Anthony Pioli. Conditional pointer aliasing and constant propagation. Master's thesis, SUNY at New Paltz, 1999. Available at http://www.mcs.newpaltz/tr as Technical Report 99-102.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....as precision on dereferenced reads) algorithm timings and memory usage are reported. These experiments on this data set showed that the precision of their flow insensitive analysis was identical to that of their flow sensitive analysis on 12 of their 21 benchmark programs [HP98] Further work [Pio99] studies the a#ect of analysis precision on constant propagation. It is di#cult to compare Hind and Pioli s results with those reported here, since all of their algorithms are context insensitive and a di#erent alias representation is used, which may alter the fixed location counts. Pointer May ....

Anthony Pioli. Conditional pointer aliasing and constant propagation. Master's thesis, SUNY at New Paltz, 1999. Available at http://www.mcs.newpaltz/tr as Technical Report 99-102.

....system is a program analysis system written in C that was created to experiment with various interprocedural analyses. The system has been used to implement six pointer alias analyses, mod ref analysis, conditional constant propagation, live variable analysis, and reaching definitions analysis [10, 11, 18, 17]. This paper describes some of the experiences in the design and implementation of the system. Figure 1 presents an overview of the NPIC system. Montana, a prototype version of IBM s Visual Age for C incremental compiler (version 4.0 [16] is used to parse source C and C code and create an ....

....PCG CFGs Graphs Figure 1: NPIC system overview. Circles represent a process and squares represent data, either in memory or in a file. The Dakota PCG and CFG structures are emphasized since they play a central role in the overall system. includes several combinations with the alias analyses [17, 18]. Not included are the Montana component and various shell scripts that automate regression testing, run various combinations of analyses, and automatically produce L A T E X [14] tables or jgraph [19] charts. This rest of this paper is organized as follows. The next section highlights the ....

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Anthony Pioli. Conditional pointer aliasing and constant propagation. Master's thesis, SUNY at New Paltz, 1999. Available at http://www.mcs.newpaltz/tr as Technical Report # 99-102.

....problem. 2.2 The Precision of Alias Analysis A less precise alias analysis will conservatively report more alias relations representing real memory locations than a more precise analysis. This spurious information can lead to less precise and efficient client analyses that use alias information [Pioli 1999; Shapiro and Horwitz 1997a] There are several factors that can affect the precision (and cost) of alias analysis. These include the following: the use of flow sensitivity; the use of context sensitivity; ACM Transactions on Programming Languages, Vol. 21, No. 4. 6 Delta Michael Hind ....

....storage requirements and analysis time. A further optimization is to share certain common alias sets, such as Out S1 and In S3 . The combination of these techniques results in a 64 83 reduction of alias sets and a 1.85 4. 50 speedup in analysis time in our benchmark suite [Hind and Pioli 1998a; Pioli 1999]. This combination allows the association of alias sets with non SEG nodes without explicitly visiting such nodes, and it serves the same purpose as the mapping function described in Choi et al. 1991] 3.3 Flow Insensitive Pointer Alias Analysis This section presents a flow insensitive alias ....

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Pioli, A. 1999. Conditional pointer aliasing and constant propagation. M.S. thesis, SUNY at New Paltz. Available at http://www.mcs.newpaltz.edu/tr as Technical Report # 99-102.

....one set per function (Burke et al. and two per CFG Node (Choi et al. 3 The analyses have been implemented in the NPIC system, an experimental program analysis system written in C . The system uses multiple and virtual inheritance to provide an extensible framework for data flow analyses [14, 26]. A prototype version of the IBM VisualAge C compiler [15] is used as the front end. The analyzed program is represented as a program call (multi ) graph (PCG) in which a node corresponds to a function, and a directed edge represents a call to the target function. 4 Each function body is ....

....The analysis is optimistic; no definitions are initially considered reaching any point, except for dummy definitions created at the entry node of a function for each parameter or nonlocal that is referenced in the function. 4. 4 Interprocedural Constant Propagation The constant propagation client [26] is an optimistic interprocedural algorithm inspired by Wegman and Zadeck s Conditional Constant algorithm [38] The algorithm tracks values of variables interprocedurally throughout the program and uses this information to simultaneously evaluate conditional branches where possible, thereby ....

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A. Pioli. Conditional pointer aliasing and constant propagation. Master's thesis, SUNY at New Paltz, 1999. Available at http://www.mcs.newpaltz.edu/tr as Technical Report # 99-102.

