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Tue, 09 Feb 2021 10:27:57 -0800 (PST) Received: from zen.lan (localhost [127.0.0.1]) by zen.linaroharston (Postfix) with ESMTP id DAA841FF93; Tue, 9 Feb 2021 18:27:50 +0000 (GMT) From: =?utf-8?q?Alex_Benn=C3=A9e?= To: qemu-devel@nongnu.org Subject: [PATCH v1 07/12] accel/tcg: actually cache our partial icount TB Date: Tue, 9 Feb 2021 18:27:43 +0000 Message-Id: <20210209182749.31323-8-alex.bennee@linaro.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20210209182749.31323-1-alex.bennee@linaro.org> References: <20210209182749.31323-1-alex.bennee@linaro.org> MIME-Version: 1.0 Received-SPF: pass client-ip=2a00:1450:4864:20::333; envelope-from=alex.bennee@linaro.org; helo=mail-wm1-x333.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: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Richard Henderson , robhenry@microsoft.com, aaron@os.amperecomputing.com, cota@braap.org, Paolo Bonzini , kuhn.chenqun@huawei.com, =?utf-8?q?Ale?= =?utf-8?q?x_Benn=C3=A9e?= Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" When we exit a block under icount with instructions left to execute we might need a shorter than normal block to take us to the next deterministic event. Instead of creating a throwaway block on demand we use the existing compile flags mechanism to ensure we fetch (or compile and fetch) a block with exactly the number of instructions we need. Signed-off-by: Alex Bennée --- accel/tcg/cpu-exec.c | 18 ++++++++++-------- 1 file changed, 10 insertions(+), 8 deletions(-) diff --git a/accel/tcg/cpu-exec.c b/accel/tcg/cpu-exec.c index d9ef69121c..7f477af891 100644 --- a/accel/tcg/cpu-exec.c +++ b/accel/tcg/cpu-exec.c @@ -730,16 +730,18 @@ static inline void cpu_loop_exec_tb(CPUState *cpu, TranslationBlock *tb, /* Ensure global icount has gone forward */ icount_update(cpu); /* Refill decrementer and continue execution. */ - insns_left = MIN(0xffff, cpu->icount_budget); + insns_left = MIN(CF_COUNT_MASK, cpu->icount_budget); cpu_neg(cpu)->icount_decr.u16.low = insns_left; cpu->icount_extra = cpu->icount_budget - insns_left; - if (!cpu->icount_extra && insns_left < tb->icount) { - /* Execute any remaining instructions, then let the main loop - * handle the next event. - */ - if (insns_left > 0) { - cpu_exec_nocache(cpu, insns_left, tb, false); - } + + /* + * If the next tb has more instructions than we have left to + * execute we need to ensure we find/generate a TB with exactly + * insns_left instructions in it. + */ + if (!cpu->icount_extra && insns_left > 0 && insns_left < tb->icount) { + g_assert(insns_left < CF_COUNT_MASK); + cpu->cflags_next_tb = (tb->cflags & ~CF_COUNT_MASK) | insns_left; } #endif }