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[114.34.229.221]) by smtp.gmail.com with ESMTPSA id e1sm2196056pfl.162.2020.09.10.01.13.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 10 Sep 2020 01:13:20 -0700 (PDT) From: Greentime Hu To: greentime.hu@sifive.com, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, aou@eecs.berkeley.edu, palmer@dabbelt.com, paul.walmsley@sifive.com Cc: Andrew Waterman Subject: [RFC PATCH v7 21/21] riscv: Optimize task switch codes of vector Date: Thu, 10 Sep 2020 16:12:16 +0800 Message-Id: <50eb3d9d0a92d6faa39e9fedb941863426daca76.1599719352.git.greentime.hu@sifive.com> X-Mailer: git-send-email 2.28.0 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This patch replacees 2 instructions with 1 instruction to do the same thing . rs1=x0 with rd != x0 is a special form of the instruction that sets vl to MAXVL. Suggested-by: Andrew Waterman Signed-off-by: Greentime Hu --- arch/riscv/kernel/vector.S | 9 +++------ 1 file changed, 3 insertions(+), 6 deletions(-) diff --git a/arch/riscv/kernel/vector.S b/arch/riscv/kernel/vector.S index 4f0c5a166e4e..f7223c81b11a 100644 --- a/arch/riscv/kernel/vector.S +++ b/arch/riscv/kernel/vector.S @@ -27,8 +27,7 @@ #define x_vl t2 #define x_vcsr t3 #define incr t4 -#define m_one t5 -#define status t6 +#define status t5 ENTRY(__vstate_save) li status, SR_VS @@ -38,8 +37,7 @@ ENTRY(__vstate_save) csrr x_vtype, CSR_VTYPE csrr x_vl, CSR_VL csrr x_vcsr, CSR_VCSR - li m_one, -1 - vsetvli incr, m_one, e8, m8 + vsetvli incr, x0, e8, m8 vse8.v v0, (datap) add datap, datap, incr vse8.v v8, (datap) @@ -61,8 +59,7 @@ ENTRY(__vstate_restore) li status, SR_VS csrs CSR_STATUS, status - li m_one, -1 - vsetvli incr, m_one, e8, m8 + vsetvli incr, x0, e8, m8 vle8.v v0, (datap) add datap, datap, incr vle8.v v8, (datap) -- 2.28.0