StackThreads/MP: version 0.77 User's Guide

9.5: What Does stgcc Command Do?

stgcc (stg++) is a simple script that drives compilation. It retains the same interface as gcc (stg++); it accepts the same set of command line options, except for those that fundamentally conflict with execution scheme of StackThreads/MP. The following descriptions about stgcc also apply to stg++.

stgcc is not a preprocessor or a compiler that understands C/C++ syntax and translates C/C++ programs in non-trivial ways. In fact, it feeds given C/C++ programs directly to gcc, passing command line (almost) as is. As a consequence, you can use almost all command line options and non-standard extensions supported by gcc.

What is stgcc then? It is a postprocessor of gcc. Whatever options you gave to stgcc, it lets gcc to generate assembly code and postprocess the assembly. The postprocessor is written in an AWK script and does the following jobs:

• It scans the assembly instructions of procedures and examines their stack frame formats. Information about stack frame formats are collected in a static table and attached to the original assembly file.
• It modifies the epilogue sequence of procedures for frame management purposes. It inserts about five instructions to each procedure.
• Upon linking, it calls an AWK script (called stlink.awk) to collect tables for all object files (Therefor it is mandatory to call stgcc to generate final executable).

Options of gcc that specifies where to stop compilation process (which are -E, -S, and -c) are also supported. Compilation transparently proceeds, if necessary, by compiling the postprocessed assembly file into an object file and by linking object files into executable.

There are other minor things that stgcc do:

• It automatically gives -I$ST_DIR to gcc, so that standard include files are automatically searched.
• It automatically links StackThreads/MP library.