[Bug sanitizer/67286] asan doen't work on Android(32bit ARM)

["weiguo.zhou at spreadtrum dot com" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67286

--- Comment #12 from weiguo.zhou <weiguo.zhou at spreadtrum dot com> ---
(In reply to weiguo.zhou from comment #8)
> (In reply to Yury Gribov from comment #5)
> > (In reply to Dmitry Vyukov from comment #4)
> > > +eugeni can provide more details.
> > 
> > Please! E.g. how do you build compiler and runtime?
> 
> 
> the keypoint to generate a gcc-based cross-compiler toolchain for
> android/arm32 as following:
> 
> 1) generate an stage-1 cross-compile gcc toolchain with  the existing native
> gcc;
> 2) build the sysroot from scratch with the stage-1 cross-compile toolchain;
> 3) generate the final cross-compile gcc_toolchain with the corresponding
> sysroot.
> 
> 
> you can see the keypoint is that we should "create a right sysroot" for the
> final cross-compile gcc-toolchain for android/arm32.


1) generate an stage-1 cross-compile gcc toolchain with  the existing native
 gcc;
2) build the sysroot from scratch with the stage-1 cross-compile toolchain;
3) generate the final cross-compile gcc_toolchain (with --enable-libsanitizer
option) with the corresponding sysroot;so the final cross-compile could
instrument the check code according to the excellent paper
<<address_sanity_checker.pdf>>;

4) reset the PATH environment variable, the generate the libasan.so.2 with the
final cross-compile gcc-toolchain:
   mkdir libasan-for-android-build
   cd libasan-for-android-build
   ../gcc-source-tree/libsanitizer/configure --host=arm-linux-androideabi
--prefix=/tmp/toolchain-build-linux-4.9.2/prefix --enable-shared
--disable-static

don't use any cross-tool like utility here. we should "create anything we need
from scratch". 

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