[lld] r244904 - Store the offset in the output section, no in the file.

[Rafael Espíndola via llvm-commits]

Sure, I will do that in a sec.

On 13 August 2015 at 22:18, Rui Ueyama <ruiu at google.com> wrote:
> Can you make the same change for COFF so that the two are not going to
> unnecessarily diverge?
>
> On Fri, Aug 14, 2015 at 12:54 AM, Rafael Espindola via llvm-commits
> <llvm-commits at lists.llvm.org> wrote:
>>
>> Author: rafael
>> Date: Thu Aug 13 10:54:36 2015
>> New Revision: 244904
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=244904&view=rev
>> Log:
>> Store the offset in the output section, no in the file.
>>
>> That is the value that is stable as the we layout the output sections.
>>
>> Modified:
>>     lld/trunk/ELF/Chunks.cpp
>>     lld/trunk/ELF/Chunks.h
>>     lld/trunk/ELF/Writer.cpp
>>
>> Modified: lld/trunk/ELF/Chunks.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Chunks.cpp?rev=244904&r1=244903&r2=244904&view=diff
>>
>> ==============================================================================
>> --- lld/trunk/ELF/Chunks.cpp (original)
>> +++ lld/trunk/ELF/Chunks.cpp Thu Aug 13 10:54:36 2015
>> @@ -33,7 +33,7 @@ template <class ELFT> void SectionChunk<
>>      return;
>>    // Copy section contents from source object file to output file.
>>    ArrayRef<uint8_t> Data = *Obj->getSectionContents(Header);
>> -  memcpy(Buf + FileOff, Data.data(), Data.size());
>> +  memcpy(Buf + OutputSectionOff, Data.data(), Data.size());
>>
>>    // FIXME: Relocations
>>  }
>>
>> Modified: lld/trunk/ELF/Chunks.h
>> URL:
>> http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Chunks.h?rev=244904&r1=244903&r2=244904&view=diff
>>
>> ==============================================================================
>> --- lld/trunk/ELF/Chunks.h (original)
>> +++ lld/trunk/ELF/Chunks.h Thu Aug 13 10:54:36 2015
>> @@ -37,17 +37,18 @@ public:
>>    virtual void writeTo(uint8_t *Buf) = 0;
>>
>>    // The writer sets and uses the addresses.
>> -  uint64_t getFileOff() { return FileOff; }
>> +  uint64_t getOutputSectionOff() { return OutputSectionOff; }
>>    uint32_t getAlign() { return Align; }
>> -  void setFileOff(uint64_t V) { FileOff = V; }
>> +  void setOutputSectionOff(uint64_t V) { OutputSectionOff = V; }
>>
>>    // Returns the section name if this is a section chunk.
>>    // It is illegal to call this function on non-section chunks.
>>    virtual StringRef getSectionName() const = 0;
>>
>>  protected:
>> -  // The offset from beginning of the output file. The writer sets a
>> value.
>> -  uint64_t FileOff = 0;
>> +  // 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;
>>
>> Modified: lld/trunk/ELF/Writer.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Writer.cpp?rev=244904&r1=244903&r2=244904&view=diff
>>
>> ==============================================================================
>> --- lld/trunk/ELF/Writer.cpp (original)
>> +++ lld/trunk/ELF/Writer.cpp Thu Aug 13 10:54:36 2015
>> @@ -50,8 +50,8 @@ public:
>>
>>    // Returns the size of the section in the output file.
>>    uintX_t getSize() { return Header.sh_size; }
>> -
>>    uintX_t getFlags() { return Header.sh_flags; }
>> +  uintX_t getOffset() { return Header.sh_offset; }
>>
>>  private:
>>    StringRef Name;
>> @@ -122,8 +122,6 @@ template <class ELFT> void OutputSection
>>    if (Header.sh_size == 0)
>>      return;
>>    Header.sh_offset = Off;
>> -  for (Chunk *C : Chunks)
>> -    C->setFileOff(C->getFileOff() + Off);
>>  }
>>
>>  template <class ELFT>
>> @@ -131,7 +129,7 @@ void OutputSection<ELFT>::addSectionChun
>>    Chunks.push_back(C);
>>    uintX_t Off = Header.sh_size;
>>    Off = RoundUpToAlignment(Off, C->getAlign());
>> -  C->setFileOff(Off);
>> +  C->setOutputSectionOff(Off);
>>    Off += C->getSize();
>>    Header.sh_size = Off;
>>    Header.sh_type = C->getSectionHdr()->sh_type;
>> @@ -275,8 +273,9 @@ template <class ELFT> void Writer<ELFT>:
>>  template <class ELFT> void Writer<ELFT>::writeSections() {
>>    uint8_t *Buf = Buffer->getBufferStart();
>>    for (OutputSection<ELFT> *Sec : OutputSections) {
>> +    uint8_t *SecBuf = Buf + Sec->getOffset();
>>      for (Chunk *C : Sec->getChunks())
>> -      C->writeTo(Buf);
>> +      C->writeTo(SecBuf);
>>    }
>>
>>    // String table.
>>
>>
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