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llvm-6502/lib/Target/Mips/MipsISelLowering.cpp
Dan Gohman 4406604047 Split ISD::LABEL into ISD::DBG_LABEL and ISD::EH_LABEL, eliminating 
the need for a flavor operand, and add a new SDNode subclass,
LabelSDNode, for use with them to eliminate the need for a label id
operand.

Change instruction selection to let these label nodes through
unmodified instead of creating copies of them. Teach the MachineInstr
emitter how to emit a MachineInstr directly from an ISD label node.

This avoids the need for allocating SDNodes for the label id and
flavor value, as well as SDNodes for each of the post-isel label,
label id, and label flavor.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@52943 91177308-0d34-0410-b5e6-96231b3b80d8
2008-07-01 00:05:16 +00:00

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//===-- MipsISelLowering.cpp - Mips 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 Mips uses to lower LLVM code into a
// selection DAG.
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "mips-lower"
#include "MipsISelLowering.h"
#include "MipsMachineFunction.h"
#include "MipsTargetMachine.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Function.h"
#include "llvm/Intrinsics.h"
#include "llvm/CallingConv.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/ValueTypes.h"
#include "llvm/Support/Debug.h"
#include <queue>
#include <set>
using namespace llvm;
const char *MipsTargetLowering::
getTargetNodeName(unsigned Opcode) const
{
switch (Opcode)
{
case MipsISD::JmpLink : return "MipsISD::JmpLink";
case MipsISD::Hi : return "MipsISD::Hi";
case MipsISD::Lo : return "MipsISD::Lo";
case MipsISD::Ret : return "MipsISD::Ret";
case MipsISD::SelectCC : return "MipsISD::SelectCC";
default : return NULL;
}
}
MipsTargetLowering::
MipsTargetLowering(MipsTargetMachine &TM): TargetLowering(TM)
{
// Mips does not have i1 type, so use i32 for
// setcc operations results (slt, sgt, ...).
setSetCCResultContents(ZeroOrOneSetCCResult);
// JumpTable targets must use GOT when using PIC_
setUsesGlobalOffsetTable(true);
// Set up the register classes
addRegisterClass(MVT::i32, Mips::CPURegsRegisterClass);
// Custom
setOperationAction(ISD::GlobalAddress, MVT::i32, Custom);
setOperationAction(ISD::GlobalTLSAddress, MVT::i32, Custom);
setOperationAction(ISD::RET, MVT::Other, Custom);
setOperationAction(ISD::JumpTable, MVT::i32, Custom);
setOperationAction(ISD::SELECT_CC, MVT::i32, Custom);
// Load extented operations for i1 types must be promoted
setLoadXAction(ISD::EXTLOAD, MVT::i1, Promote);
setLoadXAction(ISD::ZEXTLOAD, MVT::i1, Promote);
setLoadXAction(ISD::SEXTLOAD, MVT::i1, Promote);
// Mips does not have these NodeTypes below.
setOperationAction(ISD::BR_JT, MVT::Other, Expand);
setOperationAction(ISD::BR_CC, MVT::Other, Expand);
setOperationAction(ISD::SELECT_CC, MVT::Other, Expand);
setOperationAction(ISD::SELECT, MVT::i32, Expand);
setOperationAction(ISD::SIGN_EXTEND_INREG, MVT::i1, Expand);
// Mips not supported intrinsics.
setOperationAction(ISD::MEMBARRIER, MVT::Other, Expand);
setOperationAction(ISD::CTPOP, MVT::i32, Expand);
setOperationAction(ISD::CTTZ , MVT::i32, Expand);
setOperationAction(ISD::CTLZ , MVT::i32, Expand);
setOperationAction(ISD::ROTL , MVT::i32, Expand);
setOperationAction(ISD::ROTR , MVT::i32, Expand);
setOperationAction(ISD::BSWAP, MVT::i32, Expand);
setOperationAction(ISD::SHL_PARTS, MVT::i32, Expand);
setOperationAction(ISD::SRA_PARTS, MVT::i32, Expand);
setOperationAction(ISD::SRL_PARTS, MVT::i32, Expand);
// We don't have line number support yet.
