How step into TableGen-generated files from xcode?

I hope to make Xcode my primary debugging tool for LLVM, but there’s just one quirk in an otherwise wonderfully working IDE. Using Xcode 4.5 with clang 3.0, I’m unable to set a breakpoint in any TableGen-generated .inc files. I notice Xcode doesn’t do syntax highlighting either, despite explicitly setting the filetype in the “Identity and Type” window.

I can see that I’ve built object files with the correct debug symbols:

$ objdump --dwarf=decodedline lib/Target/ARM/ | grep “.inc”

Anyone else seeing this?