Jeff Law <l...@redhat.com> writes:
> @@ -1080,6 +1070,18 @@ add_removable_extension (const_rtx expr, rtx_insn
> *insn,
> }
> }
>
> + /* Fourth, if the extended version occupies more registers than the
> + original and the source of the extension is the same hard register
> + as the destination of the extension, then we can not eliminate
> + the extension without deep analysis, so just punt.
> +
> + We allow this when the registers are different because the
> + code in combine_reaching_defs will handle that case correctly. */
> + if ((HARD_REGNO_NREGS (REGNO (dest), mode)
> + != HARD_REGNO_NREGS (REGNO (reg), GET_MODE (reg)))
> + && REGNO (dest) == REGNO (reg))
> + return;
> +
> /* Then add the candidate to the list and insert the reaching
> definitions
> into the definition map. */
> ext_cand e = {expr, code, mode, insn};
I might be wrong, but the check looks specific to little-endian. Would
it make sense to use reg_overlap_mentioned_p instead of the REGNO check?
Thanks,
Richard
