jart/disaster

disaster.el

Disassemble C, C++ or Fortran code under cursor

Disaster lets you press C-c d to see the compiled assembly code for the C, C++ or Fortran file you're currently editing. It even jumps to and highlights the line of assembly corresponding to the line beneath your cursor.

It works in the following manner:

• If there is a Makefile, creating a .o file using make
• If there is a compile_commands.json file, use it to get the compilation command for the file.
• If none of the above files is presnet, use the default system compiler.

After compiling the source to a .o file, disaster runs that file through objdump to generate the human-readable assembly.

Installation

Make sure to place disaster.el somewhere in the load-path, then you should be able to run M-x disaster. If you want, you add the following lines to your .emacs file to register the C-c d shortcut for invoking disaster:

(add-to-list 'load-path "/PATH/TO/DISASTER")
(require 'disaster)
(define-key c-mode-map (kbd "C-c d") 'disaster)
(define-key fortran-mode-map (kbd "C-c d") 'disaster)

Doom Emacs

For Doom Emacs users, you can add this snippet to your packages.el.

(package! disaster
  :recipe (:host github :repo "jart/disaster"))

And this to your config.el:

(use-package! disaster
  :commands (disaster)
  :init
  ;; If you prefer viewing assembly code in `nasm-mode` instead of `asm-mode`
  (setq disaster-assembly-mode #'nasm-mode)

  (map! :localleader
        :map (c++-mode-map c-mode-map fortran-mode-map)
        :desc "Disaster" "d" #'disaster))

Customization Documentation

disaster-make-flags

Command line options to pass to make if a Makefile is found.

disaster-assembly-mode

Which mode to use to view assembly code.

disaster-cc

The command for your C compiler.

disaster-cxx

The command for your C++ compiler.

disaster-fortran

The command for your Fortran compiler.

disaster-cflags

Command line options to use when compiling C.

disaster-cxxflags

Command line options to use when compiling C++.

disaster-fortranflags

Command line options to use when compiling Fortran.

disaster-objdump

The command name and flags for running objdump.

disaster-buffer-compiler

Buffer name to use for assembler output.

disaster-buffer-assembly

Buffer name to use for objdump assembly output.

disaster-project-root-files

List of lists of files that may indicate software project root directory. Sublist are ordered from highest to lowest precedence.

disaster-c-regexp

Regexp for C source files.

disaster-cpp-regexp

Regexp for C++ source files.

disaster-fortran-regexp

Regexp for Fortran source files.

Function and Macro Documentation

(disaster-create-compile-command-make MAKE-ROOT CWD REL-OBJ OBJ-FILEPROJ-ROOT REL-FILE FILE)

Create compile command for a Make-based project. MAKE-ROOT: path to build root, CWD: path to current source file, REL-OBJ: path to object file (relative to project root), OBJ-FILE: full path to object file (build root!) PROJ-ROOT: path to project root, REL-FILE FILE.

(disaster-create-compile-command-compile-db MAKE-ROOT CWD REL-OBJOBJ-FILE PROJ-ROOT REL-FILE)

Create compile command from a "compile_commands.json" file. MAKE-ROOT: path to build root, CWD: path to current source file, REL-OBJ: path to object file (relative to project root), OBJ-FILE: full path to object file (build root!) PROJ-ROOT: path to project root, REL-FILE FILE.

(disaster-get-object-file-path-compile-db COMPILE-CMD)

Get the .o object file name from a full COMPILE-CMD.

(disaster-create-compile-command USE-COMPILE-DB MAKE-ROOT CWD REL-OBJOBJ-FILE PROJ-ROOT REL-FILE FILE)

Create the actual compile command.

• USE-COMPILE-DB: non NIL to use the compiler found in compile_commands.json, generated by CMake or Bear for example, NIL to use Make or default compiler options,
• MAKE-ROOT: path to build root,
• CWD: path to current source file,
• REL-OBJ: path to object file (relative to project root),
• OBJ-FILE: full path to object file (build root!)
• PROJ-ROOT: path to project root, REL-FILE FILE.

(disaster &optional FILE LINE)

Show assembly code for current line of C/C++ file. Here's the logic path it follows:

• Is there a complile_commands.json in this directory? Get the object file name for the current file, and run it associated command.
• Is there a Makefile in this directory? Run make bufname.o.
• Or is there a Makefile in a parent directory? Run make -C .. bufname.o.
• Or is this a C file? Run cc -g -c -o bufname.o bufname.c
• Or is this a C++ file? Run c++ -g -c -o bufname.o bufname.c
• If build failed, display errors in compile-mode.
• Run objdump inside a new window while maintaining focus.
• Jump to line matching current line. If FILE and LINE are not specified, the current editing location is used.

(disaster-find-project-root &optional LOOKS FILE)

General-purpose Heuristic to detect bottom directory of project. First, this will try to use (vc-root-dir) to guess the project root directory, and falls back to manual check wich works by scanning parent directories of FILE (using disaster--find-parent-dirs) for certain types of files like a .projectile file or a Makefile (which is less preferred). The canonical structure of LOOKS is a list of lists of files to look for in each parent directory where sublists are ordered from highest precedence to lowest. However you may specify LOOKS as a single string or a list of strings for your convenience. If LOOKS is not specified, it'll default to disaster-project-root-files.

(disaster-find-build-root USE-COMPILE-DB PROJECT-ROOT)

Find the root of build directory. USE-COMPILE-DB: non nil to use compile_commands.json, PROJECT-ROOT: root directory of the project.