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llvm-project/llvm/lib/Target/RISCV/RISCVISelLowering.cpp

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//===-- RISCVISelLowering.cpp - RISCV 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 defines the interfaces that RISCV uses to lower LLVM code into a
// selection DAG.
//
//===----------------------------------------------------------------------===//
#include "RISCVISelLowering.h"
#include "RISCV.h"
#include "RISCVMachineFunctionInfo.h"
#include "RISCVRegisterInfo.h"
#include "RISCVSubtarget.h"
#include "RISCVTargetMachine.h"
#include "llvm/CodeGen/CallingConvLower.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/SelectionDAGISel.h"
#include "llvm/CodeGen/TargetLoweringObjectFileImpl.h"
#include "llvm/CodeGen/ValueTypes.h"
#include "llvm/IR/DiagnosticInfo.h"
#include "llvm/IR/DiagnosticPrinter.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
using namespace llvm;
#define DEBUG_TYPE "riscv-lower"
RISCVTargetLowering::RISCVTargetLowering(const TargetMachine &TM,
const RISCVSubtarget &STI)
: TargetLowering(TM), Subtarget(STI) {
MVT XLenVT = Subtarget.getXLenVT();
// Set up the register classes.
addRegisterClass(XLenVT, &RISCV::GPRRegClass);
// Compute derived properties from the register classes.
computeRegisterProperties(STI.getRegisterInfo());
setStackPointerRegisterToSaveRestore(RISCV::X2);
for (auto N : {ISD::EXTLOAD, ISD::SEXTLOAD, ISD::ZEXTLOAD})
setLoadExtAction(N, XLenVT, MVT::i1, Promote);
// TODO: add all necessary setOperationAction calls.
setOperationAction(ISD::DYNAMIC_STACKALLOC, XLenVT, Expand);
setOperationAction(ISD::BR_JT, MVT::Other, Expand);
setOperationAction(ISD::BR_CC, XLenVT, Expand);
setOperationAction(ISD::SELECT, XLenVT, Custom);
setOperationAction(ISD::SELECT_CC, XLenVT, Expand);
setOperationAction(ISD::STACKSAVE, MVT::Other, Expand);
setOperationAction(ISD::STACKRESTORE, MVT::Other, Expand);
setOperationAction(ISD::VASTART, MVT::Other, Custom);
setOperationAction(ISD::VAARG, MVT::Other, Expand);
setOperationAction(ISD::VACOPY, MVT::Other, Expand);
setOperationAction(ISD::VAEND, MVT::Other, Expand);
for (auto VT : {MVT::i1, MVT::i8, MVT::i16})
setOperationAction(ISD::SIGN_EXTEND_INREG, VT, Expand);
setOperationAction(ISD::ADDC, XLenVT, Expand);
setOperationAction(ISD::ADDE, XLenVT, Expand);
setOperationAction(ISD::SUBC, XLenVT, Expand);
setOperationAction(ISD::SUBE, XLenVT, Expand);
if (!Subtarget.hasStdExtM()) {
setOperationAction(ISD::MUL, XLenVT, Expand);
setOperationAction(ISD::MULHS, XLenVT, Expand);
setOperationAction(ISD::MULHU, XLenVT, Expand);
setOperationAction(ISD::SDIV, XLenVT, Expand);
setOperationAction(ISD::UDIV, XLenVT, Expand);
setOperationAction(ISD::SREM, XLenVT, Expand);
setOperationAction(ISD::UREM, XLenVT, Expand);
}
setOperationAction(ISD::SDIVREM, XLenVT, Expand);
setOperationAction(ISD::UDIVREM, XLenVT, Expand);
setOperationAction(ISD::SMUL_LOHI, XLenVT, Expand);
setOperationAction(ISD::UMUL_LOHI, XLenVT, Expand);
setOperationAction(ISD::SHL_PARTS, XLenVT, Expand);
setOperationAction(ISD::SRL_PARTS, XLenVT, Expand);
setOperationAction(ISD::SRA_PARTS, XLenVT, Expand);
setOperationAction(ISD::ROTL, XLenVT, Expand);
setOperationAction(ISD::ROTR, XLenVT, Expand);
setOperationAction(ISD::BSWAP, XLenVT, Expand);
setOperationAction(ISD::CTTZ, XLenVT, Expand);
setOperationAction(ISD::CTLZ, XLenVT, Expand);
setOperationAction(ISD::CTPOP, XLenVT, Expand);
setOperationAction(ISD::GlobalAddress, XLenVT, Custom);
setOperationAction(ISD::BlockAddress, XLenVT, Custom);
setBooleanContents(ZeroOrOneBooleanContent);
// Function alignments (log2).
setMinFunctionAlignment(3);
setPrefFunctionAlignment(3);
// Effectively disable jump table generation.
setMinimumJumpTableEntries(INT_MAX);
}
EVT RISCVTargetLowering::getSetCCResultType(const DataLayout &DL, LLVMContext &,
EVT VT) const {
if (!VT.isVector())
return getPointerTy(DL);
return VT.changeVectorElementTypeToInteger();
}
// Changes the condition code and swaps operands if necessary, so the SetCC
// operation matches one of the comparisons supported directly in the RISC-V
// ISA.
static void normaliseSetCC(SDValue &LHS, SDValue &RHS, ISD::CondCode &CC) {
switch (CC) {
default:
break;
case ISD::SETGT:
case ISD::SETLE:
case ISD::SETUGT:
case ISD::SETULE:
CC = ISD::getSetCCSwappedOperands(CC);
std::swap(LHS, RHS);
break;
}
}
// Return the RISC-V branch opcode that matches the given DAG integer
// condition code. The CondCode must be one of those supported by the RISC-V
// ISA (see normaliseSetCC).
