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//===-- X86AsmPrinter.h - X86 implementation of AsmPrinter ------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#ifndef X86ASMPRINTER_H
#define X86ASMPRINTER_H
#include "X86Subtarget.h"
#include "llvm/CodeGen/AsmPrinter.h"
#include "llvm/CodeGen/StackMaps.h"
#include "llvm/Target/TargetMachine.h"
// Implemented in X86MCInstLower.cpp
namespace {
class X86MCInstLower;
}
namespace llvm {
class MCStreamer;
class MCSymbol;
class LLVM_LIBRARY_VISIBILITY X86AsmPrinter : public AsmPrinter {
const X86Subtarget *Subtarget;
StackMaps SM;
void GenerateExportDirective(const MCSymbol *Sym, bool IsData);
// This utility class tracks the length of a stackmap instruction's 'shadow'.
// It is used by the X86AsmPrinter to ensure that the stackmap shadow
// invariants (i.e. no other stackmaps, patchpoints, or control flow within
// the shadow) are met, while outputting a minimal number of NOPs for padding.
//
// To minimise the number of NOPs used, the shadow tracker counts the number
// of instruction bytes output since the last stackmap. Only if there are too
// few instruction bytes to cover the shadow are NOPs used for padding.
class StackMapShadowTracker {
public:
StackMapShadowTracker(TargetMachine &TM);
~StackMapShadowTracker();
void startFunction(MachineFunction &MF);
void count(MCInst &Inst, const MCSubtargetInfo &STI);
// Called to signal the start of a shadow of RequiredSize bytes.
void reset(unsigned RequiredSize) {
RequiredShadowSize = RequiredSize;
CurrentShadowSize = 0;
InShadow = true;
}
// Called before every stackmap/patchpoint, and at the end of basic blocks,
// to emit any necessary padding-NOPs.
void emitShadowPadding(MCStreamer &OutStreamer, const MCSubtargetInfo &STI);
private:
TargetMachine &TM;
std::unique_ptr<MCCodeEmitter> CodeEmitter;
bool InShadow;
// RequiredShadowSize holds the length of the shadow specified in the most
// recently encountered STACKMAP instruction.
// CurrentShadowSize counts the number of bytes encoded since the most
// recently encountered STACKMAP, stopping when that number is greater than
// or equal to RequiredShadowSize.
unsigned RequiredShadowSize, CurrentShadowSize;
};
StackMapShadowTracker SMShadowTracker;
// All instructions emitted by the X86AsmPrinter should use this helper
// method.
//
// This helper function invokes the SMShadowTracker on each instruction before
// outputting it to the OutStream. This allows the shadow tracker to minimise
// the number of NOPs used for stackmap padding.
void EmitAndCountInstruction(MCInst &Inst);
void InsertStackMapShadows(MachineFunction &MF);
void LowerSTACKMAP(const MachineInstr &MI);
void LowerPATCHPOINT(const MachineInstr &MI);
void LowerTlsAddr(X86MCInstLower &MCInstLowering, const MachineInstr &MI);
public:
explicit X86AsmPrinter(TargetMachine &TM, MCStreamer &Streamer)
: AsmPrinter(TM, Streamer), SM(*this), SMShadowTracker(TM) {
Subtarget = &TM.getSubtarget<X86Subtarget>();
}
const char *getPassName() const override {
return "X86 Assembly / Object Emitter";
}
const X86Subtarget &getSubtarget() const { return *Subtarget; }
void EmitStartOfAsmFile(Module &M) override;
void EmitEndOfAsmFile(Module &M) override;
void EmitInstruction(const MachineInstr *MI) override;
void EmitBasicBlockEnd(const MachineBasicBlock &MBB) override {
SMShadowTracker.emitShadowPadding(OutStreamer, getSubtargetInfo());
}
bool PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
unsigned AsmVariant, const char *ExtraCode,
raw_ostream &OS) override;
bool PrintAsmMemoryOperand(const MachineInstr *MI, unsigned OpNo,
unsigned AsmVariant, const char *ExtraCode,
raw_ostream &OS) override;
/// \brief Return the symbol for the specified constant pool entry.
MCSymbol *GetCPISymbol(unsigned CPID) const override;
bool runOnMachineFunction(MachineFunction &F) override;
};
} // end namespace llvm
#endif
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