On 23 September 2012 17:33, Blue Swirl <blauwir...@gmail.com> wrote: > Avoid this warning: > CC arm-softmmu/hw/arm/../arm_gic.o > /src/qemu/hw/arm/../arm_gic.c:432:17: error: implicit truncation from > 'unsigned int' to bitfield changes value from 4294967040 to 0 > [-Werror,-Wconstant-conversion] > GIC_CLEAR_PENDING(irq + i, ALL_CPU_MASK); > ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > /src/qemu/hw/arm/../arm_gic_internal.h:43:62: note: expanded from: > #define GIC_CLEAR_PENDING(irq, cm) s->irq_state[irq].pending &= ~(cm) > ^ ~~~~~ > > 4294967040 is 0xffffff00 and field 'pending' is effectively 8 bits > wide, so the masking has no effect except for avoiding the warning.
foo &= ~SOME_FLAGS; is an entirely legitimate and common C idiom, and I think clang is being overexuberant in warning here: we should disable this warning instead of working around it in the code. > Signed-off-by: Blue Swirl <blauwir...@gmail.com> > --- > hw/arm_gic_internal.h | 3 ++- > 1 files changed, 2 insertions(+), 1 deletions(-) > > diff --git a/hw/arm_gic_internal.h b/hw/arm_gic_internal.h > index db4fad5..219aef3 100644 > --- a/hw/arm_gic_internal.h > +++ b/hw/arm_gic_internal.h > @@ -40,7 +40,8 @@ > #define GIC_CLEAR_ENABLED(irq, cm) s->irq_state[irq].enabled &= ~(cm) > #define GIC_TEST_ENABLED(irq, cm) ((s->irq_state[irq].enabled & (cm)) != 0) > #define GIC_SET_PENDING(irq, cm) s->irq_state[irq].pending |= (cm) > -#define GIC_CLEAR_PENDING(irq, cm) s->irq_state[irq].pending &= ~(cm) > +#define GIC_CLEAR_PENDING(irq, cm) \ > + s->irq_state[irq].pending &= ~(cm) & ALL_CPU_MASK > #define GIC_TEST_PENDING(irq, cm) ((s->irq_state[irq].pending & (cm)) != 0) > #define GIC_SET_ACTIVE(irq, cm) s->irq_state[irq].active |= (cm) > #define GIC_CLEAR_ACTIVE(irq, cm) s->irq_state[irq].active &= ~(cm) This patch makes GIC_CLEAR_PENDING different from GIC_CLEAR_ACTIVE, GIC_CLEAR_LEVEL and GIC_CLEAR_ENABLED, which is odd since the operation should be identical for all those cases. -- PMM
