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Rikard Falkeborn
f747e6667e
GENMASK() has an input check which uses __builtin_choose_expr() to enable a compile time sanity check of its inputs if they are known at compile time. However, it turns out that __builtin_constant_p() does not always return a compile time constant [0]. It was thought this problem was fixed with gcc 4.9 [1], but apparently this is not the case [2]. Switch to use __is_constexpr() instead which always returns a compile time constant, regardless of its inputs. Link: https://lore.kernel.org/lkml/[email protected] [0] Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=19449 [1] Link: https://lore.kernel.org/lkml/[email protected] [2] Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: Rikard Falkeborn <[email protected]> Reported-by: Tetsuo Handa <[email protected]> Acked-by: Arnd Bergmann <[email protected]> Reviewed-by: Andy Shevchenko <[email protected]> Cc: Ard Biesheuvel <[email protected]> Cc: Yury Norov <[email protected]> Cc: Peter Zijlstra <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
15 lines
421 B
C
15 lines
421 B
C
#ifndef _LINUX_CONST_H
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#define _LINUX_CONST_H
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#include <vdso/const.h>
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/*
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* This returns a constant expression while determining if an argument is
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* a constant expression, most importantly without evaluating the argument.
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* Glory to Martin Uecker <[email protected]>
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*/
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#define __is_constexpr(x) \
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(sizeof(int) == sizeof(*(8 ? ((void *)((long)(x) * 0l)) : (int *)8)))
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#endif /* _LINUX_CONST_H */
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