[PATCH] D42960: [ELF] DEMO: Example for adding .eh_frame pieces to map file

[Rafael Avila de Espindola via llvm-commits]

The changes are isolated to MapFile.cpp, so I would be OK with this.

Could you please rebase and add a testcase?

Thanks,
Rafael

James Henderson via Phabricator via llvm-commits
<llvm-commits at lists.llvm.org> writes:

> jhenderson created this revision.
> jhenderson added a reviewer: ruiu.
> Herald added a subscriber: emaste.
>
> This is an example implementation for adding .eh_frame pieces to the map file. See the RFC on the mailing list: http://lists.llvm.org/pipermail/llvm-dev/2018-February/120993.html. Credit to @andrewng for this.
>
> I wouldn't expect to check this in as-is. It's intended only as a demonstration of how this might be achieved. I imagine a similar approach would work for meregeable section pieces.
>
>
> Repository:
>   rLLD LLVM Linker
>
> https://reviews.llvm.org/D42960
>
> Files:
>   ELF/MapFile.cpp
>   ELF/SyntheticSections.h
>
>
> Index: ELF/SyntheticSections.h
> ===================================================================
> --- ELF/SyntheticSections.h
> +++ ELF/SyntheticSections.h
> @@ -83,6 +83,7 @@
>    };
>  
>    std::vector<FdeData> getFdeData() const;
> +  std::vector<CieRecord *> const &getCieRecords() const { return CieRecords; }
>  
>  private:
>    uint64_t Size = 0;
> Index: ELF/MapFile.cpp
> ===================================================================
> --- ELF/MapFile.cpp
> +++ ELF/MapFile.cpp
> @@ -142,6 +142,58 @@
>        if (!ISD)
>          continue;
>        for (InputSection *IS : ISD->Sections) {
> +        if (IS == InX::EhFrame) {
> +          uint64_t InputStart = 0, InputEnd = 0, OutputStart = 0, OutputEnd = 0;
> +
> +          auto AddEntry = [&](InputSectionBase *IS) {
> +            writeHeader(OS, (OSec->Addr + OutputStart),
> +                        (OutputEnd - OutputStart), IS->Alignment);
> +
> +            std::string InputName = toString(IS);
> +            if (InputStart) {
> +              auto Pos = InputName.size();
> +              if (Pos && (InputName.back() == ')'))
> +                --Pos;
> +              InputName.insert(Pos, "+" + std::to_string(InputStart));
> +            }
> +
> +            OS << indent(1) << InputName << '\n';
> +          };
> +
> +          InputSectionBase *IS = nullptr;
> +
> +          auto ProcessPiece = [&](const EhSectionPiece *P) {
> +            uint64_t InputOff = P->InputOff;
> +            uint64_t OutputOff = P->OutputOff;
> +            if (P->Sec != IS || (OutputOff != OutputEnd) ||
> +                (InputOff != InputEnd)) {
> +              if (IS)
> +                AddEntry(IS);
> +              InputStart = InputOff;
> +              OutputStart = OutputOff;
> +              IS = P->Sec;
> +            }
> +
> +            auto Size = P->Size;
> +            OutputEnd = OutputOff + Size;
> +            InputEnd = InputOff + Size;
> +          };
> +
> +          auto CieRecords = InX::EhFrame->getCieRecords();
> +          for (const auto *Rec : CieRecords) {
> +            ProcessPiece(Rec->Cie);
> +
> +            const auto &Fdes = Rec->Fdes;
> +            for (const auto *Fde : Fdes)
> +              ProcessPiece(Fde);
> +          }
> +
> +          if (IS)
> +            AddEntry(IS);
> +
> +          continue;
> +        }
> +
>          writeHeader(OS, OSec->Addr + IS->OutSecOff, IS->getSize(),
>                      IS->Alignment);
>          OS << indent(1) << toString(IS) << '\n';
>
>
> Index: ELF/SyntheticSections.h
> ===================================================================
> --- ELF/SyntheticSections.h
> +++ ELF/SyntheticSections.h
> @@ -83,6 +83,7 @@
>    };
>  
>    std::vector<FdeData> getFdeData() const;
> +  std::vector<CieRecord *> const &getCieRecords() const { return CieRecords; }
>  
>  private:
>    uint64_t Size = 0;
> Index: ELF/MapFile.cpp
> ===================================================================
> --- ELF/MapFile.cpp
> +++ ELF/MapFile.cpp
> @@ -142,6 +142,58 @@
>        if (!ISD)
>          continue;
>        for (InputSection *IS : ISD->Sections) {
> +        if (IS == InX::EhFrame) {
> +          uint64_t InputStart = 0, InputEnd = 0, OutputStart = 0, OutputEnd = 0;
> +
> +          auto AddEntry = [&](InputSectionBase *IS) {
> +            writeHeader(OS, (OSec->Addr + OutputStart),
> +                        (OutputEnd - OutputStart), IS->Alignment);
> +
> +            std::string InputName = toString(IS);
> +            if (InputStart) {
> +              auto Pos = InputName.size();
> +              if (Pos && (InputName.back() == ')'))
> +                --Pos;
> +              InputName.insert(Pos, "+" + std::to_string(InputStart));
> +            }
> +
> +            OS << indent(1) << InputName << '\n';
> +          };
> +
> +          InputSectionBase *IS = nullptr;
> +
> +          auto ProcessPiece = [&](const EhSectionPiece *P) {
> +            uint64_t InputOff = P->InputOff;
> +            uint64_t OutputOff = P->OutputOff;
> +            if (P->Sec != IS || (OutputOff != OutputEnd) ||
> +                (InputOff != InputEnd)) {
> +              if (IS)
> +                AddEntry(IS);
> +              InputStart = InputOff;
> +              OutputStart = OutputOff;
> +              IS = P->Sec;
> +            }
> +
> +            auto Size = P->Size;
> +            OutputEnd = OutputOff + Size;
> +            InputEnd = InputOff + Size;
> +          };
> +
> +          auto CieRecords = InX::EhFrame->getCieRecords();
> +          for (const auto *Rec : CieRecords) {
> +            ProcessPiece(Rec->Cie);
> +
> +            const auto &Fdes = Rec->Fdes;
> +            for (const auto *Fde : Fdes)
> +              ProcessPiece(Fde);
> +          }
> +
> +          if (IS)
> +            AddEntry(IS);
> +
> +          continue;
> +        }
> +
>          writeHeader(OS, OSec->Addr + IS->OutSecOff, IS->getSize(),
>                      IS->Alignment);
>          OS << indent(1) << toString(IS) << '\n';
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