nickdesaulniers added a comment.

In D104475#2825711 <https://reviews.llvm.org/D104475#2825711>, @MaskRay wrote:

> So if we don't want to offer guarantee for IR/C/C++ attributes, we can 
> document that users may need to additionally specify 
> `__attribute__((noinline))` to suppress inlining.

I don't generally like that approach:

1. it's not easy for developers to validate their call call chains to ensure 
that a caller with a restrictive function attribute doesn't have unrestricted 
callers inlined into the restricted caller.
2. that behavior opposes the principle of least surprise.
3. We don't have a statement attribute for call sites to say "please don't 
inline this call" which would be fine grain. noinline is a course-grain hammer; 
what if we want to inline a callee into most callers but not this one caller 
that has such a restricted function attribute?

See also D91816 <https://reviews.llvm.org/D91816> where I took the conservative 
approach for `no_stack_protector` and simply chose not to perform such inline 
substitution on caller and callee function attribute mismatch.  I find this 
behavior to be the least surprising, and the developer is provided with 
introspection as to why the compile did not perform such inlining via 
`-Rpass=inline` flag.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D104475/new/

https://reviews.llvm.org/D104475

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