| Message ID | 20221221163652.1239362-1-eric.auger@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | [v2] target/i386: Remove compilation errors when -Werror=maybe-uninitialized | expand |
On 12/21/22 17:36, Eric Auger wrote: > To avoid compilation errors when -Werror=maybe-uninitialized is used, > replace 'case 3' by 'default'. > > Otherwise we get: > > ../target/i386/ops_sse.h: In function ‘helper_vpermdq_ymm’: > ../target/i386/ops_sse.h:2495:13: error: ‘r3’ may be used > uninitialized in this function [-Werror=maybe-uninitialized] > 2495 | d->Q(3) = r3; > | ~~~~~~~~^~~~ > ../target/i386/ops_sse.h:2494:13: error: ‘r2’ may be used > uninitialized in this function [-Werror=maybe-uninitialized] > 2494 | d->Q(2) = r2; > | ~~~~~~~~^~~~ > ../target/i386/ops_sse.h:2493:13: error: ‘r1’ may be used > uninitialized in this function [-Werror=maybe-uninitialized] > 2493 | d->Q(1) = r1; > | ~~~~~~~~^~~~ > ../target/i386/ops_sse.h:2492:13: error: ‘r0’ may be used > uninitialized in this function [-Werror=maybe-uninitialized] > 2492 | d->Q(0) = r0; > | ~~~~~~~~^~~~ > > Signed-off-by: Eric Auger <eric.auger@redhat.com> > Suggested-by: Stefan Weil <sw@weilnetz.de> > Fixes: 790684776861 ("target/i386: reimplement 0x0f 0x3a, add AVX") > --- > target/i386/ops_sse.h | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/target/i386/ops_sse.h b/target/i386/ops_sse.h > index 3cbc36a59d..c442c8c10c 100644 > --- a/target/i386/ops_sse.h > +++ b/target/i386/ops_sse.h > @@ -2466,7 +2466,7 @@ void helper_vpermdq_ymm(Reg *d, Reg *v, Reg *s, uint32_t order) > r0 = s->Q(0); > r1 = s->Q(1); > break; > - case 3: > + default: > r0 = s->Q(2); > r1 = s->Q(3); > break; > @@ -2484,7 +2484,7 @@ void helper_vpermdq_ymm(Reg *d, Reg *v, Reg *s, uint32_t order) > r2 = s->Q(0); > r3 = s->Q(1); > break; > - case 3: > + default: > r2 = s->Q(2); > r3 = s->Q(3); > break; Queued, but this compiler sucks. :) Paolo
On 22/12/22 09:18, Paolo Bonzini wrote: > On 12/21/22 17:36, Eric Auger wrote: >> To avoid compilation errors when -Werror=maybe-uninitialized is used, >> replace 'case 3' by 'default'. >> >> Otherwise we get: >> >> ../target/i386/ops_sse.h: In function ‘helper_vpermdq_ymm’: >> ../target/i386/ops_sse.h:2495:13: error: ‘r3’ may be used >> uninitialized in this function [-Werror=maybe-uninitialized] >> 2495 | d->Q(3) = r3; >> | ~~~~~~~~^~~~ >> ../target/i386/ops_sse.h:2494:13: error: ‘r2’ may be used >> uninitialized in this function [-Werror=maybe-uninitialized] >> 2494 | d->Q(2) = r2; >> | ~~~~~~~~^~~~ >> ../target/i386/ops_sse.h:2493:13: error: ‘r1’ may be used >> uninitialized in this function [-Werror=maybe-uninitialized] >> 2493 | d->Q(1) = r1; >> | ~~~~~~~~^~~~ >> ../target/i386/ops_sse.h:2492:13: error: ‘r0’ may be used >> uninitialized in this function [-Werror=maybe-uninitialized] >> 2492 | d->Q(0) = r0; >> | ~~~~~~~~^~~~ With what compiler? Is that a supported one? >> Signed-off-by: Eric Auger <eric.auger@redhat.com> >> Suggested-by: Stefan Weil <sw@weilnetz.de> >> Fixes: 790684776861 ("target/i386: reimplement 0x0f 0x3a, add AVX") >> --- >> target/i386/ops_sse.h | 4 ++-- >> 1 file changed, 2 insertions(+), 2 deletions(-) >> >> diff --git a/target/i386/ops_sse.h b/target/i386/ops_sse.h >> index 3cbc36a59d..c442c8c10c 100644 >> --- a/target/i386/ops_sse.h >> +++ b/target/i386/ops_sse.h >> @@ -2466,7 +2466,7 @@ void helper_vpermdq_ymm(Reg *d, Reg *v, Reg *s, >> uint32_t order) >> r0 = s->Q(0); >> r1 = s->Q(1); >> break; >> - case 3: >> + default: >> r0 = s->Q(2); >> r1 = s->Q(3); >> break; >> @@ -2484,7 +2484,7 @@ void helper_vpermdq_ymm(Reg *d, Reg *v, Reg *s, >> uint32_t order) >> r2 = s->Q(0); >> r3 = s->Q(1); >> break; >> - case 3: >> + default: >> r2 = s->Q(2); >> r3 = s->Q(3); >> break; > > Queued, but this compiler sucks. :) Can't we simply add a dumb 'default' case? So when reviewing we don't have to evaluate 'default' means 3 here. -- >8 -- --- a/target/i386/ops_sse.h +++ b/target/i386/ops_sse.h @@ -2470,6 +2470,8 @@ void helper_vpermdq_ymm(Reg *d, Reg *v, Reg *s, uint32_t order) r0 = s->Q(2); r1 = s->Q(3); break; + default: + qemu_build_not_reached(); } switch ((order >> 4) & 3) { case 0: @@ -2488,6 +2490,8 @@ void helper_vpermdq_ymm(Reg *d, Reg *v, Reg *s, uint32_t order) r2 = s->Q(2); r3 = s->Q(3); break; + default: + qemu_build_not_reached(); } d->Q(0) = r0; d->Q(1) = r1; ---
Hi Philippe, On 12/22/22 10:01, Philippe Mathieu-Daudé wrote: > On 22/12/22 09:18, Paolo Bonzini wrote: >> On 12/21/22 17:36, Eric Auger wrote: >>> To avoid compilation errors when -Werror=maybe-uninitialized is used, >>> replace 'case 3' by 'default'. >>> >>> Otherwise we get: >>> >>> ../target/i386/ops_sse.h: In function ‘helper_vpermdq_ymm’: >>> ../target/i386/ops_sse.h:2495:13: error: ‘r3’ may be used >>> uninitialized in this function [-Werror=maybe-uninitialized] >>> 2495 | d->Q(3) = r3; >>> | ~~~~~~~~^~~~ >>> ../target/i386/ops_sse.h:2494:13: error: ‘r2’ may be used >>> uninitialized in this function [-Werror=maybe-uninitialized] >>> 2494 | d->Q(2) = r2; >>> | ~~~~~~~~^~~~ >>> ../target/i386/ops_sse.h:2493:13: error: ‘r1’ may be used >>> uninitialized in this function [-Werror=maybe-uninitialized] >>> 2493 | d->Q(1) = r1; >>> | ~~~~~~~~^~~~ >>> ../target/i386/ops_sse.h:2492:13: error: ‘r0’ may be used >>> uninitialized in this function [-Werror=maybe-uninitialized] >>> 2492 | d->Q(0) = r0; >>> | ~~~~~~~~^~~~ > > With what compiler? Is that a supported one? https://lore.kernel.org/qemu-devel/3aab489e-9d90-c1ad-0b6b-b2b5d80db723@redhat.com/ > >>> Signed-off-by: Eric Auger <eric.auger@redhat.com> >>> Suggested-by: Stefan Weil <sw@weilnetz.de> >>> Fixes: 790684776861 ("target/i386: reimplement 0x0f 0x3a, add AVX") >>> --- >>> target/i386/ops_sse.h | 4 ++-- >>> 1 file changed, 2 insertions(+), 2 deletions(-) >>> >>> diff --git a/target/i386/ops_sse.h b/target/i386/ops_sse.h >>> index 3cbc36a59d..c442c8c10c 100644 >>> --- a/target/i386/ops_sse.h >>> +++ b/target/i386/ops_sse.h >>> @@ -2466,7 +2466,7 @@ void helper_vpermdq_ymm(Reg *d, Reg *v, Reg >>> *s, uint32_t order) >>> r0 = s->Q(0); >>> r1 = s->Q(1); >>> break; >>> - case 3: >>> + default: >>> r0 = s->Q(2); >>> r1 = s->Q(3); >>> break; >>> @@ -2484,7 +2484,7 @@ void helper_vpermdq_ymm(Reg *d, Reg *v, Reg >>> *s, uint32_t order) >>> r2 = s->Q(0); >>> r3 = s->Q(1); >>> break; >>> - case 3: >>> + default: >>> r2 = s->Q(2); >>> r3 = s->Q(3); >>> break; >> >> Queued, but this compiler sucks. :) > > Can't we simply add a dumb 'default' case? So when reviewing we don't > have to evaluate 'default' means 3 here. > > -- >8 -- > --- a/target/i386/ops_sse.h > +++ b/target/i386/ops_sse.h > @@ -2470,6 +2470,8 @@ void helper_vpermdq_ymm(Reg *d, Reg *v, Reg *s, > uint32_t order) > r0 = s->Q(2); > r1 = s->Q(3); > break; > + default: > + qemu_build_not_reached(); > } > switch ((order >> 4) & 3) { > case 0: > @@ -2488,6 +2490,8 @@ void helper_vpermdq_ymm(Reg *d, Reg *v, Reg *s, > uint32_t order) > r2 = s->Q(2); > r3 = s->Q(3); > break; > + default: > + qemu_build_not_reached(); > } I guess this won't fix the fact r0, r1, r2, r3 are not initialized, will it? Thanks Eric > d->Q(0) = r0; > d->Q(1) = r1; > --- >
