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Proceedings of the acm sigplan conference on programming language design and implementation (pldi) 1999年 204-214页

作者： Leung, Allen George, Lal New York Univ New York NY United States

Static Single Assignment (SSA) is an effective intermediate representation in optimizing compilers. However, traditional SSA form and optimizations are not applicable to programs represented as native machine instructions because the use of dedicated registers imposed by calling conventions, the runtime system, and target architecture must be made explicit. We present a simple scheme for converting between programs in machine code and in SSA, such that references to dedicated physical registers in machine code are preserved. Our scheme ignores all output- and anti-dependences imposed by physical registers while a program is in SSA form, but inserts compensation code during machine code reconstruction if any naming requirements have been violated. By resolving all mismatches between the two representations in separate phases, we are able to utilize existing SSA algorithms unaltered to perform machine code optimizations.

关键词： Object oriented programming

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Program structure tree. Computing control regions in linear time

Program structure tree. Computing control regions in linear ...

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Proceedings of the acm sigplan'94 conference on programming language design and implementation (pldi)

作者： Johnson, Richard Pearson, David Pingali, Keshav Cornell Univ Ithaca United States

ISBN: (纸本)089791662X

In this paper, we describe the program structure tree (PST), a hierarchical representation of program structure based on single entry single exit (SESE) regions of the control flow graph. We give a linear-time algorithm for finding SESE regions and for building the PST of arbitrary control flow graphs (including irreducible ones). Next, we establish a connection between SESE regions and control dependence equivalence classes, and show how to use the algorithm to find control regions in linear time. Finally, we discuss some applications of the PST. Many control flow algorithms, such as construction of Static Single Assignment form, can be speeded up by applying the algorithms in a divide-and-conquer style to each SESE region on its own. The PST is also used to speed up data flow analysis by exploiting `sparsity'. Experimental results from the Perfect Club and SPEC89 benchmarks confirm that the PST approach finds and exploits program structure.

关键词： Structured programming

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Rematerialization

Rematerialization

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acm sigplan '92 conference on programming language design and implementation, pldi 1992

作者： Briggs, Preston Cooper, Keith D. Torczon, Linda Rice Univ Houston TX United States

ISBN: (纸本)0897914759

This paper examines a problem that arises during global register allocation - rematerialization. If a value cannot be kept in a register, the allocator should recognize when it is cheaper to recompute the value (rematerialize it) than to store and reload it. Chaitin's original graph-coloring allocator handled simple instances of this problem correctly. This paper details a general solution to the problem and presents experimental evidence that shows its importance. Our approach is to tag individual values in the procedure's SSA graph with information specifying how it should be spilled. We use a variant of Wegman and Zadeck's sparse simple constant algorithm to propagate tags throughout the graph. The allocator then splits live ranges into values with different tags. This isolates those values that can be easily rematerialized from values that require general spilling. We modify the base allocator to use this information when estimating spill costs and introducing spill code. Our presentation focuses on rematerialization in the context of Chaitin's allocator;however, the problem arises in any global allocator. We believe that our approach will work in other allocators - while the details of implementation will vary, the key insights should carry over directly.

关键词： Computer programming

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Context-Free language Reachability via Skewed Tabulation

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PROCEEDINGS OF THE acm ON programming languageS-PacmPL 2024年第PLDI期8卷 1830-1853页

作者： Lei, Yuxiang Bossut, Camille Sui, Yulei Zhang, Qirun Univ New South Wales Sydney NSW Australia Georgia Inst Technol Atlanta GA USA

