Compiler Explorer has a small example.
Basically, the local variable x remains stack allocated; caller passes x by const reference so callee shouldn’t modify x.
My question is, is it an legitimate optimization to SROA x?
Two-fold answer:
- Yes, in principle. I have a patch in backlog to deal with this (⚙ D113520 [SROA] Maintain shadow/backing alloca when some slices are noncapturnig read-only calls to allow alloca partitioning/promotion)
- No, not in general, and not in that example – the call should not retain the address it is passed (
nocaptureattribute)
Roman
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