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llvm-mirror/lib/Target/BPF/BPFISelLowering.cpp
Chandler Carruth ae65e281f3 Update the file headers across all of the LLVM projects in the monorepo 
to reflect the new license.

We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.

Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.

llvm-svn: 351636
2019-01-19 08:50:56 +00:00

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//===-- BPFISelLowering.cpp - BPF DAG Lowering Implementation ------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file defines the interfaces that BPF uses to lower LLVM code into a
// selection DAG.
//
//===----------------------------------------------------------------------===//
#include "BPFISelLowering.h"
#include "BPF.h"
#include "BPFSubtarget.h"
#include "BPFTargetMachine.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 "bpf-lower"
static cl::opt<bool> BPFExpandMemcpyInOrder("bpf-expand-memcpy-in-order",
cl::Hidden, cl::init(false),
cl::desc("Expand memcpy into load/store pairs in order"));
static void fail(const SDLoc &DL, SelectionDAG &DAG, const Twine &Msg) {
MachineFunction &MF = DAG.getMachineFunction();
DAG.getContext()->diagnose(
DiagnosticInfoUnsupported(MF.getFunction(), Msg, DL.getDebugLoc()));
}
static void fail(const SDLoc &DL, SelectionDAG &DAG, const char *Msg,
SDValue Val) {
MachineFunction &MF = DAG.getMachineFunction();
std::string Str;
raw_string_ostream OS(Str);
OS << Msg;
Val->print(OS);
OS.flush();
DAG.getContext()->diagnose(
DiagnosticInfoUnsupported(MF.getFunction(), Str, DL.getDebugLoc()));
}
BPFTargetLowering::BPFTargetLowering(const TargetMachine &TM,
const BPFSubtarget &STI)
: TargetLowering(TM) {
// Set up the register classes.
addRegisterClass(MVT::i64, &BPF::GPRRegClass);
if (STI.getHasAlu32())
addRegisterClass(MVT::i32, &BPF::GPR32RegClass);
// Compute derived properties from the register classes
computeRegisterProperties(STI.getRegisterInfo());
setStackPointerRegisterToSaveRestore(BPF::R11);
setOperationAction(ISD::BR_CC, MVT::i64, Custom);
setOperationAction(ISD::BR_JT, MVT::Other, Expand);
setOperationAction(ISD::BRIND, MVT::Other, Expand);
setOperationAction(ISD::BRCOND, MVT::Other, Expand);
setOperationAction(ISD::GlobalAddress, MVT::i64, Custom);
setOperationAction(ISD::DYNAMIC_STACKALLOC, MVT::i64, Custom);
setOperationAction(ISD::STACKSAVE, MVT::Other, Expand);
setOperationAction(ISD::STACKRESTORE, MVT::Other, Expand);
for (auto VT : { MVT::i32, MVT::i64 }) {
if (VT == MVT::i32 && !STI.getHasAlu32())
continue;
setOperationAction(ISD::SDIVREM, VT, Expand);
setOperationAction(ISD::UDIVREM, VT, Expand);
setOperationAction(ISD::SREM, VT, Expand);
setOperationAction(ISD::UREM, VT, Expand);
setOperationAction(ISD::MULHU, VT, Expand);
setOperationAction(ISD::MULHS, VT, Expand);
setOperationAction(ISD::UMUL_LOHI, VT, Expand);
setOperationAction(ISD::SMUL_LOHI, VT, Expand);
setOperationAction(ISD::ROTR, VT, Expand);
setOperationAction(ISD::ROTL, VT, Expand);
setOperationAction(ISD::SHL_PARTS, VT, Expand);
setOperationAction(ISD::SRL_PARTS, VT, Expand);
setOperationAction(ISD::SRA_PARTS, VT, Expand);
setOperationAction(ISD::CTPOP, VT, Expand);
setOperationAction(ISD::SETCC, VT, Expand);
setOperationAction(ISD::SELECT, VT, Expand);
setOperationAction(ISD::SELECT_CC, VT, Custom);
}
if (STI.getHasAlu32()) {
setOperationAction(ISD::BSWAP, MVT::i32, Promote);
setOperationAction(ISD::BR_CC, MVT::i32, Promote);
