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Definite Assignment Analysis
In computer science, definite assignment analysis is a data-flow analysis used by compilers to conservatively ensure that a variable or location is always assigned before it is used. Motivation In C and C++ programs, a source of particularly difficult-to-diagnose errors is the nondeterministic behavior that results from reading uninitialized variables; this behavior can vary between platforms, builds, and even from run to run. There are two common ways to solve this problem. One is to ensure that all locations are written before they are read. Rice's theorem establishes that this problem cannot be solved in general for all programs; however, it is possible to create a conservative (imprecise) analysis that will accept only programs that satisfy this constraint, while rejecting some correct programs, and definite assignment analysis is such an analysis. The Java and C# programming language specifications require that the compiler report a compile-time error if the analysis fails. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer Science
Computer science is the study of computation, information, and automation. Computer science spans Theoretical computer science, theoretical disciplines (such as algorithms, theory of computation, and information theory) to Applied science, applied disciplines (including the design and implementation of Computer architecture, hardware and Software engineering, software). Algorithms and data structures are central to computer science. The theory of computation concerns abstract models of computation and general classes of computational problem, problems that can be solved using them. The fields of cryptography and computer security involve studying the means for secure communication and preventing security vulnerabilities. Computer graphics (computer science), Computer graphics and computational geometry address the generation of images. Programming language theory considers different ways to describe computational processes, and database theory concerns the management of re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Data-flow Analysis
Data-flow analysis is a technique for gathering information about the possible set of values calculated at various points in a computer program. It forms the foundation for a wide variety of compiler optimizations and program verification techniques. A program's control-flow graph (CFG) is used to determine those parts of a program to which a particular value assigned to a variable might propagate. The information gathered is often used by compilers when optimizing compiler, optimizing a program. A canonical example of a data-flow analysis is reaching definitions. Other commonly used data-flow analyses include live variable analysis, available expressions, constant propagation, and very busy expressions, each serving a distinct purpose in compiler optimization passes. A simple way to perform data-flow analysis of programs is to set up data-flow equations for each node (computer science), node of the control-flow graph and solve them by repeatedly calculating the output from the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Compiler
In computing, a compiler is a computer program that Translator (computing), translates computer code written in one programming language (the ''source'' language) into another language (the ''target'' language). The name "compiler" is primarily used for programs that translate source code from a high-level programming language to a lower level language, low-level programming language (e.g. assembly language, object code, or machine code) to create an executable program.Compilers: Principles, Techniques, and Tools by Alfred V. Aho, Ravi Sethi, Jeffrey D. Ullman - Second Edition, 2007 There are many different types of compilers which produce output in different useful forms. A ''cross-compiler'' produces code for a different Central processing unit, CPU or operating system than the one on which the cross-compiler itself runs. A ''bootstrap compiler'' is often a temporary compiler, used for compiling a more permanent or better optimised compiler for a language. Related software ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
C Programming Language
C (''pronounced'' '' – like the letter c'') is a general-purpose programming language. It was created in the 1970s by Dennis Ritchie and remains very widely used and influential. By design, C's features cleanly reflect the capabilities of the targeted Central processing unit, CPUs. It has found lasting use in operating systems code (especially in Kernel (operating system), kernels), device drivers, and protocol stacks, but its use in application software has been decreasing. C is commonly used on computer architectures that range from the largest supercomputers to the smallest microcontrollers and embedded systems. A successor to the programming language B (programming language), B, C was originally developed at Bell Labs by Ritchie between 1972 and 1973 to construct utilities running on Unix. It was applied to re-implementing the kernel of the Unix operating system. During the 1980s, C gradually gained popularity. It has become one of the most widely used programming langu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Uninitialized Variable
In computing, an uninitialized variable is a variable (programming), variable that is declared but is not set to a definite known value before it is used. It will have ''some'' value, but not a predictable one. As such, it is a programming error and a common source of computer bug, bugs in software. Example of the C language A common assumption made by novice programmers is that all variables are set to a known value, such as zero, when they are declared. While this is true for many languages, it is not true for all of them, and so the potential for error is there. Languages such as C (programming language), C use stack (data structure), stack space for variables, and the collection of variables allocated for a subroutine is known as a stack frame. While the computer will set aside the appropriate amount of space for the stack frame, it usually does so simply by adjusting the value of the stack pointer (computer programming), pointer, and does not set the computer storage, memory ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rice's Theorem
