[LLVMdev] liveness question

[shreyas krishnan]

Thanks Bill..Can you elaborate on which pass  the info  gets found and
does it depend on adding livein to machine function in argument
lowering or anything action during instruction selection.  Also does
this live in info show in any dumps ?


thanks
shrey

On Wed, Aug 17, 2011 at 12:46 PM, Bill Wendling <wendling at apple.com> wrote:
> On Aug 17, 2011, at 11:54 AM, shreyas krishnan wrote:
>
>> Hi
>>   if I have a function that has an formal argument assigned to  say
>> register R0 and I have the following code fragment as my first basic
>> block
>>
>>
>> BB#0
>>   %reg100023<dead> =   // for some reason could not be removed
>>      ...
>>                   = R0 <kill>
>>
>>
>> What prevents R0 from being allocated to %reg100023
>>
> The fact that R0 is live on entry to the block and its value is used after %reg100023 has been assigned.
>
> -bw
>
>