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Twelve years have passed since the first edition of Modern Compiler Design. The book adds new material to cover the developments in compiler design and. Contribute to germanoa/compiladores development by creating an account on GitHub. Where Can I Find Necessary Files for Creating a Compiler in C?. .. This document is a companion to the textbook Modern Compiler Design by David.

Modern Compiler Design Pdf

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Ten years have passed since the first edition of Modern Compiler Design. For many computer science subjects this would be more than a life. Modern Compiler Design, First Edition For more information, see the Preface ( in PostScript or or in PDF), the Table of Contents (in PostScript or or in PDF). "Modern Compiler Design" makes the topic of compiler design more accessible DRM-free; Included format: PDF; ebooks can be used on all reading devices.

Please help improve this section by adding citations to reliable sources. Unsourced material may be challenged and removed. September Learn how and when to remove this template message A compiler implements a formal transformation from a high-level source program to a low-level target program.

Compiler design can define an end to end solution or tackle a defined subset that interfaces with other compilation tools e. Design requirements include rigorously defined interfaces both internally between compiler components and externally between supporting toolsets. In the early days, the approach taken to compiler design was directly affected by the complexity of the computer language to be processed, the experience of the person s designing it, and the resources available. Resource limitations led to the need to pass through the source code more than once.

A compiler for a relatively simple language written by one person might be a single, monolithic piece of software. However, as the source language grows in complexity the design may be split into a number of interdependent phases. Separate phases provide design improvements that focus development on the functions in the compilation process. One-pass versus multi-pass compilers[ edit ] Classifying compilers by number of passes has its background in the hardware resource limitations of computers.

Compiling involves performing lots of work and early computers did not have enough memory to contain one program that did all of this work. So compilers were split up into smaller programs which each made a pass over the source or some representation of it performing some of the required analysis and translations.

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The ability to compile in a single pass has classically been seen as a benefit because it simplifies the job of writing a compiler and one-pass compilers generally perform compilations faster than multi-pass compilers.

Thus, partly driven by the resource limitations of early systems, many early languages were specifically designed so that they could be compiled in a single pass e. In some cases the design of a language feature may require a compiler to perform more than one pass over the source. For instance, consider a declaration appearing on line 20 of the source which affects the translation of a statement appearing on line In this case, the first pass needs to gather information about declarations appearing after statements that they affect, with the actual translation happening during a subsequent pass.

The disadvantage of compiling in a single pass is that it is not possible to perform many of the sophisticated optimizations needed to generate high quality code. It can be difficult to count exactly how many passes an optimizing compiler makes. For instance, different phases of optimization may analyse one expression many times but only analyse another expression once.

Splitting a compiler up into small programs is a technique used by researchers interested in producing provably correct compilers. Proving the correctness of a set of small programs often requires less effort than proving the correctness of a larger, single, equivalent program. Three-stage compiler structure[ edit ] Compiler design Regardless of the exact number of phases in the compiler design, the phases can be assigned to one of three stages. The stages include a front end, a middle end, and a back end.

The front end verifies syntax and semantics according to a specific source language. For statically typed languages it performs type checking by collecting type information.

If the input program is syntactically incorrect or has a type error, it generates errors and warnings, highlighting[ dubious — discuss ] them on the source code. Aspects of the front end include lexical analysis, syntax analysis, and semantic analysis. The front end transforms the input program into an intermediate representation IR for further processing by the middle end. This IR is usually a lower-level representation of the program with respect to the source code.

The middle end performs optimizations on the IR that are independent of the CPU architecture being targeted. Examples of middle end optimizations are removal of useless dead code elimination or unreachable code reachability analysis , discovery and propagation of constant values constant propagation , relocation of computation to a less frequently executed place e.

Eventually producing the "optimized" IR that is used by the back end. The back end takes the optimized IR from the middle end. It may perform more analysis, transformations and optimizations that are specific for the target CPU architecture. The back end generates the target-dependent assembly code, performing register allocation in the process. The back end performs instruction scheduling , which re-orders instructions to keep parallel execution units busy by filling delay slots.

Although most algorithms for optimization are NP-hard , heuristic techniques are well-developed and currently implemented in production-quality compilers. Typically the output of a back end is machine code specialized for a particular processor and operating system. Front end[ edit ] Lexer and parser example for C. The latter sequence is transformed by the parser into a syntax tree , which is then treated by the remaining compiler phases.

The scanner and parser handles the regular and properly context-free parts of the grammar for C , respectively.

