Thanks for the helpful reply!
I took a look inside the ".\tools\compiler" folders and found a bunch of include files and a handful of C++ component source files with no extension (in .\include\c++\4.2.1). But I don't actually see the IQDC source in there. And I didn't see a license details file.
What am I missing? Where do I find it? Is there a makefile and/or manual build instructions?
I talked to the compiler team on this and found that the compiler is only LLVM based, but is not actaully LLVM and additionally it was customized for this microcontroller and then productized. We do have binutils and newlib which are GPL and LGPL respectively and provide binaries and sources for those. For all GPL components we ship sources along with the corresponding GPL binaries and those sources are found in the install directory in the compiler sources folder.