How can I dump an abstract syntax tree generated by gcc into a .dot file?

Question

I think the question's title is self explanatory, I want to dump an abstract syntax tree generated by gcc into a .dot file (Those files generated by Graphviz) because then I want to view it in a .png file or similar. Is there any way I can do that?

Thanks in advance :)

Answer 1

There are two methods, both including two steps

1. Using GCC internal vcg support

   1. Compile your code (say test.c) with vcg dumps

      gcc -fdump-tree-vcg -g test.c

   2. Use any third party tool to get dot output from vcg

      graph-easy test.c.006t.vcg --as_dot

2. Compile with raw dumps and then preprocess them with some scripts to form dot files (like in this useful article)

Both methods have their own good and bad sides -- with first you can really get only one dump of AST before gimple translation, but it is easy. With second you may convert any raw dump to dot-format, but you must support scripts, that is overhead.

What to prefer -- is on your own choice.

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UPD: times are changing. Brand new option for gcc 4.8.2 makes it possible to generate dot files immediately. Just supply:

gcc test.c -fdump-tree-all-graph

and you will get a plenty of already formatted for you dot files:

test.c.008t.lower.dot
test.c.012t.cfg.dot
test.c.016t.ssa.dot
... etc ...

Please be sure to use new versions of GCC with this option.