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//===- MCAssembler.h - Object File Generation -------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_MC_MCASSEMBLER_H
#define LLVM_MC_MCASSEMBLER_H
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/ADT/iterator.h"
#include "llvm/ADT/iterator_range.h"
#include "llvm/MC/MCDwarf.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/Support/SMLoc.h"
#include <algorithm>
#include <cassert>
#include <cstddef>
#include <cstdint>
#include <memory>
#include <string>
#include <tuple>
#include <utility>
#include <vector>
namespace llvm {
class MCBoundaryAlignFragment;
class MCCVDefRangeFragment;
class MCCVInlineLineTableFragment;
class MCDwarfCallFrameFragment;
class MCDwarfLineAddrFragment;
class MCEncodedFragment;
class MCFixup;
class MCLEBFragment;
class MCPseudoProbeAddrFragment;
class MCRelaxableFragment;
class MCSymbolRefExpr;
class raw_ostream;
class MCAsmBackend;
class MCContext;
class MCCodeEmitter;
class MCFragment;
class MCObjectWriter;
class MCSection;
class MCValue;
class MCAssembler {
public:
friend class MCObjectWriter;
using SectionListType = SmallVector<MCSection *, 0>;
using const_iterator = pointee_iterator<SectionListType::const_iterator>;
private:
MCContext &Context;
std::unique_ptr<MCAsmBackend> Backend;
std::unique_ptr<MCCodeEmitter> Emitter;
std::unique_ptr<MCObjectWriter> Writer;
bool HasLayout = false;
bool RelaxAll = false;
SectionListType Sections;
SmallVector<const MCSymbol *, 0> Symbols;
MCDwarfLineTableParams LTParams;
/// The set of function symbols for which a .thumb_func directive has
/// been seen.
//
// FIXME: We really would like this in target specific code rather than
// here. Maybe when the relocation stuff moves to target specific,
// this can go with it? The streamer would need some target specific
// refactoring too.
mutable SmallPtrSet<const MCSymbol *, 32> ThumbFuncs;
/// The bundle alignment size currently set in the assembler.
///
/// By default it's 0, which means bundling is disabled.
unsigned BundleAlignSize = 0;
/// Evaluate a fixup to a relocatable expression and the value which should be
/// placed into the fixup.
///
/// \param Fixup The fixup to evaluate.
/// \param DF The fragment the fixup is inside.
/// \param Target [out] On return, the relocatable expression the fixup
/// evaluates to.
/// \param Value [out] On return, the value of the fixup as currently laid
/// out.
/// \param WasForced [out] On return, the value in the fixup is set to the
/// correct value if WasForced is true, even if evaluateFixup returns false.
/// \return Whether the fixup value was fully resolved. This is true if the
/// \p Value result is fixed, otherwise the value may change due to
/// relocation.
bool evaluateFixup(const MCFixup &Fixup, const MCFragment *DF,
MCValue &Target, const MCSubtargetInfo *STI,
uint64_t &Value, bool &WasForced) const;
/// Check whether a fixup can be satisfied, or whether it needs to be relaxed
/// (increased in size, in order to hold its value correctly).
bool fixupNeedsRelaxation(const MCFixup &Fixup, const MCRelaxableFragment *DF) const;
/// Check whether the given fragment needs relaxation.
bool fragmentNeedsRelaxation(const MCRelaxableFragment *IF) const;
/// Perform one layout iteration and return true if any offsets
/// were adjusted.
bool layoutOnce();
/// Perform relaxation on a single fragment - returns true if the fragment
/// changes as a result of relaxation.
bool relaxFragment(MCFragment &F);
bool relaxInstruction(MCRelaxableFragment &IF);
bool relaxLEB(MCLEBFragment &IF);
bool relaxBoundaryAlign(MCBoundaryAlignFragment &BF);
bool relaxDwarfLineAddr(MCDwarfLineAddrFragment &DF);
bool relaxDwarfCallFrameFragment(MCDwarfCallFrameFragment &DF);
bool relaxCVInlineLineTable(MCCVInlineLineTableFragment &DF);
bool relaxCVDefRange(MCCVDefRangeFragment &DF);
bool relaxPseudoProbeAddr(MCPseudoProbeAddrFragment &DF);
std::tuple<MCValue, uint64_t, bool>
handleFixup(MCFragment &F, const MCFixup &Fixup, const MCSubtargetInfo *STI);
public:
/// Construct a new assembler instance.
