CCInfo.AnalyzeFormalArguments(Ins, CC_Hexagon);
// For LLVM, in the case when returning a struct by value (>8byte),
// the first argument is a pointer that points to the location on caller's
// stack where the return value will be stored. For Hexagon, the location on
// caller's stack is passed only when the struct size is smaller than (and
// equal to) 8 bytes. If not, no address will be passed into callee and
// callee return the result direclty through R0/R1.
SmallVector<SDValue, 4> MemOps;
for (unsigned i = 0, e = ArgLocs.size(); i != e; ++i) {
CCValAssign &VA = ArgLocs[i];
ISD::ArgFlagsTy Flags = Ins[i].Flags;
unsigned ObjSize;
unsigned StackLocation;
int FI;
if ( (VA.isRegLoc() && !Flags.isByVal())
|| (VA.isRegLoc() && Flags.isByVal() && Flags.getByValSize() > 8)) {
// Arguments passed in registers
// 1. int, long long, ptr args that get allocated in register.
// 2. Large struct that gets an register to put its address in.
EVT RegVT = VA.getLocVT();
if (RegVT == MVT::i8 || RegVT == MVT::i16 ||
RegVT == MVT::i32 || RegVT == MVT::f32) {
unsigned VReg =
RegInfo.createVirtualRegister(&Hexagon::IntRegsRegClass);
RegInfo.addLiveIn(VA.getLocReg(), VReg);
InVals.push_back(DAG.getCopyFromReg(Chain, dl, VReg, RegVT));
} else if (RegVT == MVT::i64) {
unsigned VReg =
RegInfo.createVirtualRegister(&Hexagon::DoubleRegsRegClass);
RegInfo.addLiveIn(VA.getLocReg(), VReg);
InVals.push_back(DAG.getCopyFromReg(Chain, dl, VReg, RegVT));
} else {
assert (0);
}
} else if (VA.isRegLoc() && Flags.isByVal() && Flags.getByValSize() <= 8) {
assert (0 && "ByValSize must be bigger than 8 bytes");
} else {
// Sanity check.
assert(VA.isMemLoc());
if (Flags.isByVal()) {
// If it's a byval parameter, then we need to compute the
// "real" size, not the size of the pointer.
ObjSize = Flags.getByValSize();
} else {
ObjSize = VA.getLocVT().getStoreSizeInBits() >> 3;
}
StackLocation = HEXAGON_LRFP_SIZE + VA.getLocMemOffset();
// Create the frame index object for this incoming parameter...
FI = MFI->CreateFixedObject(ObjSize, StackLocation, true);
// Create the SelectionDAG nodes cordl, responding to a load
// from this parameter.
SDValue FIN = DAG.getFrameIndex(FI, MVT::i32);
if (Flags.isByVal()) {
// If it's a pass-by-value aggregate, then do not dereference the stack
// location. Instead, we should generate a reference to the stack
// location.
InVals.push_back(FIN);
} else {
InVals.push_back(DAG.getLoad(VA.getLocVT(), dl, Chain, FIN,
MachinePointerInfo(), false, false,
false, 0));
}
}
}
if (!MemOps.empty())
Chain = DAG.getNode(ISD::TokenFactor, dl, MVT::Other, MemOps);
if (isVarArg) {
// This will point to the next argument passed via stack.
int FrameIndex = MFI->CreateFixedObject(Hexagon_PointerSize,
HEXAGON_LRFP_SIZE +
CCInfo.getNextStackOffset(),
true);
FuncInfo->setVarArgsFrameIndex(FrameIndex);
}
return Chain;
}
SDValue
HexagonTargetLowering::LowerVASTART(SDValue Op, SelectionDAG &DAG) const {
// VASTART stores the address of the VarArgsFrameIndex slot into the
// memory location argument.
MachineFunction &MF = DAG.getMachineFunction();
HexagonMachineFunctionInfo *QFI = MF.getInfo<HexagonMachineFunctionInfo>();
SDValue Addr = DAG.getFrameIndex(QFI->getVarArgsFrameIndex(), MVT::i32);
const Value *SV = cast<SrcValueSDNode>(Op.getOperand(2))->getValue();
return DAG.getStore(Op.getOperand(0), SDLoc(Op), Addr,
Op.getOperand(1), MachinePointerInfo(SV), false,
false, 0);
}
SDValue
HexagonTargetLowering::LowerConstantPool(SDValue Op, SelectionDAG &DAG) const {
EVT ValTy = Op.getValueType();
SDLoc dl(Op);
ConstantPoolSDNode *CP = cast<ConstantPoolSDNode>(Op);
SDValue Res;
if (CP->isMachineConstantPoolEntry())
Res = DAG.getTargetConstantPool(CP->getMachineCPVal(), ValTy,
CP->getAlignment());
else
Res = DAG.getTargetConstantPool(CP->getConstVal(), ValTy,
CP->getAlignment());
return DAG.getNode(HexagonISD::CONST32, dl, ValTy, Res);
}
SDValue
HexagonTargetLowering::LowerRETURNADDR(SDValue Op, SelectionDAG &DAG) const {
const TargetRegisterInfo *TRI = DAG.getTarget().getRegisterInfo();
MachineFunction &MF = DAG.getMachineFunction();
MachineFrameInfo *MFI = MF.getFrameInfo();
MFI->setReturnAddressIsTaken(true);
if (verifyReturnAddressArgumentIsConstant(Op, DAG))
return SDValue();
EVT VT = Op.getValueType();
SDLoc dl(Op);
unsigned Depth = cast<ConstantSDNode>(Op.getOperand(0))->getZExtValue();
if (Depth) {
SDValue FrameAddr = LowerFRAMEADDR(Op, DAG);
SDValue Offset = DAG.getConstant(4, MVT::i32);
return DAG.getLoad(VT, dl, DAG.getEntryNode(),
DAG.getNode(ISD::ADD, dl, VT, FrameAddr, Offset),
MachinePointerInfo(), false, false, false, 0);
}
// Return LR, which contains the return address. Mark it an implicit live-in.