}
setOperationAction(ISD::CTTZ, MVT::i64, Custom);
setOperationAction(ISD::CTLZ, MVT::i64, Custom);
setOperationAction(ISD::CTTZ_ZERO_UNDEF, MVT::i64, Custom);
setOperationAction(ISD::CTLZ_ZERO_UNDEF, MVT::i64, Custom);
setOperationAction(ISD::SIGN_EXTEND_INREG, MVT::i1, Expand);
setOperationAction(ISD::SIGN_EXTEND_INREG, MVT::i8, Expand);
setOperationAction(ISD::SIGN_EXTEND_INREG, MVT::i16, Expand);
setOperationAction(ISD::SIGN_EXTEND_INREG, MVT::i32, Expand);
// Extended load operations for i1 types must be promoted
for (MVT VT : MVT::integer_valuetypes()) {
setLoadExtAction(ISD::EXTLOAD, VT, MVT::i1, Promote);
setLoadExtAction(ISD::ZEXTLOAD, VT, MVT::i1, Promote);
setLoadExtAction(ISD::SEXTLOAD, VT, MVT::i1, Promote);
setLoadExtAction(ISD::SEXTLOAD, VT, MVT::i8, Expand);
setLoadExtAction(ISD::SEXTLOAD, VT, MVT::i16, Expand);
setLoadExtAction(ISD::SEXTLOAD, VT, MVT::i32, Expand);
}
setBooleanContents(ZeroOrOneBooleanContent);
// Function alignments (log2)
setMinFunctionAlignment(3);
setPrefFunctionAlignment(3);
if (BPFExpandMemcpyInOrder) {
// LLVM generic code will try to expand memcpy into load/store pairs at this
// stage which is before quite a few IR optimization passes, therefore the
// loads and stores could potentially be moved apart from each other which
// will cause trouble to memcpy pattern matcher inside kernel eBPF JIT
// compilers.
//
// When -bpf-expand-memcpy-in-order specified, we want to defer the expand
// of memcpy to later stage in IR optimization pipeline so those load/store
// pairs won't be touched and could be kept in order. Hence, we set
// MaxStoresPerMem* to zero to disable the generic getMemcpyLoadsAndStores
// code path, and ask LLVM to use target expander EmitTargetCodeForMemcpy.
MaxStoresPerMemset = MaxStoresPerMemsetOptSize = 0;
MaxStoresPerMemcpy = MaxStoresPerMemcpyOptSize = 0;
MaxStoresPerMemmove = MaxStoresPerMemmoveOptSize = 0;
} else {
// inline memcpy() for kernel to see explicit copy
unsigned CommonMaxStores =
STI.getSelectionDAGInfo()->getCommonMaxStoresPerMemFunc();
MaxStoresPerMemset = MaxStoresPerMemsetOptSize = CommonMaxStores;
MaxStoresPerMemcpy = MaxStoresPerMemcpyOptSize = CommonMaxStores;
MaxStoresPerMemmove = MaxStoresPerMemmoveOptSize = CommonMaxStores;
}
// CPU/Feature control
HasAlu32 = STI.getHasAlu32();
HasJmpExt = STI.getHasJmpExt();
}
bool BPFTargetLowering::isOffsetFoldingLegal(const GlobalAddressSDNode *GA) const {
return false;
}
std::pair<unsigned, const TargetRegisterClass *>
BPFTargetLowering::getRegForInlineAsmConstraint(const TargetRegisterInfo *TRI,
StringRef Constraint,
MVT VT) const {
if (Constraint.size() == 1)
// GCC Constraint Letters
switch (Constraint[0]) {
case 'r': // GENERAL_REGS
return std::make_pair(0U, &BPF::GPRRegClass);
default:
break;
}
return TargetLowering::getRegForInlineAsmConstraint(TRI, Constraint, VT);
}
SDValue BPFTargetLowering::LowerOperation(SDValue Op, SelectionDAG &DAG) const {
switch (Op.getOpcode()) {
case ISD::BR_CC:
return LowerBR_CC(Op, DAG);
case ISD::GlobalAddress:
return LowerGlobalAddress(Op, DAG);
case ISD::SELECT_CC:
return LowerSELECT_CC(Op, DAG);
default:
llvm_unreachable("unimplemented operand");
}
}
// Calling Convention Implementation
#include "BPFGenCallingConv.inc"
SDValue BPFTargetLowering::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();
MachineRegisterInfo &RegInfo = MF.getRegInfo();
// Assign locations to all of the incoming arguments.