....function. 1 Each function body is represented by a control flow graph (CFG) The FS analysis uses this graph to build a simplified sparse evaluation graph (SEG) 10] which is intuitively a subset of the original CFG containing only interesting CFG nodes and the edges needed to connect them [20, 32]. The address taken analysis (AT) computes its solution by making a single pass over all functions in the program, adding to a global set al..l variables whose addresses have been assigned to another variable. These include actual parameters whose addresses are stored in the corresponding formal. ....

....general framework is presented as an iterative algorithm in Fig. 1 and is further described in [18, 5] Other pointer aliasing techniques are described in [5] An extension to handle virtual methods is described in [6] Improvements due to the use of a worklist based implementation are reported in [20, 32]. In theory, the FI analysis can be more precise than the AN analysis because it can ignore some alias relations based on the scope of the variables involved in the relation, at the additional storage cost of using more than one alias set. More specifically, when computing the alias relations ....

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Anthony Pioli. Conditional pointer aliasing and constant propagation. Master's thesis, SUNY at New Paltz, 1999. Available at http://www.mcs.newpaltz/tr as Technical Report # 99-102.

....possible by iterating over analyses [40, 11, 12] 2.2 Flow Sensitive Pointer Alias Analysis The pointer analysis we use is the interprocedural flow sensitive analysis of Choi et. al [8, 20] The algorithm uses a subset of the CFG, called the sparse evaluation graph (SEG) 9] to improve efficiency [21, 32]. The algorithm is a nested fixed point computation in which the outer nest corresponds to computing solutions for each function in the Program Call Graph, PCG. Each such function computation triggers the computation of a local solution for all SEG nodes in the function. A new function is visited ....

....These objects are referred to as heapn , where n is the SEG node number of the allocation statement. These names are unique throughout 2 Discussions of precision tradeoffs between this representation and an explicit representation, which would contain all four alias pairs, can be found in [28, 3, 32]. 7 the entire program. More precise heap modeling schemes can improve precision, but may also increase time space costs. 3 Combining Pointer Alias Analysis and Conditional Constant Propagation This section describe our extensions to conditional constant propagation. It then explains three ways ....

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Anthony Pioli. Conditional pointer aliasing and constant propagation. Master's thesis, SUNY at New Paltz, 1999. Available at http://www.mcs.newpaltz/tr as Technical Report # 99-102.

....information. A similar inheritance pattern is used in the implementation of the flow sensitive analysis for other types of nodes, expressions, and functions, as well as in the flow insensitive analyses. This inheritance pattern can be generalized to more than one simultaneous data flow analysis [28]. Other features of the system include ffl Dakota makes extensive use of the Abstract Factory and Factory Method patterns [14] to give analysis clients a convenient mechanism for constructing the appropriate objects. ffl Analysis and front end independence. The representation provides basic ....

Anthony Pioli. Conditional pointer aliasing and constant propagation. Master's thesis, SUNY at New Paltz, 1998. In preparation.

....in between AT and FI in the theoretical precision spectrum. 2.2 Implementation The analyses have been implemented in the NPIC system, an experimental program analysis system written in C . The system uses multiple and virtual inheritance to provide an extensible framework for data flow analyses [37]. A prototype version of the IBM VisualAge C compiler [47, 36] is used as the front end. The abstract syntax tree constructed by the front end is transformed into a PCG and a CFG for each function, which serve as input to the alias analyses. No CFG is built for library functions. We model a call ....

....information. A similar inheritance pattern is used in the implementation of the flow sensitive analysis for other types of nodes, expressions, and functions, as well as in the flow insensitive analyses. This inheritance pattern can be generalized to more than one simultaneous data flow analysis [37]. Other features of the system include ffl Dakota makes extensive use of the Abstract Factory and Factory Method patterns [18] to give analysis clients a convenient mechanism for constructing the appropriate objects. ffl Analysis and front end independence. The representation provides basic ....

Anthony Pioli. Conditional pointer aliasing and constant propagation. Master's thesis, SUNY at New Paltz, 1998. In preparation.

....in between AT and FI in the theoretical precision spectrum. 2.2 Implementation The analyses have been implemented in the NPIC system, an experimental program analysis system written in C . The system uses multiple and virtual inheritance to provide an extensible framework for data flow analyses [21, 33]. A prototype version of the IBM VisualAge C compiler [43, 32] is used as the front end. The abstract syntax tree constructed by the front end is transformed into a PCG and a CFG for each function, which serve as input to the alias analyses. No CFG is built for library functions. We model a call ....

Anthony Pioli. Conditional pointer aliasing and constant propagation. Master's thesis, SUNY at New Paltz, 1998. In preparation.

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