GCC Workbench

Extension version: 2.1.0

This repository contains GCC Workbench, a Visual Studio Code / VSCodium extension designed to make life easier for GCC compiler engineers.

It goes beyond simple syntax highlighting for GCC internals by adding navigation, visualization, and noise-filtering tools specifically tailored for GCC's internal dump files (.rtl, .gimple, .md).

What is this useful for?

GCC produces hundreds of dump files during compilation. Navigating them manually is tedious, and reading them is often cluttered with debug noise. This extension organizes that chaos into a simple workspace.

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Key Features

Source <-> RTL Mapping

Instant Hover Documentation

Understand GCC internals without leaving the editor.

• RTL Definitions: Hover over ir insns like set, parallel, or regnotes REG_DEAD to see their official documentation (parsed from rtl.def and reg-notes.def).
• Gimple Definitions: Same as above, but for gimple.

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🔧 Workbench Tools

1. Compilation Pass Explorer

Instead of ls -ltr *expand*, use the GCC Explorer sidebar view.

• Automatically finds all GCC dump files (.t, .r, .i) in your workspace.
• Sorts them chronologically by pass number (e.g., 005t -> 300r).
• Filters passes by type (GIMPLE vs RTL) or name.

2. Pass Navigation ("Surfing")

Move through the compilation pipeline without leaving the editor.

• Next/Prev Pass: Click the arrow icons in the editor title bar (or use Ctrl+Alt+] / Ctrl+Alt+[) to jump to the immediate next or previous pass file.
• Context Aware: Automatically detects if you are in a GIMPLE or RTL file and finds the correct successor.

3. Pass Diff

• Compare with Previous: One-click button to open a diff view against the previous pass.
• Instantly visualize exactly what optimizations were performed by a specific pass.

4. Focus Mode (Noise Filter)

RTL and GIMPLE dumps are often 50% metadata.

• Toggle Noise: Click the Eye Icon to hide comment lines, basic block headers.
• Helps you focus purely on the instruction logic and data flow.

5. Control Flow Visualization

• Open Graph: One-click button to render the current dump as a Control Flow Graph (CFG) using Graphviz.
• Note: Requires a generic Graphviz/DOT extension to be installed for the final rendering.

6. Intelligent MDL/RTL Editing

• Go to Definition: Jump from iterator usages or attribute names in .md files directly to their definitions.
• Hovers: Hover over standard RTL codes (like define_insn, parallel, set) to view their official documentation (parsed directly from rtl.def).

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🎨 Syntax Highlighting Support

When hacking on GCC, you often need to read and understand complex internal formats. Reading all of this as plain, uncolored text is painful. This extension provides TextMate grammars to support the following:

1. Machine Description Files (.md)

• Constructs: define_insn, define_expand, define_split, define_peephole2, iterators, attributes.
• Operands: Distinct coloring for registers, modes, and constraints.
• Embedded Code: Highlights C/C++ blocks embedded inside MD files.

2. RTL Dumps (.expand, .vregs, etc.)

• Records: insn, jump_insn, call_insn, note, barrier, code_label.
• Data: Registers (reg:DI 3), vector modes, const_int.

3. GIMPLE Dumps (.ssa, .optimized, etc.)

• Structure: Basic blocks, PHI nodes, and SSA names.
• Statements: gimple_call, gimple_assign, gimple_cond, gimple_switch.

4. match.pd Patterns

• Rules: match / simplify rules.
• Trees: Operator trees (e.g., plus, mult, bit_and) and capture logic (@x).

5. Additional Formats

• PowerPC/RS6000 Builtins: rs6000-builtin.def highlighting.
• Option Files: .opt syntax support.
• DejaGnu Scripts: .exp syntax support.

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Support the Project

GCC Workbench is an open-source labor of love dedicated to making compiler internals accessible and productive. Maintaining and innovating on these tools requires time and research.

If this extension has improved your workflow or helped you debug a complex RTL issue, consider supporting its ongoing development.

License

This project is licensed under the GNU General Public License v3.0 or later (GPL-3.0-or-later).

See the LICENSE file for details.

Credits & Legal

• DejaGnu expect scripts (.exp) Syntax: The syntax highlighting for .exp files in this extension is a derivative work based on the vscode-tcl repository by James Deucker (Copyright (c) 2019), which is licensed under the MIT License.
  • Modifications: The original YAML logic was converted to JSON and adapted for GCC DejaGnu expect scripts by Kishan Parmar in 2025.
• All other files: Original work licensed under GPL-3.0-or-later.

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Project Status & Contributing

The project is now open for the community to utilize, maintain, and evolve.

• Found a bug? Please raise an issue on the issue tracker: https://github.com/RegAlloc/gcc-workbench/issues

• Want to contribute? Everyone is welcome to continue or expand on this project. Feel free to fork the repository and raise a Pull Request here: https://github.com/RegAlloc/gcc-workbench

Publisher Trust & Security

This extension is open-source and published by Kishan Parmar.

Source code is publicly available on GitHub and can be audited by anyone.

No telemetry, tracking, or data collection is performed by this extension.