RE: CR16 Port addition

[Sumanth Gundapaneni <Sumanth.Gundapaneni@kpitcummins.com>]

Hi Joseph,

Thanks for your detailed review and useful suggestions.

>> Files built for the target need to have the exception wording 
>> referencing COPYING.RUNTIME, not no exception as here ...

>> ... or the old GPLv2 exception as here.  Please check all libgcc
>> sources in this patch for appropriate license exception wording.

The concerned files have been modified as per GPLv3.

>> In general, if possible files built for the target should be under 
>> libgcc/config not gcc/config with makefile rules under 
>> libgcc/config as well.

The files have been moved to libgcc/config.

>> Could you clarify how these source files are related to the main 
>> target-independent unwind-dw2* files 

The following link was referenced while implementing CPP Exception 
Handling for CR16. http://gcc.gnu.org/wiki/Dwarf2EHNewbiesHowto
As per the link, required changes were implemented to handle 
exceptions in C++.

However, the CR16's programming memory is 2-byte aligned and the least
significant bit of PC is always zero. The Return Address (RA) register 
always saves the value of PC right shifted by 1(PC >> 1). This 
conversion seems broken at some places during unwinding which results 
in terminate() function  being called.
 
These files were added to help fix this problem. However, we have not yet
completely solved this problem. If we are able to fix this without major 
modifications, we will move these files back in which case customized
unwind files would not be needed.

>> No, never send such a patch to gcc-patches.  Any such changes must 
>> go to config-patches 
>> GCC should not have any local changes, and the GCC and src 
>> repositories should be kept in sync.

Fortunately, config.git has cr16 target added long time back. 


Thanks and Regards,
Sumanth G