On Fri, Sep 29, 2023 at 01:01:57PM -0600, Jeff Law wrote: > > > On 8/10/23 07:04, Stefan Schulze Frielinghaus via Gcc-patches wrote: > > In the former fix in commit 41ef5a34161356817807be3a2e51fbdbe575ae85 I > > completely missed the fact that the normal form of a generated constant for > > a > > mode with fewer bits than in HOST_WIDE_INT is a sign extended version of the > > actual constant. This even holds true for unsigned constants. > > > > Fixed by masking out the upper bits for the incoming constant and sign > > extending the resulting unsigned constant. > > > > Bootstrapped and regtested on x64 and s390x. Ok for mainline? > > > [ snip] > > > > > gcc/ChangeLog: > > > > * combine.cc (simplify_compare_const): Properly handle unsigned > > constants while narrowing comparison of memory and constants. > OK. > > > > --- > > @@ -12051,15 +12052,15 @@ simplify_compare_const (enum rtx_code code, > > machine_mode mode, > > HOST_WIDE_INT_PRINT_HEX ") to (MEM %s " > > HOST_WIDE_INT_PRINT_HEX ").\n", GET_MODE_NAME (int_mode), > > GET_MODE_NAME (narrow_mode_iter), GET_RTX_NAME (code), > > - (unsigned HOST_WIDE_INT)const_op, GET_RTX_NAME (adjusted_code), > > - n); > > + (unsigned HOST_WIDE_INT) const_op & GET_MODE_MASK (int_mode), > > + GET_RTX_NAME (adjusted_code), n); > > } > > poly_int64 offset = (BYTES_BIG_ENDIAN > > ? 0 > > : (GET_MODE_SIZE (int_mode) > > - GET_MODE_SIZE (narrow_mode_iter))); > > *pop0 = adjust_address_nv (op0, narrow_mode_iter, offset); > > - *pop1 = GEN_INT (n); > > + *pop1 = gen_int_mode (n, narrow_mode_iter); > > return adjusted_code; > FWIW, I should definitely have caught this hunk earlier -- we've gone the > rounds in this same space (GEN_INT vs gen_int_mode) elsewhere. > > Again, sorry for the long wait. > > jeff
No worries at all. At least I have learned something new :) Thanks Jeff and Eric for clarification. This matches with my intuition, now, so I've pushed the patch. Cheers, Stefan
