llvm dev - Jan 2016 - Find the instructions where a particular value is defined

Hi,

I am wondering if there is anything like def-use chain which finds all
the instructions of a function where a particular value is defined?

Thanks.

-- 
Rafi

On 27 January 2016 at 17:08, Syed Rafiul Hussain via llvm-dev
<llvm-dev at lists.llvm.org> wrote:
> I am wondering if there is anything like def-use chain which finds all
> the instructions of a function where a particular value is defined?
How do you mean? LLVM IR is in SSA form, which means that each Value
has precisely one definition (which may or may not be an instruction).
If you've got a "Value *V" in C++ you can just
"dyn_cast<Instruction>(V)" to find the instruction (again, if it
exists).

Cheers.

Tim.

Sorry, I should ask the following:
finds all the instructions of a function where a particular variable is defined?
Lets consider the following code snippet:

1. void foo(){
2. int a, b;
3. if(a > 10)
4.   b = 10;
5. if(a<10)
6.   b = 5;
7. cout << b;
8. }

I would like to know the instructions where variable b can be be
defined, i.e, in this case, the instructions 4 and 6.

On Wed, Jan 27, 2016 at 8:15 PM, Tim Northover <t.p.northover at
gmail.com> wrote:
> On 27 January 2016 at 17:08, Syed Rafiul Hussain via llvm-dev
> <llvm-dev at lists.llvm.org> wrote:
>> I am wondering if there is anything like def-use chain which finds all
>> the instructions of a function where a particular value is defined?
>
> How do you mean? LLVM IR is in SSA form, which means that each Value
> has precisely one definition (which may or may not be an instruction).
> If you've got a "Value *V" in C++ you can just
> "dyn_cast<Instruction>(V)" to find the instruction (again,
if it
> exists).
>
> Cheers.
>
> Tim.


-- 
Rafi