unsigned Reg = MF.addLiveIn(TRI->getRARegister(), getRegClassFor(MVT::i32));
return DAG.getCopyFromReg(DAG.getEntryNode(), dl, Reg, VT);
}
SDValue
HexagonTargetLowering::LowerFRAMEADDR(SDValue Op, SelectionDAG &DAG) const {
const HexagonRegisterInfo *TRI =
static_cast<const HexagonRegisterInfo *>(DAG.getTarget().getRegisterInfo());
MachineFrameInfo *MFI = DAG.getMachineFunction().getFrameInfo();
MFI->setFrameAddressIsTaken(true);
EVT VT = Op.getValueType();
SDLoc dl(Op);
unsigned Depth = cast<ConstantSDNode>(Op.getOperand(0))->getZExtValue();
SDValue FrameAddr = DAG.getCopyFromReg(DAG.getEntryNode(), dl,
TRI->getFrameRegister(), VT);
while (Depth--)
FrameAddr = DAG.getLoad(VT, dl, DAG.getEntryNode(), FrameAddr,
MachinePointerInfo(),
false, false, false, 0);
return FrameAddr;
}
SDValue HexagonTargetLowering::LowerATOMIC_FENCE(SDValue Op,
SelectionDAG& DAG) const {
SDLoc dl(Op);
return DAG.getNode(HexagonISD::BARRIER, dl, MVT::Other, Op.getOperand(0));
}
SDValue HexagonTargetLowering::LowerGLOBALADDRESS(SDValue Op,
SelectionDAG &DAG) const {
SDValue Result;
const GlobalValue *GV = cast<GlobalAddressSDNode>(Op)->getGlobal();
int64_t Offset = cast<GlobalAddressSDNode>(Op)->getOffset();
SDLoc dl(Op);
Result = DAG.getTargetGlobalAddress(GV, dl, getPointerTy(), Offset);
const HexagonTargetObjectFile &TLOF =
static_cast<const HexagonTargetObjectFile &>(getObjFileLowering());
if (TLOF.IsGlobalInSmallSection(GV, getTargetMachine())) {
return DAG.getNode(HexagonISD::CONST32_GP, dl, getPointerTy(), Result);
}
return DAG.getNode(HexagonISD::CONST32, dl, getPointerTy(), Result);
}
SDValue
HexagonTargetLowering::LowerBlockAddress(SDValue Op, SelectionDAG &DAG) const {
const BlockAddress *BA = cast<BlockAddressSDNode>(Op)->getBlockAddress();
SDValue BA_SD = DAG.getTargetBlockAddress(BA, MVT::i32);
SDLoc dl(Op);
return DAG.getNode(HexagonISD::CONST32_GP, dl, getPointerTy(), BA_SD);
}
//===----------------------------------------------------------------------===//
// TargetLowering Implementation
//===----------------------------------------------------------------------===//
HexagonTargetLowering::HexagonTargetLowering(const TargetMachine &targetmachine)
: TargetLowering(targetmachine, new HexagonTargetObjectFile()),
TM(targetmachine) {
const HexagonSubtarget &Subtarget = TM.getSubtarget<HexagonSubtarget>();
// Set up the register classes.
