Re: Question about Machine Description

[yazdanbakhsh <amir.yazdanbakhsh@gmail.com>]

I have read all the documents, and changed some lines but nothing happened :(

Ian Lance Taylor-3 wrote:
> 
> yazdanbakhsh <amir.yazdanbakhsh@gmail.com> writes:
> 
>> I want to change instruction blez to ble. ble compare two registers and
>> jump
>> to the target address if the condition is true.
> 
> Read the internals manual to understand how operand predicates and
> constraints work.  See the hundreds of existing examples.  Ask if you
> have specific questions.
> 
> Ian
> 
>> Ian Lance Taylor-3 wrote:
>>> 
>>> yazdanbakhsh <amir.yazdanbakhsh@gmail.com> writes:
>>> 
>>>> Please assume I'm working with the MIPS. There is a little difference
>>>> between the MIPS and what I'm actually working on it. How can I remove
>>>> immediate logical shift right/left from the compiler?
>>>> I mean If I want the programmer writes an immediate shift, It is
>>>> compiled
>>>> to
>>>> the two instructions:
>>>>
>>>> sll %2,%2,5
>>>>
>>>> changed to:
>>>>
>>>> addi %3,%0,5
>>>> sllv %2,%2,%3
>>> 
>>> Find the insn which generates sll.  Change the operand constraints and
>>> predicates to reject an immediate operand.
>>> 
>>> E.g., in mips.md this is:
>>> 
>>> (define_insn "*<optab><mode>3"
>>>   [(set (match_operand:GPR 0 "register_operand" "=d")
>>> 	(any_shift:GPR (match_operand:GPR 1 "register_operand" "d")
>>> 		       (match_operand:SI 2 "arith_operand" "dI")))]
>>>   "!TARGET_MIPS16"
>>> {
>>>   if (CONST_INT_P (operands[2]))
>>>     operands[2] = GEN_INT (INTVAL (operands[2])
>>> 			   & (GET_MODE_BITSIZE (<MODE>mode) - 1));
>>> 
>>>   return "<d><insn>\t%0,%1,%2";
>>> }
>>>   [(set_attr "type" "shift")
>>>    (set_attr "mode" "<MODE>")])
>>> 
>>> 
>>> For operand 2, change the predicate to register_operand and remove the
>>> 'I' constraint.
>>> 
>>> Ian
>>> 
>>> 
>>
>> -- 
>> View this message in context:
>> http://old.nabble.com/Question-about-Machine-Description-tp1026428p28447744.html
>> Sent from the gcc - Dev mailing list archive at Nabble.com.
> 
> 

-- 
View this message in context: http://old.nabble.com/Question-about-Machine-Description-tp1026428p28449607.html
Sent from the gcc - Dev mailing list archive at Nabble.com.