setOperationAction(ISD::DBG_STOPPOINT, MVT::Other, Expand);
setOperationAction(ISD::DEBUG_LOC, MVT::Other, Expand);
setOperationAction(ISD::DBG_LABEL, MVT::Other, Expand);
setOperationAction(ISD::EH_LABEL, MVT::Other, Expand);
// Use the default for now
setOperationAction(ISD::STACKSAVE, MVT::Other, Expand);
setOperationAction(ISD::STACKRESTORE, MVT::Other, Expand);
setStackPointerRegisterToSaveRestore(Mips::SP);
computeRegisterProperties();
}
MVT MipsTargetLowering::getSetCCResultType(const SDOperand &) const {
return MVT::i32;
}
SDOperand MipsTargetLowering::
LowerOperation(SDOperand Op, SelectionDAG &DAG)
{
switch (Op.getOpcode())
{
case ISD::CALL: return LowerCALL(Op, DAG);
case ISD::FORMAL_ARGUMENTS: return LowerFORMAL_ARGUMENTS(Op, DAG);
case ISD::RET: return LowerRET(Op, DAG);
case ISD::GlobalAddress: return LowerGlobalAddress(Op, DAG);
case ISD::GlobalTLSAddress: return LowerGlobalTLSAddress(Op, DAG);
case ISD::JumpTable: return LowerJumpTable(Op, DAG);
case ISD::SELECT_CC: return LowerSELECT_CC(Op, DAG);
}
return SDOperand();
}
MachineBasicBlock *
MipsTargetLowering::EmitInstrWithCustomInserter(MachineInstr *MI,
MachineBasicBlock *BB)
{
const TargetInstrInfo *TII = getTargetMachine().getInstrInfo();
switch (MI->getOpcode()) {
default: assert(false && "Unexpected instr type to insert");
case Mips::Select_CC: {
// To "insert" a SELECT_CC instruction, we actually have to insert the
// diamond 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 a branch opcode to use.
const BasicBlock *LLVM_BB = BB->getBasicBlock();
ilist<MachineBasicBlock>::iterator It = BB;
++It;
// thisMBB:
// ...
// TrueVal = ...
// setcc r1, r2, r3
// bNE r1, r0, copy1MBB
// fallthrough --> copy0MBB
MachineBasicBlock *thisMBB = BB;
MachineBasicBlock *copy0MBB = new MachineBasicBlock(LLVM_BB);
MachineBasicBlock *sinkMBB = new MachineBasicBlock(LLVM_BB);
BuildMI(BB, TII->get(Mips::BNE)).addReg(MI->getOperand(1).getReg())
.addReg(Mips::ZERO).addMBB(sinkMBB);
MachineFunction *F = BB->getParent();
F->getBasicBlockList().insert(It, copy0MBB);
F->getBasicBlockList().insert(It, sinkMBB);
// Update machine-CFG edges by first adding all successors of the current
// block to the new block which will contain the Phi node for the select.
for(MachineBasicBlock::succ_iterator i = BB->succ_begin(),
e = BB->succ_end(); i != e; ++i)
sinkMBB->addSuccessor(*i);
// Next, remove all successors of the current block, and add the true
// and fallthrough blocks as its successors.
while(!BB->succ_empty())
BB->removeSuccessor(BB->succ_begin());
BB->addSuccessor(copy0MBB);
BB->addSuccessor(sinkMBB);
// copy0MBB:
// %FalseValue = ...
// # fallthrough to sinkMBB
BB = copy0MBB;
// Update machine-CFG edges
BB->addSuccessor(sinkMBB);
// sinkMBB:
// %Result = phi [ %FalseValue, copy0MBB ], [ %TrueValue, thisMBB ]
// ...
