[cfe-dev] [PATCH] Removing -fsanitize-address-zero-base-shadow

Kostya Serebryany kcc at google.com
Tue Jan 14 23:46:30 PST 2014


On Wed, Jan 15, 2014 at 11:38 AM, Evgeniy Stepanov <
eugeni.stepanov at gmail.com> wrote:

> Hi,
>
> we plan to remove -fsanitize-address-zero-base-shadow command line
> flag from clang, and disable zero-base shadow support on all platforms
> where it is not the default behavior.
>
> - It is completely unused, as far as we know. And completely undocumented,
> too.
>
Not completely undocumented:
https://code.google.com/p/address-sanitizer/wiki/ZeroBasedShadow
Still, I think we can nuke this code now. (== LGTM)



> - It is ABI-incompatible with non-zero-base shadow, which means all
> objects in a process must be built with the same setting. Failing to
> do so results in a segmentation fault at runtime.
> - It introduces a backward dependency of compiler-rt on user code,
> which is uncommon and complicates testing.
>
> For the reference, attaching patches to cfe, llvm and compiler-rt that
> remove the flag and all support for it in the ASan instrumentation
> pass and runtime library.
>
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