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c16cdc5de7
llvm-6502/lib/Target/SystemZ/SystemZISelLowering.cpp
Anton Korobeynikov c16cdc5de7 Add jump tables 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@75984 91177308-0d34-0410-b5e6-96231b3b80d8
2009-07-16 14:07:50 +00:00

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//===-- SystemZISelLowering.cpp - SystemZ 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 SystemZTargetLowering class.
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "systemz-lower"
#include "SystemZISelLowering.h"
#include "SystemZ.h"
#include "SystemZTargetMachine.h"
#include "SystemZSubtarget.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Function.h"
#include "llvm/Intrinsics.h"
#include "llvm/CallingConv.h"
#include "llvm/GlobalVariable.h"
#include "llvm/GlobalAlias.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/PseudoSourceValue.h"
#include "llvm/CodeGen/SelectionDAGISel.h"
#include "llvm/CodeGen/ValueTypes.h"
#include "llvm/Support/Debug.h"
#include "llvm/ADT/VectorExtras.h"
using namespace llvm;
SystemZTargetLowering::SystemZTargetLowering(SystemZTargetMachine &tm) :
TargetLowering(tm), Subtarget(*tm.getSubtargetImpl()), TM(tm) {
RegInfo = TM.getRegisterInfo();
// Set up the register classes.
addRegisterClass(MVT::i32, SystemZ::GR32RegisterClass);
addRegisterClass(MVT::i64, SystemZ::GR64RegisterClass);
addRegisterClass(MVT::i128, SystemZ::GR128RegisterClass);
// Compute derived properties from the register classes
computeRegisterProperties();
// Set shifts properties
setShiftAmountFlavor(Extend);
setShiftAmountType(MVT::i32);
// Provide all sorts of operation actions
setLoadExtAction(ISD::SEXTLOAD, MVT::i1, Promote);
setLoadExtAction(ISD::ZEXTLOAD, MVT::i1, Promote);
setLoadExtAction(ISD::EXTLOAD, MVT::i1, Promote);
setStackPointerRegisterToSaveRestore(SystemZ::R15D);
setSchedulingPreference(SchedulingForLatency);
setOperationAction(ISD::RET, MVT::Other, Custom);
setOperationAction(ISD::BR_JT, MVT::Other, Expand);
setOperationAction(ISD::BRCOND, MVT::Other, Expand);
setOperationAction(ISD::BR_CC, MVT::i32, Custom);
setOperationAction(ISD::BR_CC, MVT::i64, Custom);
setOperationAction(ISD::GlobalAddress, MVT::i64, Custom);
setOperationAction(ISD::JumpTable, MVT::i64, Custom);
// FIXME: Can we lower these 2 efficiently?
setOperationAction(ISD::SETCC, MVT::i32, Expand);
setOperationAction(ISD::SETCC, MVT::i64, Expand);
setOperationAction(ISD::SELECT, MVT::i32, Expand);
setOperationAction(ISD::SELECT, MVT::i64, Expand);
setOperationAction(ISD::SELECT_CC, MVT::i32, Custom);
setOperationAction(ISD::SELECT_CC, MVT::i64, Custom);
// Funny enough: we don't have 64-bit signed versions of these stuff, but have
// unsigned.