Context-free language reachability (CFL-reachability) is a prominent model for formulating program analysis problems. Almost all CFL-reachability algorithms are based on the Reps-Horwitz-Sagiv (RHS) tabulation. In essence, the RHS tabulation, based on normalized context-free grammars, is similar to the CYK algorithm for CFL-parsing. Consider a normalized rule S ::= A B and a CFL-reachability problem instance of computing S-edges in the input graph. The RHS tabulation obtains all summary edges (i.e., S-, A-, and B-edges) based on the grammar rules. However, many A- and B-edges are wasted because only a subset of those edges eventually contributes to generating S-edges in the input graph. This paper proposes a new tabulation strategy for speeding up CFL-reachability by eliminating wasted and unnecessary summary edges. We particularly focus on recursive nonterminals. Our key technical insight is that the wasted edge generations and insertions caused by recursive nonterminals can be avoided by modifying the parse trees either statically (by transforming the grammar) or dynamically (using a specialized online CFL-reachability solver). For example, if a recursive nonterminal B, generated by a rule B ::= B X, appears on the right-hand side of a rule S ::= A B, we can make S recursive (by introducing a new rule S ::= S X) and eliminate the original recursive rule (B ::= B X). Due to the rule S ::= S X, the shapes of the parse trees associated with the left-hand-side nonterminal S become more "skewed". Thus, we name our approach skewed tabulation for CFL-reachability. Skewed tabulation can significantly improve the scalability of CFL-reachability by reducing wasted and unnecessary summary edges. We have implemented skewed tabulation and applied the corresponding CFL-reachability algorithm to an alias analysis, a value-flow analysis, and a taint analysis. Our extensive evaluation based on SPEC 2017 benchmarks yields promising results. For the three client analyses, CFL-reacha

关键词： CFL-reachability tabulation schemes performance

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Pointer analysis for programs with structures and casting

Proceedings of the ACM SIGPLAN Conference on Programming Lan...

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Proceedings of the acm sigplan conference on programming language design and implementation (pldi) 1999年 91-103页

作者： Yong, Suan Hsi Horwitz, Susan Reps, Thomas Univ of Wisconsin-Madison Madison WI United States

Type casting allows a program to access an object as if it had a type different from its declared type. This complicates the design of a pointer-analysis algorithm that treats structure fields as separate objects;therefore, some previous pointer-analysis algorithms `collapse' a structure into a single variable. The disadvantage of this approach is that it can lead to very imprecise points-to information. Other algorithms treat each field as a separate object based on its offset and size. While this approach leads to more precise results, the results are not portable because the memory layout of structures is implementation dependent. This paper first describes the complications introduced by type casting, then presents a tunable pointer-analysis framework for handling structures in the presence of casting. Different instances of this framework produce algorithms with different levels of precision, portability, and efficiency. Experimental results from running our implementations of four instances of this framework show that (i) it is important to distinguish fields of structures in pointer analysis, but (ii) making conservative approximations when casting is involved usually does not cost much in terms of time, space, or the precision of the results.

关键词： Computer programming languages

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Abstractions for recursive pointer data structures. Improving the analysis and transformation of imperative programs

Abstractions for recursive pointer data structures. Improvin...

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acm sigplan '92 conference on programming language design and implementation, pldi 1992

作者： Hendren, Laurie J. Hummel, Joseph Nicolau, Alexandru McGill Univ

ISBN: (纸本)0897914759

Even though impressive progress has been made in the area of optimizing and parallelizing programs with arrays, the application of similar techniques to programs with pointer data structures has remained difficult. In this paper we introduce a new approach that leads to improved analysis and transformation of programs with recursively-defined pointer data structures. Our approach is based on a mechanism for the Abstract Description of Data Structures (ADDS), which makes explicit the important properties, such as dimensionality, of pointer data structures. Numerous examples demonstrate that ADDS definitions are both natural to specify and flexible enough to describe complex, cyclic pointer data structures. We discuss how an abstract data structure description can improve program analysis by presenting an analysis approach that combines an alias analysis technique, path matrix analysis, with information available from an ADDS declaration. Given this improved alias analysis technique, we provide a concrete example of applying a software pipelining transformation to loops involving pointer data structures.

关键词： Computer programming

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Relaxing SIMD control flow constraints using loop transformations

Relaxing SIMD control flow constraints using loop transforma...

