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Date: Wed, 20 May 2015 12:36:44 -0700 From: Dmitry Torokhov <dmitry.torokhov@...il.com> To: Shailendra Verma <shailendra.capricorn@...il.com> Cc: linux-input@...r.kernel.org, linux-kernel@...r.kernel.org Subject: Re: [PATCH] Input:evdev - Fix to avoid the execution of same instruction in every iteration of for loop. Hi Shailendra, On Thu, May 21, 2015 at 12:35:46AM +0530, Shailendra Verma wrote: > Here in for loop the instruction "len / sizeof(compat_long_t)" is used > as a terminating condition which is executing (being computed) in every > iteration of for loop. Below is the armv7-a architecture assembly code with > similar for loop having the same instruction in condition.Note that the > instruction "lsr r3, r3, #2" i.e Logical Shift Right on behalf of > "len / sizeof(compat_long_t)" is getting executed every time the loop > iterates. No, it is not. We compile kernel with -O2 and compiler is smart enough to optimize such constructs. Thanks. -- Dmitry -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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