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97 lines
3.7 KiB
C++
97 lines
3.7 KiB
C++
//===-- llvm/Target/TargetAsmBackend.h - Target Asm Backend -----*- 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_TARGET_TARGETASMBACKEND_H
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#define LLVM_TARGET_TARGETASMBACKEND_H
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#include "llvm/System/DataTypes.h"
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namespace llvm {
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class MCAsmFixup;
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class MCDataFragment;
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class MCSection;
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class Target;
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/// TargetAsmBackend - Generic interface to target specific assembler backends.
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class TargetAsmBackend {
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TargetAsmBackend(const TargetAsmBackend &); // DO NOT IMPLEMENT
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void operator=(const TargetAsmBackend &); // DO NOT IMPLEMENT
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protected: // Can only create subclasses.
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TargetAsmBackend(const Target &);
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/// TheTarget - The Target that this machine was created for.
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const Target &TheTarget;
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unsigned HasAbsolutizedSet : 1;
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unsigned HasReliableSymbolDifference : 1;
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unsigned HasScatteredSymbols : 1;
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public:
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virtual ~TargetAsmBackend();
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const Target &getTarget() const { return TheTarget; }
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/// hasAbsolutizedSet - Check whether this target "absolutizes"
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/// assignments. That is, given code like:
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/// a:
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/// ...
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/// b:
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/// tmp = a - b
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/// .long tmp
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/// will the value of 'tmp' be a relocatable expression, or the assembly time
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/// value of L0 - L1. This distinction is only relevant for platforms that
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/// support scattered symbols, since in the absence of scattered symbols (a -
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/// b) cannot change after assembly.
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bool hasAbsolutizedSet() const { return HasAbsolutizedSet; }
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/// hasReliableSymbolDifference - Check whether this target implements
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/// accurate relocations for differences between symbols. If not, differences
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/// between symbols will always be relocatable expressions and any references
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/// to temporary symbols will be assumed to be in the same atom, unless they
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/// reside in a different section.
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///
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/// This should always be true (since it results in fewer relocations with no
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/// loss of functionality), but is currently supported as a way to maintain
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/// exact object compatibility with Darwin 'as' (on non-x86_64). It should
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/// eventually should be eliminated. See also \see hasAbsolutizedSet.
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bool hasReliableSymbolDifference() const {
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return HasReliableSymbolDifference;
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}
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/// hasScatteredSymbols - Check whether this target supports scattered
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/// symbols. If so, the assembler should assume that atoms can be scattered by
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/// the linker. In particular, this means that the offsets between symbols
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/// which are in distinct atoms is not known at link time, and the assembler
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/// must generate fixups and relocations appropriately.
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///
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/// Note that the assembler currently does not reason about atoms, instead it
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/// assumes all temporary symbols reside in the "current atom".
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bool hasScatteredSymbols() const { return HasScatteredSymbols; }
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/// doesSectionRequireSymbols - Check whether the given section requires that
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/// all symbols (even temporaries) have symbol table entries.
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virtual bool doesSectionRequireSymbols(const MCSection &Section) const {
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return false;
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}
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/// isVirtualSection - Check whether the given section is "virtual", that is
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/// has no actual object file contents.
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virtual bool isVirtualSection(const MCSection &Section) const = 0;
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/// ApplyFixup - Apply the \arg Value for given \arg Fixup into the provided
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/// data fragment, at the offset specified by the fixup and following the
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/// fixup kind as appropriate.
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virtual void ApplyFixup(const MCAsmFixup &Fixup, MCDataFragment &Fragment,
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uint64_t Value) const = 0;
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};
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} // End llvm namespace
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#endif
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