This is part of the efforts adding .gnu_attribute support for PowerPC. In Clang, an extra metadata field will be added as float-abi to show current long double format. So backend can emit .gnu_attribute section data from this metadata.
Note: This patch will break 50+ more LIT tests in clang/test/OpenMP. They're all trivial changes since only the referenced metadata numbers are changed. They're not included in this review since it's quite large so that browser cannot load them easily.