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In computer science, loop inversion is a compiler optimization and loop transformation in which a while loop is replaced by an if block containing a do..while loop. When used correctly, it may improve performance due to instruction pipelining .
Loop unrolling, also known as loop unwinding, is a loop transformation technique that attempts to optimize a program's execution speed at the expense of its binary size, which is an approach known as space–time tradeoff. The transformation can be undertaken manually by the programmer or by an optimizing compiler.
In the C programming language, Duff's device is a way of manually implementing loop unrolling by interleaving two syntactic constructs of C: the do-while loop and a switch statement. Its discovery is credited to Tom Duff in November 1983, when Duff was working for Lucasfilm and used it to speed up a real-time animation program.
A diagram depicting an optimizing compiler removing a potentially useless call to assembly instruction "b" by sinking it to its point of use. Code Sinking, also known as lazy code motion, is a term for a technique that reduces wasted instructions by moving instructions to branches in which they are used: [1] If an operation is executed before a branch, and only one of the branch paths use the ...
The loop counter is used to decide when the loop should terminate and for the program flow to continue to the next instruction after the loop. A common identifier naming convention is for the loop counter to use the variable names i , j , and k (and so on if needed), where i would be the most outer loop, j the next inner loop, etc.
The programming control structures on which autoparallelization places the most focus are loops, because, in general, most of the execution time of a program takes place inside some form of loop. There are two main approaches to parallelization of loops: pipelined multi-threading and cyclic multi-threading. [ 3 ]
The GNU Compiler Collection is one compiler known to perform instruction scheduling, using the -march (both instruction set and scheduling) or -mtune (only scheduling) flags. It uses descriptions of instruction latencies and what instructions can be run in parallel (or equivalently, which "port" each use) for each microarchitecture to perform ...
A snippet of C code which prints "Hello, World!". The syntax of the C programming language is the set of rules governing writing of software in C. It is designed to allow for programs that are extremely terse, have a close relationship with the resulting object code, and yet provide relatively high-level data abstraction.