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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=2607:f8b0:4864:20::433; envelope-from=richard.henderson@linaro.org; helo=mail-pf1-x433.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On 10/25/23 11:59, Paolo Bonzini wrote: > On x86, this is more efficient because it enables generation of > more LEA instructions. > > Signed-off-by: Paolo Bonzini > --- > include/tcg/tcg.h | 4 ++++ > tcg/i386/tcg-target.h | 2 ++ > tcg/tcg-op.c | 20 ++++++++++++++++---- > 3 files changed, 22 insertions(+), 4 deletions(-) > > diff --git a/include/tcg/tcg.h b/include/tcg/tcg.h > index a9282cdcc60..48e5aeef173 100644 > --- a/include/tcg/tcg.h > +++ b/include/tcg/tcg.h > @@ -109,6 +109,10 @@ typedef uint64_t TCGRegSet; > #define TCG_TARGET_HAS_sub2_i32 1 > #endif > > +#ifndef TCG_TARGET_PREFERS_addi > +#define TCG_TARGET_PREFERS_addi 0 > +#endif I would rather do this unconditionally. Many of the tcg backends do this manually, e.g. s390x: case INDEX_op_sub_i64: a0 = args[0], a1 = args[1], a2 = args[2]; if (const_args[2]) { a2 = -a2; goto do_addi_64; } else { tcg_out_insn(s, RRFa, SGRK, a0, a1, a2); } break; While we could do something similar for i386, it would be better to not require such hoops in each backend. We would also want to perform this transformation in optimize.c. r~