1//===-- X86AsmPrinter.h - X86 implementation of AsmPrinter ------*- 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#ifndef LLVM_LIB_TARGET_X86_X86ASMPRINTER_H
11#define LLVM_LIB_TARGET_X86_X86ASMPRINTER_H
12
13#include "X86Subtarget.h"
14#include "llvm/CodeGen/AsmPrinter.h"
15#include "llvm/CodeGen/FaultMaps.h"
16#include "llvm/CodeGen/StackMaps.h"
17#include "llvm/Target/TargetMachine.h"
18
19// Implemented in X86MCInstLower.cpp
20namespace {
21  class X86MCInstLower;
22}
23
24namespace llvm {
25class MCStreamer;
26class MCSymbol;
27
28class LLVM_LIBRARY_VISIBILITY X86AsmPrinter : public AsmPrinter {
29  const X86Subtarget *Subtarget;
30  StackMaps SM;
31  FaultMaps FM;
32
33  // This utility class tracks the length of a stackmap instruction's 'shadow'.
34  // It is used by the X86AsmPrinter to ensure that the stackmap shadow
35  // invariants (i.e. no other stackmaps, patchpoints, or control flow within
36  // the shadow) are met, while outputting a minimal number of NOPs for padding.
37  //
38  // To minimise the number of NOPs used, the shadow tracker counts the number
39  // of instruction bytes output since the last stackmap. Only if there are too
40  // few instruction bytes to cover the shadow are NOPs used for padding.
41  class StackMapShadowTracker {
42  public:
43    StackMapShadowTracker(TargetMachine &TM);
44    ~StackMapShadowTracker();
45    void startFunction(MachineFunction &MF);
46    void count(MCInst &Inst, const MCSubtargetInfo &STI);
47
48    // Called to signal the start of a shadow of RequiredSize bytes.
49    void reset(unsigned RequiredSize) {
50      RequiredShadowSize = RequiredSize;
51      CurrentShadowSize = 0;
52      InShadow = true;
53    }
54
55    // Called before every stackmap/patchpoint, and at the end of basic blocks,
56    // to emit any necessary padding-NOPs.
57    void emitShadowPadding(MCStreamer &OutStreamer, const MCSubtargetInfo &STI);
58  private:
59    TargetMachine &TM;
60    const MachineFunction *MF;
61    std::unique_ptr<MCCodeEmitter> CodeEmitter;
62    bool InShadow;
63
64    // RequiredShadowSize holds the length of the shadow specified in the most
65    // recently encountered STACKMAP instruction.
66    // CurrentShadowSize counts the number of bytes encoded since the most
67    // recently encountered STACKMAP, stopping when that number is greater than
68    // or equal to RequiredShadowSize.
69    unsigned RequiredShadowSize, CurrentShadowSize;
70  };
71
72  StackMapShadowTracker SMShadowTracker;
73
74  // All instructions emitted by the X86AsmPrinter should use this helper
75  // method.
76  //
77  // This helper function invokes the SMShadowTracker on each instruction before
78  // outputting it to the OutStream. This allows the shadow tracker to minimise
79  // the number of NOPs used for stackmap padding.
80  void EmitAndCountInstruction(MCInst &Inst);
81  void LowerSTACKMAP(const MachineInstr &MI);
82  void LowerPATCHPOINT(const MachineInstr &MI, X86MCInstLower &MCIL);
83  void LowerSTATEPOINT(const MachineInstr &MI, X86MCInstLower &MCIL);
84  void LowerFAULTING_LOAD_OP(const MachineInstr &MI, X86MCInstLower &MCIL);
85
86  void LowerTlsAddr(X86MCInstLower &MCInstLowering, const MachineInstr &MI);
87
88 public:
89   explicit X86AsmPrinter(TargetMachine &TM,
90                          std::unique_ptr<MCStreamer> Streamer)
91       : AsmPrinter(TM, std::move(Streamer)), SM(*this), FM(*this),
92         SMShadowTracker(TM) {}
93
94  const char *getPassName() const override {
95    return "X86 Assembly / Object Emitter";
96  }
97
98  const X86Subtarget &getSubtarget() const { return *Subtarget; }
99
100  void EmitStartOfAsmFile(Module &M) override;
101
102  void EmitEndOfAsmFile(Module &M) override;
103
104  void EmitInstruction(const MachineInstr *MI) override;
105
106  void EmitBasicBlockEnd(const MachineBasicBlock &MBB) override {
107    SMShadowTracker.emitShadowPadding(*OutStreamer, getSubtargetInfo());
108  }
109
110  bool PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
111                       unsigned AsmVariant, const char *ExtraCode,
112                       raw_ostream &OS) override;
113  bool PrintAsmMemoryOperand(const MachineInstr *MI, unsigned OpNo,
114                             unsigned AsmVariant, const char *ExtraCode,
115                             raw_ostream &OS) override;
116
117  /// \brief Return the symbol for the specified constant pool entry.
118  MCSymbol *GetCPISymbol(unsigned CPID) const override;
119
120  bool doInitialization(Module &M) override {
121    SMShadowTracker.reset(0);
122    SM.reset();
123    return AsmPrinter::doInitialization(M);
124  }
125
126  bool runOnMachineFunction(MachineFunction &F) override;
127};
128
129} // end namespace llvm
130
131#endif
132