Results 1  10
of
19
Efficient ContextSensitive Pointer Analysis for C Programs
, 1995
"... This paper proposes an efficient technique for contextsensitive pointer analysis that is applicable to real C programs. For efficiency, we summarize the effects of procedures using partial transfer functions. A partial transfer function (PTF) describes the behavior of a procedure assuming that certa ..."
Abstract

Cited by 396 (9 self)
 Add to MetaCart
This paper proposes an efficient technique for contextsensitive pointer analysis that is applicable to real C programs. For efficiency, we summarize the effects of procedures using partial transfer functions. A partial transfer function (PTF) describes the behavior of a procedure assuming that certain alias relationships hold when it is called. We can reuse a PTF in many calling contexts as long as the aliases among the inputs to the procedure are the same. Our empirical results demonstrate that this technique is successfula single PTF per procedure is usually sufficient to obtain completely contextsensitive results. Because many C programs use features such as type casts and pointer arithmetic to circumvent the highlevel type system, our algorithm is based on a lowlevel representation of memory locations that safely handles all the features of C. We have implemented our algorithm in the SUIF compiler system and we show that it runs efficiently for a set of C benchmarks. 1 Introd...
A New Algorithm for Partial Redundancy Elimination based on SSA Form
, 1997
"... A new algorithm, SSAPRE, for performing partial redundancy elimination based entirely on SSA form is presented. It achieves optimal code motion similar to lazy code motion [KRS94a, DS93], but is formulated independently and does not involve iterative data flow analysis and bit vectors in its solutio ..."
Abstract

Cited by 65 (3 self)
 Add to MetaCart
A new algorithm, SSAPRE, for performing partial redundancy elimination based entirely on SSA form is presented. It achieves optimal code motion similar to lazy code motion [KRS94a, DS93], but is formulated independently and does not involve iterative data flow analysis and bit vectors in its solution. It not only exhibits the characteristics common to other sparse approaches, but also inherits the advantages shared by other SSAbased optimization techniques. SSAPRE also maintains its output in the same SSA form as its input. In describing the algorithm, we state theorems with proofs giving our claims about SSAPRE. We also give additional description about our practical implementation of SSAPRE, and analyze and compare its performance with a bitvectorbased implementation of PRE. We conclude with some discussion of the implications of this work. 1 Introduction The Static Single Assignment Form (SSA) has become a popular program representation in optimizing compilers, because it provid...
Practical Improvements to the Construction and Destruction of Static Single Assignment Form
, 1998
"... Static single assignment (SSA) form is a program representation becoming increasingly popular for compilerbased code optimization. In this paper, we address three problems that have arisen in our use of SSA form. Two are variations to the SSA construction algorithms presented by Cytron et al. The f ..."
Abstract

Cited by 61 (3 self)
 Add to MetaCart
Static single assignment (SSA) form is a program representation becoming increasingly popular for compilerbased code optimization. In this paper, we address three problems that have arisen in our use of SSA form. Two are variations to the SSA construction algorithms presented by Cytron et al. The first variation is a version of...
Using Static Single Assignment Form to Improve FlowInsensitive Pointer Analysis
 In Proceedings of the ACM SIGPLAN 1998 conference on Programming language design and implementation
, 1998
"... A pointeranalysis algorithm can be either flowsensitive or flowinsensitive. While flowsensitive analysis usually provides more precise information, it is also usually considerably more costly in terms of time and space. The main contribution of this paper is the presentation of another option in ..."
Abstract

Cited by 42 (0 self)
 Add to MetaCart
A pointeranalysis algorithm can be either flowsensitive or flowinsensitive. While flowsensitive analysis usually provides more precise information, it is also usually considerably more costly in terms of time and space. The main contribution of this paper is the presentation of another option in the form of an algorithm that can be `tuned' to provide a range of results that fall between the results of flowinsensitive and flowsensitive analysis. The algorithm combines a flowinsensitive pointer analysis with static single assignment (SSA) form and uses an iterative process to obtain progressively better results. 1 Introduction Having information about what pointer variables may point to is very useful (and often necessary) when performing many kinds of program analyses. Obviously, the better (or more precise) the information, the more useful the information is. A pointsto analysis that takes into account the order in which statements may be executed (i.e., a flowsensitive anal...
Partial Redundancy Elimination in SSA Form
 ACM Transactions on Programming Languages and Systems
, 1999
"... This paper presents a new approach called SSAPRE [Chow et al. 1997] that shares the optimality properties of the best prior work [Knoop et al. 1992; Knoop et al. 1994; Drechsler and Stadel 1993] and that is based on static single assignment form. Static single assignment form (SSA) is a popular prog ..."
Abstract