static unsigned getBranchOpcodeForIntCondCode(ISD::CondCode CC) {
switch (CC) {
default:
llvm_unreachable("Unsupported CondCode");
case ISD::SETEQ:
return RISCV::BEQ;
case ISD::SETNE:
return RISCV::BNE;
case ISD::SETLT:
return RISCV::BLT;
case ISD::SETGE:
return RISCV::BGE;
case ISD::SETULT:
return RISCV::BLTU;
case ISD::SETUGE:
return RISCV::BGEU;
}
}
SDValue RISCVTargetLowering::LowerOperation(SDValue Op,
SelectionDAG &DAG) const {
switch (Op.getOpcode()) {
default:
report_fatal_error("unimplemented operand");
case ISD::GlobalAddress:
return lowerGlobalAddress(Op, DAG);
case ISD::BlockAddress:
return lowerBlockAddress(Op, DAG);
case ISD::SELECT:
return lowerSELECT(Op, DAG);
case ISD::VASTART:
return lowerVASTART(Op, DAG);
case ISD::FRAMEADDR:
return LowerFRAMEADDR(Op, DAG);
case ISD::RETURNADDR:
return LowerRETURNADDR(Op, DAG);
}
}
SDValue RISCVTargetLowering::lowerGlobalAddress(SDValue Op,
SelectionDAG &DAG) const {
SDLoc DL(Op);
EVT Ty = Op.getValueType();
GlobalAddressSDNode *N = cast<GlobalAddressSDNode>(Op);
const GlobalValue *GV = N->getGlobal();
int64_t Offset = N->getOffset();
if (isPositionIndependent() || Subtarget.is64Bit())
report_fatal_error("Unable to lowerGlobalAddress");
SDValue GAHi =
DAG.getTargetGlobalAddress(GV, DL, Ty, Offset, RISCVII::MO_HI);
SDValue GALo =
DAG.getTargetGlobalAddress(GV, DL, Ty, Offset, RISCVII::MO_LO);
SDValue MNHi = SDValue(DAG.getMachineNode(RISCV::LUI, DL, Ty, GAHi), 0);
SDValue MNLo =
SDValue(DAG.getMachineNode(RISCV::ADDI, DL, Ty, MNHi, GALo), 0);
return MNLo;
}
SDValue RISCVTargetLowering::lowerBlockAddress(SDValue Op,
SelectionDAG &DAG) const {
SDLoc DL(Op);
EVT Ty = Op.getValueType();
BlockAddressSDNode *N = cast<BlockAddressSDNode>(Op);
const BlockAddress *BA = N->getBlockAddress();
int64_t Offset = N->getOffset();
if (isPositionIndependent() || Subtarget.is64Bit())
report_fatal_error("Unable to lowerBlockAddress");
SDValue BAHi = DAG.getTargetBlockAddress(BA, Ty, Offset, RISCVII::MO_HI);
SDValue BALo = DAG.getTargetBlockAddress(BA, Ty, Offset, RISCVII::MO_LO);
SDValue MNHi = SDValue(DAG.getMachineNode(RISCV::LUI, DL, Ty, BAHi), 0);
SDValue MNLo =
SDValue(DAG.getMachineNode(RISCV::ADDI, DL, Ty, MNHi, BALo), 0);
return MNLo;
}
SDValue RISCVTargetLowering::lowerExternalSymbol(SDValue Op,
SelectionDAG &DAG) const {
SDLoc DL(Op);
EVT Ty = Op.getValueType();
ExternalSymbolSDNode *N = cast<ExternalSymbolSDNode>(Op);
const char *Sym = N->getSymbol();
// TODO: should also handle gp-relative loads.
if (isPositionIndependent() || Subtarget.is64Bit())
report_fatal_error("Unable to lowerExternalSymbol");
SDValue GAHi = DAG.getTargetExternalSymbol(Sym, Ty, RISCVII::MO_HI);
SDValue GALo = DAG.getTargetExternalSymbol(Sym, Ty, RISCVII::MO_LO);
SDValue MNHi = SDValue(DAG.getMachineNode(RISCV::LUI, DL, Ty, GAHi), 0);
SDValue MNLo =
SDValue(DAG.getMachineNode(RISCV::ADDI, DL, Ty, MNHi, GALo), 0);
return MNLo;
}
SDValue RISCVTargetLowering::lowerSELECT(SDValue Op, SelectionDAG &DAG) const {
SDValue CondV = Op.getOperand(0);
SDValue TrueV = Op.getOperand(1);
SDValue FalseV = Op.getOperand(2);
SDLoc DL(Op);
MVT XLenVT = Subtarget.getXLenVT();
// If the result type is XLenVT and CondV is the output of a SETCC node
// which also operated on XLenVT inputs, then merge the SETCC node into the
// lowered RISCVISD::SELECT_CC to take advantage of the integer
// compare+branch instructions. i.e.:
// (select (setcc lhs, rhs, cc), truev, falsev)
// -> (riscvisd::select_cc lhs, rhs, cc, truev, falsev)
if (Op.getSimpleValueType() == XLenVT && CondV.getOpcode() == ISD::SETCC &&
CondV.getOperand(0).getSimpleValueType() == XLenVT) {
SDValue LHS = CondV.getOperand(0);
SDValue RHS = CondV.getOperand(1);
auto CC = cast<CondCodeSDNode>(CondV.getOperand(2));
ISD::CondCode CCVal = CC->get();
normaliseSetCC(LHS, RHS, CCVal);
SDValue TargetCC = DAG.getConstant(CCVal, DL, XLenVT);
SDVTList VTs = DAG.getVTList(Op.getValueType(), MVT::Glue);
SDValue Ops[] = {LHS, RHS, TargetCC, TrueV, FalseV};
return DAG.getNode(RISCVISD::SELECT_CC, DL, VTs, Ops);
}
// Otherwise:
// (select condv, truev, falsev)
// -> (riscvisd::select_cc condv, zero, setne, truev, falsev)
SDValue Zero = DAG.getConstant(0, DL, XLenVT);
SDValue SetNE = DAG.getConstant(ISD::SETNE, DL, XLenVT);
SDVTList VTs = DAG.getVTList(Op.getValueType(), MVT::Glue);
SDValue Ops[] = {CondV, Zero, SetNE, TrueV, FalseV};
return DAG.getNode(RISCVISD::SELECT_CC, DL, VTs, Ops);
}
SDValue RISCVTargetLowering::lowerVASTART(SDValue Op, SelectionDAG &DAG) const {
MachineFunction &MF = DAG.getMachineFunction();
RISCVMachineFunctionInfo *FuncInfo = MF.getInfo<RISCVMachineFunctionInfo>();
SDLoc DL(Op);
SDValue FI = DAG.getFrameIndex(FuncInfo->getVarArgsFrameIndex(),
getPointerTy(MF.getDataLayout()));
// vastart just stores the address of the VarArgsFrameIndex slot into the
// memory location argument.
