[cfe-dev] Over-aligned vst1.64 and vld1.64 for arm-linux-androideabi

[Friedman, Eli via cfe-dev]

On 2/7/2018 5:53 PM, Greg McGary via cfe-dev wrote:
> I am seeing clang for arm-linux-androideabi emit 16-byte-aligned 
> vst1.64 and vld1.64, but the ABI only guarantees 8-byte alignment. 
> Result at runtime is SIGBUS. Since clang emits "#define 
> __BIGGEST_ALIGNMENT__ 8", it is aware of the ABI's maximum alignment.

__BIGGEST_ALIGNMENT__ is not the alignment of any particular object; 
some pointers have lower alignment, some pointers have higher 
alignment.  And the compiler will raise the alignment of a load or store 
if it can prove the pointer is sufficiently aligned.

It's hard to say more without a testcase.

-Eli

-- 
Employee of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project

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