llvm dev - Aug 2012 - [LLVMdev] generate a weird 'and' instruction

When I use the next code to print all the opcode name in a file xx.o whose
source file contains statements "if (diff != 0)
klee_assume(diff>0)", then
an opcode name 'and' was printed. Where is the 'and' instruction
from? I
checked the file xx.ll of xx.o and I didn't find a 'and' instruction
of
these two statements.
Besides, when I commented out statement "if (diff != 0)", the
'and'
instruction disappeared.

  for (llvm::Module::iterator itf = module->begin(); itf != module->end();
++itf) {
        llvm::Function *f = itf;
        for (llvm::Function::iterator itb = f->begin(); itb != f->end();
++itb) {
            llvm::BasicBlock *bb = itb;
            for (llvm::BasicBlock::iterator iti = bb->begin(); iti
!bb->end(); ++iti) {
                llvm::Instruction *i = iti;
                *msg << i->getOpcodeName() << "\n";
            }
        }
    }

--------------------------------------------
Qiuping Yi
Institute Of Software
Chinese Academy of Sciences
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On Tue, Aug 21, 2012 at 04:19:58PM +0800, Qiuping Yi
wrote:
> When I use the next code to print all the opcode name in a file xx.o whose
> source file contains statements "if (diff != 0)
klee_assume(diff>0)", then an
> opcode name 'and' was printed. Where is the 'and'
instruction from? I checked
> the file xx.ll of xx.o and I didn't find a 'and' instruction of
these two
> statements. 
> Besides, when I commented out statement "if (diff != 0)", the
'and' instruction
> disappeared.
  Perhaps you can provide your example C code and LLVM bitcode.

Regards,
chenwj

-- 
Wei-Ren Chen (陳韋任)
Computer Systems Lab, Institute of Information Science,
Academia Sinica, Taiwan (R.O.C.)
Tel:886-2-2788-3799 #1667
Homepage: http://people.cs.nctu.edu.tw/~chenwj