Messages in this thread | | | Date | Tue, 13 Nov 2007 17:02:01 -0800 | From | "H. Peter Anvin" <> | Subject | Re: [patch 5/8] Immediate Values - x86 Optimization (update) |
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Mathieu Desnoyers wrote: > > Ok, so the most flexible solution that I see, that should fit for both > i386 and x86_64 would be : > > > 1 byte : "=Q" : Any register accessible as rh: a, b, c, and d. > 2, 4 bytes : "=R" : Legacy register—the eight integer registers available > on all i386 processors (a, b, c, d, si, di, bp, sp). > 8 bytes : (only for x86_64) > "=r" : A register operand is allowed provided that it is in a > general register. > > That should make sure x86_64 won't try to use REX prefixed opcodes for > 1, 2 and 4 bytes values. > > Does it make sense ? >
That's probably the best bet.
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