const Value *SV = cast<SrcValueSDNode>(Op.getOperand(2))->getValue();
return DAG.getStore(Op.getOperand(0), DL, FI, Op.getOperand(1),
MachinePointerInfo(SV));
}
SDValue RISCVTargetLowering::LowerFRAMEADDR(SDValue Op,
SelectionDAG &DAG) const {
const RISCVRegisterInfo &RI = *Subtarget.getRegisterInfo();
MachineFunction &MF = DAG.getMachineFunction();
MachineFrameInfo &MFI = MF.getFrameInfo();
MFI.setFrameAddressIsTaken(true);
unsigned FrameReg = RI.getFrameRegister(MF);
int XLenInBytes = Subtarget.getXLen() / 8;
EVT VT = Op.getValueType();
SDLoc DL(Op);
SDValue FrameAddr = DAG.getCopyFromReg(DAG.getEntryNode(), DL, FrameReg, VT);
unsigned Depth = cast<ConstantSDNode>(Op.getOperand(0))->getZExtValue();
while (Depth--) {
int Offset = -(XLenInBytes * 2);
SDValue Ptr = DAG.getNode(ISD::ADD, DL, VT, FrameAddr,
DAG.getIntPtrConstant(Offset, DL));
FrameAddr =
DAG.getLoad(VT, DL, DAG.getEntryNode(), Ptr, MachinePointerInfo());
}
return FrameAddr;
}
SDValue RISCVTargetLowering::LowerRETURNADDR(SDValue Op,
SelectionDAG &DAG) const {
const RISCVRegisterInfo &RI = *Subtarget.getRegisterInfo();
MachineFunction &MF = DAG.getMachineFunction();
MachineFrameInfo &MFI = MF.getFrameInfo();
MFI.setReturnAddressIsTaken(true);
MVT XLenVT = Subtarget.getXLenVT();
int XLenInBytes = Subtarget.getXLen() / 8;
if (verifyReturnAddressArgumentIsConstant(Op, DAG))
return SDValue();
EVT VT = Op.getValueType();
SDLoc DL(Op);
unsigned Depth = cast<ConstantSDNode>(Op.getOperand(0))->getZExtValue();
if (Depth) {
int Off = -XLenInBytes;
SDValue FrameAddr = LowerFRAMEADDR(Op, DAG);
SDValue Offset = DAG.getConstant(Off, DL, VT);
return DAG.getLoad(VT, DL, DAG.getEntryNode(),
DAG.getNode(ISD::ADD, DL, VT, FrameAddr, Offset),
MachinePointerInfo());
}
// Return the value of the return address register, marking it an implicit
// live-in.
unsigned Reg = MF.addLiveIn(RI.getRARegister(), getRegClassFor(XLenVT));
return DAG.getCopyFromReg(DAG.getEntryNode(), DL, Reg, XLenVT);
}
MachineBasicBlock *
RISCVTargetLowering::EmitInstrWithCustomInserter(MachineInstr &MI,
MachineBasicBlock *BB) const {
const TargetInstrInfo &TII = *BB->getParent()->getSubtarget().getInstrInfo();
DebugLoc DL = MI.getDebugLoc();
assert(MI.getOpcode() == RISCV::Select_GPR_Using_CC_GPR &&
"Unexpected instr type to insert");
// To "insert" a SELECT instruction, we actually have to insert the triangle
// control-flow pattern. The incoming instruction knows the destination vreg
// to set, the condition code register to branch on, the true/false values to
// select between, and the condcode to use to select the appropriate branch.
//
// We produce the following control flow:
// HeadMBB
// | \
// | IfFalseMBB
// | /
// TailMBB
const BasicBlock *LLVM_BB = BB->getBasicBlock();
MachineFunction::iterator I = ++BB->getIterator();
MachineBasicBlock *HeadMBB = BB;
MachineFunction *F = BB->getParent();
MachineBasicBlock *TailMBB = F->CreateMachineBasicBlock(LLVM_BB);
MachineBasicBlock *IfFalseMBB = F->CreateMachineBasicBlock(LLVM_BB);
F->insert(I, IfFalseMBB);
F->insert(I, TailMBB);
// Move all remaining instructions to TailMBB.
TailMBB->splice(TailMBB->begin(), HeadMBB,
std::next(MachineBasicBlock::iterator(MI)), HeadMBB->end());
// Update machine-CFG edges by transferring all successors of the current
// block to the new block which will contain the Phi node for the select.
TailMBB->transferSuccessorsAndUpdatePHIs(HeadMBB);
// Set the successors for HeadMBB.
