Re: [PATCH : RL78] Disable interrupts during hardware multiplication routines

[Kaushik M Phatak <kphatak@gmail.com>]

 Hi Mike,
Thanks for the feedback regarding the ABI.

I have added Nick and DJ in the loop to see if they can review this
patch posted last month,
https://gcc.gnu.org/ml/gcc-patches/2015-12/msg00733.html

Best Regards,
Kaushik


On Wed, Dec 9, 2015 at 10:23 PM, Mike Stump <mikestump@comcast.net> wrote:
> On Dec 9, 2015, at 1:53 AM, Kaushik M Phatak <kphatak@gmail.com> wrote:
>> Thank you for your feedback on my patch. (27 August 2015)
>> I have posted an updated patch for this issue,
>> https://gcc.gnu.org/ml/gcc-patches/2015-12/msg00733.html
>>
>> To reply to your question, the RL78 ABI does not specify anything for the MDUC
>> registers (Multiply/Divide).
>
> Three options then, either you're inventing the abi, then you decide and document what you did, you ask someone else what the abi is, or you follow the abi set by another compiler.  You cannot escape the abi.  As port contributor, you get to pick and make the best choice you can.  If you cannot, then I will pick, the registers are always saved.  Correspondingly, they are free to code-gen to be used by the compiler and optimizer.  If that's the case, then there should be no flag.  An os (aka target) that wants a different choice will responsible for adding in the code that can do something else.
>
> Let us know what your choice is.   Maybe Nick knows of a reason why the abi should be a certain way, Nick?  One we know the choice, we can then judge the patch to see if it implements the abi.