[WIP] #58686 swift_slowAlloc() _et al._ should be marked returns-nonnull to improve codegen #58688
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grynspan force-pushed the jgrynspan/58686-nonnull-allocation-annotations branch from 40eb782 to 8511a51 Compare 
compnerd approved these changes May 5, 2022
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The top-most commit looks good. A small nit: the commit message could be improved. The immediate reaction was - this is probably a bad idea, it might cause trouble for some compilers. Being more explicit with something like "attribute allocators as unfailable" might be more precise.
grynspan force-pushed the jgrynspan/58686-nonnull-allocation-annotations branch 2 times, most recently from 0a877e1 to f6848b0 Compare
Can you elaborate what you mean here? Edit: I updated the PR description to clarify what happens when |
compnerd approved these changes May 5, 2022
mikeash requested changes May 5, 2022
grynspan force-pushed the jgrynspan/58686-nonnull-allocation-annotations branch 2 times, most recently from 12d41ac to dea7e2f Compare mikeash approved these changes May 5, 2022
grynspan force-pushed the jgrynspan/58686-nonnull-allocation-annotations branch 3 times, most recently from 954986c to 2a34757 Compare | @swift-ci please test |
grynspan force-pushed the jgrynspan/58686-nonnull-allocation-annotations branch 3 times, most recently from b795fd4 to b4c04b2 Compare 
…to improve codegen
grynspan force-pushed the jgrynspan/58686-nonnull-allocation-annotations branch from b4c04b2 to 770fd10 Compare | @swift-ci please smoke test |
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This change adds the
gnu::returns_nonnull* attribute toswift_slowAlloc()and functions directly derived from it. Any code that calls these functions can be further optimized by the compiler because it knows that any paths assuming a null return value are unreachable.This attribute is distinct from Apple's
_Nonnullextension, which (in C/C++) is advisory only and does not affect codegen.* For MSVC++,
_Ret_notnull_is substituted. This macro has no impact on codegen but may produce better diagnostics when annotated functions are misused.Resolves #58686.