Cited by 33 (1 self)
 Add to MetaCart
This paper presents a new approach called SSAPRE [Chow et al. 1997] that shares the optimality properties of the best prior work [Knoop et al. 1992; Knoop et al. 1994; Drechsler and Stadel 1993] and that is based on static single assignment form. Static single assignment form (SSA) is a popular program representation in modern optimizing compilers. Its versatility stems from the fact that, in addition to representing the program, it provides accurate usedefinition (usedef) relationships among the program variables in a concise form [Cytron et al. 1991; Wolfe 1996; Chow et al. 1996]. Many efficient global optimization algorithms have been developed based on SSA. Among these optimizations are dead store elimination [Cytron et al. 1991], constant propagation [Wegman and Zadeck 1991], value numbering [Alpern et al. 1988; Rosen et al. 1988; Briggs et al. 1997], induction variable analysis [Gerlek et al. 1995; Liu et al. 1996], live range computation [Gerlek et al. 1994] and global code motion [Click 1995]. Until recently, most uses of SSA have been restricted to solving problems based essentially on program variables. SSA could not readily be applied to solving expressionbased problems because the concept of usedef for expressions is less obvious than for variables. This difficulty was mentioned by Dhamdhere et al. in the conclusion of [Dhamdhere et al. 1992]. They state, essentially, that there is no clear connection between the usedef information for variables represented by SSA form and the redundancy properties for expressions. By demonstrating such a connection and exploiting it, our work shows that an SSAbased approach to PRE and other expressionbased problems is not only plausible, but also enlightening and practical. Although this paper addresses only the PRE ...
Identifying loops using DJ graphs
, 1995
"... Loop identification is a necessary step in loop transformations for highperformance architectures. The Tarjan intervals are singleentry, strongly connected subgraphs, so they closely reflect the loop structure of a program [Tar74]. They have been used for loop identification. In this paper we give ..."
Abstract

Cited by 30 (0 self)
 Add to MetaCart
Loop identification is a necessary step in loop transformations for highperformance architectures. The Tarjan intervals are singleentry, strongly connected subgraphs, so they closely reflect the loop structure of a program [Tar74]. They have been used for loop identification. In this paper we give a simple algorithm for identifying both reducible and irreducible loops using DJ graphs. Our method can be considered as a generalization of Tarjan's intervalfinding algorithm, since we can identify nested intervals (or loops) even in the presence of irreducibility. i Contents 1 Introduction 1 2 Background and Notation 1 3 Reducible and Irreducible Loops 3 4 Our Algorithm 6 5 Conclusion and Related Work 10 List of Figures 1 An example of a flowgraph and its DJ graph : : : : : : : : : : : : : : : : : : : : 2 2 Examples of reducible and irreducible flowgraphs : : : : : : : : : : : : : : : : : : 4 3 An irreducible flowgraph with two irreducible loops : : : : : : : : : : : : : : : : : 6 4 ...
Dominators in Linear Time
, 1997
"... A linear time algorithm is presented for finding dominators in control flow graphs. ..."
Abstract

Cited by 25 (0 self)
 Add to MetaCart
A linear time algorithm is presented for finding dominators in control flow graphs.
Extended SSA Numbering: Introducing SSA properties to languages with multilevel pointers
, 1996
"... Static Single Assignment (SSA) intermediate representations have become quite popular in compiler development. One advantage of the SSA form is that each variable corresponds to exactly one definition, and thus two references of the same SSA variable must denote the same value. To date, most SSA for ..."
Abstract

Cited by 21 (4 self)
 Add to MetaCart
Static Single Assignment (SSA) intermediate representations have become quite popular in compiler development. One advantage of the SSA form is that each variable corresponds to exactly one definition, and thus two references of the same SSA variable must denote the same value. To date, most SSA forms concentrate on scalar variables, and it is difficult to extend these intermediate representations to languages with multilevel pointers like C.
On Loops, Dominators, and Dominance Frontiers
, 1999
"... This paper explores the concept of loops and loop nesting forests of controlflow graphs, using the problem of constructing the dominator tree of a graph and the problem of computing the iterated dominance frontier of a set of vertices in a graph as guiding applications. The contributions of this pa ..."
Abstract

Cited by 21 (0 self)
 Add to MetaCart
This paper explores the concept of loops and loop nesting forests of controlflow graphs, using the problem of constructing the dominator tree of a graph and the problem of computing the iterated dominance frontier of a set of vertices in a graph as guiding applications. The contributions of this paper include: (1) An axiomatic characterization, as well as a constructive characterization, of a family of loop nesting forests that includes various specific loop nesting forests that have been previously defined. (2) The definition of a new loop nesting forest, as well as an e#cient, almost linear time, algorithm for constructing this forest. (3) An illustration of how loop nesting forests can be used to transform arbitrary (potentially irreducible) problem instances into equivalent acylic graph problem instances in the case of the two problems of (a) constructing the dominator tree of a graph, and (b) computing the iterated dominance frontier of a set of vertices in a graph, leading to new, almost linear time, algorithms for these problems
Static Single Information Form
 Master's thesis, Massachussets Institute of Technology
, 1999
"... This paper presents a new intermediate format called Static Single Information (SSI) form. SSI form generalizes the traditional concept of a variable de nition to include all information de nition points, or points where the analysis may obtain information about the value in a variable. Informatio ..."
Abstract

Cited by 20 (0 self)
 Add to MetaCart
This paper presents a new intermediate format called Static Single Information (SSI) form. SSI form generalizes the traditional concept of a variable de nition to include all information de nition points, or points where the analysis may obtain information about the value in a variable. Information de nition points include conditional branches as well as assignments. Because SSI form provides a new name for each variable at each information de nition point, it provides excellent support for both predicated analyses, which exploit information gained from conditionals, and backwards dataow analyses.