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[82.69.66.36]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-477bf3b4c13sm39025065e9.13.2025.11.21.03.59.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 21 Nov 2025 03:59:32 -0800 (PST) Date: Fri, 21 Nov 2025 11:59:31 +0000 From: David Laight To: Andreas Schwab Cc: "Theodore Tso" , Guan-Chun Wu <409411716@gms.tku.edu.tw>, Andreas Dilger , linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, visitorckw@gmail.com Subject: Re: [PATCH] ext4: improve str2hashbuf by processing 4-byte chunks Message-ID: <20251121115931.411ab538@pumpkin> In-Reply-To: <87a50flko1.fsf@igel.home> References: <20251116130105.1988020-1-409411716@gms.tku.edu.tw> <20251116193513.0f90712a@pumpkin> <20251120155816.GB13687@macsyma-3.local> <87a50flko1.fsf@igel.home> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; arm-unknown-linux-gnueabihf) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Fri, 21 Nov 2025 11:55:26 +0100 Andreas Schwab wrote: > On Nov 20 2025, Theodore Tso wrote: > > > Secondly, it's not that a promotion happens before "any" arithmetic. > > If we add two 8-bit values together, promotion doesn't happen. > > That is not true. Integer promotion is applied individually to each > operand independent of context. True. You can think of the promotion happening every time a 'variable' is read into a cpu register for any operation (including an assignment). Similarly every write to a variable discards the high bits. David