Compiler load/store barrier; volatile pointer; barriers in general
- From: Luke Gorrie <luke@xxxxxxxx>
- To: luajit@xxxxxxxxxxxxx
- Date: Wed, 28 Jan 2015 08:52:50 +0100
Howdy,
Questions, questions, questions...
What are the ordering properties of loads/stores to FFI objects? Are there
situations where LuaJIT will reorder these? If so, is there a way to do a
compiler load/store barrier in cases where ordering is important?
Can LuaJIT also eliminate FFI load/store operations that it thinks are
redundant? If so, is there a way to prevent this in cases where every
read/write must really be performed (e.g. when talking to hardware with
MMIO and reading/writing for side effects)?
Generally speaking: what barriers exist in LuaJIT and is it important to
think about them? (For example are there common operations that will create
a barrier and prevent optimizations that the JIT could otherwise do?)
Cheers,
-Luke
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