setOperationAction(ISD::MULHS, MVT::i64, Expand);
setOperationAction(ISD::SMUL_LOHI, MVT::i64, Expand);
}
SDValue SystemZTargetLowering::LowerOperation(SDValue Op, SelectionDAG &DAG) {
switch (Op.getOpcode()) {
case ISD::FORMAL_ARGUMENTS: return LowerFORMAL_ARGUMENTS(Op, DAG);
case ISD::RET: return LowerRET(Op, DAG);
case ISD::CALL: return LowerCALL(Op, DAG);
case ISD::BR_CC: return LowerBR_CC(Op, DAG);
case ISD::SELECT_CC: return LowerSELECT_CC(Op, DAG);
case ISD::GlobalAddress: return LowerGlobalAddress(Op, DAG);
case ISD::JumpTable: return LowerJumpTable(Op, DAG);
default:
assert(0 && "unimplemented operand");
return SDValue();
}
}
//===----------------------------------------------------------------------===//
// Calling Convention Implementation
//===----------------------------------------------------------------------===//
#include "SystemZGenCallingConv.inc"
SDValue SystemZTargetLowering::LowerFORMAL_ARGUMENTS(SDValue Op,
SelectionDAG &DAG) {
unsigned CC = cast<ConstantSDNode>(Op.getOperand(1))->getZExtValue();
switch (CC) {
default:
assert(0 && "Unsupported calling convention");
case CallingConv::C:
case CallingConv::Fast:
return LowerCCCArguments(Op, DAG);
}
}
SDValue SystemZTargetLowering::LowerCALL(SDValue Op, SelectionDAG &DAG) {
CallSDNode *TheCall = cast<CallSDNode>(Op.getNode());
unsigned CallingConv = TheCall->getCallingConv();
switch (CallingConv) {
default:
assert(0 && "Unsupported calling convention");
case CallingConv::Fast:
case CallingConv::C:
return LowerCCCCallTo(Op, DAG, CallingConv);
}
}
/// LowerCCCArguments - transform physical registers into virtual registers and
/// generate load operations for arguments places on the stack.
// FIXME: struct return stuff
// FIXME: varargs
SDValue SystemZTargetLowering::LowerCCCArguments(SDValue Op,
SelectionDAG &DAG) {
MachineFunction &MF = DAG.getMachineFunction();
MachineFrameInfo *MFI = MF.getFrameInfo();
MachineRegisterInfo &RegInfo = MF.getRegInfo();
SDValue Root = Op.getOperand(0);
bool isVarArg = cast<ConstantSDNode>(Op.getOperand(2))->getZExtValue() != 0;
unsigned CC = MF.getFunction()->getCallingConv();
DebugLoc dl = Op.getDebugLoc();
// Assign locations to all of the incoming arguments.
SmallVector<CCValAssign, 16> ArgLocs;
CCState CCInfo(CC, isVarArg, getTargetMachine(), ArgLocs);
CCInfo.AnalyzeFormalArguments(Op.getNode(), CC_SystemZ);
assert(!isVarArg && "Varargs not supported yet");
SmallVector<SDValue, 16> ArgValues;
for (unsigned i = 0, e = ArgLocs.size(); i != e; ++i) {
CCValAssign &VA = ArgLocs[i];
if (VA.isRegLoc()) {
// Arguments passed in registers
MVT RegVT = VA.getLocVT();
switch (RegVT.getSimpleVT()) {
default:
cerr << "LowerFORMAL_ARGUMENTS Unhandled argument type: "
<< RegVT.getSimpleVT()
<< "\n";
abort();
case MVT::i64:
unsigned VReg =
RegInfo.createVirtualRegister(SystemZ::GR64RegisterClass);
RegInfo.addLiveIn(VA.getLocReg(), VReg);
SDValue ArgValue = DAG.getCopyFromReg(Root, dl, VReg, RegVT);
// If this is an 8/16/32-bit value, it is really passed promoted to 64
// 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, dl, RegVT, ArgValue,
DAG.getValueType(VA.getValVT()));
else if (VA.getLocInfo() == CCValAssign::ZExt)
ArgValue = DAG.getNode(ISD::AssertZext, dl, RegVT, ArgValue,
DAG.getValueType(VA.getValVT()));
if (VA.getLocInfo() != CCValAssign::Full)
ArgValue = DAG.getNode(ISD::TRUNCATE, dl, VA.getValVT(), ArgValue);
ArgValues.push_back(ArgValue);
}
} else {
// Sanity check
assert(VA.isMemLoc());
// Load the argument to a virtual register
unsigned ObjSize = VA.getLocVT().getSizeInBits()/8;
if (ObjSize > 8) {
cerr << "LowerFORMAL_ARGUMENTS Unhandled argument type: "
<< VA.getLocVT().getSimpleVT()
<< "\n";
}
// Create the frame index object for this incoming parameter...
