lib/Target/X86/X86AsmPrinter.h

   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/MC/MCCodeEmitter.h"
  18 #include "llvm/Target/TargetMachine.h"
  19
  20 // Implemented in X86MCInstLower.cpp
  21 namespace {
  22   class X86MCInstLower;
  23 }
  24
  25 namespace llvm {
  26 class MCStreamer;
  27 class MCSymbol;
  28
  29 class LLVM_LIBRARY_VISIBILITY X86AsmPrinter : public AsmPrinter {
  30   const X86Subtarget *Subtarget;
  31   StackMaps SM;
  32   FaultMaps FM;
  33   std::unique_ptr<MCCodeEmitter> CodeEmitter;
  34   bool EmitFPOData = false;
  35   bool NeedsRetpoline = false;
  36
  37   // This utility class tracks the length of a stackmap instruction's 'shadow'.
  38   // It is used by the X86AsmPrinter to ensure that the stackmap shadow
  39   // invariants (i.e. no other stackmaps, patchpoints, or control flow within
  40   // the shadow) are met, while outputting a minimal number of NOPs for padding.
  41   //
  42   // To minimise the number of NOPs used, the shadow tracker counts the number
  43   // of instruction bytes output since the last stackmap. Only if there are too
  44   // few instruction bytes to cover the shadow are NOPs used for padding.
  45   class StackMapShadowTracker {
  46   public:
  47     void startFunction(MachineFunction &MF) {
  48       this->MF = &MF;
  49     }
  50     void count(MCInst &Inst, const MCSubtargetInfo &STI,
  51                MCCodeEmitter *CodeEmitter);
  52
  53     // Called to signal the start of a shadow of RequiredSize bytes.
  54     void reset(unsigned RequiredSize) {
  55       RequiredShadowSize = RequiredSize;
  56       CurrentShadowSize = 0;
  57       InShadow = true;
  58     }
  59
  60     // Called before every stackmap/patchpoint, and at the end of basic blocks,
  61     // to emit any necessary padding-NOPs.
  62     void emitShadowPadding(MCStreamer &OutStreamer, const MCSubtargetInfo &STI);
  63   private:
  64     const MachineFunction *MF;
  65     bool InShadow = false;
  66
  67     // RequiredShadowSize holds the length of the shadow specified in the most
  68     // recently encountered STACKMAP instruction.
  69     // CurrentShadowSize counts the number of bytes encoded since the most
  70     // recently encountered STACKMAP, stopping when that number is greater than
  71     // or equal to RequiredShadowSize.
  72     unsigned RequiredShadowSize = 0, CurrentShadowSize = 0;
  73   };
  74
  75   StackMapShadowTracker SMShadowTracker;
  76
  77   // All instructions emitted by the X86AsmPrinter should use this helper
  78   // method.
  79   //
  80   // This helper function invokes the SMShadowTracker on each instruction before
  81   // outputting it to the OutStream. This allows the shadow tracker to minimise
  82   // the number of NOPs used for stackmap padding.
  83   void EmitAndCountInstruction(MCInst &Inst);
  84   void LowerSTACKMAP(const MachineInstr &MI);
  85   void LowerPATCHPOINT(const MachineInstr &MI, X86MCInstLower &MCIL);
  86   void LowerSTATEPOINT(const MachineInstr &MI, X86MCInstLower &MCIL);
  87   void LowerFAULTING_OP(const MachineInstr &MI, X86MCInstLower &MCIL);
  88   void LowerPATCHABLE_OP(const MachineInstr &MI, X86MCInstLower &MCIL);
  89
  90   void LowerTlsAddr(X86MCInstLower &MCInstLowering, const MachineInstr &MI);
  91
  92   // XRay-specific lowering for X86.
  93   void LowerPATCHABLE_FUNCTION_ENTER(const MachineInstr &MI,
  94                                      X86MCInstLower &MCIL);
  95   void LowerPATCHABLE_RET(const MachineInstr &MI, X86MCInstLower &MCIL);
  96   void LowerPATCHABLE_TAIL_CALL(const MachineInstr &MI, X86MCInstLower &MCIL);
  97   void LowerPATCHABLE_EVENT_CALL(const MachineInstr &MI, X86MCInstLower &MCIL);
  98   void LowerPATCHABLE_TYPED_EVENT_CALL(const MachineInstr &MI,
  99                                        X86MCInstLower &MCIL);
 100
 101   void LowerFENTRY_CALL(const MachineInstr &MI, X86MCInstLower &MCIL);
 102
 103   // Choose between emitting .seh_ directives and .cv_fpo_ directives.
 104   void EmitSEHInstruction(const MachineInstr *MI);
 105
 106 public:
 107   X86AsmPrinter(TargetMachine &TM, std::unique_ptr<MCStreamer> Streamer);
 108
 109   StringRef getPassName() const override {
 110     return "X86 Assembly Printer";
 111   }
 112
 113   const X86Subtarget &getSubtarget() const { return *Subtarget; }
 114
 115   void EmitStartOfAsmFile(Module &M) override;
 116
 117   void EmitEndOfAsmFile(Module &M) override;
 118
 119   void EmitInstruction(const MachineInstr *MI) override;
 120
 121   void EmitBasicBlockEnd(const MachineBasicBlock &MBB) override {
 122     AsmPrinter::EmitBasicBlockEnd(MBB);
 123     SMShadowTracker.emitShadowPadding(*OutStreamer, getSubtargetInfo());
 124   }
 125
 126   bool PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
 127                        unsigned AsmVariant, const char *ExtraCode,
 128                        raw_ostream &OS) override;
 129   bool PrintAsmMemoryOperand(const MachineInstr *MI, unsigned OpNo,
 130                              unsigned AsmVariant, const char *ExtraCode,
 131                              raw_ostream &OS) override;
 132
 133   bool doInitialization(Module &M) override {
 134     SMShadowTracker.reset(0);
 135     SM.reset();
 136     FM.reset();
 137     return AsmPrinter::doInitialization(M);
 138   }
 139
 140   bool runOnMachineFunction(MachineFunction &F) override;
 141   void EmitFunctionBodyStart() override;
 142   void EmitFunctionBodyEnd() override;
 143 };
 144
 145 } // end namespace llvm
 146
 147 #endif