On 22/12/22 11:07, Eric Auger wrote: > Hi Philippe, > > On 12/22/22 10:01, Philippe Mathieu-Daudé wrote: >> On 22/12/22 09:18, Paolo Bonzini wrote: >>> On 12/21/22 17:36, Eric Auger wrote: >>>> To avoid compilation errors when -Werror=maybe-uninitialized is used, >>>> replace 'case 3' by 'default'. >>>> >>>> Otherwise we get: >>>> >>>> ../target/i386/ops_sse.h: In function ‘helper_vpermdq_ymm’: >>>> ../target/i386/ops_sse.h:2495:13: error: ‘r3’ may be used >>>> uninitialized in this function [-Werror=maybe-uninitialized] >>>> 2495 | d->Q(3) = r3; >>>> | ~~~~~~~~^~~~ >>>> ../target/i386/ops_sse.h:2494:13: error: ‘r2’ may be used >>>> uninitialized in this function [-Werror=maybe-uninitialized] >>>> 2494 | d->Q(2) = r2; >>>> | ~~~~~~~~^~~~ >>>> ../target/i386/ops_sse.h:2493:13: error: ‘r1’ may be used >>>> uninitialized in this function [-Werror=maybe-uninitialized] >>>> 2493 | d->Q(1) = r1; >>>> | ~~~~~~~~^~~~ >>>> ../target/i386/ops_sse.h:2492:13: error: ‘r0’ may be used >>>> uninitialized in this function [-Werror=maybe-uninitialized] >>>> 2492 | d->Q(0) = r0; >>>> | ~~~~~~~~^~~~ >> >> With what compiler? Is that a supported one? > https://lore.kernel.org/qemu-devel/3aab489e-9d90-c1ad-0b6b-b2b5d80db723@redhat.com/ Adding the compiler version in the commit description would help: -- Using GCC 11.3.1 "cc (GCC) 11.3.1 20220421 (Red Hat 11.3.1-2)" we get: -- >>>> Signed-off-by: Eric Auger <eric.auger@redhat.com> >>>> Suggested-by: Stefan Weil <sw@weilnetz.de> >>>> Fixes: 790684776861 ("target/i386: reimplement 0x0f 0x3a, add AVX") >>>> --- >>>> target/i386/ops_sse.h | 4 ++-- >>>> 1 file changed, 2 insertions(+), 2 deletions(-) >>>> >>>> diff --git a/target/i386/ops_sse.h b/target/i386/ops_sse.h >>>> index 3cbc36a59d..c442c8c10c 100644 >>>> --- a/target/i386/ops_sse.h >>>> +++ b/target/i386/ops_sse.h >>>> @@ -2466,7 +2466,7 @@ void helper_vpermdq_ymm(Reg *d, Reg *v, Reg >>>> *s, uint32_t order) >>>> r0 = s->Q(0); >>>> r1 = s->Q(1); >>>> break; >>>> - case 3: >>>> + default: >>>> r0 = s->Q(2); >>>> r1 = s->Q(3); >>>> break; >>>> @@ -2484,7 +2484,7 @@ void helper_vpermdq_ymm(Reg *d, Reg *v, Reg >>>> *s, uint32_t order) >>>> r2 = s->Q(0); >>>> r3 = s->Q(1); >>>> break; >>>> - case 3: >>>> + default: >>>> r2 = s->Q(2); >>>> r3 = s->Q(3); >>>> break; >>> >>> Queued, but this compiler sucks. :) >> >> Can't we simply add a dumb 'default' case? So when reviewing we don't >> have to evaluate 'default' means 3 here. >> >> -- >8 -- >> --- a/target/i386/ops_sse.h >> +++ b/target/i386/ops_sse.h >> @@ -2470,6 +2470,8 @@ void helper_vpermdq_ymm(Reg *d, Reg *v, Reg *s, >> uint32_t order) >> r0 = s->Q(2); >> r1 = s->Q(3); >> break; >> + default: >> + qemu_build_not_reached(); >> } >> switch ((order >> 4) & 3) { >> case 0: >> @@ -2488,6 +2490,8 @@ void helper_vpermdq_ymm(Reg *d, Reg *v, Reg *s, >> uint32_t order) >> r2 = s->Q(2); >> r3 = s->Q(3); >> break; >> + default: >> + qemu_build_not_reached(); >> } > I guess this won't fix the fact r0, r1, r2, r3 are not initialized, will it? Well my compiler (Apple clang version 14.0.0 (clang-1400.0.29.202)) doesn't display the warning, I don't have yours handy to test it :)
Am 22. Dezember 2022 09:01:34 UTC schrieb "Philippe Mathieu-Daudé" <philmd@linaro.org>: >On 22/12/22 09:18, Paolo Bonzini wrote: >> On 12/21/22 17:36, Eric Auger wrote: >>> To avoid compilation errors when -Werror=maybe-uninitialized is used, >>> replace 'case 3' by 'default'. >>> >>> Otherwise we get: >>> >>> ../target/i386/ops_sse.h: In function ‘helper_vpermdq_ymm’: >>> ../target/i386/ops_sse.h:2495:13: error: ‘r3’ may be used >>> uninitialized in this function [-Werror=maybe-uninitialized] >>> 2495 | d->Q(3) = r3; >>> | ~~~~~~~~^~~~ >>> ../target/i386/ops_sse.h:2494:13: error: ‘r2’ may be used >>> uninitialized in this function [-Werror=maybe-uninitialized] >>> 2494 | d->Q(2) = r2; >>> | ~~~~~~~~^~~~ >>> ../target/i386/ops_sse.h:2493:13: error: ‘r1’ may be used >>> uninitialized in this function [-Werror=maybe-uninitialized] >>> 2493 | d->Q(1) = r1; >>> | ~~~~~~~~^~~~ >>> ../target/i386/ops_sse.h:2492:13: error: ‘r0’ may be used >>> uninitialized in this