libValueContext

Add context-sensitivity to your analysis using value-context

Table of Contents

• Getting Started
  • Building from source
  • Using with opt
• Usage
  • Initialize a value context object
  • Initialize a context
  • Manipulate dataflow values
  • Update the context graph
  • Retrieve the saved contexts
  • Iterate through the context graph

Getting Started

Building from source

$ git clone this_repository.git
$ cd this_repository
$ mkdir build; cd build
$ cmake .. && make
$ make install

Using with opt

• Path to the headers should be searchable by the compiler
• In your LLVM IR pass:
  • Include the header file, ValueContext/ValueContext.h
  • Use namespace ValueContextUtil

Usage

Initialize a value context object

Initialize the ValueContext object with the datatype of your dataflow value

ValueContext<AliasMap> VC(BI, Top);

Initialize a context

Initailize a context for a given llvm::Function F and initial dataflow value Initial as follows:

Context C = VC.initializeContext(F, Initial);

Manipulate dataflow values

Manipulate data structures storing dataflow values directly through getDataFlowIn and getDataFlowOut

auto DataflowValue = VC.getDataFlowIn[Context][Instruction];

Update the context graph

You may want to update the context graph after initializing a new context.

VC.updateContextGraph(InitialContext, NewContext, CallSite);

Retrieve the saved contexts

To get the previously saved context for a given llvm::Function F and initial dataflow value Initial do as follow:

auto SavedContext = VC.getSavedContext(F, Initial);

if the value of SavedContext is less than 0, implies that this context was not saved previously.

Set result for a saved context

When you reach the boundary instruction, you may want to update the result for the context C

VC.setResult(C, DataflowResutant);

Iterate through the context graph

To iterate over all the contexts which invoked this context using a function call

for (auto T : VC.getContextChild(C)) {
    // For a context Child which called the context C though callsite Inst
    // T is the pair of Child and Inst
}