[LLVMdev] LHS of an expression

[abhi232 at cc.gatech.edu]

Oh Thanks a lot Bill,
I did not get that thing when u first told it but now i tried it and it
worked fine.
Thanks once again.
cheers.
> On 7/23/07, abhi232 at cc.gatech.edu <abhi232 at cc.gatech.edu> wrote:
>> Hi Bill,
>> Thanks a lot for your response.But my problem still remains.The thing is
>> i
>> am having a data type std::vector<Value*> as i am checking for the
>> variables in Store Instructions and Malloc Instructions.For store the
>> case
>> is straightforward as discussed earlier.I want the same Value* variable
>> for malloc inst as well.
>> bcos i cannot have a different set for only instructions.
>>
>> can there be some way that i can get only the Value* and not the entire
>> Instruction* ?
>> Please help.
>
> I'm not sure I understand the problem. Instructions are inherited from
> Values, so you can store both Store and Malloc instructions in the
> same vector. You will, of course, need to get the different LHSs of
> them. To do this, use something along the lines of:
>
> std::vector<Value*> LHSs;
>
> for (std::vector<Value*>::iterator I = v.begin(), E = v.end(); I != E;
> ++I) {
>   if (StoreInst *S = dyn_cast<StoreInst*>(*I)) {
>     // Get the LHS for the store instruction
>     LHSs.push_back(S->getOperand(1));
>   } else if (MallocInst *M = dyn_cast<MallocInst*>(*I)) {
>     // M *is* the LHS of this instruction.
>     LHSs.push_back(M);
>   } else {
>     assert(0 && "Some other instruction's in my list. This is bad!");
>   }
> }
>
> // Process the LHSs vector.
>
> Does this help? Or did I get it wrong? :-)
>
> -bw
>
>> Thanks.
>> Hope my doubt is not that silly..
>> > Hi Abhinav,
>> >
>> >> If i have an IR instruction of the form
>> >> %tmp10 = call sbyte* %malloc( uint 4 )          ; <sbyte*> [#uses=1]
>> >> %tmp10 = cast sbyte* %tmp10 to int*             ; <int*> [#uses=1]
>> >> store int* %tmp10, int** %t
>> >>
>> >> which is nothin but a malloc call how can i get %tmp into maybe a
>> >> variable
>> >> set.
>> >>
>> >> If i have a store instruction then it is pretty much simpler as the
>> >> getOperand(1) can give me the LHS of the expression but in the above
>> >> case
>> >> how can we get it.
>> >>
>> >> I tried searching for some stuff and got a method called getLHS()
>> method
>> >> using BinaryOperator and takes Binops as parameter but i dont think
>> that
>> >> is of much help if i am having a malloc instruction.
>> >>
>> >> Can anybody please guide me on this thing please?
>> >
>> > The LHS of the instruction is a pointer to the instruction itself
>> > (except in cases like the store instr, which you've figured out
>> > already). You can think of the variables that are printed out in the
>> > .ll file as syntactic sugar to help with debugging. So, if you want
>> > variables in a set, you can do something like:
>> >
>> > MallocInst *M = new MallocInst(...);
>> >
>> > std::set<Instruction*> LHSs;
>> >
>> > LHSs.insert(M);
>> >
>> > -bw
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