1 //===-- MSP430AsmPrinter.cpp - MSP430 LLVM assembly writer ----------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file contains a printer that converts from our internal representation
10 // of machine-dependent LLVM code to the MSP430 assembly language.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "InstPrinter/MSP430InstPrinter.h"
15 #include "MSP430.h"
16 #include "MSP430InstrInfo.h"
17 #include "MSP430MCInstLower.h"
18 #include "MSP430TargetMachine.h"
19 #include "llvm/BinaryFormat/ELF.h"
20 #include "llvm/CodeGen/AsmPrinter.h"
21 #include "llvm/CodeGen/MachineConstantPool.h"
22 #include "llvm/CodeGen/MachineFunctionPass.h"
23 #include "llvm/CodeGen/MachineInstr.h"
24 #include "llvm/CodeGen/MachineModuleInfo.h"
25 #include "llvm/IR/Constants.h"
26 #include "llvm/IR/DerivedTypes.h"
27 #include "llvm/IR/Mangler.h"
28 #include "llvm/IR/Module.h"
29 #include "llvm/MC/MCAsmInfo.h"
30 #include "llvm/MC/MCInst.h"
31 #include "llvm/MC/MCSectionELF.h"
32 #include "llvm/MC/MCStreamer.h"
33 #include "llvm/MC/MCSymbol.h"
34 #include "llvm/Support/TargetRegistry.h"
35 #include "llvm/Support/raw_ostream.h"
36 using namespace llvm;
37 
38 #define DEBUG_TYPE "asm-printer"
39 
40 namespace {
41   class MSP430AsmPrinter : public AsmPrinter {
42   public:
43     MSP430AsmPrinter(TargetMachine &TM, std::unique_ptr<MCStreamer> Streamer)
44         : AsmPrinter(TM, std::move(Streamer)) {}
45 
46     StringRef getPassName() const override { return "MSP430 Assembly Printer"; }
47 
48     bool runOnMachineFunction(MachineFunction &MF) override;
49 
50     void printOperand(const MachineInstr *MI, int OpNum,
51                       raw_ostream &O, const char* Modifier = nullptr);
52     void printSrcMemOperand(const MachineInstr *MI, int OpNum,
53                             raw_ostream &O);
54     bool PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
55                          unsigned AsmVariant, const char *ExtraCode,
56                          raw_ostream &O) override;
57     bool PrintAsmMemoryOperand(const MachineInstr *MI,
58                                unsigned OpNo, unsigned AsmVariant,
59                                const char *ExtraCode, raw_ostream &O) override;
60     void EmitInstruction(const MachineInstr *MI) override;
61 
62     void EmitInterruptVectorSection(MachineFunction &ISR);
63   };
64 } // end of anonymous namespace
65 
66 
67 void MSP430AsmPrinter::printOperand(const MachineInstr *MI, int OpNum,
68                                     raw_ostream &O, const char *Modifier) {
69   const MachineOperand &MO = MI->getOperand(OpNum);
70   switch (MO.getType()) {
71   default: llvm_unreachable("Not implemented yet!");
72   case MachineOperand::MO_Register:
73     O << MSP430InstPrinter::getRegisterName(MO.getReg());
74     return;
75   case MachineOperand::MO_Immediate:
76     if (!Modifier || strcmp(Modifier, "nohash"))
77       O << '#';
78     O << MO.getImm();
79     return;
80   case MachineOperand::MO_MachineBasicBlock:
81     MO.getMBB()->getSymbol()->print(O, MAI);
82     return;
83   case MachineOperand::MO_GlobalAddress: {
84     bool isMemOp  = Modifier && !strcmp(Modifier, "mem");
85     uint64_t Offset = MO.getOffset();
86 
87     // If the global address expression is a part of displacement field with a
88     // register base, we should not emit any prefix symbol here, e.g.
