Reversion of r235560

[Aaron Ballman]

Hans -- I've reverted r235560 in r235597 as it is causing debug
assertions on Windows (unfortunately, the original commit *and* my
revert email both seem to have never been sent to llvm-commits). It
seems the iterator is being used outside of its valid range, resulting
in failed assertions (I get about 100 of these):

37>  Command 0 Stderr:
37>  0x0FD0CEE6 (0x02F3D840 0x02F333D0 0x0000009F 0x00C6F030),
?_Debug_message at std@@YAXPB_W0I at Z() + 0x26 bytes(s)
37>
37>  0x025B0144 (0xFFFFFFFF 0x00C6E8D4 0x00C6E8C4 0x025B025C),
std::_Vector_const_iterator<std::_Vector_val<std::_Simple_types<llvm::SelectionDAGBuilder::CaseCluster>
> >::operator+=() + 0x64 bytes(s), d:\program files (x86)\microsoft
visual studio 12.0\vc\include\vector, line 159 + 0x17 byte(s)
37>
37>  0x025B022A (0xFFFFFFFF 0x00C6E8D4 0x00C6E8E8 0x025AFCD8),
std::_Vector_iterator<std::_Vector_val<std::_Simple_types<llvm::SelectionDAGBuilder::CaseCluster>
> >::operator+=() + 0x1A bytes(s), d:\program files (x86)\microsoft
visual studio 12.0\vc\include\vector, line 361
37>
37>  0x025B025C (0x00000001 0xCCCCCCCC 0x0106C3B0 0x00C6EB08),
std::_Vector_iterator<std::_Vector_val<std::_Simple_types<llvm::SelectionDAGBuilder::CaseCluster>
> >::operator-=() + 0x1C bytes(s), d:\program files (x86)\microsoft
visual studio 12.0\vc\include\vector, line 373
37>
37>  0x025AFCD8 (0x00C6EA38 0x00000001 0x00C6EE5C 0x00C6F030),
std::_Vector_iterator<std::_Vector_val<std::_Simple_types<llvm::SelectionDAGBuilder::CaseCluster>
> >::operator-() + 0x38 bytes(s), d:\program files (x86)\microsoft
visual studio 12.0\vc\include\vector, line 378 + 0xC byte(s)
37>
37>  0x0257E082 (0x01069F20 0x0106C3B0 0x00C6EBF0 0x0106F128),
llvm::SelectionDAGBuilder::lowerWorkItem() + 0x522 bytes(s),
e:\llvm\llvm\lib\codegen\selectiondag\selectiondagbuilder.cpp, line
7668 + 0x11 byte(s)
37>
37>  0x02583331 (0x01015A78 0x00000002 0x01033260 0x00C6EE84),
llvm::SelectionDAGBuilder::visitSwitch() + 0x8B1 bytes(s),
e:\llvm\llvm\lib\codegen\selectiondag\selectiondagbuilder.cpp, line
7937
37>
37>  0x0257EFB8 (0x00000003 0x01015A78 0x01033260 0x00C6EEA8),
llvm::SelectionDAGBuilder::visit() + 0x78 bytes(s),
e:\llvm\llvm\include\llvm\ir\instruction.def, line 99 + 0xC byte(s)
37>
37>  0x0257EEF4 (0x01015A78 0xCCCCCCCC 0xCCCCCCCC 0xCCCCCCCC),
llvm::SelectionDAGBuilder::visit() + 0x64 bytes(s),
e:\llvm\llvm\lib\codegen\selectiondag\selectiondagbuilder.cpp, line
970
37>
37>  0x024C4DD8 (0x01017234 0x01015120 0x00C6EF23 0x00C6F2F0),
llvm::SelectionDAGISel::SelectBasicBlock() + 0x68 bytes(s),
e:\llvm\llvm\lib\codegen\selectiondag\selectiondagisel.cpp, line 605 +
0x14 byte(s)
37>
37>  0x024C4B57 (0x01017DB0 0x00C6F388 0x00C6F2FC 0xCCCCCCCC),
