[LLVMdev] Operand, instruction
krishnadhan at cse.iitb.ac.in
Tue Apr 13 22:33:33 PDT 2010
Thanks for reply.
I have used AllocaInst, it's working but i think it's only for allocating
some memory for new variable. And CallInst creates a call instruction. I am
looking for creating a add or sub instruction.
I used function instruction(), which gives me error "error: cannot allocate
an object of abstract type ‘llvm::Instruction’" and also "Instruction.h:28:
note: because the following virtual functions are pure within
‘llvm::Instruction’:", "Instruction.h:50: note: virtual llvm::Instruction*
Also i have used BinaryOperator::create(), but it gives error that there is
no function called create().
Thanks again for your reply.
John Criswell-2 wrote:
> help__me_please wrote:
>> Can you please give an example of creating an instruction (for example
>> instructions with two operand a and b)? I am trying instruction() for a
>> while, but no success yet.
> You need to look for the appropriate subclass of llvm::Instruction and
> find the method for creating a new instruction. The method is usually a
> static method and takes arguments pointing to the values to use as
> operands. Doxygen is your best resource for finding these methods.
> For example, if you look at
> http://llvm.org/doxygen/classllvm_1_1AllocaInst.html, you can see that
> the AllocaInst class (which represents an alloca instruction) has a
> standard constructor method that takes the type of object to allocate,
> the name of the new alloca instruction, an instruction before which to
> insert the alloca instruction, etc.
> As another example, the CallInst class
> (http://llvm.org/doxygen/classllvm_1_1CallInst.html) represents a call
> instruction and has a static Create() method that you can use to create
> a new call instruction.
> -- John T.
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu http://llvm.cs.uiuc.edu
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