addRegisterClass(MVT::i32, &Hexagon::IntRegsRegClass);
addRegisterClass(MVT::i64, &Hexagon::DoubleRegsRegClass);
if (Subtarget.hasV5TOps()) {
addRegisterClass(MVT::f32, &Hexagon::IntRegsRegClass);
addRegisterClass(MVT::f64, &Hexagon::DoubleRegsRegClass);
}
addRegisterClass(MVT::i1, &Hexagon::PredRegsRegClass);
computeRegisterProperties();
// Align loop entry
setPrefLoopAlignment(4);
// Limits for inline expansion of memcpy/memmove
MaxStoresPerMemcpy = 6;
MaxStoresPerMemmove = 6;
//
// Library calls for unsupported operations
//
setLibcallName(RTLIB::SINTTOFP_I128_F64, "__hexagon_floattidf");
setLibcallName(RTLIB::SINTTOFP_I128_F32, "__hexagon_floattisf");
setLibcallName(RTLIB::FPTOUINT_F32_I128, "__hexagon_fixunssfti");
setLibcallName(RTLIB::FPTOUINT_F64_I128, "__hexagon_fixunsdfti");
setLibcallName(RTLIB::FPTOSINT_F32_I128, "__hexagon_fixsfti");
setLibcallName(RTLIB::FPTOSINT_F64_I128, "__hexagon_fixdfti");
setLibcallName(RTLIB::SDIV_I32, "__hexagon_divsi3");
setOperationAction(ISD::SDIV, MVT::i32, Expand);
setLibcallName(RTLIB::SREM_I32, "__hexagon_umodsi3");
setOperationAction(ISD::SREM, MVT::i32, Expand);
setLibcallName(RTLIB::SDIV_I64, "__hexagon_divdi3");
setOperationAction(ISD::SDIV, MVT::i64, Expand);
setLibcallName(RTLIB::SREM_I64, "__hexagon_moddi3");
setOperationAction(ISD::SREM, MVT::i64, Expand);
setLibcallName(RTLIB::UDIV_I32, "__hexagon_udivsi3");
setOperationAction(ISD::UDIV, MVT::i32, Expand);
setLibcallName(RTLIB::UDIV_I64, "__hexagon_udivdi3");
setOperationAction(ISD::UDIV, MVT::i64, Expand);
setLibcallName(RTLIB::UREM_I32, "__hexagon_umodsi3");
setOperationAction(ISD::UREM, MVT::i32, Expand);
setLibcallName(RTLIB::UREM_I64, "__hexagon_umoddi3");
setOperationAction(ISD::UREM, MVT::i64, Expand);
setLibcallName(RTLIB::DIV_F32, "__hexagon_divsf3");
setOperationAction(ISD::FDIV, MVT::f32, Expand);
setLibcallName(RTLIB::DIV_F64, "__hexagon_divdf3");
setOperationAction(ISD::FDIV, MVT::f64, Expand);
setOperationAction(ISD::FSQRT, MVT::f32, Expand);
setOperationAction(ISD::FSQRT, MVT::f64, Expand);
setOperationAction(ISD::FSIN, MVT::f32, Expand);
setOperationAction(ISD::FSIN, MVT::f64, Expand);
if (Subtarget.hasV5TOps()) {
// Hexagon V5 Support.
setOperationAction(ISD::FADD, MVT::f32, Legal);
setOperationAction(ISD::FADD, MVT::f64, Legal);
setOperationAction(ISD::FP_EXTEND, MVT::f32, Legal);
setCondCodeAction(ISD::SETOEQ, MVT::f32, Legal);
setCondCodeAction(ISD::SETOEQ, MVT::f64, Legal);
setCondCodeAction(ISD::SETUEQ, MVT::f32, Legal);
setCondCodeAction(ISD::SETUEQ, MVT::f64, Legal);
setCondCodeAction(ISD::SETOGE, MVT::f32, Legal);
setCondCodeAction(ISD::SETOGE, MVT::f64, Legal);
setCondCodeAction(ISD::SETUGE, MVT::f32, Legal);
setCondCodeAction(ISD::SETUGE, MVT::f64, Legal);
setCondCodeAction(ISD::SETOGT, MVT::f32, Legal);
setCondCodeAction(ISD::SETOGT, MVT::f64, Legal);
setCondCodeAction(ISD::SETUGT, MVT::f32, Legal);
setCondCodeAction(ISD::SETUGT, MVT::f64, Legal);
setCondCodeAction(ISD::SETOLE, MVT::f32, Legal);
setCondCodeAction(ISD::SETOLE, MVT::f64, Legal);
setCondCodeAction(ISD::SETOLT, MVT::f32, Legal);
setCondCodeAction(ISD::SETOLT, MVT::f64, Legal);
setOperationAction(ISD::ConstantFP, MVT::f32, Legal);
setOperationAction(ISD::ConstantFP, MVT::f64, Legal);
setOperationAction(ISD::FP_TO_UINT, MVT::i1, Promote);
setOperationAction(ISD::FP_TO_SINT, MVT::i1, Promote);
setOperationAction(ISD::UINT_TO_FP, MVT::i1, Promote);
setOperationAction(ISD::SINT_TO_FP, MVT::i1, Promote);
setOperationAction(ISD::FP_TO_UINT, MVT::i8, Promote);
setOperationAction(ISD::FP_TO_SINT, MVT::i8, Promote);
setOperationAction(ISD::UINT_TO_FP, MVT::i8, Promote);
setOperationAction(ISD::SINT_TO_FP, MVT::i8, Promote);
setOperationAction(ISD::FP_TO_UINT, MVT::i16, Promote);
setOperationAction(ISD::FP_TO_SINT, MVT::i16, Promote);
setOperationAction(ISD::UINT_TO_FP, MVT::i16, Promote);
setOperationAction(ISD::SINT_TO_FP, MVT::i16, Promote);
setOperationAction(ISD::FP_TO_UINT, MVT::i32, Legal);
setOperationAction(ISD::FP_TO_SINT, MVT::i32, Legal);
setOperationAction(ISD::UINT_TO_FP, MVT::i32, Legal);
setOperationAction(ISD::SINT_TO_FP, MVT::i32, Legal);
setOperationAction(ISD::FP_TO_UINT, MVT::i64, Legal);
setOperationAction(ISD::FP_TO_SINT, MVT::i64, Legal);
setOperationAction(ISD::UINT_TO_FP, MVT::i64, Legal);
setOperationAction(ISD::SINT_TO_FP, MVT::i64, Legal);
setOperationAction(ISD::FABS, MVT::f32, Legal);
setOperationAction(ISD::FABS, MVT::f64, Expand);
setOperationAction(ISD::FNEG, MVT::f32, Legal);
setOperationAction(ISD::FNEG, MVT::f64, Expand);
} else {
// Expand fp<->uint.
