SH2A: "RTV/N Rn" implementation

[Naveen H.S.]

Hi,

>> This is actually what I had in mind. You just need to also modify
>> the epilogue expander to use that insn:

>>  sh_expand_epilogue (0);
>>  if (HAVE_return_rtv)
>>    emit_jump_insn (gen_return_rtv (gen_rtx_REG (SImode, R0_REG)));
>>  else
>>    emit_jump_insn (gen_return ());
  
Thanks for your valuable suggestion.
We modified the epilogue as per your suggestions. RTV/N Rn instruction 
was generated with the operand as R0 in most of the case. The redundant
transfer of register Rn to R0 before the epilogue is still generated. 
So RTV/N does not lead to any optimization in the code size.
We masked this transfer when return type of the function is INTEGER_TYPE

in the function expand_value_return (rtx val) in gcc/stmt.c. This 
resulted in some regression FAIL. RTV/N  Rn is generated only when
return type of the function is INTEGER_TYPE. How to avoid redundant move
without any regression failures?

We tried to get the register Rn from the function expand_value_return
(rtx val) in gcc/stmt.c. The register Rn can be used as the operand in
"return_rtv". The Rn register obtained from the above function is a
PSEUDO register. Kindly suggest a way to get HARD register instead of a
PSEUDO  register?

Regards,
Naveen.H.S.
KPIT Cummins Infosystems Ltd,
Pune (INDIA) 
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