HeadMBB->addSuccessor(IfFalseMBB);
HeadMBB->addSuccessor(TailMBB);
// Insert appropriate branch.
unsigned LHS = MI.getOperand(1).getReg();
unsigned RHS = MI.getOperand(2).getReg();
auto CC = static_cast<ISD::CondCode>(MI.getOperand(3).getImm());
unsigned Opcode = getBranchOpcodeForIntCondCode(CC);
BuildMI(HeadMBB, DL, TII.get(Opcode))
.addReg(LHS)
.addReg(RHS)
.addMBB(TailMBB);
// IfFalseMBB just falls through to TailMBB.
IfFalseMBB->addSuccessor(TailMBB);
// %Result = phi [ %TrueValue, HeadMBB ], [ %FalseValue, IfFalseMBB ]
BuildMI(*TailMBB, TailMBB->begin(), DL, TII.get(RISCV::PHI),
MI.getOperand(0).getReg())
.addReg(MI.getOperand(4).getReg())
.addMBB(HeadMBB)
.addReg(MI.getOperand(5).getReg())
.addMBB(IfFalseMBB);
MI.eraseFromParent(); // The pseudo instruction is gone now.
return TailMBB;
}
// Calling Convention Implementation.
// The expectations for frontend ABI lowering vary from target to target.
// Ideally, an LLVM frontend would be able to avoid worrying about many ABI
// details, but this is a longer term goal. For now, we simply try to keep the
// role of the frontend as simple and well-defined as possible. The rules can
// be summarised as:
// * Never split up large scalar arguments. We handle them here.
// * If a hardfloat calling convention is being used, and the struct may be
// passed in a pair of registers (fp+fp, int+fp), and both registers are
// available, then pass as two separate arguments. If either the GPRs or FPRs
// are exhausted, then pass according to the rule below.
// * If a struct could never be passed in registers or directly in a stack
// slot (as it is larger than 2*XLEN and the floating point rules don't
// apply), then pass it using a pointer with the byval attribute.
// * If a struct is less than 2*XLEN, then coerce to either a two-element
// word-sized array or a 2*XLEN scalar (depending on alignment).
// * The frontend can determine whether a struct is returned by reference or
// not based on its size and fields. If it will be returned by reference, the
// frontend must modify the prototype so a pointer with the sret annotation is
// passed as the first argument. This is not necessary for large scalar
// returns.
// * Struct return values and varargs should be coerced to structs containing
// register-size fields in the same situations they would be for fixed
// arguments.
static const MCPhysReg ArgGPRs[] = {
RISCV::X10, RISCV::X11, RISCV::X12, RISCV::X13,
RISCV::X14, RISCV::X15, RISCV::X16, RISCV::X17
};
// Pass a 2*XLEN argument that has been split into two XLEN values through
// registers or the stack as necessary.
static bool CC_RISCVAssign2XLen(unsigned XLen, CCState &State, CCValAssign VA1,
ISD::ArgFlagsTy ArgFlags1, unsigned ValNo2,
MVT ValVT2, MVT LocVT2,
ISD::ArgFlagsTy ArgFlags2) {
unsigned XLenInBytes = XLen / 8;
if (unsigned Reg = State.AllocateReg(ArgGPRs)) {
// At least one half can be passed via register.
State.addLoc(CCValAssign::getReg(VA1.getValNo(), VA1.getValVT(), Reg,
VA1.getLocVT(), CCValAssign::Full));
} else {
// Both halves must be passed on the stack, with proper alignment.
unsigned StackAlign = std::max(XLenInBytes, ArgFlags1.getOrigAlign());
State.addLoc(
CCValAssign::getMem(VA1.getValNo(), VA1.getValVT(),
State.AllocateStack(XLenInBytes, StackAlign),
VA1.getLocVT(), CCValAssign::Full));
State.addLoc(CCValAssign::getMem(
ValNo2, ValVT2, State.AllocateStack(XLenInBytes, XLenInBytes), LocVT2,
CCValAssign::Full));
return false;
}
if (unsigned Reg = State.AllocateReg(ArgGPRs)) {
// The second half can also be passed via register.
State.addLoc(
CCValAssign::getReg(ValNo2, ValVT2, Reg, LocVT2, CCValAssign::Full));
} else {
// The second half is passed via the stack, without additional alignment.
State.addLoc(CCValAssign::getMem(
ValNo2, ValVT2, State.AllocateStack(XLenInBytes, XLenInBytes), LocVT2,
CCValAssign::Full));
}
return false;
}
// Implements the RISC-V calling convention. Returns true upon failure.
static bool CC_RISCV(const DataLayout &DL, unsigned ValNo, MVT ValVT, MVT LocVT,
CCValAssign::LocInfo LocInfo, ISD::ArgFlagsTy ArgFlags,
CCState &State, bool IsFixed, bool IsRet, Type *OrigTy) {
unsigned XLen = DL.getLargestLegalIntTypeSizeInBits();
assert(XLen == 32 || XLen == 64);
MVT XLenVT = XLen == 32 ? MVT::i32 : MVT::i64;
assert(ValVT == XLenVT && "Unexpected ValVT");
assert(LocVT == XLenVT && "Unexpected LocVT");
// Any return value split in to more than two values can't be returned
// directly.
if (IsRet && ValNo > 1)
return true;
// If this is a variadic argument, the RISC-V calling convention requires
// that it is assigned an 'even' or 'aligned' register if it has 8-byte
// alignment (RV32) or 16-byte alignment (RV64). An aligned register should
// be used regardless of whether the original argument was split during
// legalisation or not. The argument will not be passed by registers if the
// original type is larger than 2*XLEN, so the register alignment rule does
// not apply.
unsigned TwoXLenInBytes = (2 * XLen) / 8;
if (!IsFixed && ArgFlags.getOrigAlign() == TwoXLenInBytes &&
DL.getTypeAllocSize(OrigTy) == TwoXLenInBytes) {
unsigned RegIdx = State.getFirstUnallocated(ArgGPRs);
// Skip 'odd' register if necessary.
