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281e020b4e
Give up folding an expression if the fragment of one of the operands would require laying out a fragment already being laid out. This prevents hitting an infinite recursion when a fill size expression refers to a later fragment since computing the offset of that fragment would require laying out the fill fragment and thus computing its size expression. Reviewed By: echristo Differential Revision: https://reviews.llvm.org/D79570
111 lines
3.8 KiB
C++
111 lines
3.8 KiB
C++
//===- MCAsmLayout.h - Assembly Layout Object -------------------*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_MC_MCASMLAYOUT_H
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#define LLVM_MC_MCASMLAYOUT_H
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#include "llvm/ADT/DenseMap.h"
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#include "llvm/ADT/SmallVector.h"
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namespace llvm {
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class MCAssembler;
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class MCFragment;
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class MCSection;
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class MCSymbol;
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/// Encapsulates the layout of an assembly file at a particular point in time.
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///
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/// Assembly may require computing multiple layouts for a particular assembly
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/// file as part of the relaxation process. This class encapsulates the layout
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/// at a single point in time in such a way that it is always possible to
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/// efficiently compute the exact address of any symbol in the assembly file,
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/// even during the relaxation process.
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class MCAsmLayout {
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MCAssembler &Assembler;
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/// List of sections in layout order.
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llvm::SmallVector<MCSection *, 16> SectionOrder;
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/// The last fragment which was laid out, or 0 if nothing has been laid
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/// out. Fragments are always laid out in order, so all fragments with a
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/// lower ordinal will be valid.
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mutable DenseMap<const MCSection *, MCFragment *> LastValidFragment;
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/// Make sure that the layout for the given fragment is valid, lazily
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/// computing it if necessary.
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void ensureValid(const MCFragment *F) const;
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/// Is the layout for this fragment valid?
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bool isFragmentValid(const MCFragment *F) const;
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public:
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MCAsmLayout(MCAssembler &Assembler);
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/// Get the assembler object this is a layout for.
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MCAssembler &getAssembler() const { return Assembler; }
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/// \returns whether the offset of fragment \p F can be obtained via
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/// getFragmentOffset.
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bool canGetFragmentOffset(const MCFragment *F) const;
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/// Invalidate the fragments starting with F because it has been
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/// resized. The fragment's size should have already been updated, but
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/// its bundle padding will be recomputed.
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void invalidateFragmentsFrom(MCFragment *F);
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/// Perform layout for a single fragment, assuming that the previous
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/// fragment has already been laid out correctly, and the parent section has
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/// been initialized.
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void layoutFragment(MCFragment *Fragment);
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/// \name Section Access (in layout order)
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/// @{
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llvm::SmallVectorImpl<MCSection *> &getSectionOrder() { return SectionOrder; }
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const llvm::SmallVectorImpl<MCSection *> &getSectionOrder() const {
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return SectionOrder;
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}
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/// @}
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/// \name Fragment Layout Data
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/// @{
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/// Get the offset of the given fragment inside its containing section.
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uint64_t getFragmentOffset(const MCFragment *F) const;
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/// @}
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/// \name Utility Functions
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/// @{
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/// Get the address space size of the given section, as it effects
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/// layout. This may differ from the size reported by \see getSectionSize() by
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/// not including section tail padding.
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uint64_t getSectionAddressSize(const MCSection *Sec) const;
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/// Get the data size of the given section, as emitted to the object
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/// file. This may include additional padding, or be 0 for virtual sections.
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uint64_t getSectionFileSize(const MCSection *Sec) const;
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/// Get the offset of the given symbol, as computed in the current
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/// layout.
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/// \return True on success.
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bool getSymbolOffset(const MCSymbol &S, uint64_t &Val) const;
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/// Variant that reports a fatal error if the offset is not computable.
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uint64_t getSymbolOffset(const MCSymbol &S) const;
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/// If this symbol is equivalent to A + Constant, return A.
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const MCSymbol *getBaseSymbol(const MCSymbol &Symbol) const;
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/// @}
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};
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} // end namespace llvm
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#endif
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