1 //===-- MSP430AsmPrinter.cpp - MSP430 LLVM assembly writer ----------------===//
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 // This file contains a printer that converts from our internal representation
11 // of machine-dependent LLVM code to the MSP430 assembly language.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #include "InstPrinter/MSP430InstPrinter.h"
16 #include "MSP430.h"
17 #include "MSP430InstrInfo.h"
18 #include "MSP430MCInstLower.h"
19 #include "MSP430TargetMachine.h"
20 #include "llvm/BinaryFormat/ELF.h"
21 #include "llvm/CodeGen/AsmPrinter.h"
22 #include "llvm/CodeGen/MachineConstantPool.h"
23 #include "llvm/CodeGen/MachineFunctionPass.h"
24 #include "llvm/CodeGen/MachineInstr.h"
25 #include "llvm/CodeGen/MachineModuleInfo.h"
26 #include "llvm/IR/Constants.h"
27 #include "llvm/IR/DerivedTypes.h"
28 #include "llvm/IR/Mangler.h"
29 #include "llvm/IR/Module.h"
30 #include "llvm/MC/MCAsmInfo.h"
31 #include "llvm/MC/MCInst.h"
32 #include "llvm/MC/MCSectionELF.h"
33 #include "llvm/MC/MCStreamer.h"
34 #include "llvm/MC/MCSymbol.h"
35 #include "llvm/Support/TargetRegistry.h"
36 #include "llvm/Support/raw_ostream.h"
37 using namespace llvm;
38 
39 #define DEBUG_TYPE "asm-printer"
40 
41 namespace {
42   class MSP430AsmPrinter : public AsmPrinter {
43   public:
44     MSP430AsmPrinter(TargetMachine &TM, std::unique_ptr<MCStreamer> Streamer)
45         : AsmPrinter(TM, std::move(Streamer)) {}
46 
47     StringRef getPassName() const override { return "MSP430 Assembly Printer"; }
48 
49     bool runOnMachineFunction(MachineFunction &MF) override;
50 
51     void printOperand(const MachineInstr *MI, int OpNum,
52                       raw_ostream &O, const char* Modifier = nullptr);
53     void printSrcMemOperand(const MachineInstr *MI, int OpNum,
54                             raw_ostream &O);
55     bool PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
56                          unsigned AsmVariant, const char *ExtraCode,
57                          raw_ostream &O) override;
58     bool PrintAsmMemoryOperand(const MachineInstr *MI,
59                                unsigned OpNo, unsigned AsmVariant,
60                                const char *ExtraCode, raw_ostream &O) override;
61     void EmitInstruction(const MachineInstr *MI) override;
62 
63     void EmitInterruptVectorSection(MachineFunction &ISR);
64   };
65 } // end of anonymous namespace
66 
67 
68 void MSP430AsmPrinter::printOperand(const MachineInstr *MI, int OpNum,
69                                     raw_ostream &O, const char *Modifier) {
70   const MachineOperand &MO = MI->getOperand(OpNum);
71   switch (MO.getType()) {
72   default: llvm_unreachable("Not implemented yet!");
73   case MachineOperand::MO_Register:
74     O << MSP430InstPrinter::getRegisterName(MO.getReg());
75     return;
76   case MachineOperand::MO_Immediate:
77     if (!Modifier || strcmp(Modifier, "nohash"))
78       O << '#';
79     O << MO.getImm();
80     return;
81   case MachineOperand::MO_MachineBasicBlock:
82     MO.getMBB()->getSymbol()->print(O, MAI);
83     return;
84   case MachineOperand::MO_GlobalAddress: {
85     bool isMemOp  = Modifier && !strcmp(Modifier, "mem");
86     uint64_t Offset = MO.getOffset();
87 
88     // If the global address expression is a part of displacement field with a
89     // register base, we should not emit any prefix symbol here, e.g.