int FI = MFI->CreateFixedObject(ObjSize, VA.getLocMemOffset());
// Create the SelectionDAG nodes corresponding to a load
//from this parameter
SDValue FIN = DAG.getFrameIndex(FI, MVT::i64);
ArgValues.push_back(DAG.getLoad(VA.getLocVT(), dl, Root, FIN,
PseudoSourceValue::getFixedStack(FI), 0));
}
}
ArgValues.push_back(Root);
// Return the new list of results.
return DAG.getNode(ISD::MERGE_VALUES, dl, Op.getNode()->getVTList(),
&ArgValues[0], ArgValues.size()).getValue(Op.getResNo());
}
/// LowerCCCCallTo - functions arguments are copied from virtual regs to
/// (physical regs)/(stack frame), CALLSEQ_START and CALLSEQ_END are emitted.
/// TODO: sret.
SDValue SystemZTargetLowering::LowerCCCCallTo(SDValue Op, SelectionDAG &DAG,
unsigned CC) {
CallSDNode *TheCall = cast<CallSDNode>(Op.getNode());
SDValue Chain = TheCall->getChain();
SDValue Callee = TheCall->getCallee();
bool isVarArg = TheCall->isVarArg();
DebugLoc dl = Op.getDebugLoc();
MachineFunction &MF = DAG.getMachineFunction();
// Offset to first argument stack slot.
const unsigned FirstArgOffset = 160;
// Analyze operands of the call, assigning locations to each operand.
SmallVector<CCValAssign, 16> ArgLocs;
CCState CCInfo(CC, isVarArg, getTargetMachine(), ArgLocs);
CCInfo.AnalyzeCallOperands(TheCall, CC_SystemZ);
// 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(), true));
SmallVector<std::pair<unsigned, SDValue>, 4> RegsToPass;
SmallVector<SDValue, 12> MemOpChains;
SDValue StackPtr;
// 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
SDValue Arg = TheCall->getArg(i);
// 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, 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;
}
// 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));
} else {
assert(VA.isMemLoc());
if (StackPtr.getNode() == 0)
StackPtr =
DAG.getCopyFromReg(Chain, dl,
(RegInfo->hasFP(MF) ?
SystemZ::R11D : SystemZ::R15D),
getPointerTy());
unsigned Offset = FirstArgOffset + VA.getLocMemOffset();
SDValue PtrOff = DAG.getNode(ISD::ADD, dl, getPointerTy(),
StackPtr,
DAG.getIntPtrConstant(Offset));
MemOpChains.push_back(DAG.getStore(Chain, dl, Arg, PtrOff,
PseudoSourceValue::getStack(), Offset));
}
}
// 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[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.
SDValue InFlag;
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);
}
// If the callee is a GlobalAddress node (quite common, every direct call is)
// turn it into a TargetGlobalAddress node so that legalize doesn't hack it.
// Likewise ExternalSymbol -> TargetExternalSymbol.
if (GlobalAddressSDNode *G = dyn_cast<GlobalAddressSDNode>(Callee))
Callee = DAG.getTargetGlobalAddress(G->getGlobal(), getPointerTy());
else if (ExternalSymbolSDNode *E = dyn_cast<ExternalSymbolSDNode>(Callee))
Callee = DAG.getTargetExternalSymbol(E->getSymbol(), getPointerTy());
// Returns a chain & a flag for retval copy to use.
SDVTList NodeTys = DAG.getVTList(MVT::Other, MVT::Flag);
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);
Chain = DAG.getNode(SystemZISD::CALL, dl, NodeTys, &Ops[0], Ops.size());
InFlag = Chain.getValue(1);
// Create the CALLSEQ_END node.