setOperationAction(ISD::FP_TO_SINT, MVT::i32, Expand);
setOperationAction(ISD::FP_TO_UINT, MVT::i32, Expand);
setOperationAction(ISD::SINT_TO_FP, MVT::i32, Expand);
setOperationAction(ISD::UINT_TO_FP, MVT::i32, Expand);
setLibcallName(RTLIB::SINTTOFP_I64_F32, "__hexagon_floatdisf");
setLibcallName(RTLIB::UINTTOFP_I64_F32, "__hexagon_floatundisf");
setLibcallName(RTLIB::UINTTOFP_I32_F32, "__hexagon_floatunsisf");
setLibcallName(RTLIB::SINTTOFP_I32_F32, "__hexagon_floatsisf");
setLibcallName(RTLIB::SINTTOFP_I64_F64, "__hexagon_floatdidf");
setLibcallName(RTLIB::UINTTOFP_I64_F64, "__hexagon_floatundidf");
setLibcallName(RTLIB::UINTTOFP_I32_F64, "__hexagon_floatunsidf");
setLibcallName(RTLIB::SINTTOFP_I32_F64, "__hexagon_floatsidf");
setLibcallName(RTLIB::FPTOUINT_F32_I32, "__hexagon_fixunssfsi");
setLibcallName(RTLIB::FPTOUINT_F32_I64, "__hexagon_fixunssfdi");
setLibcallName(RTLIB::FPTOSINT_F64_I64, "__hexagon_fixdfdi");
setLibcallName(RTLIB::FPTOSINT_F32_I64, "__hexagon_fixsfdi");
setLibcallName(RTLIB::FPTOUINT_F64_I32, "__hexagon_fixunsdfsi");
setLibcallName(RTLIB::FPTOUINT_F64_I64, "__hexagon_fixunsdfdi");
setLibcallName(RTLIB::ADD_F64, "__hexagon_adddf3");
setOperationAction(ISD::FADD, MVT::f64, Expand);
setLibcallName(RTLIB::ADD_F32, "__hexagon_addsf3");
setOperationAction(ISD::FADD, MVT::f32, Expand);
setLibcallName(RTLIB::FPEXT_F32_F64, "__hexagon_extendsfdf2");
setOperationAction(ISD::FP_EXTEND, MVT::f32, Expand);
setLibcallName(RTLIB::OEQ_F32, "__hexagon_eqsf2");
setCondCodeAction(ISD::SETOEQ, MVT::f32, Expand);
setLibcallName(RTLIB::OEQ_F64, "__hexagon_eqdf2");
setCondCodeAction(ISD::SETOEQ, MVT::f64, Expand);
setLibcallName(RTLIB::OGE_F32, "__hexagon_gesf2");
setCondCodeAction(ISD::SETOGE, MVT::f32, Expand);
setLibcallName(RTLIB::OGE_F64, "__hexagon_gedf2");
setCondCodeAction(ISD::SETOGE, MVT::f64, Expand);
setLibcallName(RTLIB::OGT_F32, "__hexagon_gtsf2");
setCondCodeAction(ISD::SETOGT, MVT::f32, Expand);
setLibcallName(RTLIB::OGT_F64, "__hexagon_gtdf2");
setCondCodeAction(ISD::SETOGT, MVT::f64, Expand);
setLibcallName(RTLIB::FPTOSINT_F64_I32, "__hexagon_fixdfsi");
setOperationAction(ISD::FP_TO_SINT, MVT::f64, Expand);
setLibcallName(RTLIB::FPTOSINT_F32_I32, "__hexagon_fixsfsi");
setOperationAction(ISD::FP_TO_SINT, MVT::f32, Expand);
setLibcallName(RTLIB::OLE_F64, "__hexagon_ledf2");
setCondCodeAction(ISD::SETOLE, MVT::f64, Expand);
setLibcallName(RTLIB::OLE_F32, "__hexagon_lesf2");
setCondCodeAction(ISD::SETOLE, MVT::f32, Expand);
setLibcallName(RTLIB::OLT_F64, "__hexagon_ltdf2");
setCondCodeAction(ISD::SETOLT, MVT::f64, Expand);
setLibcallName(RTLIB::OLT_F32, "__hexagon_ltsf2");
setCondCodeAction(ISD::SETOLT, MVT::f32, Expand);
setLibcallName(RTLIB::MUL_F64, "__hexagon_muldf3");
setOperationAction(ISD::FMUL, MVT::f64, Expand);
setLibcallName(RTLIB::MUL_F32, "__hexagon_mulsf3");
setOperationAction(ISD::MUL, MVT::f32, Expand);
setLibcallName(RTLIB::UNE_F64, "__hexagon_nedf2");
setCondCodeAction(ISD::SETUNE, MVT::f64, Expand);
setLibcallName(RTLIB::UNE_F32, "__hexagon_nesf2");
setLibcallName(RTLIB::SUB_F64, "__hexagon_subdf3");
setOperationAction(ISD::SUB, MVT::f64, Expand);
setLibcallName(RTLIB::SUB_F32, "__hexagon_subsf3");
setOperationAction(ISD::SUB, MVT::f32, Expand);
setLibcallName(RTLIB::FPROUND_F64_F32, "__hexagon_truncdfsf2");
setOperationAction(ISD::FP_ROUND, MVT::f64, Expand);
setLibcallName(RTLIB::UO_F64, "__hexagon_unorddf2");
setCondCodeAction(ISD::SETUO, MVT::f64, Expand);
setLibcallName(RTLIB::O_F64, "__hexagon_unorddf2");
setCondCodeAction(ISD::SETO, MVT::f64, Expand);
setLibcallName(RTLIB::O_F32, "__hexagon_unordsf2");
setCondCodeAction(ISD::SETO, MVT::f32, Expand);
setLibcallName(RTLIB::UO_F32, "__hexagon_unordsf2");
setCondCodeAction(ISD::SETUO, MVT::f32, Expand);
