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//===-- llvm/CodeGen/AsmPrinter.h - AsmPrinter Framework --------*- C++ -*-===//
// The LLVM Compiler Infrastructure
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
// This file contains a class to be used as the base class for target specific
// asm writers. This class primarily handles common functionality used by
// all asm writers.
#include "llvm/ADT/MapVector.h"
#include "llvm/ADT/Twine.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/DwarfStringPoolEntry.h"
#include "llvm/IR/InlineAsm.h"
#include "llvm/Support/DataTypes.h"
#include "llvm/Support/ErrorHandling.h"
namespace llvm {
class AsmPrinterHandler;
class BlockAddress;
class ByteStreamer;
class GCStrategy;
class Constant;
class ConstantArray;
class DIE;
class DIEAbbrev;
class GCMetadataPrinter;
class GlobalValue;
class GlobalVariable;
class MachineBasicBlock;
class MachineFunction;
class MachineInstr;
class MachineLocation;
class MachineLoopInfo;
class MachineLoop;
class MachineConstantPoolValue;
class MachineJumpTableInfo;
class MachineModuleInfo;
class MCAsmInfo;
class MCCFIInstruction;
class MCContext;
class MCExpr;
class MCInst;
class MCSection;
class MCStreamer;
class MCSubtargetInfo;
class MCSymbol;
class MCTargetOptions;
class MDNode;
class DwarfDebug;
class Mangler;
class TargetLoweringObjectFile;
class DataLayout;
class TargetMachine;
/// This class is intended to be used as a driving class for all asm writers.
class AsmPrinter : public MachineFunctionPass {
/// Target machine description.
TargetMachine &TM;
/// Target Asm Printer information.
const MCAsmInfo *MAI;
/// This is the context for the output file that we are streaming. This owns
/// all of the global MC-related objects for the generated translation unit.
MCContext &OutContext;
/// This is the MCStreamer object for the file we are generating. This
/// contains the transient state for the current translation unit that we are
/// generating (such as the current section etc).
std::unique_ptr<MCStreamer> OutStreamer;
/// The current machine function.
const MachineFunction *MF;
/// This is a pointer to the current MachineModuleInfo.
MachineModuleInfo *MMI;
/// Name-mangler for global names.
Mangler *Mang;
/// The symbol for the current function. This is recalculated at the beginning
/// of each call to runOnMachineFunction().
MCSymbol *CurrentFnSym;
/// The symbol used to represent the start of the current function for the
/// purpose of calculating its size (e.g. using the .size directive). By
/// default, this is equal to CurrentFnSym.
MCSymbol *CurrentFnSymForSize;
/// Map global GOT equivalent MCSymbols to GlobalVariables and keep track of
/// its number of uses by other globals.
typedef std::pair<const GlobalVariable *, unsigned> GOTEquivUsePair;
MapVector<const MCSymbol *, GOTEquivUsePair> GlobalGOTEquivs;
MCSymbol *CurrentFnBegin;
MCSymbol *CurrentFnEnd;
MCSymbol *CurExceptionSym;
// The garbage collection metadata printer table.
void *GCMetadataPrinters; // Really a DenseMap.
/// Emit comments in assembly output if this is true.
bool VerboseAsm;
static char ID;
/// If VerboseAsm is set, a pointer to the loop info for this function.
MachineLoopInfo *LI;
struct HandlerInfo {
AsmPrinterHandler *Handler;
const char *TimerName, *TimerGroupName;
HandlerInfo(AsmPrinterHandler *Handler, const char *TimerName,
const char *TimerGroupName)
: Handler(Handler), TimerName(TimerName),
TimerGroupName(TimerGroupName) {}
/// A vector of all debug/EH info emitters we should use. This vector
/// maintains ownership of the emitters.
SmallVector<HandlerInfo, 1> Handlers;
/// If the target supports dwarf debug info, this pointer is non-null.
DwarfDebug *DD;
explicit AsmPrinter(TargetMachine &TM, std::unique_ptr<MCStreamer> Streamer);
~AsmPrinter() override;
DwarfDebug *getDwarfDebug() { return DD; }
DwarfDebug *getDwarfDebug() const { return DD; }
/// Return true if assembly output should contain comments.
bool isVerbose() const { return VerboseAsm; }
/// Return a unique ID for the current function.
unsigned getFunctionNumber() const;
MCSymbol *getFunctionBegin() const { return CurrentFnBegin; }
MCSymbol *getFunctionEnd() const { return CurrentFnEnd; }
MCSymbol *getCurExceptionSym();
/// Return information about object file lowering.
const TargetLoweringObjectFile &getObjFileLowering() const;
/// Return information about data layout.
const DataLayout &getDataLayout() const;
/// Return information about subtarget.
const MCSubtargetInfo &getSubtargetInfo() const;
void EmitToStreamer(MCStreamer &S, const MCInst &Inst);
/// Return the target triple string.
