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Installing GNU CC on VMS  

The VMS version of GNU CC is distributed in a backup “saveset” containing both source code and precompiled binaries.

To install the gcc command so you can use the compiler easily, in the same manner as you use the VMS C compiler, you must install the VMS CLD file for GNU CC as follows.

1.
Define the VMS logical names GNU_CC and GNU_CC_INCLUDE to point to the directories where the GNU CC executables (‘gcc-cpp.exe’,‘gcc-cc1.exe’, etc.) and the C include files are kept respectively. This should be done with the following commands.

Include the appropriate disk and directory names. These commands can be placed in your system startup file so they will be executed whenever the machine is rebooted. You may, if you choose, do this via the GCC_INSTALL.COM script in the [GCC] directory.

2.
Install the GCC command with the following command line input.

3.
To install the help file, use the following input. Now, invoke the compiler with a command like ‘gcc /verbose file.c’, which is equivalent to the command ‘gcc -v -c file.c’ in Unix.

If you wish to use GNU C++ you must first install GNU CC, and then perform the following steps.

1.
Define the VMS logical name GNU_GXX_INCLUDE to point to the directory where the preprocessor will search for the C++ header files. This can be done with the following command.

Include the appropriate disk and directory name. If you are going to be using libg++, this is where the libg++ install procedure will install the libg++ header files.

2.
Obtain the file ‘gcc-cc1plus.exe’, and place this in the same directory that ‘gcc-cc1.exe’ is kept. The GNU C++ compiler can be invoked with a command like ‘gcc /plus /verbose file.cc’, which is equivalent to the command ‘g++ -v -c file.cc’ in Unix.

We try to put corresponding binaries and sources on the VMS distribution tape. But sometimes the binaries will be from an older version than the sources, because we don’t always have time to update them. (Use the ‘/version’ option to determine the version number of the binaries and compare it with the source file ‘version.c’ to tell whether this is so.) In this case, you should use the binaries you get to recompile the sources.

If you must recompile, use the following steps.

1.
Execute the command procedure, ‘vmsconfig.com’to set up the files, ‘tm.h’, ‘config.h’, ‘aux-output.c’, and ‘md.‘, and to create files, ‘tconfig.h’ and ‘hconfig.h’. This procedure also creates several linker option files used by ‘make-cc1.com’ and a data file used by ‘make-l2.com’.

2.
Setup the logical names and command tables as defined in Step 1. In addition, define the VMS logical name GNU_BISON to point to the directories where the Bison executable is kept. This should be done with the following command. You may, if you choose, use the INSTALL_BISON.COM script in the [BISON] directory.

3.
Install the BISON command with the following command.

4.
Type ‘@make-gcc’ to recompile everything (alternatively, submit the file ‘make-gcc.com’ to a batch queue).

If you wish to build the GNU C++ compiler as well as the GNU CC compiler, you must first edit make-gcc.com and follow the instructions that appear in the comments.

5.
In order to use GCC, you need a library of functions which GCC compiled code will call to perform certain tasks, and these functions are defined in the file ‘libgcc2.c’.

To compile this you should use the command procedure, ‘make-l2.com’, which will generate the library ‘libgcc2.olb’.

Build ‘libgcc2.olb’ using the compiler built from the same distribution that ‘libgcc2.c’ came from, and make-gcc.com will automatically do all of this for you.

To install the library, use the following commands.

The first command simply removes old modules that will be replaced with modules from ‘libgcc2’ under different module names. The modules new and eprintf may not actually be present in your gcclib.olb—if the VMS librarian complains about those modules not being present, simply ignore the message and continue on with the next command. The second command removes the modules that came from the previous version of the library ‘libgcc2.c’.

Whenever you update the compiler on your system, you should also update the library with the previous procedure.

6.
You may wish to build GCC in such a way that no files are written to the directory where the source files reside. An example would be the when the source files are on a read-only disk. In these cases, execute the following DCL commands (substituting your actual path names) where the directory ‘dua1:[gcc.source_dir]’ contains the source code, and the directory ‘dua0:[gcc.build_dir]’ is meant to contain all of the generated object files and executables.

Once you have done this, you can proceed building GCC as previously described. (Keep in mind that ‘gcc_build’ is a rooted logical name, and thus the device names in each element of the search list must be an actual physical device name rather than another rooted logical name).

7.
If you are building GNU CC with a previous version of GNU CC, you also should check to see that you have the newest version of the assembler. In particular, GNU CC version 2 treats global constant variables slightly differently from GNU CC version 1, and GAS version 1.38.1 does not have the patches required to work with GCC version 2. If you use GAS 1.38.1, then extern const variables will not have the read-only bit set, and the linker will generate warning messages about mismatched psect attributes for these variables. These warning messages are merely a nuisance, and can safely be ignored.

If you are compiling with a version of GNU CC older than 1.33, specify ‘/DEFINE=(“inline=”)’ as an option in all the compilations. This requires editing all the gcc commands in ‘make-cc1.com’. (The older versions had problems supporting inline.) Once you have a working 1.33 or newer GNU CC, you can change this file back.

8.
If you want to build GNU CC with the VAX C compiler, you will need to make minor changes in ‘make-cccp.com’ and ‘make-cc1.com’ to choose alternate definitions of CC, CFLAGS, and LIBS. See comments in those files. However, you must also have a working version of the GNU assembler (GNU as, also known as GAS) as it is used as the back-end for GNU CC to produce binary object modules and is not included in the GNU CC sources. GAS is also needed to compile ‘libgcc2’ in order to build ‘gcclib’ (see Step 5); ‘make-l2.com’ expects to be able to find it operational in ‘gnu_cc:[000000]gnu-as.exe’.

To use GNU CC on VMS, you need the VMS driver programs ‘gcc.exe’, ‘gcc.com’, and ‘gcc.cld’. They are distributed with the VMS binaries (‘gcc-vms’) rather than the GNU CC sources. GAS is also included in ‘gcc-vms’, as is Bison.

Once you have successfully built GNU CC with VAX C, you should use the resulting compiler to rebuild itself.

Before doing this, be sure to restore the CC, CFLAGS, and LIBS definitions in ‘make-cccp.com’ and ‘make-cc1.com’. The second generation compiler will be able to take advantage of many optimizations that must be suppressed when building with other compilers.

Under previous versions of GNU CC, the generated code would occasionally give strange results when linked with the sharable ‘VAXCRTL’ library. Now this should work.

Even with this version, however, GNU CC itself should not be linked with the sharable ‘VAXCRTL’. The version of qsort in ‘VAXCRTL’ has a bug (known to be present in VMS versions V4.6 through V5.5) which causes the compiler to fail.

The executables are generated by ‘make-cc1.com’ and ‘make-cccp.com’ use the object library version of ‘VAXCRTL’ in order to make use of the qsort routine in ‘gcclib.olb’.

If you wish to link the compiler executables with the shareable image version of  ‘VAXCRTL’, you should edit the file ‘tm.h’ (created by ‘vmsconfig.com’) to define the macro QSORT_WORKAROUND.

QSORT_WORKAROUND is always defined when GNU CC is compiled with VAX C, to avoid a problem in case ‘gcclib.olb’ is not yet available.

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