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RE: sysdep/*/locks.h
- From: Andrew Haley <aph at redhat dot com>
- To: "Boehm, Hans" <hans_boehm at hp dot com>
- Cc: Hans Boehm <Hans dot Boehm at hp dot com>, java-patches at gcc dot gnu dot org
- Date: Wed, 21 Jan 2004 19:22:46 +0000
- Subject: RE: sysdep/*/locks.h
- References: <0C3EFB691636964BBF914AE56AE83A89501ED3@hplex4.hpl.hp.com>
Boehm, Hans writes:
> Is it better to just pass the address (as opposed to its contents)
> as an "r" input? That probably costs an additional add
> instruction, since gcc can no longer use base+offset addressing.
You need to tell gcc that your operand must be written to before the
asm executes. I suppose you could pass the mem operand and its
address, but only refer to the address in the asm.
> But I really hate to rely on programming language constructs whose
> semantics are defined only by the gcc back-end source code.
Maybe we should get the gcc behavour documented. Perhaps it is
already; I haven't looked.
Andrew.