[LLVMdev] Illegal pointer type

[Sanjiv.Gupta at microchip.com]

>I am assuming a 16-bit value will be stored in a pair of 8-bit 
> registers? 
 
One related question is how to make sure that the correct register pair is allocated to the16-bit quantity when using two 8-bit operations.
In other words, how we can make sure that the 16-bit pointer is stored into [AH, AL] and not in [AH, BL] ?
 
i.e.
GR8  = [ AH, BH, AL, BL];
GR16 = [AX, BX] ;    // AX, BX are subreg pairs of ah,al and bh, bl
 
the DAG looks like   Wrapper:i16 (GR16)  = MoveToHi:i8 (GR8)  , MoveToLo:i8 (GR8)
 
Now how to make sure that if MoveToHi gets AH , then 
     1.   MoveToLo should get AL, 
     2.   the Wrapper should get AX 
 
- Sanjiv 


On Sep 19, 2008, at 5:01 AM, Sachin.Punyani at microchip.com wrote:

>
>
>> -----Original Message-----
>> From: llvmdev-bounces at cs.uiuc.edu [mailto:llvmdev-
>> bounces at cs.uiuc.edu]
> On
>> Behalf Of Bill Wendling
>> Sent: Friday, September 19, 2008 4:38 AM
>>
>> On Thu, Sep 18, 2008 at 7:12 AM,  <Sachin.Punyani at microchip.com>
> wrote:
>>> What changes would be required in LLVM to support illegal pointer
> type?
>>>
>> Hi Sachin,
>>
>> The question's a bit broad. And I don't think the answer you want is
>> as simple as "don't run the legalizer" (which probably won't work). 
>> Do
>> you have a more specific question?
>
> I am trying to ask a broad question. My target has 16 bit pointers but
> register size is 8 bit only. What changes in LLVM would be required to
> support 16 bit pointers on 8 bit registers?
>
> Regards
> Sachin
>
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