1//===-- X86AsmPrinter.h - X86 implementation of AsmPrinter ------*- C++ -*-===//
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#ifndef LLVM_LIB_TARGET_X86_X86ASMPRINTER_H
10#define LLVM_LIB_TARGET_X86_X86ASMPRINTER_H
11
12#include "X86Subtarget.h"
13#include "llvm/CodeGen/AsmPrinter.h"
14#include "llvm/CodeGen/FaultMaps.h"
15#include "llvm/CodeGen/StackMaps.h"
16#include "llvm/MC/MCCodeEmitter.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 = nullptr;
30  StackMaps SM;
31  FaultMaps FM;
32  std::unique_ptr<MCCodeEmitter> CodeEmitter;
33  bool EmitFPOData = false;
34  bool NeedsRetpoline = false;
35
36  // This utility class tracks the length of a stackmap instruction's 'shadow'.
37  // It is used by the X86AsmPrinter to ensure that the stackmap shadow
38  // invariants (i.e. no other stackmaps, patchpoints, or control flow within
39  // the shadow) are met, while outputting a minimal number of NOPs for padding.
40  //
41  // To minimise the number of NOPs used, the shadow tracker counts the number
42  // of instruction bytes output since the last stackmap. Only if there are too
43  // few instruction bytes to cover the shadow are NOPs used for padding.
44  class StackMapShadowTracker {
45  public:
46    void startFunction(MachineFunction &MF) {
47      this->MF = &MF;
48    }
49    void count(MCInst &Inst, const MCSubtargetInfo &STI,
50               MCCodeEmitter *CodeEmitter);
51
52    // Called to signal the start of a shadow of RequiredSize bytes.
53    void reset(unsigned RequiredSize) {
54      RequiredShadowSize = RequiredSize;
55      CurrentShadowSize = 0;
56      InShadow = true;
57    }
58
59    // Called before every stackmap/patchpoint, and at the end of basic blocks,
60    // to emit any necessary padding-NOPs.
61    void emitShadowPadding(MCStreamer &OutStreamer, const MCSubtargetInfo &STI);
62  private:
63    const MachineFunction *MF = nullptr;
64    bool InShadow = false;
65
66    // RequiredShadowSize holds the length of the shadow specified in the most
67    // recently encountered STACKMAP instruction.
68    // CurrentShadowSize counts the number of bytes encoded since the most
69    // recently encountered STACKMAP, stopping when that number is greater than
70    // or equal to RequiredShadowSize.
71    unsigned RequiredShadowSize = 0, CurrentShadowSize = 0;
72  };
73
74  StackMapShadowTracker SMShadowTracker;
75
76  // All instructions emitted by the X86AsmPrinter should use this helper
77  // method.
78  //
79  // This helper function invokes the SMShadowTracker on each instruction before
80  // outputting it to the OutStream. This allows the shadow tracker to minimise
81  // the number of NOPs used for stackmap padding.
82  void EmitAndCountInstruction(MCInst &Inst);
83  void LowerSTACKMAP(const MachineInstr &MI);
84  void LowerPATCHPOINT(const MachineInstr &MI, X86MCInstLower &MCIL);
85  void LowerSTATEPOINT(const MachineInstr &MI, X86MCInstLower &MCIL);
86  void LowerFAULTING_OP(const MachineInstr &MI, X86MCInstLower &MCIL);
87  void LowerPATCHABLE_OP(const MachineInstr &MI, X86MCInstLower &MCIL);
88
89  void LowerTlsAddr(X86MCInstLower &MCInstLowering, const MachineInstr &MI);
90
91  // XRay-specific lowering for X86.
92  void LowerPATCHABLE_FUNCTION_ENTER(const MachineInstr &MI,
93                                     X86MCInstLower &MCIL);
94  void LowerPATCHABLE_RET(const MachineInstr &MI, X86MCInstLower &MCIL);
95  void LowerPATCHABLE_TAIL_CALL(const MachineInstr &MI, X86MCInstLower &MCIL);
96  void LowerPATCHABLE_EVENT_CALL(const MachineInstr &MI, X86MCInstLower &MCIL);
97  void LowerPATCHABLE_TYPED_EVENT_CALL(const MachineInstr &MI,
98                                       X86MCInstLower &MCIL);
99
100  void LowerFENTRY_CALL(const MachineInstr &MI, X86MCInstLower &MCIL);
101
102  // Choose between emitting .seh_ directives and .cv_fpo_ directives.
103  void EmitSEHInstruction(const MachineInstr *MI);
104
105  void PrintSymbolOperand(const MachineOperand &MO, raw_ostream &O) override;
106  void PrintOperand(const MachineInstr *MI, unsigned OpNo, raw_ostream &O);
107  void PrintModifiedOperand(const MachineInstr *MI, unsigned OpNo,
108                            raw_ostream &O, const char *Modifier);
109  void PrintPCRelImm(const MachineInstr *MI, unsigned OpNo, raw_ostream &O);
110  void PrintLeaMemReference(const MachineInstr *MI, unsigned OpNo,
111                            raw_ostream &O, const char *Modifier);
112  void PrintMemReference(const MachineInstr *MI, unsigned OpNo, raw_ostream &O,
113                         const char *Modifier);
114  void PrintIntelMemReference(const MachineInstr *MI, unsigned OpNo,
115                              raw_ostream &O, const char *Modifier);
116
117public:
118  X86AsmPrinter(TargetMachine &TM, std::unique_ptr<MCStreamer> Streamer);
119
120  StringRef getPassName() const override {
121    return "X86 Assembly Printer";
122  }
123
124  const X86Subtarget &getSubtarget() const { return *Subtarget; }
125
126  void EmitStartOfAsmFile(Module &M) override;
127
128  void EmitEndOfAsmFile(Module &M) override;
129
130  void EmitInstruction(const MachineInstr *MI) override;
131
132  void EmitBasicBlockEnd(const MachineBasicBlock &MBB) override {
133    AsmPrinter::EmitBasicBlockEnd(MBB);
134    SMShadowTracker.emitShadowPadding(*OutStreamer, getSubtargetInfo());
135  }
136
137  bool PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
138                       const char *ExtraCode, raw_ostream &OS) override;
139  bool PrintAsmMemoryOperand(const MachineInstr *MI, unsigned OpNo,
140                             const char *ExtraCode, raw_ostream &OS) override;
141
142  bool doInitialization(Module &M) override {
143    SMShadowTracker.reset(0);
144    SM.reset();
145    FM.reset();
146    return AsmPrinter::doInitialization(M);
147  }
148
149  bool runOnMachineFunction(MachineFunction &F) override;
150  void EmitFunctionBodyStart() override;
151  void EmitFunctionBodyEnd() override;
152};
153
154} // end namespace llvm
155
156#endif
157