Messages in this thread | | | Date | Wed, 20 Feb 2013 21:49:43 -0600 | From | Kim Phillips <> | Subject | Re: [RFC] arm: use built-in byte swap function |
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On Wed, 20 Feb 2013 10:43:18 -0500 Nicolas Pitre <nico@fluxnic.net> wrote:
> On Wed, 20 Feb 2013, Woodhouse, David wrote: > > On Wed, 2013-02-20 at 09:06 -0500, Nicolas Pitre wrote: > > > ... in which case there is no harm shipping a .c file and trivially > > > enforcing -O2, the rest being equal. > > > > For today's compilers, unless the wind changes. > > We'll adapt if necessary. Going with -O2 should remain pretty safe anyway.
Alas, not so for gcc 4.4 - I had forgotten I had tested Ubuntu/Linaro 4.4.7-1ubuntu2 here:
https://patchwork.kernel.org/patch/2101491/
add -O2 to that test script and gcc 4.4 *always* emits calls to __bswap[sd]i2, even with -march=armv6k+.
I'll try working on an assembly version given it probably makes more sense, future-gcc-immunity-wise.
Otherwise we're back to the old 'if GCC_VERSION >= 40500' in arch/arm/include/asm/swab.h...
Kim
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