Messages in this thread | | | From | Linus Torvalds <> | Date | Tue, 14 Nov 2017 14:43:14 -0800 | Subject | Re: bit tweaks [was: Re: [nfsd4] potentially hardware breaking regression in 4.14-rc and 4.13.11] |
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On Tue, Nov 14, 2017 at 2:24 PM, Rasmus Villemoes <linux@rasmusvillemoes.dk> wrote: > > Can you be more specific? That's not what I see with gcc 7.1.
I have gcc-7.2.1, and it made a horrible mess of the do_mount() code.
Look for the comment "/* Separate the per-mountpoint flags */" and do the obvious conversion of the simple single-bit stuff.
My gcc actually turned those into jumps after _after_ I converted it into the ternary operation, and then the ternary conversion actually did much worse, because it actually had two sides (one with a zero value, and one with the bit value to be set).
I didn't have time to look into _why_ that code generated branch-overs, when the otherwise similar reverse case in fs/statfs.c did not.
Linus
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