[lld] r244972 - ELF: Drop the Chunk base class.
Rafael Espíndola via llvm-commits
llvm-commits at lists.llvm.org
Thu Aug 13 18:36:06 PDT 2015
Rui, do you remember why on COFF you made Chunk be the virtual interface?
I tried to use that for the string table, but it was very unnatural.
We would have an OutputSection with a single StringTableChunk and
there was no convenient place to call finalize. Everything just worked
by adding a virtual interface to OutputSeciton.
On 13 August 2015 at 18:21, Rafael Espindola via llvm-commits
<llvm-commits at lists.llvm.org> wrote:
> Author: rafael
> Date: Thu Aug 13 17:21:37 2015
> New Revision: 244972
>
> URL: http://llvm.org/viewvc/llvm-project?rev=244972&view=rev
> Log:
> ELF: Drop the Chunk base class.
>
> With OutputSection being a virtual interface, each concrete OutputSection
> handles only one type of chunk and we don't need a base Chunk class.
>
> So for we have a class that handles input sections and one that handles
> the string table, but this extends naturally for other outputs (symbol table,
> merging of SHF_MERGE sections, etc.).
>
> Modified:
> lld/trunk/ELF/Chunks.h
> lld/trunk/ELF/Writer.cpp
>
> Modified: lld/trunk/ELF/Chunks.h
> URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Chunks.h?rev=244972&r1=244971&r2=244972&view=diff
> ==============================================================================
> --- lld/trunk/ELF/Chunks.h (original)
> +++ lld/trunk/ELF/Chunks.h Thu Aug 13 17:21:37 2015
> @@ -19,51 +19,38 @@ namespace elf2 {
> class Defined;
> template <class ELFT> class ObjectFile;
>
> -// A Chunk represents a chunk of data that will occupy space in the
> -// output (if the resolver chose that). It may or may not be backed by
> -// a section of an input file. It could be linker-created data, or
> -// doesn't even have actual data (if common or bss).
> -class Chunk {
> +// A chunk corresponding a section of an input file.
> +template <class ELFT> class SectionChunk {
> + typedef llvm::object::Elf_Shdr_Impl<ELFT> Elf_Shdr;
> + typedef llvm::object::Elf_Rel_Impl<ELFT, true> Elf_Rela;
> + typedef llvm::object::Elf_Rel_Impl<ELFT, false> Elf_Rel;
> +
> public:
> - virtual ~Chunk() = default;
> + SectionChunk(llvm::object::ELFFile<ELFT> *Obj, const Elf_Shdr *Header);
>
> // Returns the size of this chunk (even if this is a common or BSS.)
> - virtual size_t getSize() const = 0;
> + size_t getSize() const { return Header->sh_size; }
>
> // Write this chunk to a mmap'ed file, assuming Buf is pointing to
> - // beginning of the file. Because this function may use VA values
> - // of other chunks for relocations, you need to set them properly
> - // before calling this function.
> - virtual void writeTo(uint8_t *Buf) = 0;
> + // beginning of the output section.
> + void writeTo(uint8_t *Buf);
> +
> + StringRef getSectionName() const;
> + const Elf_Shdr *getSectionHdr() const { return Header; }
>
> // The writer sets and uses the addresses.
> uint64_t getOutputSectionOff() { return OutputSectionOff; }
> uint32_t getAlign() { return Align; }
> void setOutputSectionOff(uint64_t V) { OutputSectionOff = V; }
>
> -protected:
> +private:
> // The offset from beginning of the output sections this chunk was assigned
> // to. The writer sets a value.
> uint64_t OutputSectionOff = 0;
>
> // The alignment of this chunk. The writer uses the value.
> uint32_t Align = 1;
> -};
>
> -// A chunk corresponding a section of an input file.
> -template <class ELFT> class SectionChunk : public Chunk {
> - typedef llvm::object::Elf_Shdr_Impl<ELFT> Elf_Shdr;
> - typedef llvm::object::Elf_Rel_Impl<ELFT, true> Elf_Rela;
> - typedef llvm::object::Elf_Rel_Impl<ELFT, false> Elf_Rel;
> -
> -public:
> - SectionChunk(llvm::object::ELFFile<ELFT> *Obj, const Elf_Shdr *Header);
> - size_t getSize() const override { return Header->sh_size; }
> - void writeTo(uint8_t *Buf) override;
> - StringRef getSectionName() const;
> - const Elf_Shdr *getSectionHdr() const { return Header; }
> -
> -private:
> // A file this chunk was created from.
