[LLVMdev] Get the loop trip count variable

[Zheng Wang]

Hi Eli,

Could you tell me how to extract the variable name?
The reason I want to do it at the IR level is because I have more
information at this stage, such as, constant propagation and back
edges.

Cheers,
Zheng

On 5 April 2010 21:51, Eli Friedman <eli.friedman at gmail.com> wrote:
> On Mon, Apr 5, 2010 at 1:19 PM, Zheng Wang <jason.wangz at gmail.com> wrote:
>> Hello,
>>
>> I am wondering whether I can get the variable name of loop trip count in LLVM?
>>
>> For example,
>>
>> int NUM;
>>
>> NUM=atoi(argv[i]);
>>
>> for (int i=0; i<NUM; i++)
>> {
>>    ...
>> }
>>
>> How can I get the corresponding variable name for "NUM"? Then, I can
>> instrument something in the source code to record the loop trip count
>> for a given input data set.
>>
>> BasicBlock* b = L->getHeader();
>>
>> returns the basicblock of the loop header, but I don't know how to
>> extract "NUM" from basicblock b.
>
> If you need to instrument the source, you'd probably be better off
> doing this with clang purely at the source level; by the time LLVM
> loop analyzers can tell "NUM" is the trip count, the name is likely to
> be lost due to optimization.
>
> -Eli
>



-- 
Best regards,

WANG Zheng