Re: [PATCH 4/4] target/ppc: fix warning with clang-15

["Cédric Le Goater" <clg@kaod.org>]

On 2/13/23 17:13, Pierrick Bouvier wrote:
> When compiling for windows-arm64 using clang-15, it reports a sometimes
> uninitialized variable. This seems to be a false positive, as a default
> case guards switch expressions, preventing to return an uninitialized
> value, but clang seems unhappy with assert definition.
> 
> Setting the rnd variable to zero does not hurt anyway.
> 
> ../target/ppc/dfp_helper.c:141:13: error: variable 'rnd' is used uninitialized whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized]                                                                              assert(0); /* cannot get here */                                                                                                                                                                                    ^~~~~~~~~
> ../include/qemu/osdep.h:229:20: note: expanded from macro 'assert'                                                                                                                                        #define assert(x)  g_assert(x)                                                                                                                                                                                                         ^~~~~~~~~~~
> /clangarm64/bin/../include/glib-2.0/glib/gtestutils.h:235:49: note: expanded from macro 'g_assert'                                                                                                                               if G_LIKELY (expr) ; else \
>                                                  ^~~~~~~~~~~~~~~
> /clangarm64/bin/../include/glib-2.0/glib/gmacros.h:1186:25: note: expanded from macro 'G_LIKELY'
>                          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> ../target/ppc/dfp_helper.c:144:42: note: uninitialized use occurs here
>      decContextSetRounding(&dfp->context, rnd);
> 
> Signed-off-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>

Reviewed-by: Cédric Le Goater <clg@kaod.org>

Thanks,

C.


> ---
>   target/ppc/dfp_helper.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/target/ppc/dfp_helper.c b/target/ppc/dfp_helper.c
> index cc024316d5..0b4b280683 100644
> --- a/target/ppc/dfp_helper.c
> +++ b/target/ppc/dfp_helper.c
> @@ -69,7 +69,7 @@ struct PPC_DFP {
>   
>   static void dfp_prepare_rounding_mode(decContext *context, uint64_t fpscr)
>   {
> -    enum rounding rnd;
> +    enum rounding rnd = 0;
>   
>       switch ((fpscr & FP_DRN) >> FPSCR_DRN0) {
>       case 0:
> @@ -106,7 +106,7 @@ static void dfp_prepare_rounding_mode(decContext *context, uint64_t fpscr)
>   static void dfp_set_round_mode_from_immediate(uint8_t r, uint8_t rmc,
>                                                     struct PPC_DFP *dfp)
>   {
> -    enum rounding rnd;
> +    enum rounding rnd = 0;
>       if (r == 0) {
>           switch (rmc & 3) {
>           case 0: