Add disassembler helper for GDB, that uses opcodes structure arc_instruction
and adds convenience functions to handle instruction operands. This interface
solves at least those problems with arc_instruction:
* Some instructions, like "push_s", have implicit operands which are not
directly present in arc_instruction.
* Operands of particular meaning, like branch/jump targets, have various
locations and meaning depending on type of branch/target.
* Access to operand value is abstracted into a separate function, so callee
code shouldn't bother if operand value is an immediate value or in a
register.
Testcases included in this commit are fairly limited - they test exclusively
branch instructions, something that will be used in software single stepping.
Most of the other parts of this disassembler helper are tested during prologue
analysis testing.
gdb/ChangeLog:
yyyy-mm-dd Anton Kolesov <anton.kolesov@synopsys.com>