Chain = DAG.getCALLSEQ_END(Chain,
DAG.getConstant(NumBytes, getPointerTy(), true),
DAG.getConstant(0, getPointerTy(), true),
InFlag);
InFlag = Chain.getValue(1);
// Handle result values, copying them out of physregs into vregs that we
// return.
return SDValue(LowerCallResult(Chain, InFlag, TheCall, CC, DAG),
Op.getResNo());
}
/// 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*
SystemZTargetLowering::LowerCallResult(SDValue Chain, SDValue InFlag,
CallSDNode *TheCall,
unsigned CallingConv,
SelectionDAG &DAG) {
bool isVarArg = TheCall->isVarArg();
DebugLoc dl = TheCall->getDebugLoc();
// Assign locations to each value returned by this call.
SmallVector<CCValAssign, 16> RVLocs;
CCState CCInfo(CallingConv, isVarArg, getTargetMachine(), RVLocs);
CCInfo.AnalyzeCallResult(TheCall, RetCC_SystemZ);
SmallVector<SDValue, 8> ResultVals;
// Copy all of the result registers out of their specified physreg.
for (unsigned i = 0; i != RVLocs.size(); ++i) {
CCValAssign &VA = RVLocs[i];
Chain = DAG.getCopyFromReg(Chain, dl, VA.getLocReg(),
VA.getLocVT(), InFlag).getValue(1);
SDValue RetValue = Chain.getValue(0);
InFlag = Chain.getValue(2);
// If this is an 8/16/32-bit value, it is really passed promoted to 64
// bits. Insert an assert[sz]ext to capture this, then truncate to the
// right size.
if (VA.getLocInfo() == CCValAssign::SExt)
RetValue = DAG.getNode(ISD::AssertSext, dl, VA.getLocVT(), RetValue,
DAG.getValueType(VA.getValVT()));
else if (VA.getLocInfo() == CCValAssign::ZExt)
RetValue = DAG.getNode(ISD::AssertZext, dl, VA.getLocVT(), RetValue,
DAG.getValueType(VA.getValVT()));
if (VA.getLocInfo() != CCValAssign::Full)
RetValue = DAG.getNode(ISD::TRUNCATE, dl, VA.getValVT(), RetValue);
ResultVals.push_back(RetValue);
}
ResultVals.push_back(Chain);
// Merge everything together with a MERGE_VALUES node.
return DAG.getNode(ISD::MERGE_VALUES, dl, TheCall->getVTList(),
&ResultVals[0], ResultVals.size()).getNode();
}
SDValue SystemZTargetLowering::LowerRET(SDValue 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();
DebugLoc dl = Op.getDebugLoc();
// CCState - Info about the registers and stack slot.
CCState CCInfo(CC, isVarArg, getTargetMachine(), RVLocs);
// Analize return values of ISD::RET
CCInfo.AnalyzeReturn(Op.getNode(), RetCC_SystemZ);
// 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
SDValue Chain = Op.getOperand(0);
SDValue Flag;
// Copy the result values into the output registers.
for (unsigned i = 0; i != RVLocs.size(); ++i) {
CCValAssign &VA = RVLocs[i];
SDValue ResValue = Op.getOperand(i*2+1);
assert(VA.isRegLoc() && "Can only return in registers!");
// If this is an 8/16/32-bit value, it is really should be passed promoted
// to 64 bits.
if (VA.getLocInfo() == CCValAssign::SExt)
ResValue = DAG.getNode(ISD::SIGN_EXTEND, dl, VA.getLocVT(), ResValue);
else if (VA.getLocInfo() == CCValAssign::ZExt)
ResValue = DAG.getNode(ISD::ZERO_EXTEND, dl, VA.getLocVT(), ResValue);
else if (VA.getLocInfo() == CCValAssign::AExt)
ResValue = DAG.getNode(ISD::ANY_EXTEND, dl, VA.getLocVT(), ResValue);
// ISD::RET => ret chain, (regnum1,val1), ...
