[LLVMbugs] [Bug 2149] New: inlining unwind breaks eh intrinsics

[bugzilla-daemon at cs.uiuc.edu]

http://llvm.org/bugs/show_bug.cgi?id=2149

           Summary: inlining unwind breaks eh intrinsics
           Product: libraries
           Version: 2.2
          Platform: PC
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P2
         Component: Transformation Utilities
        AssignedTo: unassignedbugs at nondot.org
        ReportedBy: jay.foad at antixlabs.com
                CC: llvmbugs at cs.uiuc.edu


The comment at the top of HandleInlinedInvoke() in
lib/Transforms/Utils/InlineFunction.cpp says:

/// HandleInlinedInvoke - If we inlined an invoke site, we need to convert
calls
/// in the body of the inlined function into invokes and turn unwind
/// instructions into branches to the invoke unwind dest.

I don't think it's safe to inline an unwind instruction and turn it into a
branch to the invoke unwind destination, because any calls to llvm.eh.exception
and llvm.eh.selector at the destination won't work.

(I'm assuming that the code generator implements these eh intrinsics by getting
the exception pointer and exception selector from well-known native registers
which are set up as part of the stack unwinding process. If you branch directly
to the invoke unwind destination then these registers won't be set up.)


My suggested solution is not to inline any function containing an unwind
instruction.


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