SmallVector<CCValAssign, 16> ArgLocs;
CCState CCInfo(CallConv, IsVarArg, MF, ArgLocs, *DAG.getContext());
CCInfo.AnalyzeFormalArguments(Ins, getHasAlu32() ? CC_BPF32 : CC_BPF64);
for (auto &VA : ArgLocs) {
if (VA.isRegLoc()) {
// Arguments passed in registers
EVT RegVT = VA.getLocVT();
MVT::SimpleValueType SimpleTy = RegVT.getSimpleVT().SimpleTy;
switch (SimpleTy) {
default: {
errs() << "LowerFormalArguments Unhandled argument type: "
<< RegVT.getEVTString() << '\n';
llvm_unreachable(0);
}
case MVT::i32:
case MVT::i64:
unsigned VReg = RegInfo.createVirtualRegister(SimpleTy == MVT::i64 ?
&BPF::GPRRegClass :
&BPF::GPR32RegClass);
RegInfo.addLiveIn(VA.getLocReg(), VReg);
SDValue ArgValue = DAG.getCopyFromReg(Chain, DL, VReg, RegVT);
// If this is an value that has been promoted to wider types, 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);
InVals.push_back(ArgValue);
break;
}
} else {
fail(DL, DAG, "defined with too many args");
InVals.push_back(DAG.getConstant(0, DL, VA.getLocVT()));
}
}
if (IsVarArg || MF.getFunction().hasStructRetAttr()) {
fail(DL, DAG, "functions with VarArgs or StructRet are not supported");
}
return Chain;
}
const unsigned BPFTargetLowering::MaxArgs = 5;
SDValue BPFTargetLowering::LowerCall(TargetLowering::CallLoweringInfo &CLI,
SmallVectorImpl<SDValue> &InVals) const {
SelectionDAG &DAG = CLI.DAG;
auto &Outs = CLI.Outs;
auto &OutVals = CLI.OutVals;
auto &Ins = CLI.Ins;
SDValue Chain = CLI.Chain;
SDValue Callee = CLI.Callee;
bool &IsTailCall = CLI.IsTailCall;
CallingConv::ID CallConv = CLI.CallConv;
bool IsVarArg = CLI.IsVarArg;
MachineFunction &MF = DAG.getMachineFunction();
// BPF target does not support tail call optimization.
IsTailCall = false;
switch (CallConv) {
default:
report_fatal_error("Unsupported calling convention");
case CallingConv::Fast:
case CallingConv::C:
break;
}
// Analyze operands of the call, assigning locations to each operand.
SmallVector<CCValAssign, 16> ArgLocs;
CCState CCInfo(CallConv, IsVarArg, MF, ArgLocs, *DAG.getContext());
CCInfo.AnalyzeCallOperands(Outs, getHasAlu32() ? CC_BPF32 : CC_BPF64);
unsigned NumBytes = CCInfo.getNextStackOffset();
if (Outs.size() > MaxArgs)
fail(CLI.DL, DAG, "too many args to ", Callee);
for (auto &Arg : Outs) {
ISD::ArgFlagsTy Flags = Arg.Flags;
if (!Flags.isByVal())
continue;
fail(CLI.DL, DAG, "pass by value not supported ", Callee);
}
auto PtrVT = getPointerTy(MF.getDataLayout());
Chain = DAG.getCALLSEQ_START(Chain, NumBytes, 0, CLI.DL);
SmallVector<std::pair<unsigned, SDValue>, MaxArgs> RegsToPass;
// Walk arg assignments
for (unsigned i = 0,
e = std::min(static_cast<unsigned>(ArgLocs.size()), MaxArgs);
i != e; ++i) {
CCValAssign &VA = ArgLocs[i];
SDValue Arg = OutVals[i];
// Promote the value if needed.
