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[2603:800c:1201:c600:483f:d486:138f:7868]) by smtp.gmail.com with ESMTPSA id u16-20020a056a00125000b004e1e36d4428sm14020623pfi.104.2022.02.28.12.44.38 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 28 Feb 2022 12:44:39 -0800 (PST) Message-ID: <9b40e3ff-a7d9-b738-336e-ac552dd40243@linaro.org> Date: Mon, 28 Feb 2022 10:44:36 -1000 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.5.0 Subject: Re: [RFC PATCH] tcg/optimize: only read val after const check Content-Language: en-US To: =?UTF-8?Q?Alex_Benn=c3=a9e?= , qemu-devel@nongnu.org References: <20220209112142.3367525-1-alex.bennee@linaro.org> From: Richard Henderson In-Reply-To: <20220209112142.3367525-1-alex.bennee@linaro.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Host-Lookup-Failed: Reverse DNS lookup failed for 2607:f8b0:4864:20::536 (failed) Received-SPF: pass client-ip=2607:f8b0:4864:20::536; envelope-from=richard.henderson@linaro.org; helo=mail-pg1-x536.google.com X-Spam_score_int: -6 X-Spam_score: -0.7 X-Spam_bar: / X-Spam_report: (-0.7 / 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, NICE_REPLY_A=-0.001, PDS_HP_HELO_NORDNS=0.659, RCVD_IN_DNSWL_NONE=-0.0001, RDNS_NONE=0.793, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=no 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" On 2/9/22 01:21, Alex Bennée wrote: > valgrind pointed out that arg_info()->val can be undefined which will > be the case if the arguments are not constant. The ordering of the > checks will have ensured we never relied on an undefined value but for > the sake of completeness re-order the code to be clear. > > Signed-off-by: Alex Bennée > --- > tcg/optimize.c | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) Thanks for this. Just missed today's pull, but applied, finally. r~ > > diff --git a/tcg/optimize.c b/tcg/optimize.c > index e573000951..06213fd434 100644 > --- a/tcg/optimize.c > +++ b/tcg/optimize.c > @@ -552,10 +552,10 @@ static bool do_constant_folding_cond_eq(TCGCond c) > static int do_constant_folding_cond(TCGType type, TCGArg x, > TCGArg y, TCGCond c) > { > - uint64_t xv = arg_info(x)->val; > - uint64_t yv = arg_info(y)->val; > - > if (arg_is_const(x) && arg_is_const(y)) { > + uint64_t xv = arg_info(x)->val; > + uint64_t yv = arg_info(y)->val; > + > switch (type) { > case TCG_TYPE_I32: > return do_constant_folding_cond_32(xv, yv, c); > @@ -567,7 +567,7 @@ static int do_constant_folding_cond(TCGType type, TCGArg x, > } > } else if (args_are_copies(x, y)) { > return do_constant_folding_cond_eq(c); > - } else if (arg_is_const(y) && yv == 0) { > + } else if (arg_is_const(y) && arg_info(y)->val == 0) { > switch (c) { > case TCG_COND_LTU: > return 0;