Modern Compiler Design

The front end analyzes the source code to build an internal representation of the program, called the intermediate representation IR. It also manages the symbol table , a data structure mapping each symbol in the source code to associated information such as location, type and scope. While the frontend can be a single monolithic function or program, as in a scannerless parser , it is more commonly implemented and analyzed as several phases, which may execute sequentially or concurrently.

This method is favored due to its modularity and separation of concerns. Most commonly today, the frontend is broken into three phases: lexical analysis also known as lexing , syntax analysis also known as scanning or parsing , and semantic analysis.

Lexing and parsing comprise the syntactic analysis word syntax and phrase syntax, respectively , and in simple cases these modules the lexer and parser can be automatically generated from a grammar for the language, though in more complex cases these require manual modification. The lexical grammar and phrase grammar are usually context-free grammars , which simplifies analysis significantly, with context-sensitivity handled at the semantic analysis phase.

The semantic analysis phase is generally more complex and written by hand, but can be partially or fully automated using attribute grammars. These phases themselves can be further broken down: lexing as scanning and evaluating, and parsing as building a concrete syntax tree CST, parse tree and then transforming it into an abstract syntax tree AST, syntax tree. In some cases additional phases are used, notably line reconstruction and preprocessing, but these are rare.

The main phases of the front end include the following: Line reconstruction converts the input character sequence to a canonical form ready for the parser. Languages which strop their keywords or allow arbitrary spaces within identifiers require this phase. The top-down , recursive-descent , table-driven parsers used in the s typically read the source one character at a time and did not require a separate tokenizing phase. Preprocessing supports macro substitution and conditional compilation.

Typically the preprocessing phase occurs before syntactic or semantic analysis; e. However, some languages such as Scheme support macro substitutions based on syntactic forms. Lexical analysis also known as lexing or tokenization breaks the source code text into a sequence of small pieces called lexical tokens.

A token is a pair consisting of a token name and an optional token value. The lexeme syntax is typically a regular language , so a finite state automaton constructed from a regular expression can be used to recognize it.

The software doing lexical analysis is called a lexical analyzer. This may not be a separate step—it can be combined with the parsing step in scannerless parsing , in which case parsing is done at the character level, not the token level. Syntax analysis also known as parsing involves parsing the token sequence to identify the syntactic structure of the program. This phase typically builds a parse tree , which replaces the linear sequence of tokens with a tree structure built according to the rules of a formal grammar which define the language's syntax.

The parse tree is often analyzed, augmented, and transformed by later phases in the compiler.

This phase performs semantic checks such as type checking checking for type errors , or object binding associating variable and function references with their definitions , or definite assignment requiring all local variables to be initialized before use , rejecting incorrect programs or issuing warnings.

Semantic analysis usually requires a complete parse tree, meaning that this phase logically follows the parsing phase, and logically precedes the code generation phase, though it is often possible to fold multiple phases into one pass over the code in a compiler implementation. Middle end[ edit ] The middle end, also known as optimizer, performs optimizations on the intermediate representation in order to improve the performance and the quality of the produced machine code.

The main phases of the middle end include the following: Analysis : This is the gathering of program information from the intermediate representation derived from the input; data-flow analysis is used to build use-define chains , together with dependence analysis , alias analysis , pointer analysis , escape analysis , etc.

Accurate analysis is the basis for any compiler optimization. The control flow graph of every compiled function and the call graph of the program are usually also built during the analysis phase. Optimization : the intermediate language representation is transformed into functionally equivalent but faster or smaller forms. Popular optimizations are inline expansion , dead code elimination , constant propagation , loop transformation and even automatic parallelization. Compiler analysis is the prerequisite for any compiler optimization, and they tightly work together.

For example, dependence analysis is crucial for loop transformation. The scope of compiler analysis and optimizations vary greatly; their scope may range from operating within a basic block , to whole procedures, or even the whole program. There is a trade-off between the granularity of the optimizations and the cost of compilation.

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For example, peephole optimizations are fast to perform during compilation but only affect a small local fragment of the code, and can be performed independently of the context in which the code fragment appears.

In contrast, interprocedural optimization requires more compilation time and memory space, but enable optimizations which are only possible by considering the behavior of multiple functions simultaneously. The free software GCC was criticized for a long time for lacking powerful interprocedural optimizations, but it is changing in this respect.

Another open source compiler with full analysis and optimization infrastructure is Open64 , which is used by many organizations for research and commercial purposes. Due to the extra time and space needed for compiler analysis and optimizations, some compilers skip them by default. Users have to use compilation options to explicitly tell the compiler which optimizations should be enabled.

The back end is responsible for the CPU architecture specific optimizations and for code generation [44]. The main phases of the back end include the following: Machine dependent optimizations: optimizations that depend on the details of the CPU architecture that the compiler targets. Code generation : the transformed intermediate language is translated into the output language, usually the native machine language of the system.