switch (VA.getLocInfo()) {
default:
llvm_unreachable("Unknown loc info");
case CCValAssign::Full:
break;
case CCValAssign::SExt:
Arg = DAG.getNode(ISD::SIGN_EXTEND, CLI.DL, VA.getLocVT(), Arg);
break;
case CCValAssign::ZExt:
Arg = DAG.getNode(ISD::ZERO_EXTEND, CLI.DL, VA.getLocVT(), Arg);
break;
case CCValAssign::AExt:
Arg = DAG.getNode(ISD::ANY_EXTEND, CLI.DL, VA.getLocVT(), Arg);
break;
}
// Push arguments into RegsToPass vector
if (VA.isRegLoc())
RegsToPass.push_back(std::make_pair(VA.getLocReg(), Arg));
else
llvm_unreachable("call arg pass bug");
}
SDValue InFlag;
// 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.
for (auto &Reg : RegsToPass) {
Chain = DAG.getCopyToReg(Chain, CLI.DL, Reg.first, Reg.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(), CLI.DL, PtrVT,
G->getOffset(), 0);
} else if (ExternalSymbolSDNode *E = dyn_cast<ExternalSymbolSDNode>(Callee)) {
Callee = DAG.getTargetExternalSymbol(E->getSymbol(), PtrVT, 0);
fail(CLI.DL, DAG, Twine("A call to built-in function '"
+ StringRef(E->getSymbol())
+ "' is not supported."));
}
// 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 (auto &Reg : RegsToPass)
Ops.push_back(DAG.getRegister(Reg.first, Reg.second.getValueType()));
if (InFlag.getNode())
Ops.push_back(InFlag);
Chain = DAG.getNode(BPFISD::CALL, CLI.DL, NodeTys, Ops);
InFlag = Chain.getValue(1);
// Create the CALLSEQ_END node.
Chain = DAG.getCALLSEQ_END(
Chain, DAG.getConstant(NumBytes, CLI.DL, PtrVT, true),
DAG.getConstant(0, CLI.DL, PtrVT, true), InFlag, CLI.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, CLI.DL, DAG,
InVals);
}
SDValue
BPFTargetLowering::LowerReturn(SDValue Chain, CallingConv::ID CallConv,
bool IsVarArg,
const SmallVectorImpl<ISD::OutputArg> &Outs,
const SmallVectorImpl<SDValue> &OutVals,
const SDLoc &DL, SelectionDAG &DAG) const {
unsigned Opc = BPFISD::RET_FLAG;
// CCValAssign - represent the assignment of the return value to a location
SmallVector<CCValAssign, 16> RVLocs;
MachineFunction &MF = DAG.getMachineFunction();
// CCState - Info about the registers and stack slot.
CCState CCInfo(CallConv, IsVarArg, MF, RVLocs, *DAG.getContext());
if (MF.getFunction().getReturnType()->isAggregateType()) {
fail(DL, DAG, "only integer returns supported");
return DAG.getNode(Opc, DL, MVT::Other, Chain);
}
// Analize return values.
CCInfo.AnalyzeReturn(Outs, getHasAlu32() ? RetCC_BPF32 : RetCC_BPF64);
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];
assert(VA.isRegLoc() && "Can only return in registers!");
Chain = DAG.getCopyToReg(Chain, DL, VA.getLocReg(), OutVals[i], Flag);
// Guarantee that all emitted copies are stuck together,
// avoiding something bad.
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(Opc, DL, MVT::Other, RetOps);
}
SDValue BPFTargetLowering::LowerCallResult(
SDValue Chain, SDValue InFlag, CallingConv::ID CallConv, bool IsVarArg,
const SmallVectorImpl<ISD::InputArg> &Ins, const SDLoc &DL,
SelectionDAG &DAG, SmallVectorImpl<SDValue> &InVals) const {
MachineFunction &MF = DAG.getMachineFunction();
// Assign locations to each value returned by this call.
