bugfix: bpf: DATASEC names might be wrong in the BTF data

[agentzh]

Summary

This is because GlobalVariable objects' section fields were almost never set except for user-defined section names. So here we always set the section field.

[agentzh]

Rebased to the latest main branch of llvm-project.

[vtjnash]

Can you upload the full diff (git diff -U100000 or arc diff --update D116852) and fix the clang-format check?

[RKSimon]

We need some kind of test coverage.

llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp

590

I'm not very familiar with this code, but altering const variables like this doesn't seem like a good idea - is there any kind of existing 'fixup' call that we can use instead?

[yonghong-song]

Please provide a test case to show what is the problem and how the patch addressed the problem, so reviewers can check whether this is the best approach to fix the problem or not.

llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp

   // Determine to which section this global should be emitted.
   MCSection *TheSection = getObjFileLowering().SectionForGlobal(GV, GVKind, TM);
 
+  ((GlobalVariable *) GV)->setSection(TheSection->getName());
+
   // If we have a bss global going to a section that supports the
   // zerofill directive, do so here.
   if (GVKind.isBSS() && MAI->hasMachoZeroFillDirective() &&