llvm dev - Mar 2012 - [LLVMdev] How to set constant pool section?

Hi,

In the document: http://llvm.org/docs/WritingAnLLVMBackend.html
described example like:

SparcTargetAsmInfo::SparcTargetAsmInfo(const SparcTargetMachine &TM) {
  Data16bitsDirective = "\t.half\t";
  Data32bitsDirective = "\t.word\t";
  Data64bitsDirective = 0;  // .xword is only supported by V9.
  ZeroDirective = "\t.skip\t";
  CommentString = "!";
  ConstantPoolSection = "\t.section \".rodata\",#alloc\n";
}

That is wrong for LLVM 3.0

In latest LLVM versions, Sparc have MC subtarget and:

SparcELFMCAsmInfo::SparcELFMCAsmInfo(const Target &T, StringRef TT) {
  IsLittleEndian = false;
  Triple TheTriple(TT);
  if (TheTriple.getArch() == Triple::sparcv9)
    PointerSize = 8;

  Data16bitsDirective = "\t.half\t";
  Data32bitsDirective = "\t.word\t";
  Data64bitsDirective = 0;  // .xword is only supported by V9.
  ZeroDirective = "\t.skip\t";
  CommentString = "!";
  HasLEB128 = true;
  SupportsDebugInformation = true;

  SunStyleELFSectionSwitchSyntax = true;
  UsesELFSectionDirectiveForBSS = true;

  WeakRefDirective = "\t.weak\t";

  PrivateGlobalPrefix = ".L";
}

But I can not find in Sparc, or any other backend code to set
ConstantPoolSection.

I tried in my backend deriving MCAsmInfo, but it seems, that
ConstantPoolSection is not member of MCAsmInfo.

I really need in my backend value for this section, distinct from
default. Where can I set it?

Thanks in advance for all suggestions.

---
With best regards, Konstantin

Hello
> I really need in my backend value for this section, distinct from
> default. Where can I set it?
It was renamed to ReadOnlySection. You might want to check the logic
inside CodeGen/TargetLoweringObjectFileImp.cpp (in particular -
TargetLoweringObjectFile::SelectionSectionForGlobal) to see how it's
used.

-- 
With best regards, Anton Korobeynikov
Faculty of Mathematics and Mechanics, Saint Petersburg State University

Hi,

Thanks for pointing direction. As far, as I understand by reversing,
logic, that I want to overwrite is digged into:

lib/MC/MCSectionELF.cpp

MCSectionELF::PrintSwitchToSection

  if (ShouldOmitSectionDirective(SectionName, MAI)) {
    OS << '\t' << getSectionName() << '\n';
    return;
  }

// otherwise print ".section" directive and then section name

So I need to overwrite ShouldOmitSectionDirective behavior. But this
method of MCSectionELF is not virtual.
As a workaround, I stubbed it in core LLVM code
(MCSectionELF::ShouldOmitSectionDirective), and everything works, but
it is ugly. May be you can advise further?

---
With best regards, Konstantin

On Wed, Mar 14, 2012 at 9:29 PM, Anton Korobeynikov
<anton at korobeynikov.info> wrote:
> Hello
>
>> I really need in my backend value for this section, distinct from
>> default. Where can I set it?
> It was renamed to ReadOnlySection. You might want to check the logic
> inside CodeGen/TargetLoweringObjectFileImp.cpp (in particular -
> TargetLoweringObjectFile::SelectionSectionForGlobal) to see how it's
> used.
>
> --
> With best regards, Anton Korobeynikov
> Faculty of Mathematics and Mechanics, Saint Petersburg State University