BB = sinkMBB;
BuildMI(BB, TII->get(Mips::PHI), MI->getOperand(0).getReg())
.addReg(MI->getOperand(2).getReg()).addMBB(copy0MBB)
.addReg(MI->getOperand(3).getReg()).addMBB(thisMBB);
delete MI; // The pseudo instruction is gone now.
return BB;
}
}
}
//===----------------------------------------------------------------------===//
// Lower helper functions
//===----------------------------------------------------------------------===//
// AddLiveIn - This helper function adds the specified physical register to the
// MachineFunction as a live in value. It also creates a corresponding
// virtual register for it.
static unsigned
AddLiveIn(MachineFunction &MF, unsigned PReg, TargetRegisterClass *RC)
{
assert(RC->contains(PReg) && "Not the correct regclass!");
unsigned VReg = MF.getRegInfo().createVirtualRegister(RC);
MF.getRegInfo().addLiveIn(PReg, VReg);
return VReg;
}
//===----------------------------------------------------------------------===//
// Misc Lower Operation implementation
//===----------------------------------------------------------------------===//
SDOperand MipsTargetLowering::
LowerGlobalAddress(SDOperand Op, SelectionDAG &DAG)
{
SDOperand ResNode;
GlobalValue *GV = cast<GlobalAddressSDNode>(Op)->getGlobal();
SDOperand GA = DAG.getTargetGlobalAddress(GV, MVT::i32);
bool isPIC = (getTargetMachine().getRelocationModel() == Reloc::PIC_);
SDOperand HiPart;
if (!isPIC) {
const MVT *VTs = DAG.getNodeValueTypes(MVT::i32);
SDOperand Ops[] = { GA };
HiPart = DAG.getNode(MipsISD::Hi, VTs, 1, Ops, 1);
} else // Emit Load from Global Pointer
HiPart = DAG.getLoad(MVT::i32, DAG.getEntryNode(), GA, NULL, 0);
// On functions and global targets not internal linked only
// a load from got/GP is necessary for PIC to work.
if ((isPIC) && ((!GV->hasInternalLinkage()) || (isa<Function>(GV))))
return HiPart;
SDOperand Lo = DAG.getNode(MipsISD::Lo, MVT::i32, GA);
ResNode = DAG.getNode(ISD::ADD, MVT::i32, HiPart, Lo);
return ResNode;
}
SDOperand MipsTargetLowering::
LowerGlobalTLSAddress(SDOperand Op, SelectionDAG &DAG)
{
assert(0 && "TLS not implemented for MIPS.");
return SDOperand(); // Not reached
}
SDOperand MipsTargetLowering::
LowerSELECT_CC(SDOperand Op, SelectionDAG &DAG)
{
SDOperand LHS = Op.getOperand(0);
SDOperand RHS = Op.getOperand(1);
SDOperand True = Op.getOperand(2);
SDOperand False = Op.getOperand(3);
SDOperand CC = Op.getOperand(4);
const MVT *VTs = DAG.getNodeValueTypes(MVT::i32);
SDOperand Ops[] = { LHS, RHS, CC };
SDOperand SetCCRes = DAG.getNode(ISD::SETCC, VTs, 1, Ops, 3);
return DAG.getNode(MipsISD::SelectCC, True.getValueType(),
SetCCRes, True, False);
}
SDOperand MipsTargetLowering::
LowerJumpTable(SDOperand Op, SelectionDAG &DAG)
{
SDOperand ResNode;
SDOperand HiPart;
MVT PtrVT = Op.getValueType();
JumpTableSDNode *JT = cast<JumpTableSDNode>(Op);
SDOperand JTI = DAG.getTargetJumpTable(JT->getIndex(), PtrVT);
if (getTargetMachine().getRelocationModel() != Reloc::PIC_) {
const MVT *VTs = DAG.getNodeValueTypes(MVT::i32);