StringRef getTargetTriple() const;
/// Return the current section we are emitting to.
const MCSection *getCurrentSection() const;
void getNameWithPrefix(SmallVectorImpl<char> &Name,
const GlobalValue *GV) const;
MCSymbol *getSymbol(const GlobalValue *GV) const;
// MachineFunctionPass Implementation.
/// Record analysis usage.
void getAnalysisUsage(AnalysisUsage &AU) const override;
/// Set up the AsmPrinter when we are working on a new module. If your pass
/// overrides this, it must make sure to explicitly call this implementation.
bool doInitialization(Module &M) override;
/// Shut down the asmprinter. If you override this in your pass, you must make
/// sure to call it explicitly.
bool doFinalization(Module &M) override;
/// Emit the specified function out to the OutStreamer.
bool runOnMachineFunction(MachineFunction &MF) override {
return false;
// Coarse grained IR lowering routines.
/// This should be called when a new MachineFunction is being processed from
/// runOnMachineFunction.
void SetupMachineFunction(MachineFunction &MF);
/// This method emits the body and trailer for a function.
void EmitFunctionBody();
void emitCFIInstruction(const MachineInstr &MI);
void emitFrameAlloc(const MachineInstr &MI);
enum CFIMoveType { CFI_M_None, CFI_M_EH, CFI_M_Debug };
CFIMoveType needsCFIMoves();
bool needsSEHMoves();
/// Print to the current output stream assembly representations of the
/// constants in the constant pool MCP. This is used to print out constants
/// which have been "spilled to memory" by the code generator.
virtual void EmitConstantPool();
/// Print assembly representations of the jump tables used by the current
/// function to the current output stream.
void EmitJumpTableInfo();
/// Emit the specified global variable to the .s file.
virtual void EmitGlobalVariable(const GlobalVariable *GV);
/// Check to see if the specified global is a special global used by LLVM. If
/// so, emit it and return true, otherwise do nothing and return false.
bool EmitSpecialLLVMGlobal(const GlobalVariable *GV);
/// Emit an alignment directive to the specified power of two boundary. For
/// example, if you pass in 3 here, you will get an 8 byte alignment. If a
/// global value is specified, and if that global has an explicit alignment
/// requested, it will override the alignment request if required for
/// correctness.
void EmitAlignment(unsigned NumBits, const GlobalObject *GO = nullptr) const;
/// Lower the specified LLVM Constant to an MCExpr.
const MCExpr *lowerConstant(const Constant *CV);
/// \brief Print a general LLVM constant to the .s file.
void EmitGlobalConstant(const Constant *CV);
/// \brief Unnamed constant global variables solely contaning a pointer to
/// another globals variable act like a global variable "proxy", or GOT
/// equivalents, i.e., it's only used to hold the address of the latter. One
/// optimization is to replace accesses to these proxies by using the GOT
/// entry for the final global instead. Hence, we select GOT equivalent
/// candidates among all the module global variables, avoid emitting them
/// unnecessarily and finally replace references to them by pc relative
/// accesses to GOT entries.
void computeGlobalGOTEquivs(Module &M);
/// \brief Constant expressions using GOT equivalent globals may not be
/// eligible for PC relative GOT entry conversion, in such cases we need to
/// emit the proxies we previously omitted in EmitGlobalVariable.
void emitGlobalGOTEquivs();
// Overridable Hooks
// Targets can, or in the case of EmitInstruction, must implement these to
// customize output.
/// This virtual method can be overridden by targets that want to emit
/// something at the start of their file.
virtual void EmitStartOfAsmFile(Module &) {}
/// This virtual method can be overridden by targets that want to emit
/// something at the end of their file.
virtual void EmitEndOfAsmFile(Module &) {}
/// Targets can override this to emit stuff before the first basic block in
/// the function.
virtual void EmitFunctionBodyStart() {}
/// Targets can override this to emit stuff after the last basic block in the
/// function.
virtual void EmitFunctionBodyEnd() {}
/// Targets can override this to emit stuff at the start of a basic block.
