> PR 58079 is about the do_SUBST assert: > > /* Sanity check that we're replacing oldval with a CONST_INT > that is a valid sign-extension for the original mode. */ > gcc_assert (INTVAL (newval) > == trunc_int_for_mode (INTVAL (newval), GET_MODE (oldval))); > > triggering while trying to optimise the temporary result: > > (eq (const_int -73 [0xffffffffffffffb7]) > (reg:QI 234 [ MEM[(const u8 *)buf_7(D) + 4B] ]) > > combine_simplify_rtx calls simplify_comparison, which first canonicalises > the order so that the constant is second and then promotes the comparison > to SImode (the first supported comparison mode on MIPS). So we end up with: > > (eq (zero_extend:SI (reg:QI 234 [ MEM[(const u8 *)buf_7(D) + 4B] ])) > (const_int 183 [0xb7])) > > So far so good. But combine_simplify_rtx then tries to install the > new operands in-place, with the second part of: > > /* If the code changed, return a whole new comparison. */ > if (new_code != code) > return gen_rtx_fmt_ee (new_code, mode, op0, op1); > > /* Otherwise, keep this operation, but maybe change its operands. > This also converts (ne (compare FOO BAR) 0) to (ne FOO BAR). */ > SUBST (XEXP (x, 0), op0); > SUBST (XEXP (x, 1), op1); > > And this triggers the assert because we're replacing a QImode register > with the non-QImode constant 183. > > One fix would be to extend the new_code != code condition, as below. > This should avoid the problem cases without generating too much > garbage rtl. But if the condition's getting this complicated, > perhaps it'd be better just to avoid SUBST here? I.e. > > if (new_code != code || op0 != XEXP (x, 0) || op1 != XEXP (x, 1)) > return gen_rtx_fmt_ee (new_code, mode, op0, op1); > > Just asking though. :-) > > Tested on mipsisa64-elf. OK to install?
Yes, this fixes the error. Thanks Jürgen
