Messages in this thread Patch in this message | | | Date | Mon, 7 Jan 2019 13:16:50 -0500 | From | "Michael S. Tsirkin" <> | Subject | Re: [PATCH RFC 2/4] include/linux/compiler.h: allow memory operands |
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On Mon, Jan 07, 2019 at 05:54:27PM +0000, Will Deacon wrote: > On Wed, Jan 02, 2019 at 03:57:54PM -0500, Michael S. Tsirkin wrote: > > We don't really care whether the variable is in-register > > or in-memory. Relax the constraint accordingly. > > > > Signed-off-by: Michael S. Tsirkin <mst@redhat.com> > > --- > > include/linux/compiler.h | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/include/linux/compiler.h b/include/linux/compiler.h > > index 1ad367b4cd8d..6601d39e8c48 100644 > > --- a/include/linux/compiler.h > > +++ b/include/linux/compiler.h > > @@ -154,7 +154,7 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val, > > #ifndef OPTIMIZER_HIDE_VAR > > /* Make the optimizer believe the variable can be manipulated arbitrarily. */ > > #define OPTIMIZER_HIDE_VAR(var) \ > > - __asm__ ("" : "=r" (var) : "0" (var)) > > + __asm__ ("" : "=rm" (var) : "0" (var)) > > #endif > > I think this can break for architectures with write-back addressing modes > such as arm, where the "m" constraint is assumed to be evaluated precisely > once in the asm block. > > Will
Thanks, I'll drop this patch.
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