-//===-- llvm/MC/MCAsmBack.h - MC Asm Backend --------------------*- C++ -*-===//
+//===-- llvm/MC/MCAsmBackend.h - MC Asm Backend -----------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
#ifndef LLVM_MC_MCASMBACKEND_H
#define LLVM_MC_MCASMBACKEND_H
+#include "llvm/ADT/ArrayRef.h"
#include "llvm/MC/MCDirectives.h"
+#include "llvm/MC/MCDwarf.h"
#include "llvm/MC/MCFixup.h"
-#include "llvm/MC/MCFixupKindInfo.h"
#include "llvm/Support/DataTypes.h"
+#include "llvm/Support/ErrorHandling.h"
namespace llvm {
class MCAsmLayout;
class MCAssembler;
class MCELFObjectTargetWriter;
-class MCFixup;
+struct MCFixupKindInfo;
class MCFragment;
class MCInst;
-class MCInstFragment;
+class MCRelaxableFragment;
class MCObjectWriter;
class MCSection;
class MCValue;
-template<typename T>
-class SmallVectorImpl;
class raw_ostream;
-/// MCAsmBackend - Generic interface to target specific assembler backends.
+/// Generic interface to target specific assembler backends.
class MCAsmBackend {
- MCAsmBackend(const MCAsmBackend &); // DO NOT IMPLEMENT
- void operator=(const MCAsmBackend &); // DO NOT IMPLEMENT
+ MCAsmBackend(const MCAsmBackend &) = delete;
+ void operator=(const MCAsmBackend &) = delete;
+
protected: // Can only create subclasses.
MCAsmBackend();
- unsigned HasReliableSymbolDifference : 1;
+ unsigned HasDataInCodeSupport : 1;
public:
virtual ~MCAsmBackend();
- /// createObjectWriter - Create a new MCObjectWriter instance for use by the
- /// assembler backend to emit the final object file.
- virtual MCObjectWriter *createObjectWriter(raw_ostream &OS) const = 0;
-
- /// createELFObjectTargetWriter - Create a new ELFObjectTargetWriter to enable
- /// non-standard ELFObjectWriters.
- virtual MCELFObjectTargetWriter *createELFObjectTargetWriter() const {
- assert(0 && "createELFObjectTargetWriter is not supported by asm backend");
- return 0;
- }
+ /// lifetime management
+ virtual void reset() {}
- /// hasReliableSymbolDifference - Check whether this target implements
- /// accurate relocations for differences between symbols. If not, differences
- /// between symbols will always be relocatable expressions and any references
- /// to temporary symbols will be assumed to be in the same atom, unless they
- /// reside in a different section.
- ///
- /// This should always be true (since it results in fewer relocations with no
- /// loss of functionality), but is currently supported as a way to maintain
- /// exact object compatibility with Darwin 'as' (on non-x86_64). It should
- /// eventually should be eliminated.
- bool hasReliableSymbolDifference() const {
- return HasReliableSymbolDifference;
- }
+ /// Create a new MCObjectWriter instance for use by the assembler backend to
+ /// emit the final object file.
+ virtual MCObjectWriter *createObjectWriter(raw_pwrite_stream &OS) const = 0;
- /// doesSectionRequireSymbols - Check whether the given section requires that
- /// all symbols (even temporaries) have symbol table entries.
- virtual bool doesSectionRequireSymbols(const MCSection &Section) const {
- return false;
+ /// Create a new ELFObjectTargetWriter to enable non-standard
+ /// ELFObjectWriters.
+ virtual MCELFObjectTargetWriter *createELFObjectTargetWriter() const {
+ llvm_unreachable("createELFObjectTargetWriter is not supported by asm "
+ "backend");
}
- /// isSectionAtomizable - Check whether the given section can be split into
- /// atoms.
- ///
- /// \see MCAssembler::isSymbolLinkerVisible().
- virtual bool isSectionAtomizable(const MCSection &Section) const {
- return true;
- }
+ /// Check whether this target implements data-in-code markers. If not, data
+ /// region directives will be ignored.
+ bool hasDataInCodeSupport() const { return HasDataInCodeSupport; }
- /// @name Target Fixup Interfaces
+ /// \name Target Fixup Interfaces
/// @{
- /// getNumFixupKinds - Get the number of target specific fixup kinds.
+ /// Get the number of target specific fixup kinds.
virtual unsigned getNumFixupKinds() const = 0;
- /// getFixupKindInfo - Get information on a fixup kind.