setOperationAction(ISD::FABS, MVT::f32, Expand);
setOperationAction(ISD::FABS, MVT::f64, Expand);
setOperationAction(ISD::FNEG, MVT::f32, Expand);
setOperationAction(ISD::FNEG, MVT::f64, Expand);
}
setLibcallName(RTLIB::SREM_I32, "__hexagon_modsi3");
setOperationAction(ISD::SREM, MVT::i32, Expand);
setIndexedLoadAction(ISD::POST_INC, MVT::i8, Legal);
setIndexedLoadAction(ISD::POST_INC, MVT::i16, Legal);
setIndexedLoadAction(ISD::POST_INC, MVT::i32, Legal);
setIndexedLoadAction(ISD::POST_INC, MVT::i64, Legal);
setIndexedStoreAction(ISD::POST_INC, MVT::i8, Legal);
setIndexedStoreAction(ISD::POST_INC, MVT::i16, Legal);
setIndexedStoreAction(ISD::POST_INC, MVT::i32, Legal);
setIndexedStoreAction(ISD::POST_INC, MVT::i64, Legal);
setOperationAction(ISD::BUILD_PAIR, MVT::i64, Expand);
// Turn FP extload into load/fextend.
setLoadExtAction(ISD::EXTLOAD, MVT::f32, Expand);
// Hexagon has a i1 sign extending load.
setLoadExtAction(ISD::SEXTLOAD, MVT::i1, Expand);
// Turn FP truncstore into trunc + store.
setTruncStoreAction(MVT::f64, MVT::f32, Expand);
// Custom legalize GlobalAddress nodes into CONST32.
setOperationAction(ISD::GlobalAddress, MVT::i32, Custom);
setOperationAction(ISD::GlobalAddress, MVT::i8, Custom);
setOperationAction(ISD::BlockAddress, MVT::i32, Custom);
// Truncate action?
setOperationAction(ISD::TRUNCATE, MVT::i64, Expand);
// Hexagon doesn't have sext_inreg, replace them with shl/sra.
setOperationAction(ISD::SIGN_EXTEND_INREG, MVT::i1, Expand);
// Hexagon has no REM or DIVREM operations.
setOperationAction(ISD::UREM, MVT::i32, Expand);
setOperationAction(ISD::SREM, MVT::i32, Expand);
setOperationAction(ISD::SDIVREM, MVT::i32, Expand);
setOperationAction(ISD::UDIVREM, MVT::i32, Expand);
setOperationAction(ISD::SREM, MVT::i64, Expand);
setOperationAction(ISD::SDIVREM, MVT::i64, Expand);
setOperationAction(ISD::UDIVREM, MVT::i64, Expand);
setOperationAction(ISD::BSWAP, MVT::i64, Expand);
// Lower SELECT_CC to SETCC and SELECT.
setOperationAction(ISD::SELECT_CC, MVT::i1, Expand);
setOperationAction(ISD::SELECT_CC, MVT::i32, Expand);
setOperationAction(ISD::SELECT_CC, MVT::i64, Expand);
if (Subtarget.hasV5TOps()) {
// We need to make the operation type of SELECT node to be Custom,
// such that we don't go into the infinite loop of
// select -> setcc -> select_cc -> select loop.
setOperationAction(ISD::SELECT, MVT::f32, Custom);
setOperationAction(ISD::SELECT, MVT::f64, Custom);
setOperationAction(ISD::SELECT_CC, MVT::f32, Expand);
setOperationAction(ISD::SELECT_CC, MVT::f64, Expand);
} else {
// Hexagon has no select or setcc: expand to SELECT_CC.
setOperationAction(ISD::SELECT, MVT::f32, Expand);
setOperationAction(ISD::SELECT, MVT::f64, Expand);
}
if (EmitJumpTables) {
setOperationAction(ISD::BR_JT, MVT::Other, Custom);
} else {
setOperationAction(ISD::BR_JT, MVT::Other, Expand);
}
// Increase jump tables cutover to 5, was 4.
setMinimumJumpTableEntries(5);
setOperationAction(ISD::BR_CC, MVT::f32, Expand);
setOperationAction(ISD::BR_CC, MVT::f64, Expand);
setOperationAction(ISD::BR_CC, MVT::i1, Expand);
setOperationAction(ISD::BR_CC, MVT::i32, Expand);
setOperationAction(ISD::BR_CC, MVT::i64, Expand);
setOperationAction(ISD::ATOMIC_FENCE, MVT::Other, Custom);
setOperationAction(ISD::FSIN, MVT::f64, Expand);
setOperationAction(ISD::FCOS, MVT::f64, Expand);
setOperationAction(ISD::FREM, MVT::f64, Expand);
setOperationAction(ISD::FSIN, MVT::f32, Expand);
setOperationAction(ISD::FCOS, MVT::f32, Expand);
setOperationAction(ISD::FREM, MVT::f32, Expand);
setOperationAction(ISD::FSINCOS, MVT::f64, Expand);
setOperationAction(ISD::FSINCOS, MVT::f32, Expand);
// In V4, we have double word add/sub with carry. The problem with
// modelling this instruction is that it produces 2 results - Rdd and Px.
