1 //===- MipsELFStreamer.h - ELF Object Output --------------------*- 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 // This is a custom MCELFStreamer which allows us to insert some hooks before
11 // emitting data into an actual object file.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #ifndef LLVM_LIB_TARGET_MIPS_MCTARGETDESC_MIPSELFSTREAMER_H
16 #define LLVM_LIB_TARGET_MIPS_MCTARGETDESC_MIPSELFSTREAMER_H
17 
18 #include "MipsOptionRecord.h"
19 #include "llvm/ADT/SmallVector.h"
20 #include "llvm/MC/MCELFStreamer.h"
21 #include <memory>
22 
23 namespace llvm {
24 
25 class MCAsmBackend;
26 class MCCodeEmitter;
27 class MCContext;
28 class MCSubtargetInfo;
29 struct MCDwarfFrameInfo;
30 
31 class MipsELFStreamer : public MCELFStreamer {
32   SmallVector<std::unique_ptr<MipsOptionRecord>, 8> MipsOptionRecords;
33   MipsRegInfoRecord *RegInfoRecord;
34   SmallVector<MCSymbol*, 4> Labels;
35 
36 public:
37   MipsELFStreamer(MCContext &Context, std::unique_ptr<MCAsmBackend> MAB,
38                   std::unique_ptr<MCObjectWriter> OW,
39                   std::unique_ptr<MCCodeEmitter> Emitter);
40 
41   /// Overriding this function allows us to add arbitrary behaviour before the
42   /// \p Inst is actually emitted. For example, we can inspect the operands and
43   /// gather sufficient information that allows us to reason about the register
44   /// usage for the translation unit.
45   void EmitInstruction(const MCInst &Inst, const MCSubtargetInfo &STI,
46                        bool = false) override;
47 
48   /// Overriding this function allows us to record all labels that should be
49   /// marked as microMIPS. Based on this data marking is done in
50   /// EmitInstruction.
51   void EmitLabel(MCSymbol *Symbol, SMLoc Loc = SMLoc()) override;
52 
53   /// Overriding this function allows us to dismiss all labels that are
54   /// candidates for marking as microMIPS when .section directive is processed.
55   void SwitchSection(MCSection *Section,
56                      const MCExpr *Subsection = nullptr) override;
57 
58   /// Overriding these functions allows us to dismiss all labels that are
59   /// candidates for marking as microMIPS when .word/.long/.4byte etc
60   /// directives are emitted.
61   void EmitValueImpl(const MCExpr *Value, unsigned Size, SMLoc Loc) override;
62   void EmitIntValue(uint64_t Value, unsigned Size) override;
63 
64   // Overriding these functions allows us to avoid recording of these labels
65   // in EmitLabel and later marking them as microMIPS.
66   void EmitCFIStartProcImpl(MCDwarfFrameInfo &Frame) override;
67   void EmitCFIEndProcImpl(MCDwarfFrameInfo &Frame) override;
68   MCSymbol *EmitCFILabel() override;
69 
70   /// Emits all the option records stored up until the point it's called.
71   void EmitMipsOptionRecords();
72 
73   /// Mark labels as microMIPS, if necessary for the subtarget.
74   void createPendingLabelRelocs();
75 };
76 
77 MCELFStreamer *createMipsELFStreamer(MCContext &Context,
78                                      std::unique_ptr<MCAsmBackend> MAB,
79                                      std::unique_ptr<MCObjectWriter> OW,
80                                      std::unique_ptr<MCCodeEmitter> Emitter,
81                                      bool RelaxAll);
82 } // end namespace llvm
83 
84 #endif // LLVM_LIB_TARGET_MIPS_MCTARGETDESC_MIPSELFSTREAMER_H
85