This is a branch folding/tail merge problem, mine.

I believe the following patch fixes it, could you try? The resulting executable doesn't work on Darwin
but the eh layout may well be different...

Index: BranchFolding.cpp

====
RCS file: /var/cvs/llvm/llvm/lib/CodeGen/BranchFolding.cpp,v
retrieving revision 1.56
diff -u -b -r1.56 BranchFolding.cpp
--- BranchFolding.cpp 23 May 2007 21:07:20 -0000 1.56
+++ BranchFolding.cpp 23 May 2007 23:58:37 -0000
@@ -717,11 +717,19 @@
I->getOperand(i).setMachineBasicBlock(New);
}

• // Update the successor information.

• // Update the successor information. If New was already a successor, just
• // remove the link to Old instead of creating another one. PR 1444.
• bool HadSuccessorNew = false;
  std::vector<MachineBasicBlock*> Succs(BB->succ_begin(), BB->succ_end());
  for (int i = Succs.size()-1; i >= 0; --i)
• if (Succs[i] == New) {

•  HadSuccessorNew = true;
  

•  break;
  

• }
• for (int i = Succs.size()-1; i >= 0; --i)
  if (Succs[i] == Old) {
  BB->removeSuccessor(Old);

•  if (!HadSuccessorNew)
   BB->addSuccessor(New);
  

  }
  }

This patch works, thanks, Dale!

Fixed here.
http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20070521/050010.html
http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20070521/050013.html

I was hoping that this would fix #1794 as well, which seems to be
a similar kind of problem, but unfortunately it didn't.