[LLVMdev] [PATCH] Removing -fsanitize-address-zero-base-shadow

[Evgeniy Stepanov]

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.
- 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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