132 lines
4.6 KiB
C++
132 lines
4.6 KiB
C++
//===-- X86AsmPrinter.h - X86 implementation of AsmPrinter ------*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_LIB_TARGET_X86_X86ASMPRINTER_H
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#define LLVM_LIB_TARGET_X86_X86ASMPRINTER_H
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#include "X86Subtarget.h"
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#include "llvm/CodeGen/AsmPrinter.h"
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#include "llvm/CodeGen/FaultMaps.h"
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#include "llvm/CodeGen/StackMaps.h"
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#include "llvm/Target/TargetMachine.h"
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// Implemented in X86MCInstLower.cpp
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namespace {
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class X86MCInstLower;
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}
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namespace llvm {
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class MCStreamer;
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class MCSymbol;
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class LLVM_LIBRARY_VISIBILITY X86AsmPrinter : public AsmPrinter {
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const X86Subtarget *Subtarget;
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StackMaps SM;
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FaultMaps FM;
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// This utility class tracks the length of a stackmap instruction's 'shadow'.
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// It is used by the X86AsmPrinter to ensure that the stackmap shadow
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// invariants (i.e. no other stackmaps, patchpoints, or control flow within
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// the shadow) are met, while outputting a minimal number of NOPs for padding.
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//
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// To minimise the number of NOPs used, the shadow tracker counts the number
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// of instruction bytes output since the last stackmap. Only if there are too
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// few instruction bytes to cover the shadow are NOPs used for padding.
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class StackMapShadowTracker {
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public:
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StackMapShadowTracker(TargetMachine &TM);
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~StackMapShadowTracker();
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void startFunction(MachineFunction &MF);
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void count(MCInst &Inst, const MCSubtargetInfo &STI);
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// Called to signal the start of a shadow of RequiredSize bytes.
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void reset(unsigned RequiredSize) {
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RequiredShadowSize = RequiredSize;
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CurrentShadowSize = 0;
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InShadow = true;
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}
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// Called before every stackmap/patchpoint, and at the end of basic blocks,
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// to emit any necessary padding-NOPs.
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void emitShadowPadding(MCStreamer &OutStreamer, const MCSubtargetInfo &STI);
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private:
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TargetMachine &TM;
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const MachineFunction *MF;
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std::unique_ptr<MCCodeEmitter> CodeEmitter;
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bool InShadow;
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// RequiredShadowSize holds the length of the shadow specified in the most
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// recently encountered STACKMAP instruction.
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// CurrentShadowSize counts the number of bytes encoded since the most
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// recently encountered STACKMAP, stopping when that number is greater than
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// or equal to RequiredShadowSize.
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unsigned RequiredShadowSize, CurrentShadowSize;
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};
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StackMapShadowTracker SMShadowTracker;
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// All instructions emitted by the X86AsmPrinter should use this helper
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// method.
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//
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// This helper function invokes the SMShadowTracker on each instruction before
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// outputting it to the OutStream. This allows the shadow tracker to minimise
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// the number of NOPs used for stackmap padding.
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void EmitAndCountInstruction(MCInst &Inst);
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void LowerSTACKMAP(const MachineInstr &MI);
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void LowerPATCHPOINT(const MachineInstr &MI, X86MCInstLower &MCIL);
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void LowerSTATEPOINT(const MachineInstr &MI, X86MCInstLower &MCIL);
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void LowerFAULTING_LOAD_OP(const MachineInstr &MI, X86MCInstLower &MCIL);
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void LowerTlsAddr(X86MCInstLower &MCInstLowering, const MachineInstr &MI);
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public:
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explicit X86AsmPrinter(TargetMachine &TM,
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std::unique_ptr<MCStreamer> Streamer)
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: AsmPrinter(TM, std::move(Streamer)), SM(*this), FM(*this),
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SMShadowTracker(TM) {}
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const char *getPassName() const override {
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return "X86 Assembly / Object Emitter";
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}
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const X86Subtarget &getSubtarget() const { return *Subtarget; }
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void EmitStartOfAsmFile(Module &M) override;
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void EmitEndOfAsmFile(Module &M) override;
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void EmitInstruction(const MachineInstr *MI) override;
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void EmitBasicBlockEnd(const MachineBasicBlock &MBB) override {
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SMShadowTracker.emitShadowPadding(*OutStreamer, getSubtargetInfo());
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}
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bool PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
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unsigned AsmVariant, const char *ExtraCode,
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raw_ostream &OS) override;
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bool PrintAsmMemoryOperand(const MachineInstr *MI, unsigned OpNo,
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unsigned AsmVariant, const char *ExtraCode,
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raw_ostream &OS) override;
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/// \brief Return the symbol for the specified constant pool entry.
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MCSymbol *GetCPISymbol(unsigned CPID) const override;
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bool doInitialization(Module &M) override {
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SMShadowTracker.reset(0);
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SM.reset();
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return AsmPrinter::doInitialization(M);
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}
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bool runOnMachineFunction(MachineFunction &F) override;
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};
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} // end namespace llvm
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#endif
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