UVa CS Zephyr Software EDG Installation

Installing EDG-based Zephyr compilers

Prerequisites

• Source code for the EDG C++ front end, version 2.40. This source is not included in the ``everything you need'' bundle, because it is available only under license from EDG, and you will need to license and download the source from EDG. Licenses to academic researchers are normally free of charge.

  Unpack the EDG front end in the edg directory, which will create the directory edg/release_2.40.

• Sparc-solaris VPO, version 2.0.
• The noweb literate-programming system. At the very least you need notangle to convert *.nw files to *.c and *.h files. You may also want noweave to make nice documents from the *.nw files.

Preliminaries

1. Build and install noweb, using the instructions in the noweb distribution.
2. Build VPO, using the instructions in the VPO distribution.
3. Check your PATH variable to ensure that the commands notangle, gcc, lorder, tsort, and ranlib all work. On a Solaris system, you will probably need to put /usr/ccs/bin in your PATH

Building the compiler

• cd edg-backends/sparc-solaris
• Modify the compiler driver script bin/eccp. This is a Bourne shell script and you will be changing settings of shell variables.
  • Set ZEPHYR_BASE to the location of your base directory (the one that contains the edg-backends directory).
  • Set VPO to point to your sparc-solaris VPO binary.
  • vpoflag is set to minimal optimization. You can change it in the script or override it on the eccp command line with -Vxxx. Be aware, however that VPO 2.0 has not been tested at higher levels of optimization.
• In the edg-backends/sparc-solaris directory, run make, which builds the following:
  • ./bin/edgcpfe -- parses a C or C++ source file and writes on stdout an input file for sparc-solaris VPO.
  • ./lib/decode -- a filter that converts raw VPO input on stdin to human readable form on stdout.
  • ./lib/libC.a -- EDG's minimal C++ run time library. The library is compiled with eccp itself. The library has just enough support for C++ language features (operators new and delete, exception handling, initializations before main(), cleanup after exit(), etc.) This library does not contain iostreams or any other class libraries.

Using the compiler

Compile with the ./bin/eccp driver script. You may want to make a symbolic link to it in a directory in your PATH.

By default, eccp compiles C++.

To compile ANSI C, use eccp --c or eccp -m.

To compile C++ with exception handling, use eccp -x. This option adds a fair amount of extra code to each function, so you probably don't want to use -x unless you need it.

Use the -k flag to ``keep'' all intermediate files. The *.cex file is the raw vpo input file. The *.dec file is the decoded *.cex file. You'll also get a *.s and a *.o file. You may also get several *.munch.* files. The eccp driver script may need to build a *.munch.c file on the fly that defines an array of pointers to initialization functions. The driver script compiles this file and links it in with the rest of the program, which causes the run time library to call the initialization functions when the C++ program starts.

Incompatibilities

Do not try to link C++ code with class libraries compiled by other C++ compilers; name mangling is probably different. Get source for the libraries you want to use, and compile them with eccp.

There is one major incompatibility between code compiled with EDG and code from Sun and GNU compilers; they use different calling conventions for functions returning structs by value. (Passing structs by value is compatible.) If a function returns a struct by value, be sure both the caller and callee are compiled with EDG or neither are compiled with EDG.

If you compile code that calls alloca(), you'll probably need to link with a portable version of alloca(). Sun and GNU compilers both treat alloca() as a special case, replacing it inline assembly code that manipulates the stack. EDG does not tolerate this stack manipulation, so you must obtain a callable alloca() and link with it.

Documentation

The EDG C++ front end document edg/release_2.40/doc/plm.PostScript is very large and includes a section on command line options for edgcpfe. The eccp driver script does not recognize most edgcpfe options, so it just passes any unrecognized options to edgcpfe.

The annotated source for the sparc-solaris VPO input generating back end is edg-backends/sparc-solaris/sparc-vpo-be.c.PostScript. It is built from the noweb source file sparc-vpo-be.c.nw. Any *.nw file can be formatted with noweave.