Mips16ISelLowering.cpp | Explore in Territory

//===-- Mips16ISelLowering.h - Mips16 DAG Lowering Interface ----*- C++ -*-===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// Subclass of MipsTargetLowering specialized for mips16.
//
//===----------------------------------------------------------------------===//
#include "Mips16ISelLowering.h"
#include "MCTargetDesc/MipsBaseInfo.h"
#include "Mips16HardFloatInfo.h"
#include "MipsMachineFunction.h"
#include "MipsRegisterInfo.h"
#include "MipsTargetMachine.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/TargetInstrInfo.h"
#include "llvm/Support/CommandLine.h"

usingnamespacellvm;

#define DEBUG_TYPE …

static cl::opt<bool> DontExpandCondPseudos16(
  "mips16-dont-expand-cond-pseudo",
  cl::init(false),
  cl::desc("Don't expand conditional move related "
           "pseudos for Mips 16"),
  cl::Hidden);

namespace {
struct Mips16Libcall { … };

struct Mips16IntrinsicHelperType{ … };
}

// Libcalls for which no helper is generated. Sorted by name for binary search.
static const Mips16Libcall HardFloatLibCalls[] = …;

static const Mips16IntrinsicHelperType Mips16IntrinsicHelper[] = …;

Mips16TargetLowering::Mips16TargetLowering(const MipsTargetMachine &TM,
                                           const MipsSubtarget &STI)
    : … { … }

const MipsTargetLowering *
llvm::createMips16TargetLowering(const MipsTargetMachine &TM,
                                 const MipsSubtarget &STI) { … }

bool Mips16TargetLowering::allowsMisalignedMemoryAccesses(
    EVT VT, unsigned, Align, MachineMemOperand::Flags, unsigned *Fast) const { … }

MachineBasicBlock *
Mips16TargetLowering::EmitInstrWithCustomInserter(MachineInstr &MI,
                                                  MachineBasicBlock *BB) const { … }

bool Mips16TargetLowering::isEligibleForTailCallOptimization(
    const CCState &CCInfo, unsigned NextStackOffset,
    const MipsFunctionInfo &FI) const { … }

void Mips16TargetLowering::setMips16HardFloatLibCalls() { … }

//
// The Mips16 hard float is a crazy quilt inherited from gcc. I have a much
// cleaner way to do all of this but it will have to wait until the traditional
// gcc mechanism is completed.
//
// For Pic, in order for Mips16 code to call Mips32 code which according the abi
// have either arguments or returned values placed in floating point registers,
// we use a set of helper functions. (This includes functions which return type
//  complex which on Mips are returned in a pair of floating point registers).
//
// This is an encoding that we inherited from gcc.
// In Mips traditional O32, N32 ABI, floating point numbers are passed in
// floating point argument registers 1,2 only when the first and optionally
// the second arguments are float (sf) or double (df).
// For Mips16 we are only concerned with the situations where floating point
// arguments are being passed in floating point registers by the ABI, because
// Mips16 mode code cannot execute floating point instructions to load those
// values and hence helper functions are needed.
// The possibilities are (), (sf), (sf, sf), (sf, df), (df), (df, sf), (df, df)
// the helper function suffixs for these are:
//                        0,  1,    5,        9,         2,   6,        10
// this suffix can then be calculated as follows:
// for a given argument Arg:
//     Arg1x, Arg2x = 1 :  Arg is sf
//                    2 :  Arg is df
//                    0:   Arg is neither sf or df
// So this stub is the string for number Arg1x + Arg2x*4.
// However not all numbers between 0 and 10 are possible, we check anyway and
// assert if the impossible exists.
//

unsigned int Mips16TargetLowering::getMips16HelperFunctionStubNumber
  (ArgListTy &Args) const { … }

//
// Prefixes are attached to stub numbers depending on the return type.
// return type: float  sf_
//              double df_
//              single complex sc_
//              double complext dc_
//              others  NO PREFIX
//
//
// The full name of a helper function is__mips16_call_stub +
//    return type dependent prefix + stub number
//
// FIXME: This is something that probably should be in a different source file
// and perhaps done differently but my main purpose is to not waste runtime
// on something that we can enumerate in the source. Another possibility is
// to have a python script to generate these mapping tables. This will do
// for now. There are a whole series of helper function mapping arrays, one
// for each return type class as outlined above. There there are 11 possible
// entries. Ones with 0 are ones which should never be selected.
//
// All the arrays are similar except for ones which return neither
// sf, df, sc, dc, in which we only care about ones which have sf or df as a
// first parameter.
//
#define P_ …
#define MAX_STUB_NUMBER …
#define T1 …
#define T …
#define P …
static char const * vMips16Helper[MAX_STUB_NUMBER+1] = …;
#undef P
#define P …
static char const * sfMips16Helper[MAX_STUB_NUMBER+1] = …;
#undef P
#define P …
static char const * dfMips16Helper[MAX_STUB_NUMBER+1] = …;
#undef P
#define P …
static char const * scMips16Helper[MAX_STUB_NUMBER+1] = …;
#undef P
#define P …
static char const * dcMips16Helper[MAX_STUB_NUMBER+1] = …;
#undef P
#undef P_


const char* Mips16TargetLowering::
  getMips16HelperFunction
    (Type* RetTy, ArgListTy &Args, bool &needHelper) const { … }

void Mips16TargetLowering::
getOpndList(SmallVectorImpl<SDValue> &Ops,
            std::deque< std::pair<unsigned, SDValue> > &RegsToPass,
            bool IsPICCall, bool GlobalOrExternal, bool InternalLinkage,
            bool IsCallReloc, CallLoweringInfo &CLI, SDValue Callee,
            SDValue Chain) const { … }

MachineBasicBlock *
Mips16TargetLowering::emitSel16(unsigned Opc, MachineInstr &MI,
                                MachineBasicBlock *BB) const { … }

MachineBasicBlock *
Mips16TargetLowering::emitSelT16(unsigned Opc1, unsigned Opc2, MachineInstr &MI,
                                 MachineBasicBlock *BB) const { … }

MachineBasicBlock *
Mips16TargetLowering::emitSeliT16(unsigned Opc1, unsigned Opc2,
                                  MachineInstr &MI,
                                  MachineBasicBlock *BB) const { … }

MachineBasicBlock *
Mips16TargetLowering::emitFEXT_T8I816_ins(unsigned BtOpc, unsigned CmpOpc,
                                          MachineInstr &MI,
                                          MachineBasicBlock *BB) const { … }

MachineBasicBlock *Mips16TargetLowering::emitFEXT_T8I8I16_ins(
    unsigned BtOpc, unsigned CmpiOpc, unsigned CmpiXOpc, bool ImmSigned,
    MachineInstr &MI, MachineBasicBlock *BB) const { … }

static unsigned Mips16WhichOp8uOr16simm
  (unsigned shortOp, unsigned longOp, int64_t Imm) { … }

MachineBasicBlock *
Mips16TargetLowering::emitFEXT_CCRX16_ins(unsigned SltOpc, MachineInstr &MI,
                                          MachineBasicBlock *BB) const { … }

MachineBasicBlock *
Mips16TargetLowering::emitFEXT_CCRXI16_ins(unsigned SltiOpc, unsigned SltiXOpc,
                                           MachineInstr &MI,
                                           MachineBasicBlock *BB) const { … }
llvm/llvm/lib/Target/Mips/Mips16ISelLowering.cpp
