On 2/4/21 10:02 AM, Stefan Weil wrote: > Is there a Git repository which makes pulling all changes easier?
https://gitlab.com/rth7680/qemu/-/tree/tci-next > Regarding misaligned bytecode access, there exist two solutions. We could > either use code which handles that correctly (I had sent a patch using memcpy > two years ago and recently sent a V2 which uses the QEMU standard functions > for > that). Or we can align the data like it is done in Richard's patches. For me > it > is not obvious which one is better. I think it is obvious. If a host requires aligned access, a single aligned load requires only one instruction, and an unaligned access requires lots. E.g., for sparc, int foo(void *p) { int x; __builtin_memcpy(&x, p, 4); return x; } ldub [%i0], %g3 ldub [%i0+1], %g2 stb %g3, [%fp+2043] stb %g2, [%fp+2044] ldub [%i0+2], %g3 ldub [%i0+3], %g2 stb %g3, [%fp+2045] stb %g2, [%fp+2046] ldsw [%fp+2043], %i0 Such unaligned accesses are *really* slow. > While a single access is faster for aligned > data, this might be different for sequential access on misaligned data which > might profit from better caching of smaller bytecode. I believe you'll find that the rewrite encoding is smaller already. r~
