On 10/29/20 1:28 PM, Thomas Huth wrote:
> To be able to compile this file with -Werror=implicit-fallthrough,
> we need to add some fallthrough annotations to the case statements
> that might fall through. Unfortunately, the typical "/* fallthrough */"
> comments do not work here as expected since some case labels are
> wrapped in macros and the compiler fails to match the comments in
> this case. But using __attribute__((fallthrough)) seems to work fine,
> so let's use that instead.
>
> Signed-off-by: Thomas Huth <[email protected]>
> ---
> tcg/optimize.c | 10 ++++++++++
> 1 file changed, 10 insertions(+)
>
> diff --git a/tcg/optimize.c b/tcg/optimize.c
> index 220f4601d5..c2768c9770 100644
> --- a/tcg/optimize.c
> +++ b/tcg/optimize.c
> @@ -26,6 +26,12 @@
> #include "qemu/osdep.h"
> #include "tcg/tcg-op.h"
>
> +#if __has_attribute(fallthrough)
> +# define fallthrough() __attribute__((fallthrough))
> +#else
> +# define fallthrough() do {} while (0)
> +#endif
This looks something we can reuse, what about adding it
as QEMU_FALLTHROUGH in "qemu/compiler.h"?
> +
> #define CASE_OP_32_64(x) \
> glue(glue(case INDEX_op_, x), _i32): \
> glue(glue(case INDEX_op_, x), _i64)
> @@ -855,6 +861,7 @@ void tcg_optimize(TCGContext *s)
> if ((arg_info(op->args[1])->mask & 0x80) != 0) {
> break;
> }
> + fallthrough();
> CASE_OP_32_64(ext8u):
> mask = 0xff;
> goto and_const;
> @@ -862,6 +869,7 @@ void tcg_optimize(TCGContext *s)
> if ((arg_info(op->args[1])->mask & 0x8000) != 0) {
> break;
> }
> + fallthrough();
> CASE_OP_32_64(ext16u):
> mask = 0xffff;
> goto and_const;
> @@ -869,6 +877,7 @@ void tcg_optimize(TCGContext *s)
> if ((arg_info(op->args[1])->mask & 0x80000000) != 0) {
> break;
> }
> + fallthrough();
> case INDEX_op_ext32u_i64:
> mask = 0xffffffffU;
> goto and_const;
> @@ -886,6 +895,7 @@ void tcg_optimize(TCGContext *s)
> if ((arg_info(op->args[1])->mask & 0x80000000) != 0) {
> break;
> }
> + fallthrough();
> case INDEX_op_extu_i32_i64:
> /* We do not compute affected as it is a size changing op. */
> mask = (uint32_t)arg_info(op->args[1])->mask;
>
