On 07/03/2014 11:25 AM, Al Viro wrote: > On Thu, Jul 03, 2014 at 07:51:04AM +0100, Al Viro wrote: > >> FWIW, why not just generate >> trunc_i64_i32 tmp, va >> trunc_i64_i32 tmp2, vb >> muls2_i32 tmp2, tmp, tmp, tmp2 >> ext32s_i64 vc, tmp2 >> maybe_overflow_32 tmp >> where maybe_overflow throws IOV unless tmp is 0 or -1? >> to suffice for mull/v. mulq/v would be >> muls2_i64 vc, tmp, va, vb >> maybe_overflow_64 tmp >> addl/v: >> trunc_i64_i32 tmp, va >> trunc_i64_i32 tmp2, vb >> add2_i32 tmp2, tmp, tmp, zero, tmp2, zero >> ext32s_i64 vc, tmp2 >> maybe_overflow_32 tmp >> etc. > > Grr... Wrong check, obviously - we want to check that tmp + MSB(tmp2) is 0. > Something like > setcond_32 tmp2, tmp2, zero, TCG_COND_LT > add_i32 tmp, tmp2, tmp > call helper_IOV_if_not_zero tmp > for 32bit ones and > setcond_64 tmp2, vc, zero, TCG_COND_LT > add_i64 tmp, tmp2, tmp > call helper_IOV_if_not_zero tmp > for 64bit ones, or would it be better just to pass both arguments to helper > and let it deal with the check? I'm not familiar enough with TCG, sorry... >
I believe I have a tidy solution to these /v insns. New patch set shortly. r~
