[cfe-dev] standalone tool: best way to find built-in includes?

[Sean Silva]

On Fri, Nov 21, 2014 at 5:59 PM, Christian Convey <
christian.convey at gmail.com> wrote:

> Hi Sean:
> > It's actually possible for it to fail to build with the wrong builtin
> headers. E.g. an intrinsic was changed from using an __builtin_* function
> to using a different one that is not present in the other compiler.
>
> Are you basically reinforcing Manuel's warning, by saying there's a
> real-world example of this happening?
>

Yes.

-- Sean Silva


>
> Thanks,
> Christian
>
> On Fri, Nov 21, 2014 at 7:50 PM, Sean Silva <chisophugis at gmail.com> wrote:
> >
> >
> > On Fri, Nov 21, 2014 at 8:00 AM, Manuel Klimek <klimek at google.com>
> wrote:
> >>
> >> On Fri Nov 21 2014 at 4:40:44 PM Christian Convey
> >> <christian.convey at gmail.com> wrote:
> >>>
> >>> Hi Manuel,
> >>>
> >>> What really matters is that when my tool analyzes the target program's
> >>> source, it assumes the same standard headers that are normally used to
> >>> build that target program.
> >>>
> >>> For example, the target program might normally be built with clang
> >>> 3.4, but my analysis tool is built on clang 3.6.  When my tool
> >>> analyzes the source code of the target program, I want the analysis to
> >>> be as though the target program #include'd the 3.4 builtins, not the
> >>> 3.6 builtins.  Because my goal is to obtain the same AST as the one
> >>> created during the target program's normal (3.4) build process.
> >>
> >>
> >> The builtin headers are implementation details of the compiler. If you
> >> compile a file with a tool based on clang 3.6 and builtin headers of
> clang
> >> 3.4 the probability that you *don't* get a correct AST is higher.
> >
> >
> > It's actually possible for it to fail to build with the wrong builtin
> > headers. E.g. an intrinsic was changed from using an __builtin_*
> function to
> > using a different one that is not present in the other compiler.
> >
> > -- Sean Silva
> >
> >>
> >>
> >> If you want to get the same AST, you have to use the same version of
> >> clang. The question is, why is it important to you whether it's the same
> >> AST?
> >>
> >>>
> >>>
> >>> If I understand your suggestion, my analysis would give me an AST
> >>> based on the clang 3.6 builtins, not based on the 3.4 builtins.  Is
> >>> that correct?
> >>>
> >>> Thanks,
> >>> Christian
> >>>
> >>>
> >>>
> >>>
> >>>
> >>> On Fri, Nov 21, 2014 at 4:35 AM, Manuel Klimek <klimek at google.com>
> wrote:
> >>> > +1 to needs some refactoring, but generally the trick is: you don't
> >>> > want to
> >>> > use the builtin includes that are used by the clang you used to
> produce
> >>> > the
> >>> > compilation database, but the one that is current at the version at
> >>> > which
> >>> > you built your *tool*.
> >>> >
> >>> > Thus, optimally you'll install your tool into some/bin and the
> builtin
> >>> > headers into some/lib/clang/<version>.
> >>> >
> >>> > Cheers,
> >>> > /Manuel
> >>> >
> >>> > On Fri Nov 21 2014 at 5:23:16 AM Sean Silva <chisophugis at gmail.com>
> >>> > wrote:
> >>> >>
> >>> >> You can set CLANG_RESOURCE_DIR in CMake, or pass -resource-dir (the
> >>> >> default resource dir is created by
> >>> >> `llvm::sys::path::append(<exe-path>,
> >>> >> "..", "lib", "clang", CLANG_VERSION_STRING)`).
> >>> >>
> >>> >> This logic is actually duplicated in more than one place
> >>> >> unfortunately.
> >>> >> e.g. in CompilerInvocation::GetResourcesPath
> >>> >> (lib/Frontend/CompilerInvocation.cpp) and Driver::Driver
> >>> >> (lib/Driver/Driver.cpp); there's also some nastiness in
> >>> >> CIndexer::getClangResourcesPath. Needs some refactoring.
> >>> >>
> >>> >> -- Sean Silva
> >>> >>
> >>> >> On Thu, Nov 20, 2014 at 6:32 PM, Christian Convey
> >>> >> <christian.convey at gmail.com> wrote:
> >>> >>>
> >>> >>> Hi guys,
> >>> >>>
> >>> >>> I'm developed a standalone tool for analyzing source code.  It uses
> >>> >>> CommonOptionParser and ClangTool in what I think are the standard
> >>> >>> ways.
> >>> >>>
> >>> >>> My tool analyzes some other code ("foo.c") we have.  We build foo.c
> >>> >>> with clang the system-wide installed version of clang.  Thanks to
> >>> >>> cmake, we also produce a compilation database for that build of
> >>> >>> foo.c.
> >>> >>>
> >>> >>> I'd really like to ensure that when my analysis tool runs, I'd like
> >>> >>> it
> >>> >>> to simulate, as closely as possible, the way we normally build
> foo.c.
> >>> >>> In particular, I'd like to be sure it's using the same builtin
> >>> >>> headers
> >>> >>> and gcc-provided headers.
> >>> >>>
> >>> >>> Unfortunately, I can't easily copy my analysis tools executable
> into
> >>> >>> the same directory as the clang which we use to build foo.c.
> >>> >>>
> >>> >>> So here's my question: Is there a good way for me to force my tool
> to
> >>> >>> search the same include directories, in the same order, as our
> normal
> >>> >>> copy of clang does when it's building foo.c?
> >>> >>>
> >>> >>> I've tried running "clang -### ..." in the build system for foo.c,
> so
> >>> >>> that (I think) I get explicit information about the flags being
> >>> >>> passed
> >>> >>> to the front-end.  However, I haven't found a way to pass those
> flags
> >>> >>> to my analysis tool in a way that CommonOptionsParser and/or
> >>> >>> ClangTool
> >>> >>> find acceptable.  For example, they reject "-cc1".
> >>> >>>
> >>> >>> Thanks,
> >>> >>> Christian
> >>> >>> _______________________________________________
> >>> >>> cfe-dev mailing list
> >>> >>> cfe-dev at cs.uiuc.edu
> >>> >>> http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev
> >>> >>
> >>> >>
> >>> >> _______________________________________________
> >>> >> cfe-dev mailing list
> >>> >> cfe-dev at cs.uiuc.edu
> >>> >> http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev
> >
> >
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/cfe-dev/attachments/20141124/3a93c672/attachment.html>