BitVector

BitVector can be used to implement IFDS data flow framework. The transfer function can be defined in the following form:

$$ f(x) = (x - Kill) \cup Gen $$

Here, Kill and Gen are represented by BitVector, which is an 0-1 array.

The operations of BitVector

• Construction: bitVector1(10, true);
• AND: bitVector1 &= bitVector2;
• OR: bitVector1 |= bitVector3;
• NOT: bitVector1.flip()

CFG traversal

Refer to CFG.h()

• Get the BasicBlock of the Instruction: getParent
• Get the predecessors of the BasicBlock: pred_begin, pred_end

Reference

• How to operate LLVM BitVector [link]
• LLVM Doc, CFG [link]
• LLVM Doc, BitVector [link]