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Single Compilation Unit
Single compilation unit (SCU) is a computer programming technique for the C and C++ languages, which reduces compilation time for programs spanning multiple files. Specifically, it allows the compiler to keep data from shared header files, definitions and templates, so that it need not recreate them for each file. It is an instance of program optimization. The technique can be applied to an entire program or to some subset of source files; when applied to an entire program, it is also known as a unity build. Purpose In the C/C++ compilation model (formally "translation environment"), individual / source files are preprocessed into translation units, which are then compiled separately by the compiler into multiple object ( or ) files. These object files can then be linked together to create a single executable file or library. However, this leads to multiple passes being performed on common header files, and with C++, multiple template instantiations of the same templates in d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer Programming
Computer programming or coding is the composition of sequences of instructions, called computer program, programs, that computers can follow to perform tasks. It involves designing and implementing algorithms, step-by-step specifications of procedures, by writing source code, code in one or more programming languages. Programmers typically use high-level programming languages that are more easily intelligible to humans than machine code, which is directly executed by the central processing unit. Proficient programming usually requires expertise in several different subjects, including knowledge of the Domain (software engineering), application domain, details of programming languages and generic code library (computing), libraries, specialized algorithms, and Logic#Formal logic, formal logic. Auxiliary tasks accompanying and related to programming include Requirements analysis, analyzing requirements, Software testing, testing, debugging (investigating and fixing problems), imple ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Interprocedural Optimization
Interprocedural optimization (IPO) is a collection of compiler techniques used in computer programming to improve performance in programs containing many frequently used Function (computer science), functions of small or medium length. IPO differs from other compiler optimizations by analyzing the entire program as opposed to a single function or block of code. IPO seeks to reduce or eliminate duplicate calculations and inefficient use of memory and to simplify iterative sequences such as loops. If a call to another routine occurs within a loop, IPO analysis may determine that it is best to Inline expansion, inline that routine. Additionally, IPO may re-order the routines for better memory layout and Memory locality, locality. IPO may also include typical compiler optimizations applied on a whole-program level, for example, dead code elimination (DCE), which removes code that is never executed. IPO also tries to ensure better use of constants. Modern compilers offer IPO as an opti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
C Preprocessor
The C preprocessor (CPP) is a text file processor that is used with C, C++ and other programming tools. The preprocessor provides for file inclusion (often header files), macro expansion, conditional compilation, and line control. Although named in association with C and used with C, the preprocessor capabilities are not inherently tied to the C language. It can and is used to process other kinds of files. C, C++, and Objective-C compilers provide a preprocessor capability, as it is required by the definition of each language. Some compilers provide extensions and deviations from the target language standard. Some provide options to control standards compliance. For instance, the GNU C preprocessor can be made more standards compliant by supplying certain command-line flags. The C# programming language also allows for directives, even though they cannot be used for creating macros, and is generally more intended for features such as conditional compilation. C# seldom re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Precompiled Header
In computer programming, a precompiled header (PCH) is a ( C or C++) header file that is compiled into an intermediate form that is faster to process for the compiler. Usage of precompiled headers may significantly reduce compilation time, especially when applied to large header files, header files that include many other header files, or header files that are included in many translation units. Rationale In the C and C++ programming languages, a header file is a file whose text may be automatically included in another source file by the C preprocessor by the use of a preprocessor directive in the source file. Header files can sometimes contain very large amounts of source code (for instance, the header files windows.h and Cocoa/Cocoa.h on Microsoft Windows and OS X, respectively). This is especially true with the advent of large "header" libraries that make extensive use of templates, like the Eigen math library and Boost C++ libraries. They are written almost entirel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Register Allocation
In compiler optimization, register allocation is the process of assigning local automatic variables and Expression (computer science), expression results to a limited number of processor registers. Register allocation can happen over a basic block (''local register allocation''), over a whole function/Subroutine, procedure (''global register allocation''), or across function boundaries traversed via call-graph (''interprocedural register allocation''). When done per function/procedure the calling convention may require insertion of save/restore around each Call site, call-site. Context Principle {, class="wikitable floatright" , + Different number of general-purpose registers in the most common architectures , - ! Architecture ! scope="col" , 32 bit ! scope="col" , 64 bit , - ! scope="row" , ARM , 15 , 31 , - ! scope="row" , Intel x86 , 8 , 16 , - ! scope="row" , MIPS , 32 , 32 , - ! scope="row" , POWER/PowerPC , 32 , 32 , - ! scope ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Side Effect (computer Science)