SDOperand Ops[] = { JTI };
HiPart = DAG.getNode(MipsISD::Hi, VTs, 1, Ops, 1);
} else // Emit Load from Global Pointer
HiPart = DAG.getLoad(MVT::i32, DAG.getEntryNode(), JTI, NULL, 0);
SDOperand Lo = DAG.getNode(MipsISD::Lo, MVT::i32, JTI);
ResNode = DAG.getNode(ISD::ADD, MVT::i32, HiPart, Lo);
return ResNode;
}
//===----------------------------------------------------------------------===//
// Calling Convention Implementation
//
// The lower operations present on calling convention works on this order:
// LowerCALL (virt regs --> phys regs, virt regs --> stack)
// LowerFORMAL_ARGUMENTS (phys --> virt regs, stack --> virt regs)
// LowerRET (virt regs --> phys regs)
// LowerCALL (phys regs --> virt regs)
//
//===----------------------------------------------------------------------===//
#include "MipsGenCallingConv.inc"
//===----------------------------------------------------------------------===//
// CALL Calling Convention Implementation
//===----------------------------------------------------------------------===//
/// Mips custom CALL implementation
SDOperand MipsTargetLowering::
LowerCALL(SDOperand Op, SelectionDAG &DAG)
{
unsigned CallingConv = cast<ConstantSDNode>(Op.getOperand(1))->getValue();
// By now, only CallingConv::C implemented
switch (CallingConv) {
default:
assert(0 && "Unsupported calling convention");
case CallingConv::Fast:
case CallingConv::C:
return LowerCCCCallTo(Op, DAG, CallingConv);
}
}
/// LowerCCCCallTo - functions arguments are copied from virtual
/// regs to (physical regs)/(stack frame), CALLSEQ_START and
/// CALLSEQ_END are emitted.
/// TODO: isVarArg, isTailCall, sret.
SDOperand MipsTargetLowering::
LowerCCCCallTo(SDOperand Op, SelectionDAG &DAG, unsigned CC)
{
MachineFunction &MF = DAG.getMachineFunction();
SDOperand Chain = Op.getOperand(0);
SDOperand Callee = Op.getOperand(4);
bool isVarArg = cast<ConstantSDNode>(Op.getOperand(2))->getValue() != 0;
MachineFrameInfo *MFI = MF.getFrameInfo();
// Analyze operands of the call, assigning locations to each operand.
SmallVector<CCValAssign, 16> ArgLocs;
CCState CCInfo(CC, isVarArg, getTargetMachine(), ArgLocs);
// To meet ABI, Mips must always allocate 16 bytes on
// the stack (even if less than 4 are used as arguments)
int VTsize = MVT(MVT::i32).getSizeInBits()/8;
MFI->CreateFixedObject(VTsize, (VTsize*3));
CCInfo.AnalyzeCallOperands(Op.Val, CC_Mips);
// Get a count of how many bytes are to be pushed on the stack.
unsigned NumBytes = CCInfo.getNextStackOffset();
Chain = DAG.getCALLSEQ_START(Chain,DAG.getConstant(NumBytes,
getPointerTy()));
SmallVector<std::pair<unsigned, SDOperand>, 8> RegsToPass;
SmallVector<SDOperand, 8> MemOpChains;
int LastStackLoc = 0;
// Walk the register/memloc assignments, inserting copies/loads.
for (unsigned i = 0, e = ArgLocs.size(); i != e; ++i) {
CCValAssign &VA = ArgLocs[i];
// Arguments start after the 5 first operands of ISD::CALL
SDOperand Arg = Op.getOperand(5+2*VA.getValNo());
// Promote the value if needed.
