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Wed, 25 Feb 2026 05:34:21 -0800 (PST) Received: from linaro.org ([2a10:d582:31e:0:506c:58b9:ee75:9229]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-483bd70b3f3sm77196845e9.6.2026.02.25.05.34.20 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 25 Feb 2026 05:34:21 -0800 (PST) Date: Wed, 25 Feb 2026 13:34:19 +0000 From: Jim MacArthur To: qemu-devel@nongnu.org Cc: richard.henderson@linaro.org Subject: Re: [PATCH v2 1/6] tcg/optimize: Lower unsupported deposit during optimize Message-ID: References: <20260204052456.970605-1-richard.henderson@linaro.org> <20260204052456.970605-2-richard.henderson@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260204052456.970605-2-richard.henderson@linaro.org> Received-SPF: pass client-ip=2a00:1450:4864:20::32d; envelope-from=jim.macarthur@linaro.org; helo=mail-wm1-x32d.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: qemu development 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 Wed, Feb 04, 2026 at 03:24:51PM +1000, Richard Henderson wrote: > The expansions that we chose in tcg-op.c may be less than optimial. > Delay lowering until optimize, so that we have propagated constants > and have computed known zero/one masks. > > Signed-off-by: Richard Henderson > + /* Lower invalid deposit into zero as AND + SHL or SHL + AND. */ > + if (!valid) { > + if (TCG_TARGET_extract_valid(ctx->type, 0, ofs + len) && > + !TCG_TARGET_extract_valid(ctx->type, 0, len)) { > + op2 = opt_insert_before(ctx, op, INDEX_op_shl, 3); > + op2->args[0] = ret; > + op2->args[1] = arg2; > + op2->args[2] = arg_new_constant(ctx, ofs); > + > + op->opc = INDEX_op_extract; > + op->args[1] = ret; > + op->args[2] = 0; > + op->args[3] = ofs + len; > + goto done; > + } I also had questions about extract vs shift/and here. You've explained this on patch 6, but a comment here about it might help future developers. Nonetheless, Reviewed-by: Jim MacArthur