llvm/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 "llvm/CodeGen/AsmPrinter.h"
  13 #include "llvm/CodeGen/FaultMaps.h"
  14 #include "llvm/CodeGen/StackMaps.h"
  15
  16 // Implemented in X86MCInstLower.cpp
  17 namespace {
  18   class X86MCInstLower;
  19 }
  20
  21 namespace llvm {
  22 class MCCodeEmitter;
  23 class MCStreamer;
  24 class X86Subtarget;
  25 class TargetMachine;
  26
  27 class LLVM_LIBRARY_VISIBILITY X86AsmPrinter : public AsmPrinter {
  28   const X86Subtarget *Subtarget = nullptr;
  29   StackMaps SM;
  30   FaultMaps FM;
  31   std::unique_ptr<MCCodeEmitter> CodeEmitter;
  32   bool EmitFPOData = false;
  33   bool NeedsRetpoline = false;
  34
  35   // This utility class tracks the length of a stackmap instruction's 'shadow'.
  36   // It is used by the X86AsmPrinter to ensure that the stackmap shadow
  37   // invariants (i.e. no other stackmaps, patchpoints, or control flow within
  38   // the shadow) are met, while outputting a minimal number of NOPs for padding.
  39   //
  40   // To minimise the number of NOPs used, the shadow tracker counts the number
  41   // of instruction bytes output since the last stackmap. Only if there are too
  42   // few instruction bytes to cover the shadow are NOPs used for padding.
  43   class StackMapShadowTracker {
  44   public:
  45     void startFunction(MachineFunction &MF) {
  46       this->MF = &MF;
  47     }
  48     void count(MCInst &Inst, const MCSubtargetInfo &STI,
  49                MCCodeEmitter *CodeEmitter);
  50
  51     // Called to signal the start of a shadow of RequiredSize bytes.
  52     void reset(unsigned RequiredSize) {
  53       RequiredShadowSize = RequiredSize;
  54       CurrentShadowSize = 0;
  55       InShadow = true;
  56     }
  57
  58     // Called before every stackmap/patchpoint, and at the end of basic blocks,
  59     // to emit any necessary padding-NOPs.
  60     void emitShadowPadding(MCStreamer &OutStreamer, const MCSubtargetInfo &STI);
  61   private:
  62     const MachineFunction *MF = nullptr;
  63     bool InShadow = false;
  64
  65     // RequiredShadowSize holds the length of the shadow specified in the most
  66     // recently encountered STACKMAP instruction.
  67     // CurrentShadowSize counts the number of bytes encoded since the most
  68     // recently encountered STACKMAP, stopping when that number is greater than
  69     // or equal to RequiredShadowSize.
  70     unsigned RequiredShadowSize = 0, CurrentShadowSize = 0;
  71   };
  72
  73   StackMapShadowTracker SMShadowTracker;
  74
  75   // All instructions emitted by the X86AsmPrinter should use this helper
  76   // method.
  77   //
  78   // This helper function invokes the SMShadowTracker on each instruction before
  79   // outputting it to the OutStream. This allows the shadow tracker to minimise
  80   // the number of NOPs used for stackmap padding.
  81   void EmitAndCountInstruction(MCInst &Inst);
  82   void LowerSTACKMAP(const MachineInstr &MI);
  83   void LowerPATCHPOINT(const MachineInstr &MI, X86MCInstLower &MCIL);
  84   void LowerSTATEPOINT(const MachineInstr &MI, X86MCInstLower &MCIL);
  85   void LowerFAULTING_OP(const MachineInstr &MI, X86MCInstLower &MCIL);
  86   void LowerPATCHABLE_OP(const MachineInstr &MI, X86MCInstLower &MCIL);
  87
  88   void LowerTlsAddr(X86MCInstLower &MCInstLowering, const MachineInstr &MI);
  89
  90   // XRay-specific lowering for X86.
  91   void LowerPATCHABLE_FUNCTION_ENTER(const MachineInstr &MI,
  92                                      X86MCInstLower &MCIL);
  93   void LowerPATCHABLE_RET(const MachineInstr &MI, X86MCInstLower &MCIL);
  94   void LowerPATCHABLE_TAIL_CALL(const MachineInstr &MI, X86MCInstLower &MCIL);
  95   void LowerPATCHABLE_EVENT_CALL(const MachineInstr &MI, X86MCInstLower &MCIL);
  96   void LowerPATCHABLE_TYPED_EVENT_CALL(const MachineInstr &MI,
  97                                        X86MCInstLower &MCIL);
  98
  99   void LowerFENTRY_CALL(const MachineInstr &MI, X86MCInstLower &MCIL);
 100
 101   // Choose between emitting .seh_ directives and .cv_fpo_ directives.
 102   void EmitSEHInstruction(const MachineInstr *MI);
 103
 104   void PrintSymbolOperand(const MachineOperand &MO, raw_ostream &O) override;
 105   void PrintOperand(const MachineInstr *MI, unsigned OpNo, raw_ostream &O);
 106   void PrintModifiedOperand(const MachineInstr *MI, unsigned OpNo,
 107                             raw_ostream &O, const char *Modifier);
 108   void PrintPCRelImm(const MachineInstr *MI, unsigned OpNo, raw_ostream &O);
 109   void PrintLeaMemReference(const MachineInstr *MI, unsigned OpNo,
 110                             raw_ostream &O, const char *Modifier);
 111   void PrintMemReference(const MachineInstr *MI, unsigned OpNo, raw_ostream &O,
 112                          const char *Modifier);
 113   void PrintIntelMemReference(const MachineInstr *MI, unsigned OpNo,
 114                               raw_ostream &O, const char *Modifier);
 115
 116 public:
 117   X86AsmPrinter(TargetMachine &TM, std::unique_ptr<MCStreamer> Streamer);
 118
 119   StringRef getPassName() const override {
 120     return "X86 Assembly Printer";
 121   }
 122
 123   const X86Subtarget &getSubtarget() const { return *Subtarget; }
 124
 125   void emitStartOfAsmFile(Module &M) override;
 126
 127   void emitEndOfAsmFile(Module &M) override;
 128
 129   void emitInstruction(const MachineInstr *MI) override;
 130
 131   void emitBasicBlockEnd(const MachineBasicBlock &MBB) override {
 132     AsmPrinter::emitBasicBlockEnd(MBB);
 133     SMShadowTracker.emitShadowPadding(*OutStreamer, getSubtargetInfo());
 134   }
 135
 136   bool PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
 137                        const char *ExtraCode, raw_ostream &O) override;
 138   bool PrintAsmMemoryOperand(const MachineInstr *MI, unsigned OpNo,
 139                              const char *ExtraCode, raw_ostream &O) override;
 140
 141   bool doInitialization(Module &M) override {
 142     SMShadowTracker.reset(0);
 143     SM.reset();
 144     FM.reset();
 145     return AsmPrinter::doInitialization(M);
 146   }
 147
 148   bool runOnMachineFunction(MachineFunction &MF) override;
 149   void emitFunctionBodyStart() override;
 150   void emitFunctionBodyEnd() override;
 151 };
 152
 153 } // end namespace llvm
 154
 155 #endif