goasm-mode

An Emacs minor mode for viewing Go compiler assembly output. Generates Plan 9 pseudo-assembly scoped to the current function, with source-line-to-assembly navigation and syntax highlighting.

Features

• Per-function assembly - Generates assembly output for the Go function at point using go build -gcflags '-S'
• Source-to-assembly navigation - Jump the assembly view to the instructions corresponding to the current source line
• Assembly-to-source navigation - Jump from an assembly line back to the corresponding source line
• Jump-to-address navigation - Follow branch/jump instructions to their target offset, or jump to any byte offset manually
• Instruction documentation - Inline eldoc hints for assembly instructions, plus d to open full documentation in a browser (x86/ARM/Go pseudo-instructions)
• Assembly highlighting - Matching assembly lines are highlighted when navigating from source
• Syntax highlighting - Assembly instructions, registers, hex addresses, and source references are font-locked in the output buffer
• Auto-recompilation - Moving to a different function and navigating automatically re-generates assembly

Requirements

• Emacs 27.1+
• Go compiler (go on PATH)
• A Go project with a go.mod file

Installation

Manual

Clone the repository and add it to your load path:

(add-to-list 'load-path "/path/to/goasm-mode")
(require 'goasm-mode)

use-package

(use-package goasm-mode
  :load-path "/path/to/goasm-mode"
  :hook (go-mode . goasm-minor-mode))

Usage

Enable the minor mode in a Go buffer:

M-x goasm-minor-mode

Or add it to your go-mode hook:

(add-hook 'go-mode-hook #'goasm-minor-mode)

Key Bindings

In a Go source buffer (goasm-minor-mode):

Key	Command	Description
C-c !	goasm-show	Generate assembly for the function at point
C-c .	goasm-goto-line	Show assembly for the current source line (compiles automatically if needed)

In the *goasm* assembly buffer:

Key	Command	Description
l	goasm-goto-source	Jump to the source line referenced by the current assembly line
d	goasm-describe-instruction	Open documentation for the instruction on the current line
f	goasm-follow-jump	Follow the branch/jump instruction on the current line to its target
j	goasm-jump-to-address	Jump to an assembly line by byte offset (decimal or 0x hex)

Workflow

1. Open a Go source file and enable goasm-minor-mode
2. Place your cursor inside a function
3. Press C-c . to see the assembly for the current line — assembly is compiled automatically on first use and when you move to a different function
4. Move to other source lines and press C-c . again to jump the assembly view and highlight the matching instructions
5. In the *goasm* buffer, press l on any assembly line to jump back to the corresponding source line
6. Hover on any instruction to see a short description via eldoc, or press d to open full documentation in your browser
7. On a branch/jump instruction (e.g. JMP 16, BGT 8), press f to follow it to its target offset — use C-u C-SPC to jump back
8. Press j to jump to any byte offset by typing it (decimal or 0x hex)

You can also use C-c ! to explicitly generate assembly without navigating to a specific line.

Customization

Variable	Default	Description
goasm-go-command	"go"	Path to the Go executable
goasm-build-flags	nil	Additional flags passed to go build

Development

Running Tests

make test    # Run the ERT test suite
make lint    # Byte-compile and check for warnings
make clean   # Remove compiled files

License

GPL-3.0. See LICENSE for details.

Author

Roman Nestertsov