CellSPU:

CellSPU:
- Ensure that (operation) legalization emits proper FDIV libcall when needed.
- Fix various bugs encountered during llvm-spu-gcc build, along with various
  cleanups.
- Start supporting double precision comparisons for remaining libgcc2 build.
  Discovered interesting DAGCombiner feature, which is currently solved via
  custom lowering (64-bit constants are not legal on CellSPU, but DAGCombiner
  insists on inserting one anyway.)
- Update README.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@62664 91177308-0d34-0410-b5e6-96231b3b80d8