/// By default, this method prints the label for the specified
/// MachineBasicBlock, an alignment (if present) and a comment describing it
/// if appropriate.
virtual void EmitBasicBlockStart(const MachineBasicBlock &MBB) const;
/// Targets can override this to emit stuff at the end of a basic block.
virtual void EmitBasicBlockEnd(const MachineBasicBlock &MBB) {}
/// Targets should implement this to emit instructions.
virtual void EmitInstruction(const MachineInstr *) {
llvm_unreachable("EmitInstruction not implemented");
/// Return the symbol for the specified constant pool entry.
virtual MCSymbol *GetCPISymbol(unsigned CPID) const;
virtual void EmitFunctionEntryLabel();
virtual void EmitMachineConstantPoolValue(MachineConstantPoolValue *MCPV);
/// Targets can override this to change how global constants that are part of
/// a C++ static/global constructor list are emitted.
virtual void EmitXXStructor(const Constant *CV) { EmitGlobalConstant(CV); }
/// Return true if the basic block has exactly one predecessor and the control
/// transfer mechanism between the predecessor and this block is a
/// fall-through.
virtual bool
isBlockOnlyReachableByFallthrough(const MachineBasicBlock *MBB) const;
/// Targets can override this to customize the output of IMPLICIT_DEF
/// instructions in verbose mode.
virtual void emitImplicitDef(const MachineInstr *MI) const;
// Symbol Lowering Routines.
MCSymbol *createTempSymbol(const Twine &Name) const;
/// Return the MCSymbol for a private symbol with global value name as its
/// base, with the specified suffix.
MCSymbol *getSymbolWithGlobalValueBase(const GlobalValue *GV,
StringRef Suffix) const;
/// Return the MCSymbol for the specified ExternalSymbol.
MCSymbol *GetExternalSymbolSymbol(StringRef Sym) const;
/// Return the symbol for the specified jump table entry.
MCSymbol *GetJTISymbol(unsigned JTID, bool isLinkerPrivate = false) const;
/// Return the symbol for the specified jump table .set
/// FIXME: privatize to AsmPrinter.
MCSymbol *GetJTSetSymbol(unsigned UID, unsigned MBBID) const;
/// Return the MCSymbol used to satisfy BlockAddress uses of the specified
/// basic block.
MCSymbol *GetBlockAddressSymbol(const BlockAddress *BA) const;
MCSymbol *GetBlockAddressSymbol(const BasicBlock *BB) const;
// Emission Helper Routines.
/// This is just convenient handler for printing offsets.
void printOffset(int64_t Offset, raw_ostream &OS) const;
/// Emit a byte directive and value.
void EmitInt8(int Value) const;
/// Emit a short directive and value.
void EmitInt16(int Value) const;
/// Emit a long directive and value.
void EmitInt32(int Value) const;
/// Emit something like ".long Hi-Lo" where the size in bytes of the directive
/// is specified by Size and Hi/Lo specify the labels. This implicitly uses
/// .set if it is available.
void EmitLabelDifference(const MCSymbol *Hi, const MCSymbol *Lo,
unsigned Size) const;
/// Emit something like ".long Label+Offset" where the size in bytes of the
/// directive is specified by Size and Label specifies the label. This
/// implicitly uses .set if it is available.
void EmitLabelPlusOffset(const MCSymbol *Label, uint64_t Offset,
unsigned Size, bool IsSectionRelative = false) const;
/// Emit something like ".long Label" where the size in bytes of the directive
/// is specified by Size and Label specifies the label.
void EmitLabelReference(const MCSymbol *Label, unsigned Size,
bool IsSectionRelative = false) const {
EmitLabelPlusOffset(Label, 0, Size, IsSectionRelative);
// Dwarf Emission Helper Routines
/// Emit the specified signed leb128 value.
void EmitSLEB128(int64_t Value, const char *Desc = nullptr) const;
/// Emit the specified unsigned leb128 value.
void EmitULEB128(uint64_t Value, const char *Desc = nullptr,
unsigned PadTo = 0) const;
/// Emit a .byte 42 directive for a DW_CFA_xxx value.
void EmitCFAByte(unsigned Val) const;
/// Emit a .byte 42 directive that corresponds to an encoding. If verbose
/// assembly output is enabled, we output comments describing the encoding.
/// Desc is a string saying what the encoding is specifying (e.g. "LSDA").
void EmitEncodingByte(unsigned Val, const char *Desc = nullptr) const;
/// Return the size of the encoding in bytes.
unsigned GetSizeOfEncodedValue(unsigned Encoding) const;
/// Emit reference to a ttype global with a specified encoding.
void EmitTTypeReference(const GlobalValue *GV, unsigned Encoding) const;
/// Emit a reference to a symbol for use in dwarf. Different object formats
/// represent this in different ways. Some use a relocation others encode
/// the label offset in its section.
void emitDwarfSymbolReference(const MCSymbol *Label,
bool ForceOffset = false) const;
/// Emit the 4-byte offset of a string from the start of its section.
