Hi,
On Fri, 6 Mar 2015 10:09:30, Eric Botcazou wrote:
>
>> Hmm. As you also modify the no-strict-volatile-bitfield path I'm not sure
>> you don't regress the case where EP_insv can work on memory. I agree
>> that simplifying the strict-volatile-bitfield path to extract the memory
>> within strict-volatile-bitfield constraints to a reg and then using the
>> regular path is a good thing.
>>
>> Eric?
>
> Even if the no-strict-volatile-bitfield path isn't touched, I don't understand
>
> @@ -976,7 +976,7 @@ store_bit_field (rtx str_rtx, unsigned HOST_WIDE_I
> /* Storing any naturally aligned field can be done with a simple
> store. For targets that support fast unaligned memory, any
> naturally sized, unit aligned field can be done directly. */
> - if (simple_mem_bitfield_p (str_rtx, bitsize, bitnum, fieldmode))
> + if (bitsize == GET_MODE_BITSIZE (fieldmode))
> {
> str_rtx = adjust_bitfield_address (str_rtx, fieldmode,
> bitnum / BITS_PER_UNIT);
>
>
> {
> - rtx result;
> -
> /* Extraction of a full MODE1 value can be done with a load as long as
> the field is on a byte boundary and is sufficiently aligned. */
> - if (simple_mem_bitfield_p (str_rtx, bitsize, bitnum, mode1))
> - result = adjust_bitfield_address (str_rtx, mode1,
> - bitnum / BITS_PER_UNIT);
> - else
> + if (bitsize == GET_MODE_BITSIZE(mode1))
> {
> - str_rtx = narrow_bit_field_mem (str_rtx, mode1, bitsize, bitnum,
> - &bitnum);
> - result = extract_fixed_bit_field_1 (mode, str_rtx, bitsize, bitnum,
> - target, unsignedp);
> + rtx result = adjust_bitfield_address (str_rtx, mode1,
> + bitnum / BITS_PER_UNIT);
>
>
> adjust_bitfield_address takes (bitnum / BITS_PER_UNIT) so don't you need to
> make sure that bitnum % BITS_PER_UNIT == 0?
>
I know it because strict_volatile_bitfield_p checks this:
/* Check for cases of unaligned fields that must be split. */
if (bitnum % BITS_PER_UNIT + bitsize> modesize
Therefore, if bitsize == modesize, we know that bitnum % BITS_PER_UNIT
must be zero.
> In any case, the comments are now totally out of sync.
>
> --
> Eric Botcazou
