[llvm-dev] RFC: Add guard intrinsics to LLVM

[Andrew Trick via llvm-dev]

> On Feb 22, 2016, at 9:58 PM, Sanjoy Das <sanjoy at playingwithpointers.com> wrote:
> 
> You'd still have to be careful around
> inaccessiblememonly and friends, though.

I either missed that attribute or forgot about it. The semantics aren’t well specified. I would hope that it works as follows:
inaccessiblememonly functions, without further constraints, cannot be reordered w.r.t each other or CSE’d. However, readonly + inaccessiblememory attributes could be combined to allow both of those transformations.

@trap_on could be reordered with readonly + inaccessiblememory.

I’m suggesting that readonly should refer to both accessible (LLVM) and inaccessible (system) memory.

-Andy
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