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Re: [PATCH] Mark sparc %fsr load and store inline asms as volatile.
From: Roland McGrath <roland@hack.frob.com>
Date: Fri, 11 May 2012 14:11:41 -0700 (PDT)
> I wonder if sparc might be acquiring fma* built-ins one of these
> days?
The FMA builtins are target agnostic, but you can only invoke them if
the cpu you are compiling for actually has the special fused
instructions.
This is indicated by certain CPP macros being defined.
So it's not useful for our purposes here.
Better for us would be builtins to access the FPU status register
state, and then express the dependencies inside of GCC so it can't
reorder those relative to other float operations.
It's by far not an easy task and I've discussed this with Richard
Henderson on other occaisions, because he wants to do it too.