lib/Target/X86/X86AsmPrinter.h

   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
  20 namespace {
  21   class X86MCInstLower;
  22 }
  23
  24 namespace llvm {
  25 class MCStreamer;
  26 class MCSymbol;
  27
  28 class LLVM_LIBRARY_VISIBILITY X86AsmPrinter : public AsmPrinter {
  29   const X86Subtarget *Subtarget;
  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;
  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);
 116
 117 public:
 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