Question

I am using BasicBlock iterator to iterate over the instructions in the basic block. Does the Instruction class provide any direct methods to check whether the instruction is an ‘and’ or ‘or’ instruction. If not, is any typecasting necessary?

Answer 1

There is Instruction *I; I->getOpcode() method

getOpcode() returns a member of one of the enums like Instruction::Add.
Definition at line 82 of file Instruction.h.

Casting is not needed when BasicBlock is iterated. It is needed when iterator may return not an Instruction, e.g. when iterating over def-use structures.

Usage is like:

BasicBlock *b = ...;
for (BasicBlock::iterator i = b->begin(), ie = b->end(); i != ie; ++i) {
   Instruction* I = &*i; // get Instr pointer from iterator.
   switch (I->getOpcode()) {
       case Instruction::And: // code
       case Instruction::Or: // code
       default: // other type
   }
}

Documentation used to write this answer: http://llvm.org/docs/ProgrammersManual.html