// To model update of Px, we will have to use Defs[p0..p3] which will
// cause any predicate live range to spill. So, we pretend we dont't
// have these instructions.
setOperationAction(ISD::ADDE, MVT::i8, Expand);
setOperationAction(ISD::ADDE, MVT::i16, Expand);
setOperationAction(ISD::ADDE, MVT::i32, Expand);
setOperationAction(ISD::ADDE, MVT::i64, Expand);
setOperationAction(ISD::SUBE, MVT::i8, Expand);
setOperationAction(ISD::SUBE, MVT::i16, Expand);
setOperationAction(ISD::SUBE, MVT::i32, Expand);
setOperationAction(ISD::SUBE, MVT::i64, Expand);
setOperationAction(ISD::ADDC, MVT::i8, Expand);
setOperationAction(ISD::ADDC, MVT::i16, Expand);
setOperationAction(ISD::ADDC, MVT::i32, Expand);
setOperationAction(ISD::ADDC, MVT::i64, Expand);
setOperationAction(ISD::SUBC, MVT::i8, Expand);
setOperationAction(ISD::SUBC, MVT::i16, Expand);
setOperationAction(ISD::SUBC, MVT::i32, Expand);
setOperationAction(ISD::SUBC, MVT::i64, Expand);
setOperationAction(ISD::CTPOP, MVT::i32, Expand);
setOperationAction(ISD::CTPOP, MVT::i64, Expand);
setOperationAction(ISD::CTTZ, MVT::i32, Expand);
setOperationAction(ISD::CTTZ, MVT::i64, Expand);
setOperationAction(ISD::CTTZ_ZERO_UNDEF, MVT::i32, Expand);
setOperationAction(ISD::CTTZ_ZERO_UNDEF, MVT::i64, Expand);
setOperationAction(ISD::CTLZ, MVT::i32, Expand);
setOperationAction(ISD::CTLZ, MVT::i64, Expand);
setOperationAction(ISD::CTLZ_ZERO_UNDEF, MVT::i32, Expand);
setOperationAction(ISD::CTLZ_ZERO_UNDEF, MVT::i64, Expand);
setOperationAction(ISD::ROTL, MVT::i32, Expand);
setOperationAction(ISD::ROTR, MVT::i32, Expand);
setOperationAction(ISD::BSWAP, MVT::i32, Expand);
setOperationAction(ISD::FCOPYSIGN, MVT::f64, Expand);
setOperationAction(ISD::FCOPYSIGN, MVT::f32, Expand);
setOperationAction(ISD::FPOW, MVT::f64, Expand);
setOperationAction(ISD::FPOW, MVT::f32, Expand);
setOperationAction(ISD::SHL_PARTS, MVT::i32, Expand);
setOperationAction(ISD::SRA_PARTS, MVT::i32, Expand);
setOperationAction(ISD::SRL_PARTS, MVT::i32, Expand);
setOperationAction(ISD::UMUL_LOHI, MVT::i32, Expand);
setOperationAction(ISD::SMUL_LOHI, MVT::i32, Expand);
setOperationAction(ISD::SMUL_LOHI, MVT::i64, Expand);
setOperationAction(ISD::UMUL_LOHI, MVT::i64, Expand);
setOperationAction(ISD::EH_RETURN, MVT::Other, Custom);
if (Subtarget.isSubtargetV2()) {
setExceptionPointerRegister(Hexagon::R20);
setExceptionSelectorRegister(Hexagon::R21);
} else {
setExceptionPointerRegister(Hexagon::R0);
setExceptionSelectorRegister(Hexagon::R1);
}
// VASTART needs to be custom lowered to use the VarArgsFrameIndex.
setOperationAction(ISD::VASTART, MVT::Other, Custom);
// Use the default implementation.
setOperationAction(ISD::VAARG, MVT::Other, Expand);
setOperationAction(ISD::VACOPY, MVT::Other, Expand);
setOperationAction(ISD::VAEND, MVT::Other, Expand);
setOperationAction(ISD::STACKSAVE, MVT::Other, Expand);
setOperationAction(ISD::STACKRESTORE, MVT::Other, Expand);
setOperationAction(ISD::DYNAMIC_STACKALLOC, MVT::i32, Custom);
setOperationAction(ISD::INLINEASM, MVT::Other, Custom);
setMinFunctionAlignment(2);
// Needed for DYNAMIC_STACKALLOC expansion.