switch (VA.getLocInfo()) {
default: assert(0 && "Unknown loc info!");
case CCValAssign::Full: break;
case CCValAssign::SExt:
Arg = DAG.getNode(ISD::SIGN_EXTEND, VA.getLocVT(), Arg);
break;
case CCValAssign::ZExt:
Arg = DAG.getNode(ISD::ZERO_EXTEND, VA.getLocVT(), Arg);
break;
case CCValAssign::AExt:
Arg = DAG.getNode(ISD::ANY_EXTEND, VA.getLocVT(), Arg);
break;
}
// 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));
continue;
}
assert(VA.isMemLoc());
// Create the frame index object for this incoming parameter
// This guarantees that when allocating Local Area the firsts
// 16 bytes which are alwayes reserved won't be overwritten.
LastStackLoc = (16 + VA.getLocMemOffset());
int FI = MFI->CreateFixedObject(VA.getValVT().getSizeInBits()/8,
LastStackLoc);
SDOperand PtrOff = DAG.getFrameIndex(FI,getPointerTy());
// emit ISD::STORE whichs stores the
// parameter value to a stack Location
MemOpChains.push_back(DAG.getStore(Chain, Arg, PtrOff, NULL, 0));
}
// 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, MVT::Other,
&MemOpChains[0], MemOpChains.size());
// 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 emited instructions must be
// stuck together.
SDOperand InFlag;
for (unsigned i = 0, e = RegsToPass.size(); i != e; ++i) {
Chain = DAG.getCopyToReg(Chain, RegsToPass[i].first,
RegsToPass[i].second, InFlag);
InFlag = Chain.getValue(1);
}
// 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 (GlobalAddressSDNode *G = dyn_cast<GlobalAddressSDNode>(Callee))
Callee = DAG.getTargetGlobalAddress(G->getGlobal(), getPointerTy());
else if (ExternalSymbolSDNode *S = dyn_cast<ExternalSymbolSDNode>(Callee))
Callee = DAG.getTargetExternalSymbol(S->getSymbol(), getPointerTy());
// MipsJmpLink = #chain, #target_address, #opt_in_flags...
// = Chain, Callee, Reg#1, Reg#2, ...
//
// Returns a chain & a flag for retval copy to use.
SDVTList NodeTys = DAG.getVTList(MVT::Other, MVT::Flag);
SmallVector<SDOperand, 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.Val)
Ops.push_back(InFlag);
Chain = DAG.getNode(MipsISD::JmpLink, NodeTys, &Ops[0], Ops.size());
InFlag = Chain.getValue(1);
// Create the CALLSEQ_END node.
Chain = DAG.getCALLSEQ_END(Chain,
DAG.getConstant(NumBytes, getPointerTy()),
DAG.getConstant(0, getPointerTy()),
InFlag);
InFlag = Chain.getValue(1);
// Create a stack location to hold GP when PIC is used. This stack
// location is used on function prologue to save GP and also after all
// emited CALL's to restore GP.
if (getTargetMachine().getRelocationModel() == Reloc::PIC_) {
// Function can have an arbitrary number of calls, so
// hold the LastStackLoc with the biggest offset.
int FI;
MipsFunctionInfo *MipsFI = MF.getInfo<MipsFunctionInfo>();
if (LastStackLoc >= MipsFI->getGPStackOffset()) {
LastStackLoc = (!LastStackLoc) ? (16) : (LastStackLoc+4);
// Create the frame index only once. SPOffset here can be anything
// (this will be fixed on processFunctionBeforeFrameFinalized)
if (MipsFI->getGPStackOffset() == -1) {
FI = MFI->CreateFixedObject(4, 0);
MipsFI->setGPFI(FI);
}
MipsFI->setGPStackOffset(LastStackLoc);
}
// Reload GP value.
