Messages in this thread |  | | | From | (H. Peter Anvin) | | Subject | Re: [PATCH] 498+ days uptime | | Date | 26 Aug 1998 07:37:34 GMT |
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Followup to: <35E316CB.A9E09B15@gmx.de> By author: Edgar Toernig <froese@gmx.de> In newsgroup: linux.dev.kernel > > But the worst thing is register usage. The x86 has very few registers > and 64-bit arithmetic requires a lot. So, gcc has to generate a > lot of code just to shuffle register contents. Nearly every 64-bit > operator has to flush all registers to the stack and restore them > later. And this makes a difference in execution time and memory > usage... >
Actually, on x86 64-bit arithmetric is quite cheap, because x86 with its 8-bit CPU heritage has explicit support for multiword arithmetric (adc, sbb, 64-bit mul/imul/div/idiv).
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