[lld] r238936 - COFF: Change OutputSections' type from vector<unique_ptr<T>> to vector<T*>.
Aaron Ballman
aaron at aaronballman.com
Wed Jun 3 09:55:28 PDT 2015
On Wed, Jun 3, 2015 at 12:44 PM, Rui Ueyama <ruiu at google.com> wrote:
> Author: ruiu
> Date: Wed Jun 3 11:44:00 2015
> New Revision: 238936
>
> URL: http://llvm.org/viewvc/llvm-project?rev=238936&view=rev
> Log:
> COFF: Change OutputSections' type from vector<unique_ptr<T>> to vector<T*>.
>
> This is mainly for readability. OutputSection objects are still owned
> by the writer using SpecificBumpPtrAllocator.
I think clear ownership semantics are more readable than naked
pointers. If this is just for readability, it seems like a step in the
wrong direction for maintenance. Am I simply missing something?
~Aaron
>
> Modified:
> lld/trunk/COFF/Writer.cpp
> lld/trunk/COFF/Writer.h
>
> Modified: lld/trunk/COFF/Writer.cpp
> URL: http://llvm.org/viewvc/llvm-project/lld/trunk/COFF/Writer.cpp?rev=238936&r1=238935&r2=238936&view=diff
> ==============================================================================
> --- lld/trunk/COFF/Writer.cpp (original)
> +++ lld/trunk/COFF/Writer.cpp Wed Jun 3 11:44:00 2015
> @@ -117,14 +117,14 @@ void Writer::createSections() {
> StringRef SectionName = P.first;
> std::vector<Chunk *> &Chunks = P.second;
> std::stable_sort(Chunks.begin(), Chunks.end(), Comp);
> - auto Sec =
> - llvm::make_unique<OutputSection>(SectionName, OutputSections.size());
> + size_t SectIdx = OutputSections.size();
> + auto Sec = new (CAlloc.Allocate()) OutputSection(SectionName, SectIdx);
> for (Chunk *C : Chunks) {
> - C->setOutputSection(Sec.get());
> + C->setOutputSection(Sec);
> Sec->addChunk(C);
> Sec->addPermissions(C->getPermissions());
> }
> - OutputSections.push_back(std::move(Sec));
> + OutputSections.push_back(Sec);
> }
> }
>
> @@ -210,9 +210,7 @@ void Writer::createImportTables() {
> // The Windows loader doesn't seem to like empty sections,
> // so we remove them if any.
> void Writer::removeEmptySections() {
> - auto IsEmpty = [](const std::unique_ptr<OutputSection> &S) {
> - return S->getVirtualSize() == 0;
> - };
> + auto IsEmpty = [](OutputSection *S) { return S->getVirtualSize() == 0; };
> OutputSections.erase(
> std::remove_if(OutputSections.begin(), OutputSections.end(), IsEmpty),
> OutputSections.end());
> @@ -225,7 +223,7 @@ void Writer::assignAddresses() {
> HeaderSize + sizeof(coff_section) * OutputSections.size(), PageSize);
> uint64_t RVA = 0x1000; // The first page is kept unmapped.
> uint64_t FileOff = SizeOfHeaders;
> - for (std::unique_ptr<OutputSection> &Sec : OutputSections) {
> + for (OutputSection *Sec : OutputSections) {
> Sec->setRVA(RVA);
> Sec->setFileOffset(FileOff);
> RVA += RoundUpToAlignment(Sec->getVirtualSize(), PageSize);
> @@ -320,7 +318,7 @@ void Writer::writeHeader() {
> // Name field in the section table is 8 byte long. Longer names need
> // to be written to the string table. First, construct string table.
> std::vector<char> Strtab;
> - for (std::unique_ptr<OutputSection> &Sec : OutputSections) {
> + for (OutputSection *Sec : OutputSections) {
> StringRef Name = Sec->getName();
> if (Name.size() <= COFF::NameSize)
> continue;
> @@ -330,7 +328,7 @@ void Writer::writeHeader() {
> }
>
> // Write section table
> - for (std::unique_ptr<OutputSection> &Sec : OutputSections) {
> + for (OutputSection *Sec : OutputSections) {
> Sec->writeHeader(Buf);
> Buf += sizeof(coff_section);
> }
> @@ -365,7 +363,7 @@ std::error_code Writer::openFile(StringR
> // Write section contents to a mmap'ed file.
> void Writer::writeSections() {
> uint8_t *Buf = Buffer->getBufferStart();
> - for (std::unique_ptr<OutputSection> &Sec : OutputSections) {
> + for (OutputSection *Sec : OutputSections) {
> // Fill gaps between functions in .text with INT3 instructions
> // instead of leaving as NUL bytes (which can be interpreted as
> // ADD instructions).
> @@ -377,15 +375,15 @@ void Writer::writeSections() {
> }
>
> OutputSection *Writer::findSection(StringRef Name) {
> - for (std::unique_ptr<OutputSection> &Sec : OutputSections)
> + for (OutputSection *Sec : OutputSections)
> if (Sec->getName() == Name)
> - return Sec.get();
> + return Sec;
> return nullptr;
> }
>
> uint32_t Writer::getSizeOfInitializedData() {
> uint32_t Res = 0;
> - for (std::unique_ptr<OutputSection> &S : OutputSections)
> + for (OutputSection *S : OutputSections)
> if (S->getPermissions() & IMAGE_SCN_CNT_INITIALIZED_DATA)
> Res += S->getRawSize();
> return Res;
> @@ -407,15 +405,16 @@ OutputSection *Writer::createSection(Str
> .Default(0);
> if (!Perm)
> llvm_unreachable("unknown section name");
> - auto Sec = new OutputSection(Name, OutputSections.size());
> + size_t SectIdx = OutputSections.size();
> + auto Sec = new (CAlloc.Allocate()) OutputSection(Name, SectIdx);
> Sec->addPermissions(Perm);
> - OutputSections.push_back(std::unique_ptr<OutputSection>(Sec));
> + OutputSections.push_back(Sec);
> return Sec;
> }
>
> void Writer::applyRelocations() {
> uint8_t *Buf = Buffer->getBufferStart();
> - for (std::unique_ptr<OutputSection> &Sec : OutputSections)
> + for (OutputSection *Sec : OutputSections)
> for (Chunk *C : Sec->getChunks())
> C->applyRelocations(Buf);
> }
>
> Modified: lld/trunk/COFF/Writer.h
> URL: http://llvm.org/viewvc/llvm-project/lld/trunk/COFF/Writer.h?rev=238936&r1=238935&r2=238936&view=diff
> ==============================================================================
> --- lld/trunk/COFF/Writer.h (original)
> +++ lld/trunk/COFF/Writer.h Wed Jun 3 11:44:00 2015
> @@ -92,7 +92,8 @@ private:
>
> SymbolTable *Symtab;
> std::unique_ptr<llvm::FileOutputBuffer> Buffer;
> - std::vector<std::unique_ptr<OutputSection>> OutputSections;
> + llvm::SpecificBumpPtrAllocator<OutputSection> CAlloc;
> + std::vector<OutputSection *> OutputSections;
> Chunk *ImportAddressTable = nullptr;
> uint32_t ImportDirectoryTableSize = 0;
> uint32_t ImportAddressTableSize = 0;
>
>
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