[llvm-dev] [RFC] Adding a globalmemonly attribute for functions that only access global memory

[James Y Knight via llvm-dev]

On Tue, Sep 14, 2021 at 2:03 PM Philip Reames via llvm-dev <
llvm-dev at lists.llvm.org> wrote:

> In fact, the original motivation for the globalmemonly proposal could be
> alternatively solved with:
>
> @errno = external global i32
>
> declare void @mathfunc(float, float) globalmayalias(@errno)


How would that work, since errno generally isn't a global (or a
compiler-supported thread-local)? It's typically something along the lines
of:
  int* __errno_location(void) __attribute__((const));
  #define errno *__errno_location()
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