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Re: [PATCH] Fix expansion issues on type changing MEM_REFs on LHS (PR middle-end/48335)
> result is set there from store_field, and result is only used in
> if (result)
> preserve_temp_slots (result);
> afterwards. store_field might want to preserve_temp_slots perhaps, so
> clearing result afterwards might be wrong.
You're very likely right, but then this should apply to the case just above.
> You mean just with the MEM_P test? So something like:
>
> @@ -418,8 +418,11 @@ store_bit_field_1 (rtx str_rtx, unsigned
> && bitsize == GET_MODE_BITSIZE (fieldmode)
> && (!MEM_P (op0)
> ? ((GET_MODE_SIZE (fieldmode) >= UNITS_PER_WORD
> - || GET_MODE_SIZE (GET_MODE (op0)) == GET_MODE_SIZE (fieldmode))
> - && byte_offset % GET_MODE_SIZE (fieldmode) == 0)
> + || GET_MODE_SIZE (GET_MODE (op0)) == GET_MODE_SIZE (fieldmode))
> + && byte_offset % GET_MODE_SIZE (fieldmode) == 0
> + && (GET_MODE (op0) == fieldmode
> + || validate_subreg (fieldmode, GET_MODE (op0), op0,
> + byte_offset)))
>
> : (! SLOW_UNALIGNED_ACCESS (fieldmode, MEM_ALIGN (op0))
> :
> || (offset * BITS_PER_UNIT % bitsize == 0
>
> && MEM_ALIGN (op0) % GET_MODE_BITSIZE (fieldmode) == 0))))
>
> instead?
Yes, but I think that this can be further simplified. The test:
byte_offset % GET_MODE_SIZE (fieldmode) == 0
is the first thing the call to validate_subreg does. And it's clear that the
case GET_MODE (op0) == fieldmode requires byte_offset to be 0. So I think:
Index: expmed.c
===================================================================
--- expmed.c (revision 171818)
+++ expmed.c (working copy)
@@ -419,7 +419,9 @@ store_bit_field_1 (rtx str_rtx, unsigned
&& (!MEM_P (op0)
? ((GET_MODE_SIZE (fieldmode) >= UNITS_PER_WORD
|| GET_MODE_SIZE (GET_MODE (op0)) == GET_MODE_SIZE (fieldmode))
- && byte_offset % GET_MODE_SIZE (fieldmode) == 0)
+ && ((GET_MODE (op0) == fieldmode && byte_offset == 0)
+ || validate_subreg (fieldmode, GET_MODE (op0), op0,
+ byte_offset)))
: (! SLOW_UNALIGNED_ACCESS (fieldmode, MEM_ALIGN (op0))
|| (offset * BITS_PER_UNIT % bitsize == 0
&& MEM_ALIGN (op0) % GET_MODE_BITSIZE (fieldmode) == 0))))
should work.
--
Eric Botcazou