FI = MipsFI->getGPFI();
SDOperand FIN = DAG.getFrameIndex(FI,getPointerTy());
SDOperand GPLoad = DAG.getLoad(MVT::i32, Chain, FIN, NULL, 0);
Chain = GPLoad.getValue(1);
Chain = DAG.getCopyToReg(Chain, DAG.getRegister(Mips::GP, MVT::i32),
GPLoad, SDOperand(0,0));
InFlag = Chain.getValue(1);
}
// Handle result values, copying them out of physregs into vregs that we
// return.
return SDOperand(LowerCallResult(Chain, InFlag, Op.Val, CC, DAG), Op.ResNo);
}
/// 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.
SDNode *MipsTargetLowering::
LowerCallResult(SDOperand Chain, SDOperand InFlag, SDNode *TheCall,
unsigned CallingConv, SelectionDAG &DAG) {
bool isVarArg = cast<ConstantSDNode>(TheCall->getOperand(2))->getValue() != 0;
// Assign locations to each value returned by this call.
SmallVector<CCValAssign, 16> RVLocs;
CCState CCInfo(CallingConv, isVarArg, getTargetMachine(), RVLocs);
CCInfo.AnalyzeCallResult(TheCall, RetCC_Mips);
SmallVector<SDOperand, 8> ResultVals;
// Copy all of the result registers out of their specified physreg.
for (unsigned i = 0; i != RVLocs.size(); ++i) {
Chain = DAG.getCopyFromReg(Chain, RVLocs[i].getLocReg(),
RVLocs[i].getValVT(), InFlag).getValue(1);
InFlag = Chain.getValue(2);
ResultVals.push_back(Chain.getValue(0));
}
ResultVals.push_back(Chain);
// Merge everything together with a MERGE_VALUES node.
return DAG.getMergeValues(TheCall->getVTList(), &ResultVals[0],
ResultVals.size()).Val;
}
//===----------------------------------------------------------------------===//
// FORMAL_ARGUMENTS Calling Convention Implementation
//===----------------------------------------------------------------------===//
/// Mips custom FORMAL_ARGUMENTS implementation
SDOperand MipsTargetLowering::
LowerFORMAL_ARGUMENTS(SDOperand Op, SelectionDAG &DAG)
{
unsigned CC = cast<ConstantSDNode>(Op.getOperand(1))->getValue();
switch(CC)
{
default:
assert(0 && "Unsupported calling convention");
case CallingConv::C:
return LowerCCCArguments(Op, DAG);
}
}
/// LowerCCCArguments - transform physical registers into
/// virtual registers and generate load operations for
/// arguments places on the stack.
/// TODO: isVarArg, sret
SDOperand MipsTargetLowering::
LowerCCCArguments(SDOperand Op, SelectionDAG &DAG)
{
SDOperand Root = Op.getOperand(0);
MachineFunction &MF = DAG.getMachineFunction();
MachineFrameInfo *MFI = MF.getFrameInfo();
MipsFunctionInfo *MipsFI = MF.getInfo<MipsFunctionInfo>();
bool isVarArg = cast<ConstantSDNode>(Op.getOperand(2))->getValue() != 0;
unsigned CC = DAG.getMachineFunction().getFunction()->getCallingConv();
unsigned StackReg = MF.getTarget().getRegisterInfo()->getFrameRegister(MF);
// GP holds the GOT address on PIC calls.
if (getTargetMachine().getRelocationModel() == Reloc::PIC_)
AddLiveIn(MF, Mips::GP, Mips::CPURegsRegisterClass);
// Assign locations to all of the incoming arguments.
