[cfe-dev] Need Help Printing Preprocessed Code and Modifying CFG

[David Blaikie]

Attempting source to source transformations this way (via the ast/cfg) is
generally not recommended. These devices are not intended (and thus don't
work very well) for this purpose.

What's the goal of transforming the source in this way? If you're trying to
instrument/test the resulting program behavior, consider an approach like
the sanitizers (address/memory/thread sanitizer) that instruments code
within clang's generation phase. If you're attempting to rewrite code,
consider something like the ASTMatchers & tooling library.
On Jul 2, 2013 7:06 PM, "Kevin Boos" <kevinaboos at gmail.com> wrote:

> Hello all,
>
> I'm working with a Clang plugin (it must be a plugin for kernel
> compilation reasons) that analyzes drivers in the Linux kernel for
> virtualization security purposes.
>
> I start by modifying the body of a function in a way that certain
> statements are deleted. Then I need to print out that modified source code
> so that it can be compiled and preferably human-readable. However, I want
> to expand all macros so that there are minimal external symbols in the
> generated code. I tried using the Rewriter class for this, but the Rewriter
> apparently prints out original source code only and cannot expand macros...
> *is there an alternative source printer that can print the preprocessed
> code? *
> For reference, when calling "printPretty()" on the function's body Stmt*,
> the macros are expanded just like I want.
>
> My second question is about actually deleting those certain statement
> nodes in a CFG. I remember reading somewhere in the Clang docs that the CFG
> is a constant data structure that can't be modified.* Is there a way to
> delete statements from the underlying AST so that they wouldn't appear in
> the CFG and also not appear in the re-printed source code? * To be clear,
> I'm using the CFG for other analysis reasons, but I don't really care if
> the Stmt nodes are deleted from the AST directly or from inside a CFG basic
> block.
>
> Thanks in advance,
> Kevin Boos
> Rice University Ph.D. Candidate
>
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>
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