// So i*2+1 index only the regnums
Chain = DAG.getCopyToReg(Chain, dl, VA.getLocReg(), ResValue, Flag);
// Guarantee that all emitted copies are stuck together,
// avoiding something bad.
Flag = Chain.getValue(1);
}
if (Flag.getNode())
return DAG.getNode(SystemZISD::RET_FLAG, dl, MVT::Other, Chain, Flag);
// Return Void
return DAG.getNode(SystemZISD::RET_FLAG, dl, MVT::Other, Chain);
}
SDValue SystemZTargetLowering::EmitCmp(SDValue LHS, SDValue RHS,
ISD::CondCode CC, SDValue &SystemZCC,
SelectionDAG &DAG) {
assert(!LHS.getValueType().isFloatingPoint() && "We don't handle FP yet");
// FIXME: Emit a test if RHS is zero
bool isUnsigned = false;
SystemZCC::CondCodes TCC;
switch (CC) {
default: assert(0 && "Invalid integer condition!");
case ISD::SETEQ:
TCC = SystemZCC::E;
break;
case ISD::SETNE:
TCC = SystemZCC::NE;
break;
case ISD::SETULE:
isUnsigned = true; // FALLTHROUGH
case ISD::SETLE:
TCC = SystemZCC::LE;
break;
case ISD::SETUGE:
isUnsigned = true; // FALLTHROUGH
case ISD::SETGE:
TCC = SystemZCC::HE;
break;
case ISD::SETUGT:
isUnsigned = true;
case ISD::SETGT:
TCC = SystemZCC::H; // FALLTHROUGH
break;
case ISD::SETULT:
isUnsigned = true;
case ISD::SETLT: // FALLTHROUGH
TCC = SystemZCC::L;
break;
}
SystemZCC = DAG.getConstant(TCC, MVT::i32);
DebugLoc dl = LHS.getDebugLoc();
return DAG.getNode((isUnsigned ? SystemZISD::UCMP : SystemZISD::CMP),
dl, MVT::Flag, LHS, RHS);
}
SDValue SystemZTargetLowering::LowerBR_CC(SDValue Op, SelectionDAG &DAG) {
SDValue Chain = Op.getOperand(0);
ISD::CondCode CC = cast<CondCodeSDNode>(Op.getOperand(1))->get();
SDValue LHS = Op.getOperand(2);
SDValue RHS = Op.getOperand(3);
SDValue Dest = Op.getOperand(4);
DebugLoc dl = Op.getDebugLoc();
SDValue SystemZCC;
SDValue Flag = EmitCmp(LHS, RHS, CC, SystemZCC, DAG);
return DAG.getNode(SystemZISD::BRCOND, dl, Op.getValueType(),
Chain, Dest, SystemZCC, Flag);
}
SDValue SystemZTargetLowering::LowerSELECT_CC(SDValue Op, SelectionDAG &DAG) {
SDValue LHS = Op.getOperand(0);
SDValue RHS = Op.getOperand(1);
SDValue TrueV = Op.getOperand(2);
SDValue FalseV = Op.getOperand(3);
ISD::CondCode CC = cast<CondCodeSDNode>(Op.getOperand(4))->get();
DebugLoc dl = Op.getDebugLoc();
SDValue SystemZCC;
SDValue Flag = EmitCmp(LHS, RHS, CC, SystemZCC, DAG);
SDVTList VTs = DAG.getVTList(Op.getValueType(), MVT::Flag);
SmallVector<SDValue, 4> Ops;
Ops.push_back(TrueV);
Ops.push_back(FalseV);
Ops.push_back(SystemZCC);
Ops.push_back(Flag);
return DAG.getNode(SystemZISD::SELECT, dl, VTs, &Ops[0], Ops.size());
}
SDValue SystemZTargetLowering::LowerGlobalAddress(SDValue Op,
SelectionDAG &DAG) {
DebugLoc dl = Op.getDebugLoc();
GlobalValue *GV = cast<GlobalAddressSDNode>(Op)->getGlobal();
SDValue GA = DAG.getTargetGlobalAddress(GV, getPointerTy());
// FIXME: Verify stuff for constant globals entries
