1 //===- ARCMCInstLower.cpp - ARC MachineInstr to MCInst ----------*- C++ -*-===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 ///
10 /// \file
11 /// This file contains code to lower ARC MachineInstrs to their
12 /// corresponding MCInst records.
13 ///
14 //===----------------------------------------------------------------------===//
15 
16 #include "ARCMCInstLower.h"
17 #include "llvm/CodeGen/AsmPrinter.h"
18 #include "llvm/CodeGen/MachineFunction.h"
19 #include "llvm/CodeGen/MachineInstr.h"
20 #include "llvm/CodeGen/MachineOperand.h"
21 #include "llvm/MC/MCContext.h"
22 #include "llvm/MC/MCExpr.h"
23 #include "llvm/MC/MCInst.h"
24 
25 using namespace llvm;
26 
27 ARCMCInstLower::ARCMCInstLower(MCContext *C, AsmPrinter &AsmPrinter)
28     : Ctx(C), Printer(AsmPrinter) {}
29 
30 MCOperand ARCMCInstLower::LowerSymbolOperand(const MachineOperand &MO,
31                                              MachineOperandType MOTy,
32                                              unsigned Offset) const {
33   MCSymbolRefExpr::VariantKind Kind = MCSymbolRefExpr::VK_None;
34   const MCSymbol *Symbol;
35 
36   switch (MOTy) {
37   case MachineOperand::MO_MachineBasicBlock:
38     Symbol = MO.getMBB()->getSymbol();
39     break;
40   case MachineOperand::MO_GlobalAddress:
41     Symbol = Printer.getSymbol(MO.getGlobal());
42     Offset += MO.getOffset();
43     break;
44   case MachineOperand::MO_BlockAddress:
45     Symbol = Printer.GetBlockAddressSymbol(MO.getBlockAddress());
46     Offset += MO.getOffset();
47     break;
48   case MachineOperand::MO_ExternalSymbol:
49     Symbol = Printer.GetExternalSymbolSymbol(MO.getSymbolName());
50     Offset += MO.getOffset();
51     break;
52   case MachineOperand::MO_JumpTableIndex:
53     Symbol = Printer.GetJTISymbol(MO.getIndex());
54     break;
55   case MachineOperand::MO_ConstantPoolIndex:
56     Symbol = Printer.GetCPISymbol(MO.getIndex());
57     Offset += MO.getOffset();
58     break;
59   default:
60     llvm_unreachable("<unknown operand type>");
61   }
62 
63   assert(Symbol && "Symbol creation failed.\n");
64   const MCSymbolRefExpr *MCSym = MCSymbolRefExpr::create(Symbol, Kind, *Ctx);
65 
66   if (!Offset)
67     return MCOperand::createExpr(MCSym);
68 
69   // Assume offset is never negative.
70   assert(Offset > 0);
71 
72   const MCConstantExpr *OffsetExpr = MCConstantExpr::create(Offset, *Ctx);
73   const MCBinaryExpr *Add = MCBinaryExpr::createAdd(MCSym, OffsetExpr, *Ctx);
74   return MCOperand::createExpr(Add);
75 }
76 
77 MCOperand ARCMCInstLower::LowerOperand(const MachineOperand &MO,
78                                        unsigned Offset) const {
79   MachineOperandType MOTy = MO.getType();
80 
81   switch (MOTy) {
82   default:
83     llvm_unreachable("unknown operand type");
84   case MachineOperand::MO_Register:
85     // Ignore all implicit register operands.
86     if (MO.isImplicit())
87       break;
88     return MCOperand::createReg(MO.getReg());
89   case MachineOperand::MO_Immediate:
90     return MCOperand::createImm(MO.getImm() + Offset);
91   case MachineOperand::MO_MachineBasicBlock:
92   case MachineOperand::MO_GlobalAddress:
93   case MachineOperand::MO_ExternalSymbol:
94   case MachineOperand::MO_JumpTableIndex:
95   case MachineOperand::MO_ConstantPoolIndex:
96   case MachineOperand::MO_BlockAddress:
97     return LowerSymbolOperand(MO, MOTy, Offset);
98   case MachineOperand::MO_RegisterMask:
99     break;
100   }
101 
102   return {};
103 }
104 
105 void ARCMCInstLower::Lower(const MachineInstr *MI, MCInst &OutMI) const {
106   OutMI.setOpcode(MI->getOpcode());
107 
108   for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
109     const MachineOperand &MO = MI->getOperand(i);
110     MCOperand MCOp = LowerOperand(MO);
111 
112     if (MCOp.isValid())
113       OutMI.addOperand(MCOp);
114   }
115 }
116