SmallVector<CCValAssign, 16> RVLocs;
CCState CCInfo(CallConv, IsVarArg, MF, RVLocs, *DAG.getContext());
if (Ins.size() >= 2) {
fail(DL, DAG, "only small returns supported");
for (unsigned i = 0, e = Ins.size(); i != e; ++i)
InVals.push_back(DAG.getConstant(0, DL, Ins[i].VT));
return DAG.getCopyFromReg(Chain, DL, 1, Ins[0].VT, InFlag).getValue(1);
}
CCInfo.AnalyzeCallResult(Ins, getHasAlu32() ? RetCC_BPF32 : RetCC_BPF64);
// Copy all of the result registers out of their specified physreg.
for (auto &Val : RVLocs) {
Chain = DAG.getCopyFromReg(Chain, DL, Val.getLocReg(),
Val.getValVT(), InFlag).getValue(1);
InFlag = Chain.getValue(2);
InVals.push_back(Chain.getValue(0));
}
return Chain;
}
static void NegateCC(SDValue &LHS, SDValue &RHS, ISD::CondCode &CC) {
switch (CC) {
default:
break;
case ISD::SETULT:
case ISD::SETULE:
case ISD::SETLT:
case ISD::SETLE:
CC = ISD::getSetCCSwappedOperands(CC);
std::swap(LHS, RHS);
break;
}
}
SDValue BPFTargetLowering::LowerBR_CC(SDValue Op, SelectionDAG &DAG) const {
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);
SDLoc DL(Op);
if (!getHasJmpExt())
NegateCC(LHS, RHS, CC);
return DAG.getNode(BPFISD::BR_CC, DL, Op.getValueType(), Chain, LHS, RHS,
DAG.getConstant(CC, DL, MVT::i64), Dest);
}
SDValue BPFTargetLowering::LowerSELECT_CC(SDValue Op, SelectionDAG &DAG) const {
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();
SDLoc DL(Op);
if (!getHasJmpExt())
NegateCC(LHS, RHS, CC);
SDValue TargetCC = DAG.getConstant(CC, DL, LHS.getValueType());
SDVTList VTs = DAG.getVTList(Op.getValueType(), MVT::Glue);
SDValue Ops[] = {LHS, RHS, TargetCC, TrueV, FalseV};
return DAG.getNode(BPFISD::SELECT_CC, DL, VTs, Ops);
}
const char *BPFTargetLowering::getTargetNodeName(unsigned Opcode) const {
switch ((BPFISD::NodeType)Opcode) {
case BPFISD::FIRST_NUMBER:
break;
case BPFISD::RET_FLAG:
return "BPFISD::RET_FLAG";
case BPFISD::CALL:
return "BPFISD::CALL";
case BPFISD::SELECT_CC:
return "BPFISD::SELECT_CC";
case BPFISD::BR_CC:
return "BPFISD::BR_CC";
case BPFISD::Wrapper:
return "BPFISD::Wrapper";
case BPFISD::MEMCPY:
return "BPFISD::MEMCPY";
}
return nullptr;
}
SDValue BPFTargetLowering::LowerGlobalAddress(SDValue Op,
SelectionDAG &DAG) const {
auto N = cast<GlobalAddressSDNode>(Op);
assert(N->getOffset() == 0 && "Invalid offset for global address");
SDLoc DL(Op);
const GlobalValue *GV = N->getGlobal();
SDValue GA = DAG.getTargetGlobalAddress(GV, DL, MVT::i64);
return DAG.getNode(BPFISD::Wrapper, DL, MVT::i64, GA);
}
unsigned
BPFTargetLowering::EmitSubregExt(MachineInstr &MI, MachineBasicBlock *BB,
unsigned Reg, bool isSigned) const {
const TargetInstrInfo &TII = *BB->getParent()->getSubtarget().getInstrInfo();
const TargetRegisterClass *RC = getRegClassFor(MVT::i64);
int RShiftOp = isSigned ? BPF::SRA_ri : BPF::SRL_ri;
MachineFunction *F = BB->getParent();
