| Message ID | 20230213161352.17199-5-pierrick.bouvier@linaro.org |
|---|---|
| State | New |
| Headers | show |
| Series | Adds support for running QEMU natively on windows-arm64 | expand |
On 13/2/23 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> > --- > 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; Could DEC_ROUND_DEFAULT be clearer?
On 2/14/23 08:14, Philippe Mathieu-Daudé wrote: > On 13/2/23 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> >> --- >> 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; > > Could DEC_ROUND_DEFAULT be clearer? > I missed that macro definition, and that seems like a good default value. I'll change to this.
On 2/13/23 06:13, 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); I think the problem is with assert(0) not being seen to terminate. Replace these with g_assert_not_reached(). r~
On 2/14/23 19:10, Richard Henderson wrote: > On 2/13/23 06:13, 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); > > I think the problem is with assert(0) not being seen to terminate. > Replace these with g_assert_not_reached(). > Indeed, that solves the issue. Thanks for the suggestion, I'll use this instead. > > r~ >
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:
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> --- target/ppc/dfp_helper.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)