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34

Keldysh Institute of Applied Mathematics

Russian Academy of Sciences

Fortran DVM compiler

Detailed design

Mart 2000

Contents

1 Compiler role 3

2 Command line format 3

3 The general scheme of compiler 5

3.1 Parsing 5

3.2 Transforming parse tree 5

3.3 Generating code in Fortran 77 5

3.4 Generating code in HPF 5

4 Basic data structures 5

4.1 Parse tree 6

4.2 Symbol and Type table 6

5 Detailed description of compiler modules 8

5.1 Translating Fortran DVM constructs (module dvm.cpp) 8

5.1.1 Distributed array creation and remapping 13

5.1.2 Distributed array referencing 17

5.1.3 Parallel loop 19

5.2 Translating input/output statements (module io.cpp) 22

5.3 Restructuring parse tree (module stmt.cpp) 25

5.4 Translating HPF-DVM constructs (module hpf.cpp) 29

5.4.1 Processing distributed array references in HPF-DVM 29

5.4.2 INDEPENDENT loop 30

This report presents the detailed description of the Fortran-DVM (FDVM) compiler implementation. The basic data structures, the control scheme, and the functions of compiler modules are considered.

1Compiler role

Fortran DVM (FDVM) language is an extension of the Fortran 77 language for parallel programming. The extension is implemented as special comments (directives) that annotate sequential program in Fortran 77.

The input to the compiler is source code in Fortran DVM or HPF-DVM language. The compiler produces the following output programs.

• Parallel program in Fortran 77 language including runtime system function calls (Lib-DVM) for parallel execution.

• Sequential program in Fortran 77 language which includes calls of functions accumulating information for debugging and performance analyzing.

• HPF program.

2Command line format

The format of the FDVM compiler command line is illustrated below:

dvm fdv [ <options> ] <file-name>

Source program is placed in input file <file-name>.fdv or <file-name>.hpf.

On the command-line <options> are the compiler options:

3The general scheme of compiler

Sage ++ system is used as a tool for designing FDVM compiler.

Sage++ is an object oriented toolkit for building program transformation systems for Fortran 77, Fortran 90, C and C++ languages. It is designed as an open C++ class library that provides the user with a set of parsers, a structured parse tree, a symbol and type table. The heart of the system is a set of functions that allow to restructure the parse tree and a mechanism (called unparsing) for generating new source code from the restructured internal form.

The FDVM compiler consists of four components:

• Parsing

• Transforming parse tree

• Generating code in Fortran 77

• Generating code in HPF

3.1Parsing

The Fortran parser of Sage++ which is based on the GNU Bison version of YACC is extended to add language extensions (DVM directives) to Fortran system. It consists of the following modules:

The parser reads the source, checks the concrete syntax, constructs a parse tree, and writes its internal representation in a .dep file.

3.2Transforming parse tree

Second phase of compiling involves analyzing and restructuring internal representation of FDVM program. A DVM directive is substituted for a sequence of Lib‑DVM function calls. Afterwards new source code is generated from restructured internal form.

Back-end of the compiler is written in C++ language using Sage++ class library.

The Sage++ library is organized as a class hierarchy that provides access to the parse tree, symbol table and type table for each file in an application project. There are five basic families of classes in the library: Project and Files, Statements, Expressions, Symbols, and Types.

Project and Files correspond to source files. Statements correspond to the basic source statements in Fortran 77 and DVM directives. Expressions are contained within statements. Symbols are the basic user defined identifiers. Types are associated with each identifier and expression.

The file libSage++.h contains all the class definitions.

Seven modules compound the translator:

3.3Generating code in Fortran 77

Generating new source code from the restructured internal form is implemented by the File class member function (unparse( )) of Sage++ class library.

3.4Generating code in HPF

When the source FDVM program is converted in HPF program the following routines and tables are used for unparsing:

4Basic data structures

The definitions of data structures of internal representation are contained in the files:

• bif.h (parse tree node for statement)

• ll.h (parse tree node for expression)

• symb.h (Symbol and Type Table elements)

4.1Parse tree

The structures of parse tree nodes for a statement and an expression are given in Fig. 4.1 and Fig.4.2 accordingly. The Fig. 4.4 illustrates the fragment of parse tree.

4.2Symbol and Type table

The Fig.4.3 presents the Symbol and Type Table entries.

variant tag

identification tag

index

global line number

local line number

declaration specifier

pointer to the label

pointer to the next statement node

pointer to the source filename

pointer to the control parent node

property list

list of nodes(list of procedures)

pointer to the comment

symbol table entry

L-value expr tree

R-value expr tree

spare expr tree

do-label (used by do)

null

null

null

null

Fig. 4.1. Parse tree node representing a statement (bif node).

variant tag

identification tag

pointer to the next node (by allocation order)

pointer to the Type table element

constant value

pointer to the Symbol table element

L-value expr tree

R-value expr tree

Fig. 4.2. Parse tree node representing an expression (low level node).

Parse Tree

Характеристики

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