if (RegIdx != array_lengthof(ArgGPRs) && RegIdx % 2 == 1)
State.AllocateReg(ArgGPRs);
}
SmallVectorImpl<CCValAssign> &PendingLocs = State.getPendingLocs();
SmallVectorImpl<ISD::ArgFlagsTy> &PendingArgFlags =
State.getPendingArgFlags();
assert(PendingLocs.size() == PendingArgFlags.size() &&
"PendingLocs and PendingArgFlags out of sync");
// Split arguments might be passed indirectly, so keep track of the pending
// values.
if (ArgFlags.isSplit() || !PendingLocs.empty()) {
LocVT = XLenVT;
LocInfo = CCValAssign::Indirect;
PendingLocs.push_back(
CCValAssign::getPending(ValNo, ValVT, LocVT, LocInfo));
PendingArgFlags.push_back(ArgFlags);
if (!ArgFlags.isSplitEnd()) {
return false;
}
}
// If the split argument only had two elements, it should be passed directly
// in registers or on the stack.
if (ArgFlags.isSplitEnd() && PendingLocs.size() <= 2) {
assert(PendingLocs.size() == 2 && "Unexpected PendingLocs.size()");
// Apply the normal calling convention rules to the first half of the
// split argument.
CCValAssign VA = PendingLocs[0];
ISD::ArgFlagsTy AF = PendingArgFlags[0];
PendingLocs.clear();
PendingArgFlags.clear();
return CC_RISCVAssign2XLen(XLen, State, VA, AF, ValNo, ValVT, LocVT,
ArgFlags);
}
// Allocate to a register if possible, or else a stack slot.
unsigned Reg = State.AllocateReg(ArgGPRs);
unsigned StackOffset = Reg ? 0 : State.AllocateStack(XLen / 8, XLen / 8);
// If we reach this point and PendingLocs is non-empty, we must be at the
// end of a split argument that must be passed indirectly.
if (!PendingLocs.empty()) {
assert(ArgFlags.isSplitEnd() && "Expected ArgFlags.isSplitEnd()");
assert(PendingLocs.size() > 2 && "Unexpected PendingLocs.size()");
for (auto &It : PendingLocs) {
if (Reg)
It.convertToReg(Reg);
else
It.convertToMem(StackOffset);
State.addLoc(It);
}
PendingLocs.clear();
PendingArgFlags.clear();
return false;
}
assert(LocVT == XLenVT && "Expected an XLenVT at this stage");
if (Reg) {
State.addLoc(CCValAssign::getReg(ValNo, ValVT, Reg, LocVT, LocInfo));
} else {
State.addLoc(
CCValAssign::getMem(ValNo, ValVT, StackOffset, LocVT, LocInfo));
}
return false;
}
void RISCVTargetLowering::analyzeInputArgs(
MachineFunction &MF, CCState &CCInfo,
const SmallVectorImpl<ISD::InputArg> &Ins, bool IsRet) const {
unsigned NumArgs = Ins.size();
FunctionType *FType = MF.getFunction().getFunctionType();
for (unsigned i = 0; i != NumArgs; ++i) {
MVT ArgVT = Ins[i].VT;
ISD::ArgFlagsTy ArgFlags = Ins[i].Flags;
Type *ArgTy = nullptr;
if (IsRet)
ArgTy = FType->getReturnType();
else if (Ins[i].isOrigArg())
ArgTy = FType->getParamType(Ins[i].getOrigArgIndex());
if (CC_RISCV(MF.getDataLayout(), i, ArgVT, ArgVT, CCValAssign::Full,
ArgFlags, CCInfo, /*IsRet=*/true, IsRet, ArgTy)) {
DEBUG(dbgs() << "InputArg #" << i << " has unhandled type "
<< EVT(ArgVT).getEVTString() << '\n');
llvm_unreachable(nullptr);
}
}
}
void RISCVTargetLowering::analyzeOutputArgs(
MachineFunction &MF, CCState &CCInfo,
const SmallVectorImpl<ISD::OutputArg> &Outs, bool IsRet,
CallLoweringInfo *CLI) const {
unsigned NumArgs = Outs.size();
for (unsigned i = 0; i != NumArgs; i++) {
MVT ArgVT = Outs[i].VT;
ISD::ArgFlagsTy ArgFlags = Outs[i].Flags;
Type *OrigTy = CLI ? CLI->getArgs()[Outs[i].OrigArgIndex].Ty : nullptr;
if (CC_RISCV(MF.getDataLayout(), i, ArgVT, ArgVT, CCValAssign::Full,
ArgFlags, CCInfo, Outs[i].IsFixed, IsRet, OrigTy)) {
DEBUG(dbgs() << "OutputArg #" << i << " has unhandled type "
<< EVT(ArgVT).getEVTString() << "\n");
llvm_unreachable(nullptr);
}
}
}
// The caller is responsible for loading the full value if the argument is
// passed with CCValAssign::Indirect.
static SDValue unpackFromRegLoc(SelectionDAG &DAG, SDValue Chain,
const CCValAssign &VA, const SDLoc &DL) {
MachineFunction &MF = DAG.getMachineFunction();
MachineRegisterInfo &RegInfo = MF.getRegInfo();
EVT LocVT = VA.getLocVT();
SDValue Val;
unsigned VReg = RegInfo.createVirtualRegister(&RISCV::GPRRegClass);
RegInfo.addLiveIn(VA.getLocReg(), VReg);
Val = DAG.getCopyFromReg(Chain, DL, VReg, LocVT);
switch (VA.getLocInfo()) {
default:
llvm_unreachable("Unexpected CCValAssign::LocInfo");
case CCValAssign::Full:
case CCValAssign::Indirect:
return Val;
}
}
// The caller is responsible for loading the full value if the argument is
// passed with CCValAssign::Indirect.
