Messages in this thread | | | Date | Sun, 18 Aug 2019 07:20:36 -0500 | From | Segher Boessenkool <> | Subject | Re: [RFC PATCH] powerpc: use __builtin_trap() in BUG/WARN macros. |
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Hi Christophe,
On Sat, Aug 17, 2019 at 06:37:50PM +0000, Christophe Leroy wrote: > #define BUG() do { \ > + __builtin_trap(); \
GCC will optimise away all code after this, it knows it is unreachable. But you want to keep that BUG_ENTRY stuff I think?
The same will happen with a BUG_ON if the compiler can prove your condition is always true.
> __asm__ __volatile__( \ > - "1: twi 31,0,0\n" \ > + "1:\n" \ > _EMIT_BUG_ENTRY \ > : : "i" (__FILE__), "i" (__LINE__), \ > "i" (0), "i" (sizeof(struct bug_entry))); \
(GCC wil generate a different trap btw; what is called "trap" as extended mnemonic, that is, "tw 31,0,0", not the same thing as "twi", if that matters for the exception handler).
Segher
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