const HexagonRegisterInfo *QRI =
static_cast<const HexagonRegisterInfo *>(TM.getRegisterInfo());
setStackPointerRegisterToSaveRestore(QRI->getStackRegister());
setSchedulingPreference(Sched::VLIW);
}
const char*
HexagonTargetLowering::getTargetNodeName(unsigned Opcode) const {
switch (Opcode) {
default: return nullptr;
case HexagonISD::CONST32: return "HexagonISD::CONST32";
case HexagonISD::CONST32_GP: return "HexagonISD::CONST32_GP";
case HexagonISD::CONST32_Int_Real: return "HexagonISD::CONST32_Int_Real";
case HexagonISD::ADJDYNALLOC: return "HexagonISD::ADJDYNALLOC";
case HexagonISD::CMPICC: return "HexagonISD::CMPICC";
case HexagonISD::CMPFCC: return "HexagonISD::CMPFCC";
case HexagonISD::BRICC: return "HexagonISD::BRICC";
case HexagonISD::BRFCC: return "HexagonISD::BRFCC";
case HexagonISD::SELECT_ICC: return "HexagonISD::SELECT_ICC";
case HexagonISD::SELECT_FCC: return "HexagonISD::SELECT_FCC";
case HexagonISD::Hi: return "HexagonISD::Hi";
case HexagonISD::Lo: return "HexagonISD::Lo";
case HexagonISD::FTOI: return "HexagonISD::FTOI";
case HexagonISD::ITOF: return "HexagonISD::ITOF";
case HexagonISD::CALL: return "HexagonISD::CALL";
case HexagonISD::RET_FLAG: return "HexagonISD::RET_FLAG";
case HexagonISD::BR_JT: return "HexagonISD::BR_JT";
case HexagonISD::TC_RETURN: return "HexagonISD::TC_RETURN";
case HexagonISD::EH_RETURN: return "HexagonISD::EH_RETURN";
}
}
bool
HexagonTargetLowering::isTruncateFree(Type *Ty1, Type *Ty2) const {
EVT MTy1 = EVT::getEVT(Ty1);
EVT MTy2 = EVT::getEVT(Ty2);
if (!MTy1.isSimple() || !MTy2.isSimple()) {
return false;
}
return ((MTy1.getSimpleVT() == MVT::i64) && (MTy2.getSimpleVT() == MVT::i32));
}
bool HexagonTargetLowering::isTruncateFree(EVT VT1, EVT VT2) const {
if (!VT1.isSimple() || !VT2.isSimple()) {
return false;
}
return ((VT1.getSimpleVT() == MVT::i64) && (VT2.getSimpleVT() == MVT::i32));
}
bool
HexagonTargetLowering::allowTruncateForTailCall(Type *Ty1, Type *Ty2) const {
// Assuming the caller does not have either a signext or zeroext modifier, and
// only one value is accepted, any reasonable truncation is allowed.
if (!Ty1->isIntegerTy() || !Ty2->isIntegerTy())
return false;
// FIXME: in principle up to 64-bit could be made safe, but it would be very
// fragile at the moment: any support for multiple value returns would be
// liable to disallow tail calls involving i64 -> iN truncation in many cases.
return Ty1->getPrimitiveSizeInBits() <= 32;
}
SDValue
HexagonTargetLowering::LowerEH_RETURN(SDValue Op, SelectionDAG &DAG) const {
SDValue Chain = Op.getOperand(0);
SDValue Offset = Op.getOperand(1);
SDValue Handler = Op.getOperand(2);
SDLoc dl(Op);
// Mark function as containing a call to EH_RETURN.
HexagonMachineFunctionInfo *FuncInfo =
DAG.getMachineFunction().getInfo<HexagonMachineFunctionInfo>();
FuncInfo->setHasEHReturn();
unsigned OffsetReg = Hexagon::R28;
SDValue StoreAddr = DAG.getNode(ISD::ADD, dl, getPointerTy(),
DAG.getRegister(Hexagon::R30, getPointerTy()),
DAG.getIntPtrConstant(4));
Chain = DAG.getStore(Chain, dl, Handler, StoreAddr, MachinePointerInfo(),
false, false, 0);
Chain = DAG.getCopyToReg(Chain, dl, OffsetReg, Offset);
// Not needed we already use it as explict input to EH_RETURN.
// MF.getRegInfo().addLiveOut(OffsetReg);
return DAG.getNode(HexagonISD::EH_RETURN, dl, MVT::Other, Chain);
}
SDValue
HexagonTargetLowering::LowerOperation(SDValue Op, SelectionDAG &DAG) const {
switch (Op.getOpcode()) {
default: llvm_unreachable("Should not custom lower this!");
case ISD::ConstantPool: return LowerConstantPool(Op, DAG);
case ISD::EH_RETURN: return LowerEH_RETURN(Op, DAG);
// Frame & Return address. Currently unimplemented.
