Comment by newpavlov
1 year ago
There is also a middle ground of requiring to pad 16/48-bit sequences with 16-bit NOP to align them to 32 bits. I agree that at this time it's not clear whether the C extension is a good idea or not (same with the V extension).
The C extension authors did consider requiring alignment/padding to prevent the misaligned 32-bit instruction issues, but they specifically mention rejecting it since it ate up all the code size savings.
Did they specifically analyze doing alignment on a cache line basis?
This would require specifying a cache line size in the ABI, which is a somewhat odd uarch detail to bubble up. While 64-bytes is conventional for large application processors and has been for a long time, I wouldn't want to make it a requirement.
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that seems really tough for compilers.
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