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no-op delay loops

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Hi,

It seems that gcc happily compiles

for (i = 0; i < 1000000000; ++i) ;

into simply

i = 1000000000;

(which is then usually eliminated as a dead store). At least at -O2, and
when i is not declared volatile. So it would seem that the loops at

arch/mips/pci/pci-rt2880.c:235
arch/mips/pmcs-msp71xx/msp_setup.c:80
arch/mips/sni/reset.c:35

actually don't do anything. (In the middle one, i is 'register', but
that doesn't change anything.) Is mips compiled with some special flags
that would make gcc actually emit code for the above?

Rasmus
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Thread

no-op delay loops Rasmus Villemoes <linux@rasmusvillemoes.dk> - 2015-11-27 10:00 +0100
  Re: no-op delay loops yalin wang <yalin.wang2010@gmail.com> - 2015-11-27 10:10 +0100
    Re: no-op delay loops Andy Shevchenko <andy.shevchenko@gmail.com> - 2015-11-27 10:30 +0100
  Re: no-op delay loops Arnd Bergmann <arnd@arndb.de> - 2015-11-27 12:20 +0100
  Re: no-op delay loops Ralf Baechle <ralf@linux-mips.org> - 2015-11-27 12:50 +0100

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