#ifndef LLVM_TARGET_TARGETASMBACKEND_H
#define LLVM_TARGET_TARGETASMBACKEND_H
+#include "llvm/System/DataTypes.h"
+
namespace llvm {
+class MCDataFragment;
+class MCFixup;
+class MCInst;
+class MCObjectFormat;
+class MCObjectWriter;
+class MCSection;
+template<typename T>
+class SmallVectorImpl;
class Target;
+class raw_ostream;
/// TargetAsmBackend - Generic interface to target specific assembler backends.
class TargetAsmBackend {
/// TheTarget - The Target that this machine was created for.
const Target &TheTarget;
+ unsigned HasReliableSymbolDifference : 1;
+ unsigned HasScatteredSymbols : 1;
+
public:
virtual ~TargetAsmBackend();
const Target &getTarget() const { return TheTarget; }
- /// hasAbsolutizedSet - Check whether this target "absolutizes"
- /// assignments. That is, given code like:
- /// a:
- /// ...
- /// b:
- /// tmp = a - b
- /// .long tmp
- /// will the value of 'tmp' be a relocatable expression, or the assembly time
- /// value of L0 - L1. This distinction is only relevant for platforms that
- /// support scattered symbols, since in the absence of scattered symbols (a -
- /// b) cannot change after assembly.
- virtual bool hasAbsolutizedSet() const { return false; }
+ virtual const MCObjectFormat &getObjectFormat() const = 0;
+
+ /// 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;
+
+ /// 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;
+ }
/// hasScatteredSymbols - Check whether this target supports scattered
/// symbols. If so, the assembler should assume that atoms can be scattered by
///
/// Note that the assembler currently does not reason about atoms, instead it
/// assumes all temporary symbols reside in the "current atom".
- virtual bool hasScatteredSymbols() const { return false; }
+ bool hasScatteredSymbols() const { return HasScatteredSymbols; }
+
+ /// 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;
+ }
+
+ /// isSectionAtomizable - Check whether the given section can be split into
+ /// atoms.
+ ///
+ /// \see MCAssembler::isSymbolLinkerVisible().
+ virtual bool isSectionAtomizable(const MCSection &Section) const {
+ return true;
+ }
+
+ /// isVirtualSection - Check whether the given section is "virtual", that is
+ /// has no actual object file contents.
+ virtual bool isVirtualSection(const MCSection &Section) const = 0;
+
+ /// getPointerSize - Get the pointer size in bytes.
+ virtual unsigned getPointerSize() const = 0;
+
+ /// 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, MCDataFragment &Fragment,
+ uint64_t Value) const = 0;
+
+ /// MayNeedRelaxation - Check whether the given instruction may need
+ /// relaxation.
+ ///
+ /// \param Inst - The instruction to test.
+ virtual bool MayNeedRelaxation(const MCInst &Inst) const = 0;
+
+ /// RelaxInstruction - 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
+ /// output.
+ /// \parm Res [output] - 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.
+ ///
+ /// \return - True on success.
+ virtual bool WriteNopData(uint64_t Count, MCObjectWriter *OW) const = 0;
};
} // End llvm namespace