hctim wrote:
> > Yeah, `clang/test/CodeGen/memtag-globals-asm.cpp` is for MTE Globals, not
> > ASan - and the sizes of the GVs should be multiple-of-16 bytes:
> > https://github.com/ARM-software/abi-aa/blob/main/memtagabielf64/memtagabielf64.rst#compilation
> > What problem are you trying to solve here?
>
> ASAN pass identifies the global variables that needs to be instrumented and
> replaces them with new globals with size equal to actual size + redzone size.
> To identify such instrumented global variables, added SanitizerMetadata to
> the new global, which will have NoAddress set to false(which implies asan
> instrumented global). At asm printer stage, such gloabal would be identified
> and actual value without redzone size would be emitted.
>
> This change was done under assumption that any target would only want the
> actual size of global in the elf and not the padded size. AMDGPU needs this
> change. Please let me know if it causes issue with other targets?
Under MTE globals (not asan, but the test you're changing in
memtag-globals-asm.cpp), there are no redzones - the round-to-16-byte size is
what we want to be in the ELF.
Copying the sanitizer metadata over seems fine, but reusing `NoAddress` as an
identifier that this is a sanitizer-instrumented GV is wrong. Other GVs that
are explicitly not asan-ified (e.g. by using the
`__attribute__((no_sanitize("address")))` attribute) end up with the same
attribute.
Also, to the premise, _why_ is ANDGPU unhappy about having the sizeof(GV) ==
global+redzone in the ELF?
https://github.com/llvm/llvm-project/pull/66666
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