llvm dev - Oct 2016 - creating an .init section

Hi,

I would like to create an .init section in the LLVM backend. Can anyone shed me
the light on how to do it?  Do I have to create it in the clang?

Thanks,

Jin
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I don't use '.init', but I do use '.ctors' and
'.dtors' for our target.
This is implemented in '<Target>TargetObjectFile.cpp', in my case
as
follows:

 

MCSection *SHAVETargetObjectFile::getStaticCtorSection(unsigned Priority,

                                                       const MCSymbol * /*
KeySym */) const {

  std::string ctorsSectionName;

 

  if (Priority == 65535u)

    ctorsSectionName = ".ctors";

  else

    ctorsSectionName = std::string(".ctors.") + utostr(65535u -
Priority);

 

  return getSHAVESection(ctorsSectionName, DATA);

}

 

and in 'SelectSectionForGlobal' in the same file, I have:

 

  if (const GlobalVariable *GV = dyn_cast<GlobalVariable>(GV1)) {

    const StringRef gvName = GV->getName();

    bool isLLVMSpecial = StringSwitch<bool>(gvName)

                          .Case("llvm.used", true)

                          .Case("llvm.metadata", true)

                          .Case("llvm.global_ctors", true)

                          .Case("llvm.global_dtors", true)

                          .Default(false);

 

    if (isLLVMSpecial) {

      if (gvName == "llvm.global_ctors")

        return getStaticCtorSection();

 

Then use '__attribute__((constructor))' on the function definition you
want
to run in the initialisation phase.

 

            MartinO

 

From: llvm-dev [mailto:llvm-dev-bounces at lists.llvm.org] On Behalf Of Lin,
Jin via llvm-dev
Sent: 14 October 2016 19:10
To: llvm-dev at lists.llvm.org
Subject: [llvm-dev] creating an .init section

 

Hi,

 

I would like to create an .init section in the LLVM backend. Can anyone shed
me the light on how to do it?  Do I have to create it in the clang?

 

Thanks,

 

Jin

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Thank a lot Martin. I will give a try.

Have a good weekend,

Jin

From: Martin J. O'Riordan [mailto:martin.oriordan at movidius.com]
Sent: Friday, October 14, 2016 11:52 AM
To: Lin, Jin <jin.lin at intel.com>
Cc: 'LLVM Developers' <llvm-dev at lists.llvm.org>
Subject: RE: [llvm-dev] creating an .init section

I don't use '.init', but I do use '.ctors' and
'.dtors' for our target.  This is implemented in
'<Target>TargetObjectFile.cpp', in my case as follows:

MCSection *SHAVETargetObjectFile::getStaticCtorSection(unsigned Priority,
                                                       const MCSymbol * /*
KeySym */) const {
  std::string ctorsSectionName;

  if (Priority == 65535u)
    ctorsSectionName = ".ctors";
  else
    ctorsSectionName = std::string(".ctors.") + utostr(65535u -
Priority);

  return getSHAVESection(ctorsSectionName, DATA);
}

and in 'SelectSectionForGlobal' in the same file, I have:

  if (const GlobalVariable *GV = dyn_cast<GlobalVariable>(GV1)) {
    const StringRef gvName = GV->getName();
    bool isLLVMSpecial = StringSwitch<bool>(gvName)
                          .Case("llvm.used", true)
                          .Case("llvm.metadata", true)
                          .Case("llvm.global_ctors", true)
                          .Case("llvm.global_dtors", true)
                          .Default(false);

    if (isLLVMSpecial) {
      if (gvName == "llvm.global_ctors")
        return getStaticCtorSection();

Then use '__attribute__((constructor))' on the function definition you
want to run in the initialisation phase.

            MartinO

From: llvm-dev [mailto:llvm-dev-bounces at lists.llvm.org] On Behalf Of Lin, Jin
via llvm-dev
Sent: 14 October 2016 19:10
To: llvm-dev at lists.llvm.org<mailto:llvm-dev at lists.llvm.org>
Subject: [llvm-dev] creating an .init section

Hi,

I would like to create an .init section in the LLVM backend. Can anyone shed me
the light on how to do it?  Do I have to create it in the clang?

Thanks,

Jin
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