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acm sigplan '92 conference on programming language design and implementation, pldi 1992

作者： Hanxleden, Reinhard v. Kennedy, Ken Rice Univ Houston TX United States

ISBN: (纸本)0897914759

Many loop nests in scientific codes contain a parallelizable outer loop but have an inner loop for which the number of iterations varies between different iterations of the outer loop. When running this kind of loop nest on a SIMD machine, the SIMD-inherent restriction to single program counter common to all processors will cause a performance degradation relative to comparable MIMD implementations. This problem is not due to limited parallelism or bad load balance, it is merely a problem of control flow. This paper presents a loop transformation, which we call loop flattening, that overcomes this limitation by letting each processor advance to the next loop iteration containing useful computation, if there is such an iteration for the given processor. We study a concrete example derived from a molecular dynamics code and compare performance results for flattened and unflattened versions of this kernel on two SIMD machines, the CM-2 and the DECmpp 12000. We then evaluate loop flattening from the compiler's perspective in terms of applicability, cost, profitability, and safety. We conclude with arguing that loop flattening, whether performed by the programmer or by the compiler, introduces negligible overhead and can significantly improve the performance of scientific codes for solving irregular problems.

关键词： Computer programming

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Escape analysis on lists

Escape analysis on lists

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acm sigplan '92 conference on programming language design and implementation, pldi 1992

作者： Park, Young Gil Goldberg, Benjamin New York Univ New York City NY United States

ISBN: (纸本)0897914759

Higher order functional programs constantly allocate objects dynamically. These objects are typically cons cells, closures, and records and are generally allocated in the heap and reclaimed later by some garbage collection process. This paper describes a compile time analysis, called escape analysis, for determining the lifetime of dynamically created objects in higher order functional programs, and describes optimizations that can be performed, based on the analysis, to improve storage allocation and reclamation of such objects. In particular, our analysis can be applied to programs manipulating lists, in which case optimizations can be performed to allow cons cells in spines of lists to be either reclaimed immediately or reused without incurring any garbage collection overhead. In a previous paper on escape analysis, we had left open the problem of performing escape analysis on lists. Escape analysis simply determines when the argument (or some part of the argument) to a function call is returned by that call. This simple piece of information turns out to be sufficiently powerful to allow stack allocation of objects, compile-time garbage collection, reduction of run-time storage reclamation overhead, and other optimizations that are possible when the lifetimes of objects can be computed statically. Our approach is to define a high-level non-standard semantics that, in many ways, is similar to the standard semantics and captures the escape behavior caused by the constructs in a functional language. The advantage of our analysis lies in its conceptual simplicity and portability (i.e. no assumption is made about an underlying abstract machine).

关键词： Computer programming

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Support for garbage collection at every instruction in a JavaTM compiler

Proceedings of the ACM SIGPLAN Conference on Programming Lan...

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Proceedings of the acm sigplan conference on programming language design and implementation (pldi) 1999年 118-127页

作者： Stichnoth, James M. Lueh, Guei-Yuan Cierniak, Michal Intel Corp Santa Clara United States

A high-performance implementation of a Java Virtual Machine requires a compiler to translate Java bytecodes into native instructions, as well as an advanced garbage collector (e.g., copying or generational). When the Java heap is exhausted and the garbage collector executes, the compiler must report to the garbage collector all live object references contained in physical registers and stack locations. Typical compilers only allow certain instructions (e.g., call instructions and backward branches) to be GC-safe;if GC happens at some other instruction, the compiler may need to advance execution to the next GC-safe point. Until now, no one has ever attempted to make every compiler-generated instruction GC-safe, due to the perception that recording this information would require too much space. This kind of support could improve the GC performance in multithreaded applications. We show how to use simple compression techniques to reduce the size of the GC map to about 20% of the generated code size, a result that is competitive with the best previously published results. In addition, we extend the work of Agesen, Detlefs, and Moss, regarding the so-called `JSR Problem' (the single exception to Java's type safety property), in a way that eliminates the need for extra runtime overhead in the generated code.

关键词： Java programming language

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Introducing 1st acm sigplan TRUST Workshop on Reproducible Research Methodologies and New Publication Models in Computer Engineering

Proceedings of the ACM SIGPLAN Conference on Programming Lan...

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Proceedings of the acm sigplan conference on programming language design and implementation (pldi) 2014年

作者： Fursin, Grigori Childers, Bruce Jones, Alex K. Mosse, Daniel INRIA France University of Pittsburgh United States

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