DebugLoc DL = MI.getDebugLoc();
MachineRegisterInfo &RegInfo = F->getRegInfo();
unsigned PromotedReg0 = RegInfo.createVirtualRegister(RC);
unsigned PromotedReg1 = RegInfo.createVirtualRegister(RC);
unsigned PromotedReg2 = RegInfo.createVirtualRegister(RC);
BuildMI(BB, DL, TII.get(BPF::MOV_32_64), PromotedReg0).addReg(Reg);
BuildMI(BB, DL, TII.get(BPF::SLL_ri), PromotedReg1)
.addReg(PromotedReg0).addImm(32);
BuildMI(BB, DL, TII.get(RShiftOp), PromotedReg2)
.addReg(PromotedReg1).addImm(32);
return PromotedReg2;
}
MachineBasicBlock *
BPFTargetLowering::EmitInstrWithCustomInserterMemcpy(MachineInstr &MI,
MachineBasicBlock *BB)
const {
MachineFunction *MF = MI.getParent()->getParent();
MachineRegisterInfo &MRI = MF->getRegInfo();
MachineInstrBuilder MIB(*MF, MI);
unsigned ScratchReg;
// This function does custom insertion during lowering BPFISD::MEMCPY which
// only has two register operands from memcpy semantics, the copy source
// address and the copy destination address.
//
// Because we will expand BPFISD::MEMCPY into load/store pairs, we will need
// a third scratch register to serve as the destination register of load and
// source register of store.
//
// The scratch register here is with the Define | Dead | EarlyClobber flags.
// The EarlyClobber flag has the semantic property that the operand it is
// attached to is clobbered before the rest of the inputs are read. Hence it
// must be unique among the operands to the instruction. The Define flag is
// needed to coerce the machine verifier that an Undef value isn't a problem
// as we anyway is loading memory into it. The Dead flag is needed as the
// value in scratch isn't supposed to be used by any other instruction.
ScratchReg = MRI.createVirtualRegister(&BPF::GPRRegClass);
MIB.addReg(ScratchReg,
RegState::Define | RegState::Dead | RegState::EarlyClobber);
return BB;
}
MachineBasicBlock *
BPFTargetLowering::EmitInstrWithCustomInserter(MachineInstr &MI,
MachineBasicBlock *BB) const {
const TargetInstrInfo &TII = *BB->getParent()->getSubtarget().getInstrInfo();
DebugLoc DL = MI.getDebugLoc();
unsigned Opc = MI.getOpcode();
bool isSelectRROp = (Opc == BPF::Select ||
Opc == BPF::Select_64_32 ||
Opc == BPF::Select_32 ||
Opc == BPF::Select_32_64);
bool isMemcpyOp = Opc == BPF::MEMCPY;
#ifndef NDEBUG
bool isSelectRIOp = (Opc == BPF::Select_Ri ||
Opc == BPF::Select_Ri_64_32 ||
Opc == BPF::Select_Ri_32 ||
Opc == BPF::Select_Ri_32_64);
assert((isSelectRROp || isSelectRIOp || isMemcpyOp) &&
"Unexpected instr type to insert");
#endif
if (isMemcpyOp)
return EmitInstrWithCustomInserterMemcpy(MI, BB);
bool is32BitCmp = (Opc == BPF::Select_32 ||
Opc == BPF::Select_32_64 ||
Opc == BPF::Select_Ri_32 ||
Opc == BPF::Select_Ri_32_64);
// 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->getIterator();
// ThisMBB:
// ...
// TrueVal = ...
