| Message ID | 20190923230004.9231-4-richard.henderson@linaro.org |
|---|---|
| State | New |
| Headers | show |
| Series | Move rom and notdirty handling to cputlb | expand |
On 24.09.19 00:59, Richard Henderson wrote: > Use this as a compile-time assert that a particular > code path is not reachable. > > Signed-off-by: Richard Henderson <richard.henderson@linaro.org> > --- > include/qemu/compiler.h | 15 +++++++++++++++ > 1 file changed, 15 insertions(+) > > diff --git a/include/qemu/compiler.h b/include/qemu/compiler.h > index 20780e722d..6604ccea92 100644 > --- a/include/qemu/compiler.h > +++ b/include/qemu/compiler.h > @@ -221,4 +221,19 @@ > #define QEMU_GENERIC9(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC8(x, __VA_ARGS__)) > #define QEMU_GENERIC10(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC9(x, __VA_ARGS__)) > > +/** > + * optimize_away() I would have used the compiler-speak "optimized_out()" instead. > + * > + * The compiler, during optimization, is expected to prove that a call > + * to this function cannot be reached and remove it. If the compiler > + * supports QEMU_ERROR, this will be reported at compile time; otherwise > + * this will be reported at link time, due to the missing symbol. > + */ > +#ifdef __OPTIMIZE__ > +extern void QEMU_NORETURN QEMU_ERROR("code path is reachable") > + optimize_away(void); > +#else > +#define optimize_away() g_assert_not_reached() > +#endif > + > #endif /* COMPILER_H */ > Apart from that looks good to me.
Richard Henderson <richard.henderson@linaro.org> writes: > Use this as a compile-time assert that a particular > code path is not reachable. > > Signed-off-by: Richard Henderson <richard.henderson@linaro.org> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> > --- > include/qemu/compiler.h | 15 +++++++++++++++ > 1 file changed, 15 insertions(+) > > diff --git a/include/qemu/compiler.h b/include/qemu/compiler.h > index 20780e722d..6604ccea92 100644 > --- a/include/qemu/compiler.h > +++ b/include/qemu/compiler.h > @@ -221,4 +221,19 @@ > #define QEMU_GENERIC9(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC8(x, __VA_ARGS__)) > #define QEMU_GENERIC10(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC9(x, __VA_ARGS__)) > > +/** > + * optimize_away() > + * > + * The compiler, during optimization, is expected to prove that a call > + * to this function cannot be reached and remove it. If the compiler > + * supports QEMU_ERROR, this will be reported at compile time; otherwise > + * this will be reported at link time, due to the missing symbol. > + */ > +#ifdef __OPTIMIZE__ > +extern void QEMU_NORETURN QEMU_ERROR("code path is reachable") > + optimize_away(void); > +#else > +#define optimize_away() g_assert_not_reached() > +#endif > + > #endif /* COMPILER_H */ -- Alex Bennée
On 9/24/19 12:47 AM, David Hildenbrand wrote: > On 24.09.19 00:59, Richard Henderson wrote: >> +/** >> + * optimize_away() > > I would have used the compiler-speak "optimized_out()" instead. Hmm, that's just a matter of present vs past test. Perhaps, qemu_build_not_reached, to mirror g_assert_not_reached and QEMU_BUILD_BUG_ON? r~
On 24.09.19 19:27, Richard Henderson wrote: > On 9/24/19 12:47 AM, David Hildenbrand wrote: >> On 24.09.19 00:59, Richard Henderson wrote: >>> +/** >>> + * optimize_away() >> >> I would have used the compiler-speak "optimized_out()" instead. > > Hmm, that's just a matter of present vs past test. > > Perhaps, qemu_build_not_reached, to mirror g_assert_not_reached and > QEMU_BUILD_BUG_ON? > Would also work for me.
diff --git a/include/qemu/compiler.h b/include/qemu/compiler.h index 20780e722d..6604ccea92 100644 --- a/include/qemu/compiler.h +++ b/include/qemu/compiler.h @@ -221,4 +221,19 @@ #define QEMU_GENERIC9(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC8(x, __VA_ARGS__)) #define QEMU_GENERIC10(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC9(x, __VA_ARGS__)) +/** + * optimize_away() + * + * The compiler, during optimization, is expected to prove that a call + * to this function cannot be reached and remove it. If the compiler + * supports QEMU_ERROR, this will be reported at compile time; otherwise + * this will be reported at link time, due to the missing symbol. + */ +#ifdef __OPTIMIZE__ +extern void QEMU_NORETURN QEMU_ERROR("code path is reachable") + optimize_away(void); +#else +#define optimize_away() g_assert_not_reached() +#endif + #endif /* COMPILER_H */
Use this as a compile-time assert that a particular code path is not reachable. Signed-off-by: Richard Henderson <richard.henderson@linaro.org> --- include/qemu/compiler.h | 15 +++++++++++++++ 1 file changed, 15 insertions(+)