Messages in this thread | | | Date | Thu, 10 Oct 2013 10:45:35 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH] gcc4: Add 'asm goto' miscompilation quirk |
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* Jakub Jelinek <jakub@redhat.com> wrote:
> On Thu, Oct 10, 2013 at 10:24:30AM +0200, Ingo Molnar wrote: > > Something like the patch below? (Totally untested and all that.) > > > > Notes: > > > > - If the bug is fixed in 4.8.3 then the version check can be sharpened > > from 99999 to 40803. > > The bug is likely going to be fixed already for 4.8.2 (to be released > next week or so). > > > - I'd really prefer this quirk versus having to add the extra barrier to > > the label, as it makes the actual usage sites a lot less painful. > > Please check how much it bloats the generated code.
on Linus's latest tree plain 'asm goto' is only rarely used, so the size impact of the patch, on x86-64 defconfig, is zero:
vmlinux: text data bss dec hex filename 11166823 1448024 1187840 13802687 d29cbf vmlinux.before 11166823 1448024 1187840 13802687 d29cbf vmlinux.after 1f7c3c1fd71b4b1327965bcfbc7a77fb vmlinux.before 3b246add801bc170e47096b712942395 vmlinux.after
Using GCC 4.8.1.
> Also, for the bitops patch, you probably want an asm_volatile_goto variant.
Also, for mutex_64.h - good point, will fix that.
Thanks,
Ingo
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