Branch prediction need not be a concern at the source level. Compiler design frank pfenning lecture 17 october 22, 20 1 introduction optimizing loops is particularly important in compilation, since loops and in particular the inner loops account for much of the executions times of many programs. Loop optimization in compiler design, code motion in compiler design, induction variable in compiler design, reduction in strength in compiler design, loop fusion in compiler design, loop jamming in compiler design, loop variant in compiler design, loop unrolling in compiler design, compiler design lecture notes pdf, compiler design notes pdf jntu, compiler design study material jntu. The machineindependent codeoptimization phase consists of control. The important loop optimizations are elimination of loop invariant computations and elimination of induction variables. Survey common optimization techniques and the theory behind them. Compiler constructionoptimization wikibooks, open books. Oct 20, 2015 a compiler takes source code and converts it into byte code. This video discuss all loop optimization techniques with the help of an example.
It plays an important role in improving cache performance and making effective use of parallel processing capabilities. Compiler jobs jobs for compiler developers and related technologies. Compiler optimization and code generation lecture 1 developed by. Optimizations you should do regardless of processor compiler.
Programming experience in the context of a larger system is helpful. Compiler connection a resource for compiler developers and those who use their products and services. Global optimization compiler design i 2011 2 lecture outline global flow analysis global constant propagation liveness analysis compiler design i 2011 3 local optimization recall the simple basicblock optimizations constant propagation dead code elimination x. Optimizations provided by a compiler includes inlining small functions,code hoisting,dead store elimination,eliminating common subexpressions, loop unrolling, loop optimizations. At the highest optimization levels, these compilers produce executables that perform similarly. Good compilers with decent optimization should yield the same assembly for all of these. In order to perform hand optimization, you really need to get a handle on the data dependencies of your loops. Loop optimization is the most valuable machineindependent optimization because a programs inner loops are good candidates for improvement. Alternatives of profileguided code optimizations for onestage. Optimization before and after generating machine code, devote one or more passes over the program to improve code quality 2 compiler passes analysis of input program front end character stream lexical analysis code generation optimization intermediate code generation semantic analysis syntactic analysis annotated ast abstract syntax. Code optimization during various phases i language features that produce poor code or inhibit various optimizations. Algorithms and examples, 2nd ed kindle edition by deb, kalyanmoy. Loop optimization in compiler design loop optimization is the process of increasing execution speed and reducing the overheads associated with loops.
Updated to include the latest techniques, the compiler design handbook, second edition offers a unique opportunity for designers and researchers to update their knowledge, refine their skills, and prepare for emerging innovations. Download it once and read it on your kindle device, pc, phones or tablets. Optimization is a program transformation technique, which tries to improve the code by making it consume less resources i. Threeaddress intermediate code each instruction is of the form x. Some compilers can optimize the code so that it runs faster. You will end up using compiler design principles in almost. Code optimization in compiler design the code optimization in the synthesis phase is a program transformation technique, which tries to improve the intermediate code by making it consume fewer resources i. Loops can be optimized by the following techniques.
Nonconfidential pdf versionarm dui0375h arm compiler v5. Use features like bookmarks, note taking and highlighting while reading optimization for engineering design. Compiler optimization techniques sandro spina department of computer science, faculty of ict february 5, 2014 sandro spina optimizing compilers. On modern computers, a compiler can be considered to have satisfactory performance if it translates a moderate size source program say about lines in a matter of seconds. Fixing timing problems with better placement technology is more of a last ditch effort than a state of the art. Compiler books parsing, code generation, optimization, language design, debuggers, compiler theory. Through post code generation, optimization process can be applied on the code, but that can be seen as a part of code generation phase itself. For example if you have source code that looks like this. Code motion, induction variable elimination, and reduction in strength. Four programming assignments provide experience with implementation and evaluation of compilation techniques. In the real world, of course, it isnt particularly likely that a developer is going to explicitly write a statement like x x 1 so it isnt particularly important that a compiler optimizes that specific statement. The code generated by the compiler is an object code of some lowerlevel programming language, for example, assembly language. If we decrease the number of instructions in an inner loop then the running time of a program may be improved even if we increase the amount of code outside that loop. If your compiler supports a restrict keyword, you may get slightly better performance by grabbing vectors array and summing in a forloop a more c approach.
A code optimizing process must follow the three rules given below. An undergraduate compiler course or permission of instructor. Analysis and optimization techniques are presented in class lectures. Loop optimization in compiler design geeksforgeeks.
The examples in the document youre linking to are and are intended to be simplified examples of a particular type of optimization. We nd clang to be much more aggressive in optimizations at a lower level. The completely revised handbook includes 14 new chapters addressing topics such as worst case execution time. If you continue browsing the site, you agree to the use of cookies on this website. An important part of semantic analysis is type checking, where the compiler checks that each operator has matching. Fox, optimization methods in engineering design, addison wesley. In this video, we will discuss about the code optimization techniques in compiler design. This course is about optimizing compilers methods for automatically improving. Acquaint users with general optimization concepts and techniques. Pdf classification of compiler optimizations for high.