static SDValue unpackFromMemLoc(SelectionDAG &DAG, SDValue Chain,
const CCValAssign &VA, const SDLoc &DL) {
MachineFunction &MF = DAG.getMachineFunction();
MachineFrameInfo &MFI = MF.getFrameInfo();
EVT LocVT = VA.getLocVT();
EVT ValVT = VA.getValVT();
EVT PtrVT = MVT::getIntegerVT(DAG.getDataLayout().getPointerSizeInBits(0));
int FI = MFI.CreateFixedObject(ValVT.getSizeInBits() / 8,
VA.getLocMemOffset(), /*Immutable=*/true);
SDValue FIN = DAG.getFrameIndex(FI, PtrVT);
SDValue Val;
ISD::LoadExtType ExtType;
switch (VA.getLocInfo()) {
default:
llvm_unreachable("Unexpected CCValAssign::LocInfo");
case CCValAssign::Full:
case CCValAssign::Indirect:
ExtType = ISD::NON_EXTLOAD;
break;
}
Val = DAG.getExtLoad(
ExtType, DL, LocVT, Chain, FIN,
MachinePointerInfo::getFixedStack(DAG.getMachineFunction(), FI), ValVT);
return Val;
}
// Transform physical registers into virtual registers.
SDValue RISCVTargetLowering::LowerFormalArguments(
SDValue Chain, CallingConv::ID CallConv, bool IsVarArg,
const SmallVectorImpl<ISD::InputArg> &Ins, const SDLoc &DL,
SelectionDAG &DAG, SmallVectorImpl<SDValue> &InVals) const {
switch (CallConv) {
default:
report_fatal_error("Unsupported calling convention");
case CallingConv::C:
case CallingConv::Fast:
break;
}
MachineFunction &MF = DAG.getMachineFunction();
EVT PtrVT = getPointerTy(DAG.getDataLayout());
MVT XLenVT = Subtarget.getXLenVT();
unsigned XLenInBytes = Subtarget.getXLen() / 8;
// Used with vargs to acumulate store chains.
std::vector<SDValue> OutChains;
// Assign locations to all of the incoming arguments.
SmallVector<CCValAssign, 16> ArgLocs;
CCState CCInfo(CallConv, IsVarArg, MF, ArgLocs, *DAG.getContext());
analyzeInputArgs(MF, CCInfo, Ins, /*IsRet=*/false);
for (unsigned i = 0, e = ArgLocs.size(); i != e; ++i) {
CCValAssign &VA = ArgLocs[i];
assert(VA.getLocVT() == XLenVT && "Unhandled argument type");
SDValue ArgValue;
if (VA.isRegLoc())
ArgValue = unpackFromRegLoc(DAG, Chain, VA, DL);
else
ArgValue = unpackFromMemLoc(DAG, Chain, VA, DL);
if (VA.getLocInfo() == CCValAssign::Indirect) {
// If the original argument was split and passed by reference (e.g. i128
// on RV32), we need to load all parts of it here (using the same
// address).
InVals.push_back(DAG.getLoad(VA.getValVT(), DL, Chain, ArgValue,
MachinePointerInfo()));
unsigned ArgIndex = Ins[i].OrigArgIndex;
assert(Ins[i].PartOffset == 0);
while (i + 1 != e && Ins[i + 1].OrigArgIndex == ArgIndex) {
CCValAssign &PartVA = ArgLocs[i + 1];
unsigned PartOffset = Ins[i + 1].PartOffset;
SDValue Address = DAG.getNode(ISD::ADD, DL, PtrVT, ArgValue,
DAG.getIntPtrConstant(PartOffset, DL));
InVals.push_back(DAG.getLoad(PartVA.getValVT(), DL, Chain, Address,
MachinePointerInfo()));
++i;
}
continue;
}
InVals.push_back(ArgValue);
}
if (IsVarArg) {
ArrayRef<MCPhysReg> ArgRegs = makeArrayRef(ArgGPRs);
unsigned Idx = CCInfo.getFirstUnallocated(ArgRegs);
const TargetRegisterClass *RC = &RISCV::GPRRegClass;
MachineFrameInfo &MFI = MF.getFrameInfo();
MachineRegisterInfo &RegInfo = MF.getRegInfo();
RISCVMachineFunctionInfo *RVFI = MF.getInfo<RISCVMachineFunctionInfo>();
// Offset of the first variable argument from stack pointer, and size of
// the vararg save area. For now, the varargs save area is either zero or
// large enough to hold a0-a7.
int VaArgOffset, VarArgsSaveSize;
// If all registers are allocated, then all varargs must be passed on the
// stack and we don't need to save any argregs.
if (ArgRegs.size() == Idx) {
VaArgOffset = CCInfo.getNextStackOffset();
VarArgsSaveSize = 0;
} else {
VarArgsSaveSize = XLenInBytes * (ArgRegs.size() - Idx);
VaArgOffset = -VarArgsSaveSize;
}
// Record the frame index of the first variable argument
// which is a value necessary to VASTART.
int FI = MFI.CreateFixedObject(XLenInBytes, VaArgOffset, true);
RVFI->setVarArgsFrameIndex(FI);
// If saving an odd number of registers then create an extra stack slot to
// ensure that the frame pointer is 2*XLEN-aligned, which in turn ensures
// offsets to even-numbered registered remain 2*XLEN-aligned.
if (Idx % 2) {
FI = MFI.CreateFixedObject(XLenInBytes, VaArgOffset - (int)XLenInBytes,
true);
VarArgsSaveSize += XLenInBytes;
}
// Copy the integer registers that may have been used for passing varargs
// to the vararg save area.
for (unsigned I = Idx; I < ArgRegs.size();
++I, VaArgOffset += XLenInBytes) {
const unsigned Reg = RegInfo.createVirtualRegister(RC);
RegInfo.addLiveIn(ArgRegs[I], Reg);
SDValue ArgValue = DAG.getCopyFromReg(Chain, DL, Reg, XLenVT);
FI = MFI.CreateFixedObject(XLenInBytes, VaArgOffset, true);
SDValue PtrOff = DAG.getFrameIndex(FI, getPointerTy(DAG.getDataLayout()));
SDValue Store = DAG.getStore(Chain, DL, ArgValue, PtrOff,
MachinePointerInfo::getFixedStack(MF, FI));
cast<StoreSDNode>(Store.getNode())
->getMemOperand()
->setValue((Value *)nullptr);
OutChains.push_back(Store);
}
RVFI->setVarArgsSaveSize(VarArgsSaveSize);
}
// All stores are grouped in one node to allow the matching between
// the size of Ins and InVals. This only happens for vararg functions.
if (!OutChains.empty()) {
OutChains.push_back(Chain);
Chain = DAG.getNode(ISD::TokenFactor, DL, MVT::Other, OutChains);
}
return Chain;
}
// Lower a call to a callseq_start + CALL + callseq_end chain, and add input
// and output parameter nodes.
SDValue RISCVTargetLowering::LowerCall(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;
CLI.IsTailCall = false;
CallingConv::ID CallConv = CLI.CallConv;
bool IsVarArg = CLI.IsVarArg;
EVT PtrVT = getPointerTy(DAG.getDataLayout());
MVT XLenVT = Subtarget.getXLenVT();
MachineFunction &MF = DAG.getMachineFunction();
// Analyze the operands of the call, assigning locations to each operand.
SmallVector<CCValAssign, 16> ArgLocs;
CCState ArgCCInfo(CallConv, IsVarArg, MF, ArgLocs, *DAG.getContext());
analyzeOutputArgs(MF, ArgCCInfo, Outs, /*IsRet=*/false, &CLI);
// Get a count of how many bytes are to be pushed on the stack.
unsigned NumBytes = ArgCCInfo.getNextStackOffset();
// Create local copies for byval args
SmallVector<SDValue, 8> ByValArgs;
for (unsigned i = 0, e = Outs.size(); i != e; ++i) {
ISD::ArgFlagsTy Flags = Outs[i].Flags;
if (!Flags.isByVal())
continue;
SDValue Arg = OutVals[i];
unsigned Size = Flags.getByValSize();
unsigned Align = Flags.getByValAlign();
int FI = MF.getFrameInfo().CreateStackObject(Size, Align, /*isSS=*/false);
SDValue FIPtr = DAG.getFrameIndex(FI, getPointerTy(DAG.getDataLayout()));
SDValue SizeNode = DAG.getConstant(Size, DL, XLenVT);
Chain = DAG.getMemcpy(Chain, DL, FIPtr, Arg, SizeNode, Align,
/*IsVolatile=*/false,
/*AlwaysInline=*/false,
/*isTailCall=*/false, MachinePointerInfo(),
MachinePointerInfo());
ByValArgs.push_back(FIPtr);
}
Chain = DAG.getCALLSEQ_START(Chain, NumBytes, 0, CLI.DL);
// Copy argument values to their designated locations.
SmallVector<std::pair<unsigned, SDValue>, 8> RegsToPass;
SmallVector<SDValue, 8> MemOpChains;
SDValue StackPtr;
for (unsigned i = 0, j = 0, e = ArgLocs.size(); i != e; ++i) {
CCValAssign &VA = ArgLocs[i];
SDValue ArgValue = OutVals[i];
ISD::ArgFlagsTy Flags = Outs[i].Flags;
// Promote the value if needed.
// For now, only handle fully promoted and indirect arguments.
switch (VA.getLocInfo()) {
case CCValAssign::Full:
break;
case CCValAssign::Indirect: {
// Store the argument in a stack slot and pass its address.
SDValue SpillSlot = DAG.CreateStackTemporary(Outs[i].ArgVT);
int FI = cast<FrameIndexSDNode>(SpillSlot)->getIndex();
MemOpChains.push_back(
DAG.getStore(Chain, DL, ArgValue, SpillSlot,
MachinePointerInfo::getFixedStack(MF, FI)));
// If the original argument was split (e.g. i128), we need
// to store all parts of it here (and pass just one address).
unsigned ArgIndex = Outs[i].OrigArgIndex;
assert(Outs[i].PartOffset == 0);
while (i + 1 != e && Outs[i + 1].OrigArgIndex == ArgIndex) {
SDValue PartValue = OutVals[i + 1];
unsigned PartOffset = Outs[i + 1].PartOffset;
SDValue Address = DAG.getNode(ISD::ADD, DL, PtrVT, SpillSlot,
DAG.getIntPtrConstant(PartOffset, DL));
MemOpChains.push_back(
DAG.getStore(Chain, DL, PartValue, Address,
MachinePointerInfo::getFixedStack(MF, FI)));
++i;
}
ArgValue = SpillSlot;
break;
}
default:
llvm_unreachable("Unknown loc info!");
}
// Use local copy if it is a byval arg.
if (Flags.isByVal())
ArgValue = ByValArgs[j++];
if (VA.isRegLoc()) {
// Queue up the argument copies and emit them at the end.
RegsToPass.push_back(std::make_pair(VA.getLocReg(), ArgValue));
} else {
assert(VA.isMemLoc() && "Argument not register or memory");
// Work out the address of the stack slot.
if (!StackPtr.getNode())
StackPtr = DAG.getCopyFromReg(Chain, DL, RISCV::X2, PtrVT);
SDValue Address =
DAG.getNode(ISD::ADD, DL, PtrVT, StackPtr,
DAG.getIntPtrConstant(VA.getLocMemOffset(), DL));
// Emit the store.
