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Re: [OpenRISC] [PATCH v2 4/5] or1k: Initial support for FPU


On 7/3/19 5:43 PM, Segher Boessenkool wrote:
>> @@ -212,6 +214,7 @@ enum reg_class
>>  #define REG_CLASS_CONTENTS      \
>>  { { 0x00000000, 0x00000000 },	\
>>    { SIBCALL_REGS_MASK,   0 },	\
>> +  { 0x7ffffefe, 0x00000000 },	\
> 
> Above you said r0, r30, r31 are excluded, but this is r0, r8, r30, or
> in GCC register numbers, 0, 8, and 31?  You probably should mention r8
> somewhere (it's because it is the last arg, this avoid problems, I guess?),
> and the 30/31 thing is confused some way.  Maybe it is all just that one
> documentation line :-)

... and if r8 is excluded because of arguments, I suspect that this is the
wrong fix, as there's nothing inherently wrong with r7:r8 or r8:r9 as a pair,
at least that I can see.

Perhaps function_arg and/or function_arg_advance is the right place for a fix?
The calling convention says that 64-bit arguments are not split across
registers+stack, so you already shouldn't have seen (r8, [sp+0]) as a pair.


r~


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