[llvm-commits] [PATCH 3/5] Introduce a helper method to add a section to the end of a layout. This will be used by the ELF ObjectWriter code to add the metadata sections (symbol table, etc) to the end of an object file.

[Daniel Dunbar]

Hi Matt,

I'm not sure why this needs to exist in the assembler backend -- why
can't the ELF streamer just create the appropriate sections at the end
of assembly?

 - Daniel

On Mon, Jul 26, 2010 at 1:00 PM, Matt Fleming <matt at console-pimps.org> wrote:
> ---
>  include/llvm/MC/MCAssembler.h |    2 ++
>  lib/MC/MCAssembler.cpp        |   34 ++++++++++++++++++++++++++++++++++
>  2 files changed, 36 insertions(+), 0 deletions(-)
>
> diff --git a/include/llvm/MC/MCAssembler.h b/include/llvm/MC/MCAssembler.h
> index c189a1d..89d83ba 100644
> --- a/include/llvm/MC/MCAssembler.h
> +++ b/include/llvm/MC/MCAssembler.h
> @@ -679,6 +679,8 @@ public:
>   void WriteSectionData(const MCSectionData *Section, const MCAsmLayout &Layout,
>                         MCObjectWriter *OW) const;
>
> +  void AddSectionToTheEnd(MCSectionData &SD, MCAsmLayout &Layout);
> +
>  public:
>   /// Construct a new assembler instance.
>   ///
> diff --git a/lib/MC/MCAssembler.cpp b/lib/MC/MCAssembler.cpp
> index fe55e51..0444dc2 100644
> --- a/lib/MC/MCAssembler.cpp
> +++ b/lib/MC/MCAssembler.cpp
> @@ -649,6 +649,40 @@ void MCAssembler::WriteSectionData(const MCSectionData *SD,
>   assert(OW->getStream().tell() - Start == Layout.getSectionFileSize(SD));
>  }
>
> +void MCAssembler::AddSectionToTheEnd(MCSectionData &SD, MCAsmLayout &Layout) {
> +  // Create dummy fragments and assign section ordinals.
> +  unsigned SectionIndex = 0;
> +  for (MCAssembler::iterator it = begin(), ie = end(); it != ie; ++it)
> +    SectionIndex++;
> +
> +  SD.setOrdinal(SectionIndex);
> +
> +  // Assign layout order indices to sections and fragments.
> +  unsigned FragmentIndex = 0;
> +  unsigned i = 0;
> +  for (unsigned e = Layout.getSectionOrder().size(); i != e; ++i) {
> +    MCSectionData *SD = Layout.getSectionOrder()[i];
> +
> +    for (MCSectionData::iterator it2 = SD->begin(),
> +           ie2 = SD->end(); it2 != ie2; ++it2)
> +      FragmentIndex++;
> +  }
> +
> +  SD.setLayoutOrder(i);
> +  for (MCSectionData::iterator it2 = SD.begin(),
> +         ie2 = SD.end(); it2 != ie2; ++it2) {
> +    it2->setLayoutOrder(FragmentIndex++);
> +  }
> +  Layout.getSectionOrder().push_back(&SD);
> +
> +  Layout.LayoutSection(&SD);
> +
> +  // Layout until everything fits.
> +  while (LayoutOnce(Layout))
> +    continue;
> +
> +}
> +
>  void MCAssembler::Finish(MCObjectWriter *Writer) {
>   DEBUG_WITH_TYPE("mc-dump", {
>       llvm::errs() << "assembler backend - pre-layout\n--\n";
> --
> 1.6.4.rc0
>
>