In computability theory, Rice's theorem states that all non-trivial semantic properties of programs are undecidable problem, undecidable. A ''semantic'' property is one about the program's behavior (for instance, "does the program halting problem, terminate for all inputs?"), unlike a syntactic property (for instance, "does the program contain an if-then-else statement?"). A ''non-trivial'' property is one which is neither true for every program, nor false for every program. The theorem generalizes the undecidability of the halting problem. It has far-reaching implications on the feasibility of static program analysis, static analysis of programs. It implies that it is impossible, for example, to implement a tool that checks whether any given program is correctness (computer science), correct, or even executes without error (it is possible to implement a tool that always overestimates or always underestimates, so in practice one has to decide what is less of a problem). The theorem ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Java Programming Language
Java is a high-level, general-purpose, memory-safe, object-oriented programming language. It is intended to let programmers ''write once, run anywhere'' ( WORA), meaning that compiled Java code can run on all platforms that support Java without the need to recompile. Java applications are typically compiled to bytecode that can run on any Java virtual machine (JVM) regardless of the underlying computer architecture. The syntax of Java is similar to C and C++, but has fewer low-level facilities than either of them. The Java runtime provides dynamic capabilities (such as reflection and runtime code modification) that are typically not available in traditional compiled languages. Java gained popularity shortly after its release, and has been a popular programming language since then. Java was the third most popular programming language in according to GitHub. Although still widely popular, there has been a gradual decline in use of Java in recent years with other ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
C Sharp (programming Language)
C# ( pronounced: C-sharp) ( ) is a general-purpose high-level programming language supporting multiple paradigms. C# encompasses static typing, strong typing, lexically scoped, imperative, declarative, functional, generic, object-oriented (class-based), and component-oriented programming disciplines. The principal inventors of the C# programming language were Anders Hejlsberg, Scott Wiltamuth, and Peter Golde from Microsoft. It was first widely distributed in July 2000 and was later approved as an international standard by Ecma (ECMA-334) in 2002 and ISO/ IEC (ISO/IEC 23270 and 20619) in 2003. Microsoft introduced C# along with .NET Framework and Microsoft Visual Studio, both of which are technically speaking, closed-source. At the time, Microsoft had no open-source products. Four years later, in 2004, a free and open-source project called Microsoft Mono began, providing a cross-platform compiler and runtime environment for the C# programming language. A decad ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyclone (programming Language)
The Cyclone programming language was intended to be a safe dialect of the C language. It avoids buffer overflows and other vulnerabilities that are possible in C programs by design, without losing the power and convenience of C as a tool for system programming. It is no longer supported by its original developers, with the reference tooling not supporting 64-bit platforms. The Rust language is mentioned by the original developers for having integrated many of the same ideas Cyclone had. Cyclone development was started as a joint project of Trevor Jim from AT&T Labs Research and Greg Morrisett's group at Cornell University in 2001. Version 1.0 was released on May 8, 2006. Language features Cyclone attempts to avoid some of the common pitfalls of C, while still maintaining its look and performance. To this end, Cyclone places the following limits on programs: * NULL checks are inserted to prevent segmentation faults * Pointer arithmetic is limited * Pointers must be initialize ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Compiler Optimization
An optimizing compiler is a compiler designed to generate code that is optimized in aspects such as minimizing program execution time, memory usage, storage size, and power consumption. Optimization is generally implemented as a sequence of optimizing transformations, a.k.a. compiler optimizations algorithms that transform code to produce semantically equivalent code optimized for some aspect. Optimization is limited by a number of factors. Theoretical analysis indicates that some optimization problems are NP-complete, or even undecidable. Also, producing perfectly ''optimal'' code is not possible since optimizing for one aspect often degrades performance for another. Optimization is a collection of heuristic methods for improving resource usage in typical programs. Categorization Local vs. global scope Scope describes how much of the input code is considered to apply optimizations. Local scope optimizations use information local to a basic block. Since basic blocks cont ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Common Language Infrastructure
The Common Language Infrastructure (CLI) is an open specification and technical standard originally developed by Microsoft and standardized by International Organization for Standardization, ISO/International Electrotechnical Commission, IEC (ISO/IEC 23271) and Ecma International (ECMA 335) that describes executable code and a runtime environment that allows List of CLI languages, multiple high-level languages to be used on different Computing platform, computer platforms without being rewritten for specific architectures. This implies it is platform agnostic. The .NET Framework, .NET and Mono (software), Mono are implementations of the CLI. The metadata format is also used to specify the API definitions exposed by the Windows Runtime. Overview Among other things, the CLI specification describes the following five aspects: ;The Common Type System (CTS) :A set of data types and operations that are shared by all CTS-compliant programming languages. ;The Metadata (CLI), Metadata :In ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Constant Propagation
Constant folding and constant propagation are related compiler optimizations used by many modern compilers. An advanced form of constant propagation known as sparse conditional constant propagation can more accurately propagate constants and simultaneously remove dead code. Constant folding Constant folding is the process of recognizing and evaluating constant expressions at compile time rather than computing them at runtime. Terms in constant expressions are typically simple literals, such as the integer literal 2, but they may also be variables whose values are known at compile time. Consider the statement: i = 320 * 200 * 32; Most compilers would not actually generate two multiply instructions and a store for this statement. Instead, they identify constructs such as these and substitute the computed values at compile time (in this case, 2,048,000). Constant folding can make use of arithmetic identities. If x is numeric, the value of 0 * x is zero even if the compiler ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