90     //   mov.w &foo, r1
91     // vs
92     //   mov.w glb(r1), r2
93     // Otherwise (!) msp430-as will silently miscompile the output :(
94     if (!Modifier || strcmp(Modifier, "nohash"))
95       O << (isMemOp ? '&' : '#');
96     if (Offset)
97       O << '(' << Offset << '+';
98 
99     getSymbol(MO.getGlobal())->print(O, MAI);
100 
101     if (Offset)
102       O << ')';
103 
104     return;
105   }
106   }
107 }
108 
109 void MSP430AsmPrinter::printSrcMemOperand(const MachineInstr *MI, int OpNum,
110                                           raw_ostream &O) {
111   const MachineOperand &Base = MI->getOperand(OpNum);
112   const MachineOperand &Disp = MI->getOperand(OpNum+1);
113 
114   // Print displacement first
115 
116   // Imm here is in fact global address - print extra modifier.
117   if (Disp.isImm() && !Base.getReg())
118     O << '&';
119   printOperand(MI, OpNum+1, O, "nohash");
120 
121   // Print register base field
122   if (Base.getReg()) {
123     O << '(';
124     printOperand(MI, OpNum, O);
125     O << ')';
126   }
127 }
128 
129 /// PrintAsmOperand - Print out an operand for an inline asm expression.
130 ///
131 bool MSP430AsmPrinter::PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
132                                        unsigned AsmVariant,
133                                        const char *ExtraCode, raw_ostream &O) {
134   // Does this asm operand have a single letter operand modifier?
135   if (ExtraCode && ExtraCode[0])
136     return true; // Unknown modifier.
137 
138   printOperand(MI, OpNo, O);
139   return false;
140 }
141 
142 bool MSP430AsmPrinter::PrintAsmMemoryOperand(const MachineInstr *MI,
143                                              unsigned OpNo, unsigned AsmVariant,
144                                              const char *ExtraCode,
145                                              raw_ostream &O) {
146   if (ExtraCode && ExtraCode[0]) {
147     return true; // Unknown modifier.
148   }
149   printSrcMemOperand(MI, OpNo, O);
150   return false;
151 }
152 
153 //===----------------------------------------------------------------------===//
154 void MSP430AsmPrinter::EmitInstruction(const MachineInstr *MI) {
155   MSP430MCInstLower MCInstLowering(OutContext, *this);
156 
157   MCInst TmpInst;
158   MCInstLowering.Lower(MI, TmpInst);
159   EmitToStreamer(*OutStreamer, TmpInst);
160 }
161 
162 void MSP430AsmPrinter::EmitInterruptVectorSection(MachineFunction &ISR) {
163   MCSection *Cur = OutStreamer->getCurrentSectionOnly();
164   const auto *F = &ISR.getFunction();
165   assert(F->hasFnAttribute("interrupt") &&
166          "Functions with MSP430_INTR CC should have 'interrupt' attribute");
167   StringRef IVIdx = F->getFnAttribute("interrupt").getValueAsString();
168   MCSection *IV = OutStreamer->getContext().getELFSection(
169     "__interrupt_vector_" + IVIdx,
170     ELF::SHT_PROGBITS, ELF::SHF_ALLOC | ELF::SHF_EXECINSTR);
171   OutStreamer->SwitchSection(IV);
172 
173   const MCSymbol *FunctionSymbol = getSymbol(F);
174   OutStreamer->EmitSymbolValue(FunctionSymbol, TM.getProgramPointerSize());
175   OutStreamer->SwitchSection(Cur);
176 }
177 
178 bool MSP430AsmPrinter::runOnMachineFunction(MachineFunction &MF) {
179   // Emit separate section for an interrupt vector if ISR
180   if (MF.getFunction().getCallingConv() == CallingConv::MSP430_INTR)
181     EmitInterruptVectorSection(MF);
182 
183   SetupMachineFunction(MF);
184   EmitFunctionBody();
185   return false;
186 }
187 
188 // Force static initialization.
189 extern "C" void LLVMInitializeMSP430AsmPrinter() {
190   RegisterAsmPrinter<MSP430AsmPrinter> X(getTheMSP430Target());
191 }
192