llvm::SelectionDAGISel::SelectAllBasicBlocks() + 0x907 bytes(s),
e:\llvm\llvm\lib\codegen\selectiondag\selectiondagisel.cpp, line 1313
37>
37>  0x024BE8D7 (0x010692C0 0x00C6F310 0x01025DA0 0x00C6F31C),
llvm::SelectionDAGISel::runOnMachineFunction() + 0x2F7 bytes(s),
e:\llvm\llvm\lib\codegen\selectiondag\selectiondagisel.cpp, line 465
37>
37>  0x01922635 (0x010692C0 0x00C6F328 0x010692C0 0x01025DA0),
`anonymous namespace'::PPCDAGToDAGISel::runOnMachineFunction() + 0x55
bytes(s), e:\llvm\llvm\lib\target\powerpc\ppciseldagtodag.cpp, line 82
37>
37>  0x01F11D30 (0x01017DB0 0x00C6F480 0x00C6F3C4 0x00000000),
llvm::MachineFunctionPass::runOnFunction() + 0x50 bytes(s),
e:\llvm\llvm\lib\codegen\machinefunctionpass.cpp, line 40 + 0x13
byte(s)
37>
37>  0x0216B9B5 (0x01017DB0 0x00000000 0xCCCCCCCC 0x01016FB4),
llvm::FPPassManager::runOnFunction() + 0x105 bytes(s),
e:\llvm\llvm\lib\ir\legacypassmanager.cpp, line 1538 + 0x17 byte(s)
37>
37>  0x0216BB45 (0x01016FE0 0x00C6FA30 0x00C6F48C 0x00000001),
llvm::FPPassManager::runOnModule() + 0x75 bytes(s),
e:\llvm\llvm\lib\ir\legacypassmanager.cpp, line 1558 + 0x15 byte(s)
37>
37>  0x0216CAB9 (0x01016FE0 0x00C6F4D0 0x7EFDE000 0xCCCCCCCC),
`anonymous namespace'::MPPassManager::runOnModule() + 0x1C9 bytes(s),
e:\llvm\llvm\lib\ir\legacypassmanager.cpp, line 1616 + 0x17 byte(s)
37>
37>  0x0216D151 (0x01016FE0 0x00C6F6B8 0x00C6FA30 0x01366200),
llvm::legacy::PassManagerImpl::run() + 0x101 bytes(s),
e:\llvm\llvm\lib\ir\legacypassmanager.cpp, line 1723 + 0x1B byte(s)
37>
37>  0x02167BCD (0x01016FE0 0x00C6FA80 0x00000000 0x0101F408),
llvm::legacy::PassManager::run() + 0x1D bytes(s),
e:\llvm\llvm\lib\ir\legacypassmanager.cpp, line 1757
37>
37>  0x01366200 (0x01005418 0x01001618 0x00000000 0xCCCCCCCC),
compileModule() + 0x10F0 bytes(s), e:\llvm\llvm\tools\llc\llc.cpp,
line 378
37>
37>  0x0136685C (0x00000006 0x01005418 0x00FFFFE0 0x268F3431), main()
+ 0xEC bytes(s), e:\llvm\llvm\tools\llc\llc.cpp, line 201 + 0xD
byte(s)
37>
37>  0x028C9269 (0x00C6FAE4 0x778D336A 0x7EFDE000 0x00C6FB24),
__tmainCRTStartup() + 0x199 bytes(s),
f:\dd\vctools\crt\crtw32\dllstuff\crtexe.c, line 626 + 0x19 byte(s)
37>
37>  0x028C93AD (0x7EFDE000 0x00C6FB24 0x77E992B2 0x7EFDE000),
mainCRTStartup() + 0xD bytes(s),
f:\dd\vctools\crt\crtw32\dllstuff\crtexe.c, line 466
37>
37>  0x778D336A (0x7EFDE000 0x7E23286C 0x00000000 0x00000000),
BaseThreadInitThunk() + 0x12 bytes(s)
37>
37>  0x77E992B2 (0x028C93A0 0x7EFDE000 0x00000000 0x00000000),
RtlInitializeExceptionChain() + 0x63 bytes(s)
37>
37>  0x77E99285 (0x028C93A0 0x7EFDE000 0x00000000 0x00000000),
RtlInitializeExceptionChain() + 0x36 bytes(s)
37>
37>

Since I'm unfamiliar with the code, I didn't feel comfortable
attempting a fix myself.

~Aaron