[lld] r219176 - Do not use llvm_unreachable at reachable code.

[Nick Kledzik]

On Oct 6, 2014, at 6:25 PM, Saleem Abdulrasool <compnerd at compnerd.org> wrote:

> On Mon, Oct 6, 2014 at 5:40 PM, Rui Ueyama <ruiu at google.com> wrote:
> Author: ruiu
> Date: Mon Oct  6 19:40:54 2014
> New Revision: 219176
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=219176&view=rev
> Log:
> Do not use llvm_unreachable at reachable code.
> 
> These lines can be reachable if we give a broken or unsupported
> input object file.
> 
> Should we really be relying on this for invalid input detection?  We should immediately identify if the object file is incorrect when we snarf the input object and it mismatches the target (I recently added that support).  Yes, I agree that it could be a broken input, but, shouldn't we have better detection for that in libObject rather than just happily consuming it?
What I’ve tried to do in the mach-o reader is to return an error_code/message.  For instance in PR21090 a bad relocation was reported as an error with the message of:
  `Cannot open /usr/lib/crt1.o: bad relocation (unknown type) in section __TEXT/__text (r_address=0, r_type=0, r_extern=0, r_length=0, r_pcrel=0, r_symbolnum=0)` 

-Nick


>  
> Modified:
>     lld/trunk/lib/ReaderWriter/PECOFF/WriterPECOFF.cpp
> 
> Modified: lld/trunk/lib/ReaderWriter/PECOFF/WriterPECOFF.cpp
> URL: http://llvm.org/viewvc/llvm-project/lld/trunk/lib/ReaderWriter/PECOFF/WriterPECOFF.cpp?rev=219176&r1=219175&r2=219176&view=diff
> ==============================================================================
> --- lld/trunk/lib/ReaderWriter/PECOFF/WriterPECOFF.cpp (original)
> +++ lld/trunk/lib/ReaderWriter/PECOFF/WriterPECOFF.cpp Mon Oct  6 19:40:54 2014
> @@ -558,7 +558,7 @@ void AtomChunk::applyRelocationsX86_32(u
>              targetAddr - getSectionStartAddr(targetAddr, sectionRva);
>          break;
>        default:
> -        llvm_unreachable("Unsupported relocation kind");
> +        llvm::report_fatal_error("Unsupported relocation kind");
>        }
>      }
>    }
> @@ -618,7 +618,7 @@ void AtomChunk::applyRelocationsX86_64(u
>          break;
>        default:
>          llvm::errs() << "Kind: " << (int)ref->kindValue() << "\n";
> -        llvm_unreachable("Unsupported relocation kind");
> +        llvm::report_fatal_error("Unsupported relocation kind");
>        }
>      }
>    }
> @@ -934,7 +934,7 @@ StringRef chooseSectionByContent(const D
>    }
>    llvm::errs() << "Atom: contentType=" << atom->contentType()
>                 << " permission=" << atom->permissions() << "\n";
> -  llvm_unreachable("Failed to choose section based on content");
> +  llvm::report_fatal_error("Failed to choose section based on content");
>  }
> 
>  typedef std::map<StringRef, std::vector<const DefinedAtom *> > AtomVectorMap;
> 
> 
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> 
> 
> -- 
> Saleem Abdulrasool
> compnerd (at) compnerd (dot) org
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