In computer science, an operation, function or expression is said to have a side effect if it has any observable effect other than its primary effect of reading the value of its arguments and returning a value to the invoker of the operation. Example side effects include modifying a non-local variable, a static local variable or a mutable argument passed by reference; raising errors or exceptions; performing I/O; or calling other functions with side-effects. In the presence of side effects, a program's behaviour may depend on history; that is, the order of evaluation matters. Understanding and debugging a function with side effects requires knowledge about the context and its possible histories. Side effects play an important role in the design and analysis of programming languages. The degree to which side effects are used depends on the programming paradigm. For example, imperative programming is commonly used to produce side effects, to update a system's state. By contrast ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Exception Handling
In computing and computer programming, exception handling is the process of responding to the occurrence of ''exceptions'' – anomalous or exceptional conditions requiring special processing – during the execution of a program. In general, an exception breaks the normal flow of execution and executes a pre-registered ''exception handler''; the details of how this is done depend on whether it is a hardware or software exception and how the software exception is implemented. Exceptions are defined by different layers of a computer system, and the typical layers are CPU-defined interrupts, operating system (OS)-defined signals, programming language-defined exceptions. Each layer requires different ways of exception handling although they may be interrelated, e.g. a CPU interrupt could be turned into an OS signal. Some exceptions, especially hardware ones, may be handled so gracefully that execution can resume where it was interrupted. Definition The definition of an excep ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inline Function
In the C (programming language), C and C++ programming languages, an inline function is one qualified with the Keyword (computer programming), keyword inline; this serves two purposes: # It serves as a compiler directive that suggests (but does not require) that the compiler substitute the body of the function inline by performing inline expansion, i.e. by inserting the function code at the address of each function call, thereby saving the overhead of a function call. In this respect it is analogous to the register storage class specifier, which similarly provides an optimization hint. # The second purpose of inline is to change linkage behavior; the details of this are complicated. This is necessary due to the C/C++ separate compilation + linkage model, specifically because the definition (body) of the function must be duplicated in all Translation unit (programming), translation units where it is used, to allow inlining during ''compiling'', which, if the function has external ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Link-time Optimization
Interprocedural optimization (IPO) is a collection of compiler techniques used in computer programming to improve performance in programs containing many frequently used functions of small or medium length. IPO differs from other compiler optimizations by analyzing the entire program as opposed to a single function or block of code. IPO seeks to reduce or eliminate duplicate calculations and inefficient use of memory and to simplify iterative sequences such as loops. If a call to another routine occurs within a loop, IPO analysis may determine that it is best to inline that routine. Additionally, IPO may re-order the routines for better memory layout and locality. IPO may also include typical compiler optimizations applied on a whole-program level, for example, dead code elimination (DCE), which removes code that is never executed. IPO also tries to ensure better use of constants. Modern compilers offer IPO as an option at compile-time. The actual IPO process may occur at any ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Optimizing Compiler
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] |
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] |
Distcc
In software development, distcc is a tool for speeding up compilation of source code by using distributed computing over a computer network. With the right configuration, distcc can dramatically reduce a project's compilation time. It is designed to work with the C programming language (and its derivatives like C++ and Objective-C) and to use GCC as its backend, though it provides varying degrees of compatibility with the Intel C++ Compiler and Sun Microsystems' Sun Studio Compiler Suite. Distributed under the terms of the GNU General Public License, distcc is free software. Design distcc is designed to speed up compilation by taking advantage of unused processing power on other computers. A machine with distcc installed can send code to be compiled across the network to a computer which has the distccd daemon and a compatible compiler installed. distcc works as an agent for the compiler. A distcc daemon has to run on each of the participating machines. The originating mac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
