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Re: PATCH: Add --with-build-config=bootstrap-asan support


On Mon, Nov 19, 2012 at 12:34 PM, Paolo Bonzini <bonzini@gnu.org> wrote:
> On Mon, Nov 19, 2012 at 4:06 PM, H.J. Lu <hjl.tools@gmail.com> wrote:
>> On Mon, Nov 19, 2012 at 12:01 AM, Paolo Bonzini <bonzini@gnu.org> wrote:
>>> Il 19/11/2012 05:35, H.J. Lu ha scritto:
>>>> On Sun, Nov 18, 2012 at 7:28 AM, Paolo Bonzini <bonzini@gnu.org> wrote:
>>>>> Il 18/11/2012 00:54, H.J. Lu ha scritto:
>>>>>> +@if gcc-bootstrap
>>>>>> +ifneq ($(filter bootstrap-asan,$(BUILD_CONFIG)),)
>>>>>> +LIBASAN_LIBS=-B$$r/prev-$(TARGET_SUBDIR)/libsanitizer/asan/.libs
>>>>>> +endif
>>>>>> +@endif gcc-bootstrap
>>>>>
>>>>> Do you need this to be here?  POSTSTAGE1_*_EXPORT is only used when
>>>>> bootstrapping, and they are defined with "=" so the definition could be
>>>>> placed (or so it seems at first look) in bootstrap-asan.mk.
>>>>>
>>>>
>>>> It turns out to be quite tricky:
>>>>
>>>> 1. We can't use -faddress-sanitizer in libcpp due to
>>>>
>>>> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55380
>>>
>>> Does -faddress-sanitizer add a CPP symbol that lets you work around it?
>>>  If not, it's a bug.  If so, please make libcpp revert to the dump
>>> algorithm if said symbol is defined.
>>
>> No, it doesn't define a CPP symbol.
>
> Then we have to fix this first.

I opened:

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55397

>>>> 2. We can't use  -faddress-sanitizer in libiberty since
>>>> it will make all host binaries depend on libasan.
>>>> 3. We can't use  -faddress-sanitizer in lto-plugin
>>>> since it will make linker depends on libasan.
>>>
>>> These are features, not bugs.  You asked for that explicitly.  In fact,
>>> I think that using bootstrap-asan in a combined tree should make all
>>> host binaries use asan.
>>
>> That is true.  But we have to support separate ld. My patch
>> will delegate this decision to each tool directory.
>
> So if a plugin uses asan, it cannot be linked with a program that
> doesn't use it?  Is this documented anywhere?  I suppose however that
> a plugin compiled without asan can be linked to a program that uses
> it.
>
> So, if asan-enabled lto-plugin doesn't work together with normal ld,
> the solution is to remove -faddress-sanitizer from the flags unless
> you are in a combined tree.

I will give it a try.


-- 
H.J.


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