> llvm::object::ELFFile<ELFT> *Obj;
>
>
> Modified: lld/trunk/ELF/Writer.cpp
> URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Writer.cpp?rev=244972&r1=244971&r2=244972&view=diff
> ==============================================================================
> --- lld/trunk/ELF/Writer.cpp (original)
> +++ lld/trunk/ELF/Writer.cpp Thu Aug 13 17:21:37 2015
> @@ -66,18 +66,18 @@ protected:
> ~OutputSectionBase() = default;
> };
>
> -template <bool Is64Bits>
> -class OutputSection final : public OutputSectionBase<Is64Bits> {
> +template <class ELFT>
> +class OutputSection final : public OutputSectionBase<ELFT::Is64Bits> {
> public:
> - typedef typename OutputSectionBase<Is64Bits>::uintX_t uintX_t;
> + typedef typename OutputSectionBase<ELFT::Is64Bits>::uintX_t uintX_t;
> OutputSection(StringRef Name, uint32_t sh_type, uintX_t sh_flags)
> - : OutputSectionBase<Is64Bits>(Name, sh_type, sh_flags) {}
> + : OutputSectionBase<ELFT::Is64Bits>(Name, sh_type, sh_flags) {}
>
> - void addChunk(Chunk *C);
> + void addChunk(SectionChunk<ELFT> *C);
> void writeTo(uint8_t *Buf) override;
>
> private:
> - std::vector<Chunk *> Chunks;
> + std::vector<SectionChunk<ELFT> *> Chunks;
> };
>
> template <bool Is64Bits>
> @@ -117,7 +117,7 @@ private:
>
> SymbolTable *Symtab;
> std::unique_ptr<llvm::FileOutputBuffer> Buffer;
> - llvm::SpecificBumpPtrAllocator<OutputSection<ELFT::Is64Bits>> CAlloc;
> + llvm::SpecificBumpPtrAllocator<OutputSection<ELFT>> CAlloc;
> std::vector<OutputSectionBase<ELFT::Is64Bits> *> OutputSections;
>
> uintX_t FileSize;
> @@ -155,7 +155,8 @@ template <class ELFT> void Writer<ELFT>:
> error(Buffer->commit());
> }
>
> -template <bool Is64Bits> void OutputSection<Is64Bits>::addChunk(Chunk *C) {
> +template <class ELFT>
> +void OutputSection<ELFT>::addChunk(SectionChunk<ELFT> *C) {
> Chunks.push_back(C);
> uint32_t Align = C->getAlign();
> if (Align > this->Header.sh_addralign)
> @@ -168,8 +169,8 @@ template <bool Is64Bits> void OutputSect
> this->Header.sh_size = Off;
> }
>
> -template <bool Is64Bits> void OutputSection<Is64Bits>::writeTo(uint8_t *Buf) {
> - for (Chunk *C : Chunks)
> +template <class ELFT> void OutputSection<ELFT>::writeTo(uint8_t *Buf) {
> + for (SectionChunk<ELFT> *C : Chunks)
> C->writeTo(Buf);
> }
>
> @@ -225,18 +226,17 @@ template <bool Is64Bits> struct DenseMap
>
> // Create output section objects and add them to OutputSections.
> template <class ELFT> void Writer<ELFT>::createSections() {
> - SmallDenseMap<SectionKey<ELFT::Is64Bits>, OutputSection<ELFT::Is64Bits> *>
> - Map;
> + SmallDenseMap<SectionKey<ELFT::Is64Bits>, OutputSection<ELFT> *> Map;
> for (std::unique_ptr<ObjectFileBase> &FileB : Symtab->ObjectFiles) {
> auto &File = cast<ObjectFile<ELFT>>(*FileB);
> for (SectionChunk<ELFT> *C : File.getChunks()) {
> const Elf_Shdr *H = C->getSectionHdr();
> SectionKey<ELFT::Is64Bits> Key{C->getSectionName(), H->sh_type,
> H->sh_flags};
> - OutputSection<ELFT::Is64Bits> *&Sec = Map[Key];
> + OutputSection<ELFT> *&Sec = Map[Key];
> if (!Sec) {
> Sec = new (CAlloc.Allocate())
> - OutputSection<ELFT::Is64Bits>(Key.Name, Key.sh_type, Key.sh_flags);
> + OutputSection<ELFT>(Key.Name, Key.sh_type, Key.sh_flags);
> OutputSections.push_back(Sec);
> }
> Sec->addChunk(C);
>
>
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