On Thu, Jan 14, 2010 at 08:05:58AM -0800, Richard Henderson wrote:
> On 01/14/2010 07:57 AM, Aurelien Jarno wrote:
> >On Tue, Jan 05, 2010 at 04:03:00PM -0800, Richard Henderson wrote:
> >>This avoids an unnecessary REX.W prefix when dealing with AND
> >>operands that fit into a 32-bit quantity. The most common change
> >>actually seen is movz[wb]q -> movz[wb]l.
> >>
> >>Similarly, avoid REXW in ext{8,16}u_i64 tcg opcodes.
> >>
> >>Signed-off-by: Richard Henderson<r...@twiddle.net>
> >>---
> >> tcg/x86_64/tcg-target.c | 26 ++++++++------------------
> >> 1 files changed, 8 insertions(+), 18 deletions(-)
> >>
> >>diff --git a/tcg/x86_64/tcg-target.c b/tcg/x86_64/tcg-target.c
> >>index 2339091..f584c94 100644
> >>--- a/tcg/x86_64/tcg-target.c
> >>+++ b/tcg/x86_64/tcg-target.c
> >>@@ -426,24 +426,18 @@ static inline void tgen_arithi64(TCGContext *s, int
> >>c, int r0, int64_t val)
> >> } else if ((c == ARITH_ADD&& val == -1) || (c == ARITH_SUB&& val ==
> >> 1)) {
> >> /* dec */
> >> tcg_out_modrm(s, 0xff | P_REXW, 1, r0);
> >>- } else if (val == (int8_t)val) {
> >>- tcg_out_modrm(s, 0x83 | P_REXW, c, r0);
> >>- tcg_out8(s, val);
> >>- } else if (c == ARITH_AND&& val == 0xffu) {
> >>- /* movzbl */
> >>- tcg_out_modrm(s, 0xb6 | P_EXT | P_REXW, r0, r0);
> >>- } else if (c == ARITH_AND&& val == 0xffffu) {
> >>- /* movzwl */
> >>- tcg_out_modrm(s, 0xb7 | P_EXT | P_REXW, r0, r0);
> >> } else if (c == ARITH_AND&& val == 0xffffffffu) {
> >> /* 32-bit mov zero extends */
> >> tcg_out_modrm(s, 0x8b, r0, r0);
> >>+ } else if (c == ARITH_AND&& (uint64_t)val<= 0xffffffffu) {
> >>+ /* AND with no high bits set can use a 32-bit operation. */
> >>+ tgen_arithi32(s, c, r0, val);
> >
> >Do we really want to call tgen_arithi32() here, that will redo part of
> >the above tests again? It might be better to simply remove the REX.W
> >prefix above instead.
>
> Pardon? Do you mean the inc/dec tests? Otherwise I don't see what
> "above tests again" you're talking about.
>
> I am looking to handle more than 0xff, 0xffff with the new test in
> gen_arithi64 -- 0x1234 is an appropriate mask to shorten to 32-bit
> AND as well. I have no idea if that answers your question.
>
Yes it does, I missed that fact. Viewing your patch on this side gives
it more sense. I have applied it.
--
Aurelien Jarno GPG: 1024D/F1BCDB73
aurel...@aurel32.net http://www.aurel32.net
