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Re: Regardig asm volatile query

On 07/29/2010 02:35 PM, Segher Boessenkool wrote:
>> asm volatile (
>>  "\n\t"
>> :
>> : "r" (pu8In4), "r" (s32PosInt), "r" (s16CoeffOrg), "r" (u32PosFrac),
>> "r" (u8Out), "r" (u32Step), "r" (u32TgtWidth)
>> : "r2", "r3", "r4", "r5", "r6", "r7", "r8
>>  );
> You have 7 inputs and 7 clobbers.  Assuming this is ARM or some other
> arch with about 16 regs, this is very much pushing the boundaries of
> the possible.
>> reg_org.c:12: error: can't find a register in class 'GENERAL_REGS'
>> while reloading 'asm'
>> reg_org.c:12: error: 'asm' operand has impossible constraints
>> I Want to know
>> 1-> why compilation is happening with gcc-4.2 toolchian not with gcc-4.3
> You got lucky with 4.2, and you don't with 4.3 .
>> 2-> what is the difference between gcc-4.2 and gcc4.3 related to asm
>> volatile
> Nothing really.  The compiler sometimes needs a few registers to do other
> things, but you used up all of them.

That's right.  If you look a bit more you will see that this is the same
question as
which I answered in the same way, but was ignored.

Perhaps they'll keep asking until they get an answer they like.


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