(resending this email in case the first one got caught in your spam filter. sorry.)
On Thu, Jul 17, 2014 at 10:41:02AM +0100, Will Deacon wrote: > On Wed, Jul 16, 2014 at 11:04:22PM +0100, Zi Shen Lim wrote: > > On Wed, Jul 16, 2014 at 05:17:15PM +0100, Will Deacon wrote: > > > On Tue, Jul 15, 2014 at 07:25:06AM +0100, Zi Shen Lim wrote: > > > > Introduce function to generate move wide (immediate) instructions. [...] > > > > + switch (variant) { > > > > + case AARCH64_INSN_VARIANT_32BIT: > > > > + BUG_ON(shift != 0 && shift != 16); > > > > + break; > > > > + case AARCH64_INSN_VARIANT_64BIT: > > > > + insn |= BIT(31); > > > > + BUG_ON(shift != 0 && shift != 16 && shift != 32 && > > > > + shift != 48); > > > > > > Would be neater as a nested switch, perhaps? If you reorder the > > > outer-switch, you could probably fall-through too and combine the shift > > > checks. > > > > Not sure I picture what you had in mind... I couldn't come up with a > > neater version with the properties you described. > > > > The alternative I had was using masks instead of integer values, but > > one could argue that while neater, it could also be harder to read: > > > > switch (variant) { > > case AARCH64_INSN_VARIANT_32BIT: > > BUG_ON(shift & ~BIT(4)); > > break; > > case AARCH64_INSN_VARIANT_64BIT: > > insn |= BIT(31); > > BUG_ON(shift & ~GENMASK(5, 4)); > > ... > > I was thinking of using nested switches, but that doesn't fall out like I > hoped. How about: > > switch (variant) { > case AARCH64_INSN_VARIANT_64BIT: > BUG_ON(shift != 32 && shift != 48); Sorry this won't work. For example, on the valid case of shift==0, we'll barf right here - no fallthrough. Shall we just leave the code as is? :) > case AARCH64_INSN_VARIANT_32BIT: > BUG_ON(shift != 0 && shift != 16); > }; > > ? > > Will -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/