This involves resource and storage decisions, such as deciding which variables to fit into registers and memory and the selection and scheduling of appropriate machine instructions along with their associated addressing modes see also Sethi-Ullman algorithm. Debug data may also need to be generated to facilitate debugging. Main article: Compiler correctness Compiler correctness is the branch of software engineering that deals with trying to show that a compiler behaves according to its language specification.

In this way, dent with the capability of quickly constructing robust pro- he was able to make accurate predictions in 20 minutes. The cessors for a variety of language-related applications. This example is typical of a wide variety of situations in Categories and Subject Descriptors which a person needs to perform some kind of analysis or K. Very formation Science Education—computer science education few if any of our students will write conventional compil- ers, but most will need to develop compiler-like processors to solve such ancillary problems.

We believe that a mod- General Terms ern compiler construction course should prepare students Design for these tasks [28]. In order to provide that preparation, the course must build an understanding of general principles and how those Keywords principles apply in a variety of scenarios [19].

Students come to a course with certain expectations and 1. Section 3 explains the structure we used to con- vey the course material, and how it was based on these fac- The disparity between processor and memory speeds on tors.

Section 4 presents our experience with that pi- algorithm. Several days are required to do such a prediction lot. Any opinions, findings and 2. They provide designers with a vocabulary to describe the essential aspects of a problem, and to concentrate on the Permission to make digital or hard copies of all or part of this work for decisions that are not purely mechanical.

The principles are personal or classroom use is granted without fee provided that copies are well-supported by abstractions, specification languages, and not made or distributed for profit or commercial advantage and that copies tools. Introduces the theory and practice of program- ming language translation.

Topics include com- Our approach was to use these specifications in our explana- piler design, lexical analysis, parsing, symbol ta- tions of the design principles, and to describe various possi- bles, declaration and storage management, code ble design decisions by writing the corresponding specifica- generation, and optimization techniques.

Processors implementing those decisions could then be generated immediately and their behavior observed. Lexical analysis, parsing, and symbol tables are imple- mentation techniques that support general design princi- ples. We believe that a modern compiler construction course 3. Our goal was that stu- Students in a computer science curriculum belong to an dents completing our course would be able to develop lan- occupational community [27] that creates and sustains a guages for specific problem domains, including design of ap- work culture involving task rituals, standards for behavior, propriate syntax and relevant semantics.

They would under- and work practices. Declaration and storage management, code generation, and optimization techniques imply a compiler whose target 3.

That model embodies the Wednesday, and Friday morning.

The Monday and Friday instruction set, the procedure calling convention, the strat- meetings were in a normal classroom. Wednesdays we met egy for up-level addressing, and possibly garbage collection in a lab that had 30 workstations; the students also had and exception handling. As we shall see in Section 4, a unlimited access to this lab outside of class.

During the Wednesday lab ses- tasks described in Section 1, we chose to omit the treatment sion the students were given a realistic scenario and asked of specific models of computation and concentrate on the to write specifications to yield particular outcomes. They following design principles: would then use Eli to generate a processor from those spec- ifications, and verify its behavior. It also meant that the Mon- enumerated in the definition of CSs.

The Eli compiler toolkit [3] can construct an economically Computer science students tend to boldly display their viable translator from specifications of high-level decisions, own opinions, and disqualify the opinions of peers [23].

This thus obviating the need for coding in a programming lan- communication pattern leads to an environment character- guage. The specifications we used to support our design- ized by competitiveness rather than cooperation, and con- oriented approach are: descension rather than understanding.

Assignment selection is therefore a vital Because the students in our course are using specifica- component of the course design. We wanted them to help the students to balance is solved, there is no solution space to explore. Thus the their workload over time, and to engender a more structured student must come to grips with the problem itself in every work process. Finally, we wanted them to be fun — to make assignment. Most tasks assigned in programming courses can be car- ried out in complete ignorance of any process.

Students 3. Thus they preference for working alone [23]. The basic reason is that fall back on the experimentation ritual, believing that this they regard assignments as products, for which they are paid flexibility allows them to complete the assignment in the with a grade [13]. Effectively, they are operating at the We tried to counter this attitude by reducing the weight Initial stage of the Capability Maturity Model [14]. By edge of how to construct compilers, and therefore it forces using the conversational classroom strategy for the Monday a process on its users: Component problems must be un- and Friday sessions, we validated collaboration as an impor- derstood in a certain order, because the understanding of tant technique for improving understanding.

