Andreas Arnez <ar...@linux.vnet.ibm.com> writes: > 6 Summary of Open Questions > =========================== > > 1. Out of the standard interpretations discussed under "options" > (section 4) above, which do we want to settle on? Or is the > "preferred" interpretation missing from that list? > 2. Should pieces fully or partially outside their underlying objects > be considered valid or invalid? If valid, how should they be > aligned and padded? In any case, what is the suggested treatment > by a DWARF consumer?
My dwarf knowledge is not brilliant but I have had to recently consider it for MIPS floating point ABI changes aka FPXX and friends. I don't know exactly where this fits in to your whole description but in case it has a bearing on this we now have the following uses of DW_OP_piece: 1) double precision data split over two 32-bit FPRs Uses a pair of 32-bit DW_OP_piece (ordered depending on endianness). 2) double precision data in one 64-bit FPR No need for DW_OP_piece. 3) double precision data that may be in two 32-bit FPRs or may be in one 64-bit FPR depending on hardware mode Uses a single 64-bit DW_OP_piece on the even numbered register. I'm guilty of not actually finishing this off and doing the GDB side but the theory seemed OK when I did it! From your description this behaviour best matches DW_OP_piece having ABI dependent behaviour which would make it acceptable. These three variations can potentially exist in the same program albeit that (1) and (3) can't appear in a single shared library or executable. It's all a little strange but the whole floating point MIPS o32 ABI is pretty complex now. Matthew