return DAG.getNode(SystemZISD::PCRelativeWrapper, dl, getPointerTy(), GA);
}
SDValue SystemZTargetLowering::LowerJumpTable(SDValue Op,
SelectionDAG &DAG) {
DebugLoc dl = Op.getDebugLoc();
JumpTableSDNode *JT = cast<JumpTableSDNode>(Op);
SDValue Result = DAG.getTargetJumpTable(JT->getIndex(), getPointerTy());
return DAG.getNode(SystemZISD::PCRelativeWrapper, dl, getPointerTy(), Result);
}
const char *SystemZTargetLowering::getTargetNodeName(unsigned Opcode) const {
switch (Opcode) {
case SystemZISD::RET_FLAG: return "SystemZISD::RET_FLAG";
case SystemZISD::CALL: return "SystemZISD::CALL";
case SystemZISD::BRCOND: return "SystemZISD::BRCOND";
case SystemZISD::CMP: return "SystemZISD::CMP";
case SystemZISD::UCMP: return "SystemZISD::UCMP";
case SystemZISD::SELECT: return "SystemZISD::SELECT";
case SystemZISD::PCRelativeWrapper: return "SystemZISD::PCRelativeWrapper";
default: return NULL;
}
}
//===----------------------------------------------------------------------===//
// Other Lowering Code
//===----------------------------------------------------------------------===//
MachineBasicBlock*
SystemZTargetLowering::EmitInstrWithCustomInserter(MachineInstr *MI,
MachineBasicBlock *BB) const {
const SystemZInstrInfo &TII = *TM.getInstrInfo();
DebugLoc dl = MI->getDebugLoc();
assert((MI->getOpcode() == SystemZ::Select32 ||
MI->getOpcode() == SystemZ::Select64) &&
"Unexpected instr type to insert");
// To "insert" a SELECT 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();
MachineFunction::iterator I = BB;
++I;
// thisMBB:
// ...
// TrueVal = ...
// cmpTY ccX, r1, r2
// jCC copy1MBB
// fallthrough --> copy0MBB
MachineBasicBlock *thisMBB = BB;
MachineFunction *F = BB->getParent();
MachineBasicBlock *copy0MBB = F->CreateMachineBasicBlock(LLVM_BB);
MachineBasicBlock *copy1MBB = F->CreateMachineBasicBlock(LLVM_BB);
SystemZCC::CondCodes CC = (SystemZCC::CondCodes)MI->getOperand(3).getImm();
BuildMI(BB, dl, TII.getBrCond(CC)).addMBB(copy1MBB);
F->insert(I, copy0MBB);
F->insert(I, copy1MBB);
// 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.
copy1MBB->transferSuccessors(BB);
// Next, add the true and fallthrough blocks as its successors.
BB->addSuccessor(copy0MBB);
BB->addSuccessor(copy1MBB);
// copy0MBB:
// %FalseValue = ...
// # fallthrough to copy1MBB
BB = copy0MBB;
// Update machine-CFG edges
BB->addSuccessor(copy1MBB);
// copy1MBB:
// %Result = phi [ %FalseValue, copy0MBB ], [ %TrueValue, thisMBB ]
// ...
BB = copy1MBB;
BuildMI(BB, dl, TII.get(SystemZ::PHI),
MI->getOperand(0).getReg())
.addReg(MI->getOperand(2).getReg()).addMBB(copy0MBB)
.addReg(MI->getOperand(1).getReg()).addMBB(thisMBB);
F->DeleteMachineInstr(MI); // The pseudo instruction is gone now.
return BB;
}
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