function [-Werror=maybe-uninitialized] >>> 2492 | d->Q(0) = r0; >>> | ~~~~~~~~^~~~ > >With what compiler? Is that a supported one? > >>> Signed-off-by: Eric Auger <eric.auger@redhat.com> >>> Suggested-by: Stefan Weil <sw@weilnetz.de> >>> Fixes: 790684776861 ("target/i386: reimplement 0x0f 0x3a, add AVX") >>> --- >>> target/i386/ops_sse.h | 4 ++-- >>> 1 file changed, 2 insertions(+), 2 deletions(-) >>> >>> diff --git a/target/i386/ops_sse.h b/target/i386/ops_sse.h >>> index 3cbc36a59d..c442c8c10c 100644 >>> --- a/target/i386/ops_sse.h >>> +++ b/target/i386/ops_sse.h >>> @@ -2466,7 +2466,7 @@ void helper_vpermdq_ymm(Reg *d, Reg *v, Reg *s, uint32_t order) >>> r0 = s->Q(0); >>> r1 = s->Q(1); >>> break; >>> - case 3: >>> + default: >>> r0 = s->Q(2); >>> r1 = s->Q(3); >>> break; >>> @@ -2484,7 +2484,7 @@ void helper_vpermdq_ymm(Reg *d, Reg *v, Reg *s, uint32_t order) >>> r2 = s->Q(0); >>> r3 = s->Q(1); >>> break; >>> - case 3: >>> + default: >>> r2 = s->Q(2); >>> r3 = s->Q(3); >>> break; >> >> Queued, but this compiler sucks. :) > >Can't we simply add a dumb 'default' case? So when reviewing we don't >have to evaluate 'default' means 3 here. I agree. At least it deserves a comment to preserve the original intention. Best regards, Bernhard >-- >8 -- >--- a/target/i386/ops_sse.h >+++ b/target/i386/ops_sse.h >@@ -2470,6 +2470,8 @@ void helper_vpermdq_ymm(Reg *d, Reg *v, Reg *s, uint32_t order) > r0 = s->Q(2); > r1 = s->Q(3); > break; >+ default: >+ qemu_build_not_reached(); > } > switch ((order >> 4) & 3) { > case 0: >@@ -2488,6 +2490,8 @@ void helper_vpermdq_ymm(Reg *d, Reg *v, Reg *s, uint32_t order) > r2 = s->Q(2); > r3 = s->Q(3); > break; >+ default: >+ qemu_build_not_reached(); > } > d->Q(0) = r0; > d->Q(1) = r1; >--- >
On Thu, Dec 22, 2022 at 11:07:31AM +0100, Eric Auger wrote: > Hi Philippe, > > On 12/22/22 10:01, Philippe Mathieu-Daudé wrote: > > On 22/12/22 09:18, Paolo Bonzini wrote: > >> On 12/21/22 17:36, Eric Auger wrote: > >>> To avoid compilation errors when -Werror=maybe-uninitialized is used, > >>> replace 'case 3' by 'default'. > >>> > >>> Otherwise we get: > >>> > >>> ../target/i386/ops_sse.h: In function ‘helper_vpermdq_ymm’: > >>> ../target/i386/ops_sse.h:2495:13: error: ‘r3’ may be used > >>> uninitialized in this function [-Werror=maybe-uninitialized] > >>> 2495 | d->Q(3) = r3; > >>> | ~~~~~~~~^~~~ > >>> ../target/i386/ops_sse.h:2494:13: error: ‘r2’ may be used > >>> uninitialized in this function [-Werror=maybe-uninitialized] > >>> 2494 | d->Q(2) = r2; > >>> | ~~~~~~~~^~~~ > >>> ../target/i386/ops_sse.h:2493:13: error: ‘r1’ may be used > >>> uninitialized in this function [-Werror=maybe-uninitialized] > >>> 2493 | d->Q(1) = r1; > >>> | ~~~~~~~~^~~~ > >>> ../target/i386/ops_sse.h:2492:13: error: ‘r0’ may be used > >>> uninitialized in this function [-Werror=maybe-uninitialized] > >>> 2492 | d->Q(0) = r0; > >>> | ~~~~~~~~^~~~ > > > > With what compiler? Is that a supported one? > https://lore.kernel.org/qemu-devel/3aab489e-9d90-c1ad-0b6b-b2b5d80db723@redhat.com/ > > > >>> Signed-off-by: Eric Auger <eric.auger@redhat.com> > >>> Suggested-by: Stefan Weil <sw@weilnetz.de> > >>> Fixes: 790684776861 ("target/i386: reimplement 0x0f 0x3a, add AVX") > >>> --- > >>> target/i386/ops_sse.h | 4 ++-- > >>> 1 file changed, 2 insertions(+), 2 deletions(-) > >>> > >>> diff --git a/target/i386/ops_sse.h b/target/i386/ops_sse.h > >>> index 3cbc36a59d..c442c8c10c 100644 > >>> --- a/target/i386/ops_sse.h > >>> +++ b/target/i386/ops_sse.h > >>> @@ -2466,7 +2466,7 @@ void helper_vpermdq_ymm(Reg *d, Reg *v, Reg > >>> *s, uint32_t order) > >>> r0 = s->Q(0); > >>> r1 = s->Q(1); > >>> break; > >>> - case 3: > >>> + default: > >>> r0 = s->Q(2); > >>> r1 = s->Q(3); > >>> break; > >>> @@ -2484,7 +2484,7 @@ void helper_vpermdq_ymm(Reg *d, Reg *v, Reg > >>> *s, uint32_t order) > >>> r2 = s->Q(0); > >>> r3 = s->Q(1); > >>> break; > >>> - case 3: > >>> + default: > >>> r2 = s->Q(2); > >>> r3 = s->Q(3); > >>> break; > >> > >> Queued, but this compiler sucks. :) > > > > Can't we simply add a dumb 'default' case? So when reviewing we don't > > have to evaluate 'default' means 3 here. > > > > -- >8 -- > > --- a/target/i386/ops_sse.h > > +++ b/target/i386/ops_sse.h > > @@ -2470,6 +2470,8 @@ void helper_vpermdq_ymm(Reg *d, Reg *v, Reg *s, > > uint32_t order) > > r0 = s->Q(2); > > r1 = s->Q(3); > > break; > > + default: > > + qemu_build_not_reached(); > > } > > switch ((order >> 4) & 3) { > > case 0: > > @@ -2488,6 +2490,8 @@ void helper_vpermdq_ymm(Reg *d, Reg *v, Reg *s, > > uint32_t order) > > r2 = s->Q(2); > > r3 = s->Q(3); > > break; > > + default: > > + qemu_build_not_reached(); > > } > I guess this won't fix the fact r0, r1, r2, r3 are not initialized, will it? This ultimately expands to assert() and the compiler should see that it terminates the control flow at this point, so shouldn't have a reason to warn. With regards, Daniel
Hi All, On 12/22/22 12:09, Daniel P. Berrangé wrote: > On Thu, Dec 22, 2022 at 11:07:31AM +0100, Eric Auger wrote: >> Hi Philippe, >> >> On 12/22/22 10:01, Philippe Mathieu-Daudé wrote: >>> On 22/12/22 09:18, Paolo Bonzini wrote: >>>> On 12/21/22 17:36, Eric Auger wrote: >>>>> To avoid compilation errors when -Werror=maybe-uninitialized is used, >>>>> replace 'case 3' by 'default'. >>>>> >>>>> Otherwise we get: >>>>> >>>>> ../target/i386/ops_sse.h: In function ‘helper_vpermdq_ymm’: >>>>> ../target/i386/ops_sse.h:2495:13: error: ‘r3’ may be used >>>>> uninitialized in this function [-Werror=maybe-uninitialized] >>>>> 2495 | d->Q(3) = r3; >>>>> | ~~~~~~~~^~~~ >>>>> ../target/i386/ops_sse.h:2494:13: error: ‘r2’ may be used >>>>> uninitialized in this function [-Werror=maybe-uninitialized] >>>>> 2494 | d->Q(2) = r2; >>>>> | ~~~~~~~~^~~~ >>>>> ../target/i386/ops_sse.h:2493:13: error: ‘r1’ may be used >>>>> uninitialized in this function [-Werror=maybe-uninitialized] >>>>> 2493 | d->Q(1) = r1; >>>>> | ~~~~~~~~^~~~ >>>>> ../target/i386/ops_sse.h:2492:13: error: ‘r0’ may be used >>>>> uninitialized in this function [-Werror=maybe-uninitialized] >>>>> 2492 | d->Q(0) = r0; >>>>> | ~~~~~~~~^~~~ >>> With what compiler? Is that a supported one? >> https://lore.kernel.org/qemu-devel/3aab489e-9d90-c1ad-0b6b-b2b5d80db723@redhat.com/ >>>>> Signed-off-by: Eric Auger <eric.auger@redhat.com> >>>>> Suggested-by: Stefan Weil <sw@weilnetz.de> >>>>> Fixes: 790684776861 ("target/i386: reimplement 0x0f 0x3a, add AVX") >>>>> --- >>>>> target/i386/ops_sse.h | 4 ++-- >>>>> 1 file changed, 2 insertions(+), 2 deletions(-) >>>>> >>>>> diff --git a/target/i386/ops_sse.h b/target/i386/ops_sse.h >>>>> index 3cbc36a59d..c442c8c10c 100644 >>>>> --- a/target/i386/ops_sse.h >>>>> +++ b/target/i386/ops_sse.h >>>>> @@ -2466,7 +2466,7 @@ void helper_vpermdq_ymm(Reg *d, Reg *v, Reg >>>>> *s, uint32_t order) >>>>> r0 = s->Q(0); >>>>> r1 = s->Q(1); >>>>> break; >>>>> - case 3: >>>>> + default: >>>>> r0 = s->Q(2); >>>>> r1 = s->Q(3); >>>>> break; >>>>> @@ -2484,7 +2484,7 @@ void helper_vpermdq_ymm(Reg *d, Reg *v, Reg >>>>> *s, uint32_t order) >>>>> r2 = s->Q(0); >>>>> r3 = s->Q(1); >>>>> break; >>>>> - case 3: >>>>> + default: >>>>> r2 = s->Q(2); >>>>> r3 = s->Q(3); >>>>> break; >>>> Queued, but this compiler sucks. :) >>> Can't we simply add a dumb 'default' case? So when reviewing we don't >>> have to evaluate 'default' means 3 here. >>> >>> -- >8 -- >>> --- a/target/i386/ops_sse.h >>> +++ b/target/i386/ops_sse.h >>> @@ -2470,6 +2470,8 @@ void helper_vpermdq_ymm(Reg *d, Reg *v, Reg *s, >>> uint32_t order) >>> r0 = s->Q(2); >>> r1 = s->Q(3); >>> break; >>> + default: >>> + qemu_build_not_reached(); >>> } >>> switch ((order >> 4) & 3) { >>> case 0: >>> @@ -2488,6 +2490,8 @@ void helper_vpermdq_ymm(Reg *d, Reg *v, Reg *s, >>> uint32_t order) >>> r2 = s->Q(2); >>> r3 = s->Q(3); >>> break; >>> + default: >>> + qemu_build_not_reached(); >>> } >> I guess this won't fix the fact r0, r1, r2, r3 are not initialized, will it? > This ultimately expands to assert() and the compiler should see that it > terminates the control flow at this point, so shouldn't have a reason > to warn. OK so with qemu_build_not_reached(); I get /home/augere/UPSTREAM/qemu/include/qemu/osdep.h:184:35: error: call to ‘qemu_build_not_reached_always’ declared with attribute error: code path is reachable 184 | #define qemu_build_not_reached() qemu_build_not_reached_always() | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ However with g_assert_not_reached(), it does not complain and errors are removed. So I will respin with g_assert_not_reached() if nobody advises me against that. Thanks Eric > > > With regards, > Daniel
On 22/12/22 12:18, Eric Auger wrote: > Hi All, > > On 12/22/22 12:09, Daniel P. Berrangé wrote: >> On Thu, Dec 22, 2022 at 11:07:31AM +0100, Eric Auger wrote: >>> Hi Philippe, >>> >>> On 12/22/22 10:01, Philippe Mathieu-Daudé wrote: >>>> On 22/12/22 09:18, Paolo Bonzini wrote: >>>>> On 12/21/22 17:36, Eric Auger wrote: >>>>>> To avoid compilation errors when -Werror=maybe-uninitialized is used, >>>>>> replace 'case 3' by 'default'. >>>>>> >>>>>> Otherwise we get: >>>>>> >>>>>> ../target/i386/ops_sse.h: In function ‘helper_vpermdq_ymm’: >>>>>> ../target/i386/ops_sse.h:2495:13: error: ‘r3’ may be used >>>>>> uninitialized in this function [-Werror=maybe-uninitialized] >>>>>> 2495 | d->Q(3) = r3; >>>>>> | ~~~~~~~~^~~~ >>>>>> ../target/i386/ops_sse.h:2494:13: error: ‘r2’ may be used >>>>>> uninitialized in this function [-Werror=maybe-uninitialized] >>>>>> 2494 | d->Q(2) = r2; >>>>>> | ~~~~~~~~^~~~ >>>>>> ../target/i386/ops_sse.h:2493:13: error: ‘r1’ may be used >>>>>> uninitialized in this function [-Werror=maybe-uninitialized] >>>>>> 2493 | d->Q(1) = r1; >>>>>> | ~~~~~~~~^~~~ >>>>>> ../target/i386/ops_sse.h:2492:13: error: ‘r0’ may be used >>>>>> uninitialized in this function [-Werror=maybe-uninitialized] >>>>>> 2492 | d->Q(0) = r0; >>>>>> | ~~~~~~~~^~~~ >>>> With what compiler? Is that a supported one? >>> https://lore.kernel.org/qemu-devel/3aab489e-9d90-c1ad-0b6b-b2b5d80db723@redhat.com/ >>>>>> Signed-off-by: Eric Auger <eric.auger@redhat.com> >>>>>> Suggested-by: Stefan Weil <sw@weilnetz.de> >>>>>> Fixes: 790684776861 ("target/i386: reimplement 0x0f 0x3a, add AVX") >>>>>> --- >>>>>> target/i386/ops_sse.h | 4 ++-- >>>>>> 1 file changed, 2 insertions(+), 2 deletions(-) >>>>>> >>>>>> diff --git a/target/i386/ops_sse.h b/target/i386/ops_sse.h >>>>>> index 3cbc36a59d..c442c8c10c 100644 >>>>>> --- a/target/i386/ops_sse.h >>>>>> +++ b/target/i386/ops_sse.h >>>>>> @@ -2466,7 +2466,7 @@ void helper_vpermdq_ymm(Reg *d, Reg *v, Reg >>>>>> *s, uint32_t order) >>>>>> r0 = s->Q(0); >>>>>> r1 = s->Q(1); >>>>>> break; >>>>>> - case 3: >>>>>> + default: >>>>>> r0 = s->Q(2); >>>>>> r1 = s->Q(3); >>>>>> break; >>>>>> @@ -2484,7 +2484,7 @@ void helper_vpermdq_ymm(Reg *d, Reg *v, Reg >>>>>> *s, uint32_t order) >>>>>> r2 = s->Q(0); >>>>>> r3 = s->Q(1); >>>>>> break; >>>>>> - case 3: >>>>>> + default: >>>>>> r2 = s->Q(2); >>>>>> r3 = s->Q(3); >>>>>> break; >>>>> Queued, but this compiler sucks. :) >>>> Can't we simply add a dumb 'default' case? So when reviewing we don't >>>> have to evaluate 'default' means 3 here. >>>> >>>> -- >8 -- >>>> --- a/target/i386/ops_sse.h >>>> +++ b/target/i386/ops_sse.h >>>> @@ -2470,6 +2470,8 @@ void helper_vpermdq_ymm(Reg *d, Reg *v, Reg *s, >>>> uint32_t order) >>>> r0 = s->Q(2); >>>> r1 = s->Q(3); >>>> break; >>>> + default: >>>> + qemu_build_not_reached(); >>>> } >>>> switch ((order >> 4) & 3) { >>>> case 0: >>>> @@ -2488,6 +2490,8 @@ void helper_vpermdq_ymm(Reg *d, Reg *v, Reg *s, >>>> uint32_t order) >>>> r2 = s->Q(2); >>>> r3 = s->Q(3); >>>> break; >>>> + default: >>>> + qemu_build_not_reached(); >>>> } >>> I guess this won't fix the fact r0, r1, r2, r3 are not initialized, will it? >> This ultimately expands to assert() and the compiler should see that it >> terminates the control flow at this point, so shouldn't have a reason >> to warn. > > OK so with qemu_build_not_reached(); I get > > /home/augere/UPSTREAM/qemu/include/qemu/osdep.h:184:35: error: call to > ‘qemu_build_not_reached_always’ declared with attribute error: code path > is reachable > 184 | #define qemu_build_not_reached() qemu_build_not_reached_always() > | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > > However with g_assert_not_reached(), it does not complain and errors are > removed. So I will respin with g_assert_not_reached() if nobody advises > me against that. Thank you!
On 22/12/22 13:32, Stefan Weil wrote: > Am 22.12.22 um 12:51 schrieb Philippe Mathieu-Daudé: > >> On 22/12/22 12:18, Eric Auger wrote: >>> Hi All, >>> >>> On 12/22/22 12:09, Daniel P. Berrangé wrote: >>>> On Thu, Dec 22, 2022 at 11:07:31AM +0100, Eric Auger wrote: >>>>> Hi Philippe, >>>>> >>>>> On 12/22/22 10:01, Philippe Mathieu-Daudé wrote: >>>>>> On 22/12/22 09:18, Paolo Bonzini wrote: >>>>>>> On 12/21/22 17:36, Eric Auger wrote: >>>>>>>> To avoid compilation errors when -Werror=maybe-uninitialized is >>>>>>>> used, >>>>>>>> replace 'case 3' by 'default'. >>>>>>>> >>>>>>>> Otherwise we get: >>>>>>>> >>>>>>>> ../target/i386/ops_sse.h: In function ‘helper_vpermdq_ymm’: >>>>>>>> ../target/i386/ops_sse.h:2495:13: error: ‘r3’ may be used >>>>>>>> uninitialized in this function [-Werror=maybe-uninitialized] >>>>>>>> 2495 | d->Q(3) = r3; >>>>>>>> | ~~~~~~~~^~~~ >>>>>>>> ../target/i386/ops_sse.h:2494:13: error: ‘r2’ may be used >>>>>>>> uninitialized in this function [-Werror=maybe-uninitialized] >>>>>>>> 2494 | d->Q(2) = r2; >>>>>>>> | ~~~~~~~~^~~~ >>>>>>>> ../target/i386/ops_sse.h:2493:13: error: ‘r1’ may be used >>>>>>>> uninitialized in this function [-Werror=maybe-uninitialized] >>>>>>>> 2493 | d->Q(1) = r1; >>>>>>>> | ~~~~~~~~^~~~ >>>>>>>> ../target/i386/ops_sse.h:2492:13: error: ‘r0’ may be used >>>>>>>> uninitialized in this function [-Werror=maybe-uninitialized] >>>>>>>> 2492 | d->Q(0) = r0; >>>>>>>> | ~~~~~~~~^~~~ >>>>>> With what compiler? Is that a supported one? >>>>> https://lore.kernel.org/qemu-devel/3aab489e-9d90-c1ad-0b6b-b2b5d80db723@redhat.com/ >>>>>>>> Signed-off-by: Eric Auger <eric.auger@redhat.com> >>>>>>>> Suggested-by: Stefan Weil <sw@weilnetz.de> >>>>>>>> Fixes: 790684776861 ("target/i386: reimplement 0x0f 0x3a, add AVX") >>>>>>>> --- >>>>>>>> target/i386/ops_sse.h | 4 ++-- >>>>>>>> 1 file changed, 2 insertions(+), 2 deletions(-) >>>>>>>> >>>>>>>> diff --git a/target/i386/ops_sse.h b/target/i386/ops_sse.h >>>>>>>> index 3cbc36a59d..c442c8c10c 100644 >>>>>>>> --- a/target/i386/ops_sse.h >>>>>>>> +++ b/target/i386/ops_sse.h >>>>>>>> @@ -2466,7 +2466,7 @@ void helper_vpermdq_ymm(Reg *d, Reg *v, Reg >>>>>>>> *s, uint32_t order) >>>>>>>> r0 = s->Q(0); >>>>>>>> r1 = s->Q(1); >>>>>>>> break; >>>>>>>> - case 3: >>>>>>>> + default: >>>>>>>> r0 = s->Q(2); >>>>>>>> r1 = s->Q(3); >>>>>>>> break; >>>>>>>> @@ -2484,7 +2484,7 @@ void helper_vpermdq_ymm(Reg *d, Reg *v, Reg >>>>>>>> *s, uint32_t order) >>>>>>>> r2 = s->Q(0); >>>>>>>> r3 = s->Q(1); >>>>>>>> break; >>>>>>>> - case 3: >>>>>>>> + default: >>>>>>>> r2 = s->Q(2); >>>>>>>> r3 = s->Q(3); >>>>>>>> break; >>>>>>> Queued, but this compiler sucks. :) >>>>>> Can't we simply add a dumb 'default' case? So when reviewing we don't >>>>>> have to evaluate 'default' means 3 here. >>>>>> >>>>>> -- >8 -- >>>>>> --- a/target/i386/ops_sse.h >>>>>> +++ b/target/i386/ops_sse.h >>>>>> @@ -2470,6 +2470,8 @@ void helper_vpermdq_ymm(Reg *d, Reg *v, Reg *s, >>>>>> uint32_t order) >>>>>> r0 = s->Q(2); >>>>>> r1 = s->Q(3); >>>>>> break; >>>>>> + default: >>>>>> + qemu_build_not_reached(); >>>>>> } >>>>>> switch ((order >> 4) & 3) { >>>>>> case 0: >>>>>> @@ -2488,6 +2490,8 @@ void helper_vpermdq_ymm(Reg *d, Reg *v, Reg *s, >>>>>> uint32_t order) >>>>>> r2 = s->Q(2); >>>>>> r3 = s->Q(3); >>>>>> break; >>>>>> + default: >>>>>> + qemu_build_not_reached(); >>>>>> } >>>>> I guess this won't fix the fact r0, r1, r2, r3 are not initialized, >>>>> will it? >>>> This ultimately expands to assert() and the compiler should see that it >>>> terminates the control flow at this point, so shouldn't have a reason >>>> to warn. >>> >>> OK so with qemu_build_not_reached(); I get >>> >>> /home/augere/UPSTREAM/qemu/include/qemu/osdep.h:184:35: error: call to >>> ‘qemu_build_not_reached_always’ declared with attribute error: code path >>> is reachable >>> 184 | #define qemu_build_not_reached() >>> qemu_build_not_reached_always() >>> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ >>> >>> >>> However with g_assert_not_reached(), it does not complain and errors are >>> removed. So I will respin with g_assert_not_reached() if nobody advises >>> me against that. >> >> Thank you! > > > As noted by Paolo a better compiler could know that 0, 1, 2 and 3 are > the only possible cases. Such a better compiler might complain that an > additional default case is never reached. Therefore the proposed code > might cause future compiler warnings. > > But we could use this code pattern to make the intention of the code > clearer: > > case 3: > default: /* default case added to help the compiler to avoid warnings */ > ... I'm fine with that, as long as we don't obfuscate the code for clever compiler's sake. QEMU code base is already complex enough (the devil 😈 is in the details).
diff --git a/target/i386/ops_sse.h b/target/i386/ops_sse.h index 3cbc36a59d..c442c8c10c 100644 --- a/target/i386/ops_sse.h +++ b/target/i386/ops_sse.h @@ -2466,7 +2466,7 @@ void helper_vpermdq_ymm(Reg *d, Reg *v, Reg *s, uint32_t order) r0 = s->Q(0); r1 = s->Q(1); break; - case 3: + default: r0 = s->Q(2); r1 = s->Q(3); break; @@ -2484,7 +2484,7 @@ void helper_vpermdq_ymm(Reg *d, Reg *v, Reg *s, uint32_t order) r2 = s->Q(0); r3 = s->Q(1); break; - case 3: + default: r2 = s->Q(2); r3 = s->Q(3); break;
To avoid compilation errors when -Werror=maybe-uninitialized is used, replace 'case 3' by 'default'. Otherwise we get: ../target/i386/ops_sse.h: In function ‘helper_vpermdq_ymm’: ../target/i386/ops_sse.h:2495:13: error: ‘r3’ may be used uninitialized in this function [-Werror=maybe-uninitialized] 2495 | d->Q(3) = r3; | ~~~~~~~~^~~~ ../target/i386/ops_sse.h:2494:13: error: ‘r2’ may be used uninitialized in this function [-Werror=maybe-uninitialized] 2494 | d->Q(2) = r2; | ~~~~~~~~^~~~ ../target/i386/ops_sse.h:2493:13: error: ‘r1’ may be used uninitialized in this function [-Werror=maybe-uninitialized] 2493 | d->Q(1) = r1; | ~~~~~~~~^~~~ ../target/i386/ops_sse.h:2492:13: error: ‘r0’ may be used uninitialized in this function [-Werror=maybe-uninitialized] 2492 | d->Q(0) = r0; | ~~~~~~~~^~~~ Signed-off-by: Eric Auger <eric.auger@redhat.com> Suggested-by: Stefan Weil <sw@weilnetz.de> Fixes: 790684776861 ("target/i386: reimplement 0x0f 0x3a, add AVX") --- target/i386/ops_sse.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)