In the lab, we one depends on decisions made when understanding others. We pointed out that col- cannot even be stated completely. Moreover, the vocabu- laborative efforts arrive at better outcomes more rapidly [8], lary that must be used in describing the problems to be and spent an entire class period going through a structured solved requires the students to think about those problems group decision process [26].

The overall effect, in conjunction with the assignments and milestones, is to raise the students to the 3. Procrastination is a common ritual of computer science 3. It is often cast as a calculated risk, a game in which the student uses their superior skill to complete an The compiler course has a history of cancellations due assignment even though they have begun perilously close to to low enrollment, and one semester all of the students at- the deadline [23].

We To forestall this behavior, we made the first four assign- therefore made a significant effort to promote the Fall, ments self-contained, straightforward applications of mate- pilot, and to capture and retain student interest by using a rial discussed in class and practiced in the lab. It was there- variety of scenarios for assignments and lab exercises.

Our fore quite easy to predict the amount of effort required, and emphasis was on how to apply compiler technology to real- highly unlikely that a student would hit a snag that they world problems with which the students could identify. This meant that there was no ego We also hoped a self-selected project would be more fun boost associated with pulling off a coup at the last minute. Initial registration for the tor of some kind that required name analysis and had struc- course was 28; eight dropped and one added to make the tured output.

Projects ranged from conventional compilers final count The purpose of assessing assignments was to give the stones limited procrastination, but more importantly they students motivation to carry them out and formal feedback allowed for reflection about each step of the process. We on their approach to simple problems. They were required provided detailed feedback, and were able to spot problems to demonstrate their individual grasp of the basic principles that individual groups were having with concepts and im- on the midterm examination.

Modern Compiler Design

Project assessment was arranged both to motivate the stu- dents and to give them an opportunity to reflect on and 3. Students were then allowed to understand the problem [23]. This ritual is consistent to submit an updated version, addressing any issues raised with most assignments in such courses: There are many by the professor or TA, on Friday.

The final version of each ways to obtain a particular result, and searching the solution milestone was then graded and posted on the class web site. Getting a good understanding of the problem, however, may require them to learn additional concepts. RESULTS ated from specifications , and argued that they would have The 21 students submitted 11 projects [2], only three of nothing to show unless they were allowed to submit only the which were solo efforts; no project involved more than three Python version.

Despite our omission of specific models of com- On reflection, this was as much a failure on our part as putation Section 2 , four of the projects were conventional on theirs.

We did not sufficiently guard against the expec- compilers. Students have a number of expectations for a est to assess: We already had conformance and deviance programming course, among them the idea that if they are tests for the source languages COOL [9], Tiger [10], SOOL good programmers they can get through the course on that [12], and Mystery [17] , so validation was simply a matter skill alone. There is little need for them to be concerned of running those tests.

Although Eli supports the literate with the specifics of the material, because those specifics programming paradigm [21], only one of the groups made are nothing more than what their programs must do. One other group incorporated problems that they may not fully understand.

We should minimal documentation, and two provided separate docu- have therefore been continually on the lookout for student mentation. Thus on their target machine. Without that experience, the stu- we favor the pedagogic strategy that presents the topic in dents found it extremely difficult to decide on the code to be terms of support for communicating with a computer [28]. In the future, we would strongly urge a student Any course design must select the material to be included not to attempt a conventional compiler unless they had a and perhaps more importantly the material to be omitted.

Even the relatively unsuccessful group was able to a full semester to master, we agree with the recommendation come close to their stated goals, and we believe that their [24] to move the discussion of models of computation, code main problem was a lack of time on task. Students greatly appreciated the freedom to choose their The treatment of compiler construction should be kept at own projects within the guidelines mentioned in Section a high level by using formalisms to describe decisions and 3.

It was apparent from discussions with several groups tools to implement them. This is not a typical programming that this freedom did, indeed, allow them to do something class, and the instructor must be vigilant to prevent students about which they felt passionate. The tendency to implement rather Unfortunately, one group exploited the freedom of choice than understand is only one of the aspects of student culture to turn their project into a normal programming assignment that a successful course design must deal with.

They are faced with the lighting [6] particular constructs of that language. Name consequences of their design choices, good or bad, and must analysis would be required because of relations among the decide when to go on and when to backtrack.In the late s, assembly languages were created to offer a more workable abstraction of the computer architectures. French translation, titled Compilateurs , published by Dunod , pp. Compiling involves performing lots of work and early computers did not have enough memory to contain one program that did all of this work.

Middle end[ edit ] The middle end, also known as optimizer, performs optimizations on the intermediate representation in order to improve the performance and the quality of the produced machine code. Syntax analysis also known as parsing involves parsing the token sequence to identify the syntactic structure of the program.