SmallVector<CCValAssign, 16> ArgLocs;
CCState CCInfo(CC, isVarArg, getTargetMachine(), ArgLocs);
CCInfo.AnalyzeFormalArguments(Op.Val, CC_Mips);
SmallVector<SDOperand, 8> ArgValues;
SDOperand StackPtr;
for (unsigned i = 0, e = ArgLocs.size(); i != e; ++i) {
CCValAssign &VA = ArgLocs[i];
// Arguments stored on registers
if (VA.isRegLoc()) {
MVT RegVT = VA.getLocVT();
TargetRegisterClass *RC;
if (RegVT == MVT::i32)
RC = Mips::CPURegsRegisterClass;
else
assert(0 && "support only Mips::CPURegsRegisterClass");
// Transform the arguments stored on
// physical registers into virtual ones
unsigned Reg = AddLiveIn(DAG.getMachineFunction(), VA.getLocReg(), RC);
SDOperand ArgValue = DAG.getCopyFromReg(Root, Reg, RegVT);
// If this is an 8 or 16-bit value, it is really passed promoted
// to 32 bits. Insert an assert[sz]ext to capture this, then
// truncate to the right size.
if (VA.getLocInfo() == CCValAssign::SExt)
ArgValue = DAG.getNode(ISD::AssertSext, RegVT, ArgValue,
DAG.getValueType(VA.getValVT()));
else if (VA.getLocInfo() == CCValAssign::ZExt)
ArgValue = DAG.getNode(ISD::AssertZext, RegVT, ArgValue,
DAG.getValueType(VA.getValVT()));
if (VA.getLocInfo() != CCValAssign::Full)
ArgValue = DAG.getNode(ISD::TRUNCATE, VA.getValVT(), ArgValue);
ArgValues.push_back(ArgValue);
// To meet ABI, when VARARGS are passed on registers, the registers
// must have their values written to the caller stack frame.
if (isVarArg) {
if (StackPtr.Val == 0)
StackPtr = DAG.getRegister(StackReg, getPointerTy());
// The stack pointer offset is relative to the caller stack frame.
// Since the real stack size is unknown here, a negative SPOffset
// is used so there's a way to adjust these offsets when the stack
// size get known (on EliminateFrameIndex). A dummy SPOffset is
// used instead of a direct negative address (which is recorded to
// be used on emitPrologue) to avoid mis-calc of the first stack
// offset on PEI::calculateFrameObjectOffsets.
// Arguments are always 32-bit.
int FI = MFI->CreateFixedObject(4, 0);
MipsFI->recordStoreVarArgsFI(FI, -(4+(i*4)));
SDOperand PtrOff = DAG.getFrameIndex(FI, getPointerTy());
// emit ISD::STORE whichs stores the
// parameter value to a stack Location
ArgValues.push_back(DAG.getStore(Root, ArgValue, PtrOff, NULL, 0));
}
} else {
// sanity check
assert(VA.isMemLoc());
// The stack pointer offset is relative to the caller stack frame.
// Since the real stack size is unknown here, a negative SPOffset
// is used so there's a way to adjust these offsets when the stack
// size get known (on EliminateFrameIndex). A dummy SPOffset is
// used instead of a direct negative address (which is recorded to
// be used on emitPrologue) to avoid mis-calc of the first stack
// offset on PEI::calculateFrameObjectOffsets.
// Arguments are always 32-bit.
int FI = MFI->CreateFixedObject(4, 0);
MipsFI->recordLoadArgsFI(FI, -(4+(16+VA.getLocMemOffset())));
// Create load nodes to retrieve arguments from the stack
SDOperand FIN = DAG.getFrameIndex(FI, getPointerTy());
ArgValues.push_back(DAG.getLoad(VA.getValVT(), Root, FIN, NULL, 0));
}
}
ArgValues.push_back(Root);
// Return the new list of results.
return DAG.getMergeValues(Op.Val->getVTList(), &ArgValues[0],
ArgValues.size()).getValue(Op.ResNo);
}
//===----------------------------------------------------------------------===//
// Return Value Calling Convention Implementation
//===----------------------------------------------------------------------===//
SDOperand MipsTargetLowering::
LowerRET(SDOperand Op, SelectionDAG &DAG)
{
// CCValAssign - represent the assignment of
// the return value to a location
SmallVector<CCValAssign, 16> RVLocs;
unsigned CC = DAG.getMachineFunction().getFunction()->getCallingConv();
bool isVarArg = DAG.getMachineFunction().getFunction()->isVarArg();
// CCState - Info about the registers and stack slot.