// jmp_XX r1, r2 goto Copy1MBB
// fallthrough --> Copy0MBB
MachineBasicBlock *ThisMBB = BB;
MachineFunction *F = BB->getParent();
MachineBasicBlock *Copy0MBB = F->CreateMachineBasicBlock(LLVM_BB);
MachineBasicBlock *Copy1MBB = F->CreateMachineBasicBlock(LLVM_BB);
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->splice(Copy1MBB->begin(), BB,
std::next(MachineBasicBlock::iterator(MI)), BB->end());
Copy1MBB->transferSuccessorsAndUpdatePHIs(BB);
// Next, add the true and fallthrough blocks as its successors.
BB->addSuccessor(Copy0MBB);
BB->addSuccessor(Copy1MBB);
// Insert Branch if Flag
int CC = MI.getOperand(3).getImm();
int NewCC;
switch (CC) {
case ISD::SETGT:
NewCC = isSelectRROp ? BPF::JSGT_rr : BPF::JSGT_ri;
break;
case ISD::SETUGT:
NewCC = isSelectRROp ? BPF::JUGT_rr : BPF::JUGT_ri;
break;
case ISD::SETGE:
NewCC = isSelectRROp ? BPF::JSGE_rr : BPF::JSGE_ri;
break;
case ISD::SETUGE:
NewCC = isSelectRROp ? BPF::JUGE_rr : BPF::JUGE_ri;
break;
case ISD::SETEQ:
NewCC = isSelectRROp ? BPF::JEQ_rr : BPF::JEQ_ri;
break;
case ISD::SETNE:
NewCC = isSelectRROp ? BPF::JNE_rr : BPF::JNE_ri;
break;
case ISD::SETLT:
NewCC = isSelectRROp ? BPF::JSLT_rr : BPF::JSLT_ri;
break;
case ISD::SETULT:
NewCC = isSelectRROp ? BPF::JULT_rr : BPF::JULT_ri;
break;
case ISD::SETLE:
NewCC = isSelectRROp ? BPF::JSLE_rr : BPF::JSLE_ri;
break;
case ISD::SETULE:
NewCC = isSelectRROp ? BPF::JULE_rr : BPF::JULE_ri;
break;
default:
report_fatal_error("unimplemented select CondCode " + Twine(CC));
}
unsigned LHS = MI.getOperand(1).getReg();
bool isSignedCmp = (CC == ISD::SETGT ||
CC == ISD::SETGE ||
CC == ISD::SETLT ||
CC == ISD::SETLE);
// eBPF at the moment only has 64-bit comparison. Any 32-bit comparison need
// to be promoted, however if the 32-bit comparison operands are destination
// registers then they are implicitly zero-extended already, there is no
// need of explicit zero-extend sequence for them.
//
// We simply do extension for all situations in this method, but we will
// try to remove those unnecessary in BPFMIPeephole pass.
if (is32BitCmp)
LHS = EmitSubregExt(MI, BB, LHS, isSignedCmp);
if (isSelectRROp) {
unsigned RHS = MI.getOperand(2).getReg();
if (is32BitCmp)
RHS = EmitSubregExt(MI, BB, RHS, isSignedCmp);
BuildMI(BB, DL, TII.get(NewCC)).addReg(LHS).addReg(RHS).addMBB(Copy1MBB);
} else {
int64_t imm32 = MI.getOperand(2).getImm();
// sanity check before we build J*_ri instruction.
assert (isInt<32>(imm32));
BuildMI(BB, DL, TII.get(NewCC))
.addReg(LHS).addImm(imm32).addMBB(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, BB->begin(), DL, TII.get(BPF::PHI), MI.getOperand(0).getReg())
.addReg(MI.getOperand(5).getReg())
.addMBB(Copy0MBB)
.addReg(MI.getOperand(4).getReg())
.addMBB(ThisMBB);
MI.eraseFromParent(); // The pseudo instruction is gone now.
return BB;
}
EVT BPFTargetLowering::getSetCCResultType(const DataLayout &, LLVMContext &,
EVT VT) const {
return getHasAlu32() ? MVT::i32 : MVT::i64;
}
MVT BPFTargetLowering::getScalarShiftAmountTy(const DataLayout &DL,
EVT VT) const {
return (getHasAlu32() && VT == MVT::i32) ? MVT::i32 : MVT::i64;
}
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