+ /// Get information on a fixup kind.
virtual const MCFixupKindInfo &getFixupKindInfo(MCFixupKind Kind) const;
- /// processFixupValue - Target hook to adjust the literal value of a fixup
- /// if necessary. The default does nothing.
+ /// Target hook to adjust the literal value of a fixup if necessary.
+ /// IsResolved signals whether the caller believes a relocation is needed; the
+ /// target can modify the value. The default does nothing.
virtual void processFixupValue(const MCAssembler &Asm,
const MCAsmLayout &Layout,
const MCFixup &Fixup, const MCFragment *DF,
- MCValue &Target, uint64_t &Value) {}
+ const MCValue &Target, uint64_t &Value,
+ bool &IsResolved) {}
- /// @}
-
- /// ApplyFixup - Apply the \arg Value for given \arg Fixup into the provided
- /// data fragment, at the offset specified by the fixup and following the
- /// fixup kind as appropriate.
- virtual void ApplyFixup(const MCFixup &Fixup, char *Data, unsigned DataSize,
- uint64_t Value) const = 0;
+ /// Apply the \p Value for given \p Fixup into the provided data fragment, at
+ /// the offset specified by the fixup and following the fixup kind as
+ /// appropriate.
+ virtual void applyFixup(const MCFixup &Fixup, char *Data, unsigned DataSize,
+ uint64_t Value, bool IsPCRel) const = 0;
/// @}
- /// @name Target Relaxation Interfaces
+ /// \name Target Relaxation Interfaces
/// @{
- /// MayNeedRelaxation - Check whether the given instruction may need
- /// relaxation.
+ /// Check whether the given instruction may need relaxation.
///
/// \param Inst - The instruction to test.
- virtual bool MayNeedRelaxation(const MCInst &Inst) const = 0;
+ virtual bool mayNeedRelaxation(const MCInst &Inst) const = 0;
- /// fixupNeedsRelaxation - Target specific predicate for whether a given
- /// fixup requires the associated instruction to be relaxed.
- virtual bool fixupNeedsRelaxation(const MCFixup &Fixup,
- uint64_t Value,
- const MCInstFragment *DF,
+ /// Target specific predicate for whether a given fixup requires the
+ /// associated instruction to be relaxed.
+ virtual bool fixupNeedsRelaxation(const MCFixup &Fixup, uint64_t Value,
+ const MCRelaxableFragment *DF,
const MCAsmLayout &Layout) const = 0;
- /// RelaxInstruction - Relax the instruction in the given fragment to the next
- /// wider instruction.
+ /// Relax the instruction in the given fragment to the next wider instruction.
///
- /// \param Inst - The instruction to relax, which may be the same as the
+ /// \param Inst The instruction to relax, which may be the same as the
/// output.
- /// \parm Res [output] - On return, the relaxed instruction.
- virtual void RelaxInstruction(const MCInst &Inst, MCInst &Res) const = 0;
+ /// \param [out] Res On return, the relaxed instruction.
+ virtual void relaxInstruction(const MCInst &Inst, MCInst &Res) const = 0;
/// @}
- /// WriteNopData - Write an (optimal) nop sequence of Count bytes to the given
- /// output. If the target cannot generate such a sequence, it should return an
- /// error.
+ /// Returns the minimum size of a nop in bytes on this target. The assembler
+ /// will use this to emit excess padding in situations where the padding
+ /// required for simple alignment would be less than the minimum nop size.
+ ///
+ virtual unsigned getMinimumNopSize() const { return 1; }
+
+ /// Write an (optimal) nop sequence of Count bytes to the given output. If the
+ /// target cannot generate such a sequence, it should return an error.
///
/// \return - True on success.
- virtual bool WriteNopData(uint64_t Count, MCObjectWriter *OW) const = 0;
+ virtual bool writeNopData(uint64_t Count, MCObjectWriter *OW) const = 0;
- /// HandleAssemblerFlag - Handle any target-specific assembler flags.
- /// By default, do nothing.
- virtual void HandleAssemblerFlag(MCAssemblerFlag Flag) {}
+ /// Handle any target-specific assembler flags. By default, do nothing.
+ virtual void handleAssemblerFlag(MCAssemblerFlag Flag) {}
+
+ /// \brief Generate the compact unwind encoding for the CFI instructions.
+ virtual uint32_t
+ generateCompactUnwindEncoding(ArrayRef<MCCFIInstruction>) const {
+ return 0;
+ }
};
} // End llvm namespace
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