Pointer Analysis for CASH Compiler Framework Deepak Garg Himanshu Jain Spring 2005

Project Goal Flow insensitive, context insensitive Pointer analysis for CASH Use a constraint based formulation Compare with existing pointer analysis in CASH

Possible choices: – Context sensitive vs. insensitive – Flow sensitive vs. insensitive We choose flow insensitive, context insensitive analysis – Scalable – Results reasonably good Pointer Analysis

Two popular analyses –Andersen’s analysis (O(n 3 )) –Steensgaard’s analysis (O(n  (n,n))) Both create points-to graphs for program locations Andersen’s more accurate (we will implement this) Flow & Context Insensitive Analysis

Example a = &b b = &c a = &d d = &e a bd ce Andersen’s analysis a c,e b,d Steensgaard’s analysis

Using Constraints Both analysis can be expressed in constraint-based frameworks High-level idea –Traverse IR and generate constraints that express points-to information –Use constraint solver to solve constraints

Implementing Andersen’s Traverse program expressions Give each expression e a type  written e:   is a set of program locations e:  means “e may evaluate to address of any location in  ”

Implementing Andersen’s Typing rules generate constraints on types Example:

Solving the Constraints Banshee framework –General purpose constraint solver for set- based constraints –Given specification of constraint language, generates a constraint solver for it Can be easily used for Andersen’s analysis

Where we are… Know how to use Banshee Have read about Andersen’s analysis TODO: –Are studying the existing pointer analysis in CASH –Design a constraint generation procedure for CASH IR –Interface with Banshee