89     //   mov.w &foo, r1
90     // vs
91     //   mov.w glb(r1), r2
92     // Otherwise (!) msp430-as will silently miscompile the output :(
93     if (!Modifier || strcmp(Modifier, "nohash"))
94       O << (isMemOp ? '&' : '#');
95     if (Offset)
96       O << '(' << Offset << '+';
97 
98     getSymbol(MO.getGlobal())->print(O, MAI);
99 
100     if (Offset)
101       O << ')';
102 
103     return;
104   }
105   }
106 }
107 
108 void MSP430AsmPrinter::printSrcMemOperand(const MachineInstr *MI, int OpNum,
109                                           raw_ostream &O) {
110   const MachineOperand &Base = MI->getOperand(OpNum);
111   const MachineOperand &Disp = MI->getOperand(OpNum+1);
112 
113   // Print displacement first
114 
115   // Imm here is in fact global address - print extra modifier.
116   if (Disp.isImm() && Base.getReg() == MSP430::SR)
117     O << '&';
118   printOperand(MI, OpNum+1, O, "nohash");
119 
120   // Print register base field
121   if (Base.getReg() != MSP430::SR && Base.getReg() != MSP430::PC) {
122     O << '(';
123     printOperand(MI, OpNum, O);
124     O << ')';
125   }
126 }
127 
128 /// PrintAsmOperand - Print out an operand for an inline asm expression.
129 ///
130 bool MSP430AsmPrinter::PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
131                                        unsigned AsmVariant,
132                                        const char *ExtraCode, raw_ostream &O) {
133   // Does this asm operand have a single letter operand modifier?
134   if (ExtraCode && ExtraCode[0])
135     return true; // Unknown modifier.
136 
137   printOperand(MI, OpNo, O);
138   return false;
139 }
140 
141 bool MSP430AsmPrinter::PrintAsmMemoryOperand(const MachineInstr *MI,
142                                              unsigned OpNo, unsigned AsmVariant,
143                                              const char *ExtraCode,
144                                              raw_ostream &O) {
145   if (ExtraCode && ExtraCode[0]) {
146     return true; // Unknown modifier.
147   }
148   printSrcMemOperand(MI, OpNo, O);
149   return false;
150 }
151 
152 //===----------------------------------------------------------------------===//
153 void MSP430AsmPrinter::EmitInstruction(const MachineInstr *MI) {
154   MSP430MCInstLower MCInstLowering(OutContext, *this);
155 
156   MCInst TmpInst;
157   MCInstLowering.Lower(MI, TmpInst);
158   EmitToStreamer(*OutStreamer, TmpInst);
159 }
160 
161 void MSP430AsmPrinter::EmitInterruptVectorSection(MachineFunction &ISR) {
162   MCSection *Cur = OutStreamer->getCurrentSectionOnly();
163   const auto *F = &ISR.getFunction();
164   assert(F->hasFnAttribute("interrupt") &&
165          "Functions with MSP430_INTR CC should have 'interrupt' attribute");
166   StringRef IVIdx = F->getFnAttribute("interrupt").getValueAsString();
167   MCSection *IV = OutStreamer->getContext().getELFSection(
168     "__interrupt_vector_" + IVIdx,
169     ELF::SHT_PROGBITS, ELF::SHF_ALLOC | ELF::SHF_EXECINSTR);
170   OutStreamer->SwitchSection(IV);
171 
172   const MCSymbol *FunctionSymbol = getSymbol(F);
173   OutStreamer->EmitSymbolValue(FunctionSymbol, TM.getProgramPointerSize());
174   OutStreamer->SwitchSection(Cur);
175 }
176 
177 bool MSP430AsmPrinter::runOnMachineFunction(MachineFunction &MF) {
178   // Emit separate section for an interrupt vector if ISR
179   if (MF.getFunction().getCallingConv() == CallingConv::MSP430_INTR)
180     EmitInterruptVectorSection(MF);
181 
182   SetupMachineFunction(MF);
183   EmitFunctionBody();
184   return false;
185 }
186 
187 // Force static initialization.
188 extern "C" void LLVMInitializeMSP430AsmPrinter() {
189   RegisterAsmPrinter<MSP430AsmPrinter> X(getTheMSP430Target());
190 }
191