Project Stage 1: Troubleshooting a bit - Coming soon

 

Procedure for Troubleshooting

Debugging using the following method:

1. First Error Analysis: I carefully reviewed the error logs after my initial build attempt failed.

    ./pass-instances.def:47:23: error: expected ';' at end of member declaration
    47 | NEXT_PASS_WITH_ARG (pass_mypass, 1, 1)
   

   This suggested an issue with my pass registration syntax.

2. Examining Pass Declaration Conventions: I ran the following to examine the passes that were already included in the GCC source code:
   

    cd ~/git/gcc/gcc
    grep -r "NEXT_PASS" passes.def
   

   This showed that NEXT_PASS (pass_name, number) was the proper format instead of NEXT_PASS_WITH_ARG.
   

3. Function name Pattern Analysis: I looked at various pass implementations to learn more about the name conventions:

    cd ~/git/gcc/gcc
    find . -name "tree-*.cc" | xargs grep "make_pass_"
   

   This demonstrated to me that the pattern make_pass_X, where X is the pass name without the "pass_" prefix, is what GCC wants factory functions to adhere to.

4. Investigating Makefile Formatting: I looked at both the original and my edited version to comprehend the Makefile formatting problem:

    cd ~/git/gcc/gcc
    grep -A 10 -B 10 "OBJS" Makefile.in > original_makefile_section.txt
    # After comparing my changes with the original format
   

   This showed me that I needed to put a backslash at the end of my object file entry and keep the exact same indentation (using tabs).

5. Rebuilding with Verbose Output: In order to pinpoint the precise location of the build's failure, I tried rebuilding using more verbose output:

    cd ~/gcc-build-001
    make V=1 -j 4 |& tee verbose_build.log
   

   Provided more detailed error information: issue was with the pass registration syntax.

6. Isolating Components: To narrow down the issue, I tried building just the compiler component:

    cd ~/gcc-build-001/gcc
    make -j 1 |& tee gcc_build.log
   

   This made the error messages easier to identify and address.

7. Comparing with Reference Implementations: I studied successful GCC pass implementations:

    cd ~/git/gcc/gcc
    # Example: Looking at tree-ssa-pre.cc as a reference
    less tree-ssa-pre.cc
   

   Helped me in understanding the correct structure and naming conventions for GCC passes.

8. Version-Specific Documentation: Just to be sure: checked if there were version-specific requirements for the GCC version I was working with:

    cd ~/git/gcc
    git log -1 --pretty=format:"%h %s" # To identify the specific GCC version
   

Specific Troubleshooting

1. Naming Convention Inconsistencies: My initial implementation used inconsistent naming:

    // In tree-my-pass.cc
    gimple_opt_pass *make_tree_my_pass(gcc::context *ctxt)
   
    // In tree-pass.h declaration
    extern gimple_opt_pass *make_tree_my_pass(gcc::context *ctxt);
   
    // In passes.def
    NEXT_PASS (pass_my_pass, 1)
   

   I later discovered GCC requires a specific pattern:

   • Factory function must be named make_pass_X

   • Pass registration must use pass_X

   • These names must be consistent across all files

2. Makefile Syntax Errors: The error message missing separator (did you mean TAB instead of 8 spaces?)occurred because:

    # I initially added:
    tree_my_pass.o \  # With spaces instead of tabs
   
    # Should have been:
    [TAB]tree-my-pass.o \  # With a tab character for indentation
   

   I confirmed this by examining the exact whitespace characters in the Makefile:

    cat -A Makefile.in | grep -A 3 -B 3 "tree-my-pass"
   

   This showed spaces (represented as ^I) instead of tabs where required.

3. Pass Registration Syntax Error: When I tried using NEXT_PASS_WITH_ARG, I encountered compilation errors because:

    # I tried:
    NEXT_PASS_WITH_ARG (pass_my_pass, 1, 1)
    NEXT_PASS_WITH_ARG (pass_my_pass, 0)
   
    # But examining other passes showed I should use:
    NEXT_PASS (pass_my_pass, 1)
   

   I discovered through source investigation that NEXT_PASS_WITH_ARG is used differently in the GCC codebase than I initially understood.

4. Header Inclusion Order: I found that the order of header inclusions could affect compilation:

    // Original order
    #include "tree.h"
    #include "gimple.h"
    #include "tree-pass.h"
   
    // After examining compiler warnings, I tried:
    #include "tree-pass.h"
    #include "tree.h"
    #include "gimple.h"