CCState CCInfo(CC, isVarArg, getTargetMachine(), RVLocs);
// Analize return values of ISD::RET
CCInfo.AnalyzeReturn(Op.Val, RetCC_Mips);
// If this is the first return lowered for this function, add
// the regs to the liveout set for the function.
if (DAG.getMachineFunction().getRegInfo().liveout_empty()) {
for (unsigned i = 0; i != RVLocs.size(); ++i)
if (RVLocs[i].isRegLoc())
DAG.getMachineFunction().getRegInfo().addLiveOut(RVLocs[i].getLocReg());
}
// The chain is always operand #0
SDOperand Chain = Op.getOperand(0);
SDOperand Flag;
// Copy the result values into the output registers.
for (unsigned i = 0; i != RVLocs.size(); ++i) {
CCValAssign &VA = RVLocs[i];
assert(VA.isRegLoc() && "Can only return in registers!");
// ISD::RET => ret chain, (regnum1,val1), ...
// So i*2+1 index only the regnums
Chain = DAG.getCopyToReg(Chain, VA.getLocReg(), Op.getOperand(i*2+1), Flag);
// guarantee that all emitted copies are
// stuck together, avoiding something bad
Flag = Chain.getValue(1);
}
// Return on Mips is always a "jr $ra"
if (Flag.Val)
return DAG.getNode(MipsISD::Ret, MVT::Other,
Chain, DAG.getRegister(Mips::RA, MVT::i32), Flag);
else // Return Void
return DAG.getNode(MipsISD::Ret, MVT::Other,
Chain, DAG.getRegister(Mips::RA, MVT::i32));
}
//===----------------------------------------------------------------------===//
// Mips Inline Assembly Support
//===----------------------------------------------------------------------===//
/// getConstraintType - Given a constraint letter, return the type of
/// constraint it is for this target.
MipsTargetLowering::ConstraintType MipsTargetLowering::
getConstraintType(const std::string &Constraint) const
{
if (Constraint.size() == 1) {
// Mips specific constrainy
// GCC config/mips/constraints.md
//
// 'd' : An address register. Equivalent to r
// unless generating MIPS16 code.
// 'y' : Equivalent to r; retained for
// backwards compatibility.
//
switch (Constraint[0]) {
default : break;
case 'd':
case 'y':
return C_RegisterClass;
break;
}
}
return TargetLowering::getConstraintType(Constraint);
}
std::pair<unsigned, const TargetRegisterClass*> MipsTargetLowering::
getRegForInlineAsmConstraint(const std::string &Constraint, MVT VT) const
{
if (Constraint.size() == 1) {
switch (Constraint[0]) {
case 'r':
return std::make_pair(0U, Mips::CPURegsRegisterClass);
break;
}
}
return TargetLowering::getRegForInlineAsmConstraint(Constraint, VT);
}
std::vector<unsigned> MipsTargetLowering::
getRegClassForInlineAsmConstraint(const std::string &Constraint,
MVT VT) const
{
if (Constraint.size() != 1)
return std::vector<unsigned>();
switch (Constraint[0]) {
default : break;
case 'r':
// GCC Mips Constraint Letters
case 'd':
case 'y':
return make_vector<unsigned>(Mips::V0, Mips::V1, Mips::A0,
Mips::A1, Mips::A2, Mips::A3,
Mips::T0, Mips::T1, Mips::T2,
Mips::T3, Mips::T4, Mips::T5,
Mips::T6, Mips::T7, Mips::S0,
Mips::S1, Mips::S2, Mips::S3,
Mips::S4, Mips::S5, Mips::S6,
Mips::S7, Mips::T8, Mips::T9, 0);
break;
}
return std::vector<unsigned>();
}
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