/// When possible, emit a DwarfStringPool section offset without any
/// relocations, and without using the symbol. Otherwise, defers to \a
/// emitDwarfSymbolReference().
void emitDwarfStringOffset(DwarfStringPoolEntryRef S) const;
/// Get the value for DW_AT_APPLE_isa. Zero if no isa encoding specified.
virtual unsigned getISAEncoding() { return 0; }
/// EmitDwarfRegOp - Emit a dwarf register operation.
virtual void EmitDwarfRegOp(ByteStreamer &BS,
const MachineLocation &MLoc) const;
// Dwarf Lowering Routines
/// \brief Emit frame instruction to describe the layout of the frame.
void emitCFIInstruction(const MCCFIInstruction &Inst) const;
/// \brief Emit Dwarf abbreviation table.
void emitDwarfAbbrevs(const std::vector<DIEAbbrev *>& Abbrevs) const;
/// \brief Recursively emit Dwarf DIE tree.
void emitDwarfDIE(const DIE &Die) const;
// Inline Asm Support
// These are hooks that targets can override to implement inline asm
// support. These should probably be moved out of AsmPrinter someday.
/// Print information related to the specified machine instr that is
/// independent of the operand, and may be independent of the instr itself.
/// This can be useful for portably encoding the comment character or other
/// bits of target-specific knowledge into the asmstrings. The syntax used is
/// ${:comment}. Targets can override this to add support for their own
/// strange codes.
virtual void PrintSpecial(const MachineInstr *MI, raw_ostream &OS,
const char *Code) const;
/// Print the specified operand of MI, an INLINEASM instruction, using the
/// specified assembler variant. Targets should override this to format as
/// appropriate. This method can return true if the operand is erroneous.
virtual bool PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
unsigned AsmVariant, const char *ExtraCode,
raw_ostream &OS);
/// Print the specified operand of MI, an INLINEASM instruction, using the
/// specified assembler variant as an address. Targets should override this to
/// format as appropriate. This method can return true if the operand is
/// erroneous.
virtual bool PrintAsmMemoryOperand(const MachineInstr *MI, unsigned OpNo,
unsigned AsmVariant, const char *ExtraCode,
raw_ostream &OS);
/// Let the target do anything it needs to do before emitting inlineasm.
/// \p StartInfo - the subtarget info before parsing inline asm
virtual void emitInlineAsmStart() const;
/// Let the target do anything it needs to do after emitting inlineasm.
/// This callback can be used restore the original mode in case the
/// inlineasm contains directives to switch modes.
/// \p StartInfo - the original subtarget info before inline asm
/// \p EndInfo - the final subtarget info after parsing the inline asm,
/// or NULL if the value is unknown.
virtual void emitInlineAsmEnd(const MCSubtargetInfo &StartInfo,
const MCSubtargetInfo *EndInfo) const;
/// Private state for PrintSpecial()
// Assign a unique ID to this machine instruction.
mutable const MachineInstr *LastMI;
mutable unsigned LastFn;
mutable unsigned Counter;
/// This method emits the header for the current function.
virtual void EmitFunctionHeader();
/// Emit a blob of inline asm to the output streamer.
EmitInlineAsm(StringRef Str, const MCSubtargetInfo &STI,
const MCTargetOptions &MCOptions,
const MDNode *LocMDNode = nullptr,
InlineAsm::AsmDialect AsmDialect = InlineAsm::AD_ATT) const;
/// This method formats and emits the specified machine instruction that is an
/// inline asm.
void EmitInlineAsm(const MachineInstr *MI) const;
// Internal Implementation Details
/// This emits visibility information about symbol, if this is suported by the
/// target.
void EmitVisibility(MCSymbol *Sym, unsigned Visibility,
bool IsDefinition = true) const;
void EmitLinkage(const GlobalValue *GV, MCSymbol *GVSym) const;
void EmitJumpTableEntry(const MachineJumpTableInfo *MJTI,
const MachineBasicBlock *MBB, unsigned uid) const;
void EmitLLVMUsedList(const ConstantArray *InitList);
/// Emit llvm.ident metadata in an '.ident' directive.
void EmitModuleIdents(Module &M);
void EmitXXStructorList(const Constant *List, bool isCtor);
GCMetadataPrinter *GetOrCreateGCPrinter(GCStrategy &C);