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Re: [patch,avr] Device specific instructions support for avr


2014-03-03 13:34 GMT+04:00 S, Pitchumani <Pitchumani.S@atmel.com>:
> Hi,
>
> Few AVR Xmega devices have specific instruction support than the architecture
> it belongs to. For example atxmega128b1 device has RMW instructions (XCH,LAC,
> LAS and LAT) support, but not all avrxmega6 devices have.
>
> Now, avr-gcc passes architecture name to assembler instead of device name. So,
> RMW instructions are not recognized (illegal opcode error) by assembler.
>
> To address this issue, we could add device specific ISA to device details
> in GCC. Driver can pass additional option based on specific ISA that a device
> has. Assembler can add device specific ISA to architecture ISA based on the
> option it receives.
>
> I have attached patches for avr-gcc.
>
> device-specific-isa-avr-gcc.patch:
> * Device specific ISA information is added to device details.
> * avr-gcc passes -mrmw option to assembler if the selected device
> has RMW instruction support.

I don't like additional option '-mrmw' because we already have a way
for passing device specific ISA.
IMHO better to add new avr_arch (ie atxmega128b1 is ARCH_AVRXMEGA6U)
GAS already have AVR_ISA_XMEGAU for RMW instructions.

Denis.


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