//
// FIXME: How are we going to parameterize this? Two obvious options are stay
// concrete and require clients to pass in a target like object. The other
// option is to make this abstract, and have targets provide concrete
// implementations as we do with AsmParser.
MCAssembler(MCContext &Context, std::unique_ptr<MCAsmBackend> Backend,
std::unique_ptr<MCCodeEmitter> Emitter,
std::unique_ptr<MCObjectWriter> Writer);
MCAssembler(const MCAssembler &) = delete;
MCAssembler &operator=(const MCAssembler &) = delete;
/// Compute the effective fragment size.
uint64_t computeFragmentSize(const MCFragment &F) const;
void layoutBundle(MCFragment *Prev, MCFragment *F) const;
void ensureValid(MCSection &Sec) const;
// Get the offset of the given fragment inside its containing section.
uint64_t getFragmentOffset(const MCFragment &F) const;
uint64_t getSectionAddressSize(const MCSection &Sec) const;
uint64_t getSectionFileSize(const MCSection &Sec) const;
// Get the offset of the given symbol, as computed in the current
// layout.
// \return True on success.
bool getSymbolOffset(const MCSymbol &S, uint64_t &Val) const;
// Variant that reports a fatal error if the offset is not computable.
uint64_t getSymbolOffset(const MCSymbol &S) const;
// If this symbol is equivalent to A + Constant, return A.
const MCSymbol *getBaseSymbol(const MCSymbol &Symbol) const;
/// Emit the section contents to \p OS.
void writeSectionData(raw_ostream &OS, const MCSection *Section) const;
/// Check whether a given symbol has been flagged with .thumb_func.
bool isThumbFunc(const MCSymbol *Func) const;
/// Flag a function symbol as the target of a .thumb_func directive.
void setIsThumbFunc(const MCSymbol *Func) { ThumbFuncs.insert(Func); }
/// Reuse an assembler instance
///
void reset();
MCContext &getContext() const { return Context; }
MCAsmBackend *getBackendPtr() const { return Backend.get(); }
MCCodeEmitter *getEmitterPtr() const { return Emitter.get(); }
MCAsmBackend &getBackend() const { return *Backend; }
MCCodeEmitter &getEmitter() const { return *Emitter; }
MCObjectWriter &getWriter() const { return *Writer; }
MCDwarfLineTableParams getDWARFLinetableParams() const { return LTParams; }
/// Finish - Do final processing and write the object to the output stream.
/// \p Writer is used for custom object writer (as the MCJIT does),
/// if not specified it is automatically created from backend.
void Finish();
// Layout all section and prepare them for emission.
void layout();
bool hasLayout() const { return HasLayout; }
bool getRelaxAll() const { return RelaxAll; }
void setRelaxAll(bool Value) { RelaxAll = Value; }
bool isBundlingEnabled() const { return BundleAlignSize != 0; }
unsigned getBundleAlignSize() const { return BundleAlignSize; }
void setBundleAlignSize(unsigned Size) {
assert((Size == 0 || !(Size & (Size - 1))) &&
"Expect a power-of-two bundle align size");
BundleAlignSize = Size;
}
const_iterator begin() const { return Sections.begin(); }
const_iterator end() const { return Sections.end(); }
iterator_range<pointee_iterator<
typename SmallVector<const MCSymbol *, 0>::const_iterator>>
symbols() const {
return make_pointee_range(Symbols);
}
bool registerSection(MCSection &Section);
bool registerSymbol(const MCSymbol &Symbol);
/// Write the necessary bundle padding to \p OS.
/// Expects a fragment \p F containing instructions and its size \p FSize.
void writeFragmentPadding(raw_ostream &OS, const MCEncodedFragment &F,
uint64_t FSize) const;
void dump() const;
};
} // end namespace llvm
#endif // LLVM_MC_MCASSEMBLER_H
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