On Tue, 22 Aug 2023 at 14:46, Alex Bennée <alex.ben...@linaro.org> wrote: > > > Philippe Mathieu-Daudé <phi...@linaro.org> writes: > > > While reviewing a recent patch from Richard optimizing > > deposit() [*] I ended looking at the *swap friends, taking > > some notes, which then evolved to proper documentation. > > > > [*] > > https://lore.kernel.org/qemu-devel/20230816145547.477974-3-richard.hender...@linaro.org/ > > We already have some documentation in tcg.rst: > > * - bswap16_i32/i64 *t0*, *t1*, *flags* > > - | 16 bit byte swap on the low bits of a 32/64 bit input. > | > | If *flags* & ``TCG_BSWAP_IZ``, then *t1* is known to be > zero-extended from bit 15. > | If *flags* & ``TCG_BSWAP_OZ``, then *t0* will be zero-extended from > bit 15. > | If *flags* & ``TCG_BSWAP_OS``, then *t0* will be sign-extended from > bit 15. > | > | If neither ``TCG_BSWAP_OZ`` nor ``TCG_BSWAP_OS`` are set, then the > bits of *t0* above bit 15 may contain any value. > > * - bswap32_i64 *t0*, *t1*, *flags* > > - | 32 bit byte swap on a 64-bit value. The flags are the same as for > bswap16, > except they apply from bit 31 instead of bit 15. > > * - bswap32_i32 *t0*, *t1*, *flags* > > bswap64_i64 *t0*, *t1*, *flags* > > - | 32/64 bit byte swap. The flags are ignored, but still present > for consistency with the other bswap opcodes. > > In an ideal world we could generate kdoc from the source file and > include it in the rest of the tcg docs. I'm not sure if it worth the > churn though? Richard?
I do think it would be useful to have documentation of the set of APIs you use as a writer of a TCG frontend. This is often not exactly the same as the TCG IR opcodes. (Similarly what you have to do as a backend isn't exactly the same, but the documentation need is less pressing because fewer people need to work on the backends.) thanks -- PMM
