[Dwarf-Discuss] Representing the location of smaller values in vector registers
Andreas Arnez
arnez@linux.vnet.ibm.com
Wed Mar 9 11:35:06 GMT 2016
On Fri, Mar 04 2016, Cary Coutant wrote:
> It's up to the ABI to define how smaller values are placed within a register.
Right, that seems to be the common understanding. Maybe the confusion
arose because the standard does not explicitly make this statement. Or
did I miss it?
Also, I wonder whether everybody is on the same page as to what this
really means. Consider the following questions:
* What if the object is too large for the given register? For instance,
can the ABI map the object to a register pair?
* Is DW_OP_regx(n) followed by DW_OP_piece(size of object type) always
equivalent to omitting the DW_OP_piece operation?
Answers are welcome, since I'm currently trying to fix various issues
with GDB's handling of composite location descriptions. More questions
about DWARF pieces came up as well:
https://sourceware.org/ml/gdb/2016-01/msg00013.html
--
Andreas Arnez
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