MemOpChains.push_back(
DAG.getStore(Chain, DL, ArgValue, Address, MachinePointerInfo()));
}
}
// Join the stores, which are independent of one another.
if (!MemOpChains.empty())
Chain = DAG.getNode(ISD::TokenFactor, DL, MVT::Other, MemOpChains);
SDValue Glue;
// Build a sequence of copy-to-reg nodes, chained and glued together.
for (auto &Reg : RegsToPass) {
Chain = DAG.getCopyToReg(Chain, DL, Reg.first, Reg.second, Glue);
Glue = Chain.getValue(1);
}
if (isa<GlobalAddressSDNode>(Callee)) {
Callee = lowerGlobalAddress(Callee, DAG);
} else if (isa<ExternalSymbolSDNode>(Callee)) {
Callee = lowerExternalSymbol(Callee, DAG);
}
// The first call operand is the chain and the second is the target address.
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 (auto &Reg : RegsToPass)
Ops.push_back(DAG.getRegister(Reg.first, Reg.second.getValueType()));
// Add a register mask operand representing the call-preserved registers.
const TargetRegisterInfo *TRI = Subtarget.getRegisterInfo();
const uint32_t *Mask = TRI->getCallPreservedMask(MF, CallConv);
assert(Mask && "Missing call preserved mask for calling convention");
Ops.push_back(DAG.getRegisterMask(Mask));
// Glue the call to the argument copies, if any.
if (Glue.getNode())
Ops.push_back(Glue);
// Emit the call.
SDVTList NodeTys = DAG.getVTList(MVT::Other, MVT::Glue);
Chain = DAG.getNode(RISCVISD::CALL, DL, NodeTys, Ops);
Glue = Chain.getValue(1);
// Mark the end of the call, which is glued to the call itself.
Chain = DAG.getCALLSEQ_END(Chain,
DAG.getConstant(NumBytes, DL, PtrVT, true),
DAG.getConstant(0, DL, PtrVT, true),
Glue, DL);
Glue = Chain.getValue(1);
// Assign locations to each value returned by this call.
SmallVector<CCValAssign, 16> RVLocs;
CCState RetCCInfo(CallConv, IsVarArg, MF, RVLocs, *DAG.getContext());
analyzeInputArgs(MF, RetCCInfo, Ins, /*IsRet=*/true);
// Copy all of the result registers out of their specified physreg.
for (auto &VA : RVLocs) {
// Copy the value out, gluing the copy to the end of the call sequence.
SDValue RetValue = DAG.getCopyFromReg(Chain, DL, VA.getLocReg(),
VA.getLocVT(), Glue);
Chain = RetValue.getValue(1);
Glue = RetValue.getValue(2);
assert(VA.getLocInfo() == CCValAssign::Full && "Unknown loc info!");
InVals.push_back(RetValue);
}
return Chain;
}
bool RISCVTargetLowering::CanLowerReturn(
CallingConv::ID CallConv, MachineFunction &MF, bool IsVarArg,
const SmallVectorImpl<ISD::OutputArg> &Outs, LLVMContext &Context) const {
SmallVector<CCValAssign, 16> RVLocs;
CCState CCInfo(CallConv, IsVarArg, MF, RVLocs, Context);
for (unsigned i = 0, e = Outs.size(); i != e; ++i) {
MVT VT = Outs[i].VT;
ISD::ArgFlagsTy ArgFlags = Outs[i].Flags;
if (CC_RISCV(MF.getDataLayout(), i, VT, VT, CCValAssign::Full, ArgFlags,
CCInfo, /*IsFixed=*/true, /*IsRet=*/true, nullptr))
return false;
}
return true;
}
SDValue
RISCVTargetLowering::LowerReturn(SDValue Chain, CallingConv::ID CallConv,
bool IsVarArg,
const SmallVectorImpl<ISD::OutputArg> &Outs,
const SmallVectorImpl<SDValue> &OutVals,
const SDLoc &DL, SelectionDAG &DAG) const {
// Stores the assignment of the return value to a location.
SmallVector<CCValAssign, 16> RVLocs;
// Info about the registers and stack slot.
CCState CCInfo(CallConv, IsVarArg, DAG.getMachineFunction(), RVLocs,
*DAG.getContext());
analyzeOutputArgs(DAG.getMachineFunction(), CCInfo, Outs, /*IsRet=*/true,
nullptr);
SDValue Flag;
SmallVector<SDValue, 4> RetOps(1, Chain);
// Copy the result values into the output registers.
for (unsigned i = 0, e = RVLocs.size(); i < e; ++i) {
SDValue Val = OutVals[i];
CCValAssign &VA = RVLocs[i];
assert(VA.isRegLoc() && "Can only return in registers!");
assert(VA.getLocInfo() == CCValAssign::Full &&
"Unexpected CCValAssign::LocInfo");
Chain = DAG.getCopyToReg(Chain, DL, VA.getLocReg(), Val, Flag);
// Guarantee that all emitted copies are stuck together.
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(RISCVISD::RET_FLAG, DL, MVT::Other, RetOps);
}
const char *RISCVTargetLowering::getTargetNodeName(unsigned Opcode) const {
switch ((RISCVISD::NodeType)Opcode) {
case RISCVISD::FIRST_NUMBER:
break;
case RISCVISD::RET_FLAG:
return "RISCVISD::RET_FLAG";
case RISCVISD::CALL:
return "RISCVISD::CALL";
case RISCVISD::SELECT_CC:
return "RISCVISD::SELECT_CC";
}
return nullptr;
}
std::pair<unsigned, const TargetRegisterClass *>
RISCVTargetLowering::getRegForInlineAsmConstraint(const TargetRegisterInfo *TRI,
StringRef Constraint,
MVT VT) const {
// First, see if this is a constraint that directly corresponds to a
// RISCV register class.
if (Constraint.size() == 1) {
switch (Constraint[0]) {
case 'r':
return std::make_pair(0U, &RISCV::GPRRegClass);
default:
break;
}
}
return TargetLowering::getRegForInlineAsmConstraint(TRI, Constraint, VT);
}
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