[LLVMbugs] [Bug 16763] New: internal error: atom not found in symbolIndex(___bzero) for architecture x86_64

[bugzilla-daemon at llvm.org]

http://llvm.org/bugs/show_bug.cgi?id=16763

            Bug ID: 16763
           Summary: internal error: atom not found in
                    symbolIndex(___bzero) for architecture x86_64
           Product: clang
           Version: 3.3
          Hardware: Macintosh
                OS: MacOS X
            Status: NEW
          Severity: normal
          Priority: P
         Component: -New Bugs
          Assignee: unassignedclangbugs at nondot.org
          Reporter: hanauska at equinux.com
                CC: llvmbugs at cs.uiuc.edu
    Classification: Unclassified

This is the error I get when trying to link a binary, built with LTO enabled, 
with a static library, that has also been built with clang (same version), that
has been built without LTO enabled, using a "single object prelink" (all .o
files are prelinked to a single .o file), and which has been built as universal
binary for 32 and 64 bit.

All I need to do is disabling LTO and it links without an error (and there is
also no error when I execute it). I can also disable "single object prelink"
for the library and it links without an error.

Things get even worse if I also enable LTO for the static library, in which
case several other symbols are reported missing (this time from the Objective-C
runtime - very unlikely that those symbols are really missing).

However, if I enable LTO for the static library and disable "single object
prelink", everything works again.

Other people have reported similar problems. For example, here is a post from
the Apple mailing list (and I'm pretty sure it is the same issue I am
experiencing, yet the reporter does not mention LTO explicitly):

http://lists.apple.com/archives/xcode-users/2012/Jul/msg00327.html

Here is an issue reported on StackOverflow (already a bit older, yet this
reporter *DOES* mention LTO explicitly):

http://stackoverflow.com/questions/9544452/llvm-3-0-bug-of-lto-in-xcode-4-2

I discovered this issue first with clang 3.2, but today I verified that it
still exits in 3.3.

I have already reported a bug to Apple regarding LTO and single object prelink
not playing well together for static libraries. I even sent them a sample Xcode
project that demonstrates the issue very well. As the error claims that Obj-C
runtime symbols are missing, I thought that this is rather an Apple bug than a
LLVM bug. Maybe this was a wrong conclusion.

This time clang says "internal error" and its inability to find "bzero" seems
rather a more generic bug than an Apple Xcode bug.

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