HelloDataflow-LLVM

Getting started to write Dataflow analysis in LLVM. (Without standard templates)

Code Guidelines for LLVM APIs

1. See how to access functions, basic blocks, and instructions in HelloDataflow-LLVM.
2. The following LLVM and C++ APIs might be helpful for implementing a dataflow analysis.

• Given a basic block, to find out its successor(s), use the following snippet to iterate over its successors.

//#include "llvm/IR/CFG.h"

for (BasicBlock *Succ : successors(&basic_block)) {
	...
}

• Similarly, to find out the predecessor(s) of a basic block, use the following snippet to iterate over its predecessors.

//#include "llvm/IR/CFG.h"

for (BasicBlock *Pred : predecessors(&basic_block)) {
	...
}

• Use standard C++ APIs to perform basic set operations such as union of two sets or vectors.

// #include <set>
std::vector<int> v1 = {1, 2, 3, 4, 5}; 
std::vector<int> v2 = {3, 4, 5, 6, 7}; 
std::vector<int> dest1; // create a third vector to write results

std::set_union(v1.begin(), v1.end(), v2.begin(), v2.end(),std::back_inserter(dest1)); // writes Union (v1+v2) to dest1

• In a similar way, intersection and difference operations can be performed.

std::set_difference(v1.begin(), v1.end(), v2.begin(), v2.end(),std::back_inserter(dest1)); // writes difference (v1-v2) to dest1

std::set_intersection(v1.begin(), v1.end(), v2.begin(), v2.end(),std::back_inserter(dest1)); // writes Common elements of both sets to dest1