Richard Henderson <richard.hender...@linaro.org> writes:
> On 3/18/19 12:46 PM, Peter Maydell wrote: >> Hi; for the M-profile floating point work I'm going to need I think >> three new TB flags (to control whether to generate the code to do >> the various independent things the pseudocode ExecuteFPCheck() function >> does before executing any FP insn). Unfortunately we currently have >> only 2 unused bits in the arm TB flags word. >> >> I can see two possible ways to get the 3rd bit: >> (1) overload the meaning of an existing bit which I know isn't >> relevant to M-profile (eg the XSCALE_CPAR or VECLEN or VECSTRIDE bits) >> (2) start defining new bits in the currently-unused cs_base word > > Either works. But I'd probably reuse (or eliminate) XSCALE_CPAR first. > Afaik, xscale never had vfp, so CPAR could overlap FPEXC_EL? Agree, we should certainly be efficient with the base flags first (we already have overlap for AA32/64 states). I have no problem with using cs_base after that. We could bite the bullet and expand flags to 64 bits but I guess that will be a bit of a hit for 32 bit hosts. Given how many guests use the cs_base I wonder if it's time we came up with a better name for it: extra_tb_state, extra_state, moar_bits... > > > r~ -- Alex Bennée
