Messages in this thread | | | Date | Wed, 19 Aug 2009 10:23:42 +0100 | From | "Jan Beulich" <> | Subject | Re: [PATCH] x86: make use of inc/dec conditional |
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>>> Thomas Gleixner <tglx@linutronix.de> 19.08.09 11:06 >>> >You still do not tell on which machines the INC/DEC instructions >should be avoided and why. GCC avoiding it is not a convincing >argument.
On Pentium4 (Prescott/Nocona) inc/dec not modifying the carry flag cause an extra instruction dependency on EFLAGS, and hence extra latency in when the instruction can be scheduled for execution.
Jan
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