The presence of multiple local minima calls for the application of global optimization techniques. Cpu, memory so that fasterrunning machine code will result. Optimization via a sequence of loop transformations loop optimization can be viewed as the application of a sequence of specific loop transformations listed below or in compiler transformations for highperformance computing 2 to the source code or intermediate representation, with each transformation having an associated test for legality. The lexical analyzer reads the stream of characters making up the source program and groups the characters into meaningful sequences called lexemes. Operations that do not share data dependencies can be performed in tandum. Loop optimization most programs run as a loop in the system. Loop optimization loop optimization is most valuable machineindependent optimization because programs inner loop takes bulk to time of a programmer. In optimization, highlevel general programming constructs are replaced by very efficient lowlevel programming codes. A fragment of code that resides in the loop and computes the same value at each iteration is called a loopinvariant code.
It becomes necessary to optimize the loops in order to save cpu cycles and memory. A compiler takes source code and converts it into byte code. Consider the design of a simple tubular symmetric truss shown in fig. Global optimizations need some special analysis like global data flow static analysis to span across basic block or interprocedural analysis to span function. Loop optimizations loop invariant code motion induction variables. The effectiveness of these techniques is evaluated for a vliwarchitecture elbrus compiler. Intermediate code generationimprovement, and machine code generationimprovement tasks. With profileguided optimization, the compiler can lay out basic blocks to eliminate branches for the most frequently executed paths of a function or at least improve their predictability.
Compilers often have to rewrite code to take maximal advantage of these designs. Design optimization massachusetts institute of technology. Can be seen as part of a larger global optimization problem. Optimizations provided by a compiler includes inlining small functions,code hoisting,dead store elimination,eliminating common subexpressions,loop unrolling,loop optimizations. For instance, lexicalsemanticcode generation phases require linear time in terms of size of. Rtl coding and optimization guide for use with design. Classification of compiler optimizations for high performance, small area and low power in fpgas abstract article pdf available july 2008 with 99 reads how we measure reads. This paper deals with the comparative study on various compiler optimization techniques. May 18, 2018 this video discuss all loop optimization techniques with the help of an example. Common requirements are to minimize a programs execution time, memory requirement, and power consumption the last two being popular for portable computers. Cs3300 compiler design introduction to optimizations.
Code optimization in compiler design geeksforgeeks. A fragment of code that resides in the loop and computes the same value at each iteration is called a loop invariant code. Jan 28, 2017 in this video, we will discuss about the code optimization techniques in compiler design. Introduction to machineindependent optimizations 1 nptel. These parameters are called design variables in the parlance of optimization procedures. Code generation can be considered as the final phase of compilation. Cs3300 compiler design basic block optimizations v. Krishna nandivada iit madras optimization of basic blocks it is a linear piece of code. During controlflow analysis, a program is represented as a flow graph. A design of the truss is specified by a unique set of values for the analysis variables. University of amsterdam csa computer systems architecture introduction to compiler design. Optimizations in compiler design software engineering stack. New optimization techniques in engineering reports applications and results of the novel optimization techniques considering a multitude of practical problems in the different engineering disciplines presenting both the background of the subject area.
Instead of replacing predictive heuristics, ose uses the compiler writers knowledge encoded in the heuristics to select a small number of promising optimization alternatives for a. Vazgen melikyan 7 lexical analyzer the first phase of a compiler is called lexical analysis or scanning. Pdf effects of compiler optimizations in openmp to cuda. I byname parameters i function that have side e ects, which may make code elimination or code movement impossible i alias creation, which can make redundant expression analysis very di cult i exceptions, which can cause unexpected and invisible jumps to handlers. For instance, lexicalsemanticcode generation phases require linear time in terms of size of programs, whereas certain optimization techniques may require quadratic or cubic order. Code optimization is a technique which tries to improve the code by. The objective of this course is to learn basic and advanced compiler optimization techniques, either traditional or modern in their scope, or scalarvariable based or loopoptimization based in their application or machine independent or dependent in their variety. The way to get a compiler with satisfactory performance is more or less the same way you would get any program performing well.
Intermediate code generation process introduces many inefficiencies. This paper is a minicourse about global optimization techniques in nonconvex programming. What is the importance of global optimization in compiler design. Code optimization techniques in compiler design youtube. A design problem usually involves many design parameters, of which some are highly sensitive to the proper working of the design. The objective of this course is to learn basic and advanced compiler optimization techniques, either traditional or modern in their scope, or scalarvariable based or loop optimization based in their application or machine independent or dependent in their variety. If your compiler supports a restrict keyword, you may get slightly better performance by grabbing vectors array and summing in a for loop a more c approach. In computing, an optimizing compiler is a compiler that tries to minimize or maximize some attributes of an executable computer program. During semantic analysis the compiler tries to detect constructs then have the right syntactic structure but no meaning to the operation involved. Local optimizations are those which cannot span function or basic block boundaries. What i have noticed about the industry today, is that it is focused on the wrong end of the development cycle.
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