case ISD::RETURNADDR: return LowerRETURNADDR(Op, DAG);
case ISD::FRAMEADDR: return LowerFRAMEADDR(Op, DAG);
case ISD::GlobalTLSAddress:
llvm_unreachable("TLS not implemented for Hexagon.");
case ISD::ATOMIC_FENCE: return LowerATOMIC_FENCE(Op, DAG);
case ISD::GlobalAddress: return LowerGLOBALADDRESS(Op, DAG);
case ISD::BlockAddress: return LowerBlockAddress(Op, DAG);
case ISD::VASTART: return LowerVASTART(Op, DAG);
case ISD::BR_JT: return LowerBR_JT(Op, DAG);
case ISD::DYNAMIC_STACKALLOC: return LowerDYNAMIC_STACKALLOC(Op, DAG);
case ISD::SELECT: return Op;
case ISD::INTRINSIC_WO_CHAIN: return LowerINTRINSIC_WO_CHAIN(Op, DAG);
case ISD::INLINEASM: return LowerINLINEASM(Op, DAG);
}
}
//===----------------------------------------------------------------------===//
// Hexagon Scheduler Hooks
//===----------------------------------------------------------------------===//
MachineBasicBlock *
HexagonTargetLowering::EmitInstrWithCustomInserter(MachineInstr *MI,
MachineBasicBlock *BB)
const {
switch (MI->getOpcode()) {
case Hexagon::ADJDYNALLOC: {
MachineFunction *MF = BB->getParent();
HexagonMachineFunctionInfo *FuncInfo =
MF->getInfo<HexagonMachineFunctionInfo>();
FuncInfo->addAllocaAdjustInst(MI);
return BB;
}
default: llvm_unreachable("Unexpected instr type to insert");
} // switch
}
//===----------------------------------------------------------------------===//
// Inline Assembly Support
//===----------------------------------------------------------------------===//
std::pair<unsigned, const TargetRegisterClass*>
HexagonTargetLowering::getRegForInlineAsmConstraint(const
std::string &Constraint,
MVT VT) const {
if (Constraint.size() == 1) {
switch (Constraint[0]) {
case 'r': // R0-R31
switch (VT.SimpleTy) {
default:
llvm_unreachable("getRegForInlineAsmConstraint Unhandled data type");
case MVT::i32:
case MVT::i16:
case MVT::i8:
case MVT::f32:
return std::make_pair(0U, &Hexagon::IntRegsRegClass);
case MVT::i64:
case MVT::f64:
return std::make_pair(0U, &Hexagon::DoubleRegsRegClass);
}
default:
llvm_unreachable("Unknown asm register class");
}
}
return TargetLowering::getRegForInlineAsmConstraint(Constraint, VT);
}
/// isFPImmLegal - Returns true if the target can instruction select the
/// specified FP immediate natively. If false, the legalizer will
/// materialize the FP immediate as a load from a constant pool.
bool HexagonTargetLowering::isFPImmLegal(const APFloat &Imm, EVT VT) const {
return TM.getSubtarget<HexagonSubtarget>().hasV5TOps();
}
/// isLegalAddressingMode - Return true if the addressing mode represented by
/// AM is legal for this target, for a load/store of the specified type.
bool HexagonTargetLowering::isLegalAddressingMode(const AddrMode &AM,
Type *Ty) const {
// Allows a signed-extended 11-bit immediate field.
if (AM.BaseOffs <= -(1LL << 13) || AM.BaseOffs >= (1LL << 13)-1) {
return false;
}
// No global is ever allowed as a base.
if (AM.BaseGV) {
return false;
}
int Scale = AM.Scale;
if (Scale < 0) Scale = -Scale;
switch (Scale) {
case 0: // No scale reg, "r+i", "r", or just "i".
break;
default: // No scaled addressing mode.
return false;
}
return true;
}
/// isLegalICmpImmediate - Return true if the specified immediate is legal
/// icmp immediate, that is the target has icmp instructions which can compare
/// a register against the immediate without having to materialize the
/// immediate into a register.
bool HexagonTargetLowering::isLegalICmpImmediate(int64_t Imm) const {
return Imm >= -512 && Imm <= 511;
}
/// IsEligibleForTailCallOptimization - Check whether the call is eligible
/// for tail call optimization. Targets which want to do tail call
/// optimization should implement this function.
bool HexagonTargetLowering::IsEligibleForTailCallOptimization(
SDValue Callee,
CallingConv::ID CalleeCC,
bool isVarArg,
bool isCalleeStructRet,
bool isCallerStructRet,
const SmallVectorImpl<ISD::OutputArg> &Outs,
const SmallVectorImpl<SDValue> &OutVals,
const SmallVectorImpl<ISD::InputArg> &Ins,
SelectionDAG& DAG) const {
const Function *CallerF = DAG.getMachineFunction().getFunction();
CallingConv::ID CallerCC = CallerF->getCallingConv();
bool CCMatch = CallerCC == CalleeCC;
// ***************************************************************************
// Look for obvious safe cases to perform tail call optimization that do not
// require ABI changes.
// ***************************************************************************
// If this is a tail call via a function pointer, then don't do it!
if (!(dyn_cast<GlobalAddressSDNode>(Callee))
&& !(dyn_cast<ExternalSymbolSDNode>(Callee))) {
return false;
}
// Do not optimize if the calling conventions do not match.
if (!CCMatch)
return false;
// Do not tail call optimize vararg calls.
if (isVarArg)
return false;
// Also avoid tail call optimization if either caller or callee uses struct
// return semantics.
if (isCalleeStructRet || isCallerStructRet)
return false;
// In addition to the cases above, we also disable Tail Call Optimization if
// the calling convention code that at least one outgoing argument needs to
// go on the stack. We cannot check that here because at this point that
// information is not available.
return true;
}