StackThreads/MP: version 0.77 User's Guide

8.2: Using Patched GCC

Once you successfully patch gcc sources and rebuild gcc, you setup things so that stgcc exploits it.

• Set environment variable ST_GCC_IS_PATCHED. The value does not matter. When stgcc finds that this variable is defined, it gives necessary options when it calls gcc and g++ (we hereafter only mention gcc, but the following statements also apply to g++).
• If the patched gcc replaces the original gcc or if you arrange your path variable so that you run the patched gcc by just typing gcc (g++), you are done.

  Recall that the patched gcc produces the exactly same output as the original does, unless explicit options are given, so replacing the original gcc is almost always practical. You may still want to call patched gcc only from stgcc and use the original gcc for other cases. If you are such a skeptical person, put the patched gcc to anywhere and tell stgcc the location of them by setting environment variable ST_COMPILER_PATH. For example, you may write the following line in your .cshrc.

  setenv ST_COMPILER_PATH /home/nomo/my_gcc/bin
  

  Then, stgcc calls /home/nomo/my_gcc/bin/gcc and /home/nomo/my_gcc/bin/g++ instead of gcc and g++.

• To check if it is working, try some sample programs. On i386, compile and run ex/nestcall. On SPARC, compile and run ex/strpass. Supply -O4 option to enable optimization. When you run it with no arguments, if it says OK, the patched gcc is working. Before gcc is not patched, these programs do not say OK and will produce the following outputs:
  • strpass on SPARC:

    @ harp:1014% ./strpass
    @ 1 : st_main forks foo
    @ 2 : foo blocks
    @ 3 : foo blocked, restart foo
    @ 4 : foo restarted and finishes
    @ *************************************************************
    @ Structure argument to ST_THREAD_CREATE(foo(p)) is corrupted.
    @ This is a known problem on SPARC.
    @ You may either patch gcc to fix this problem (see manual),
    @ or just avoid passing struct args to procedure calls with 
    @ ST_THREAD_CRREATE
    @ *************************************************************
    

  • nestcall on i386: