On 9/3/19 1:12 PM, Richard Biener wrote:
> On Tue, 3 Sep 2019, Bernd Edlinger wrote:
>
>> On 9/3/19 9:05 AM, Jakub Jelinek wrote:
>>> On Tue, Sep 03, 2019 at 07:02:53AM +0000, Bernd Edlinger wrote:
>>>> 2019-09-03 Bernd Edlinger <[email protected]>
>>>>
>>>> PR middle-end/91603
>>>> PR middle-end/91612
>>>> PR middle-end/91613
>>>> * expr.c (expand_expr_real_1): decl_p_1): Refactor into...
>>>> (non_mem_decl_p): ...this.
>>>> (mem_ref_refers_to_non_mem_p): Handle DECL_P as well ase MEM_REF.
>>>> (expand_assignment): Call mem_ref_referes_to_non_mem_p
>>>> unconditionally as before.
>>>
>>> Not a review, just questioning the ChangeLog entry.
>>> What is the "decl_p_1): " in there? Also, the ChangeLog mentions many
>>> functions, but the patch in reality just modifies expand_expr_real_1
>>> and nothing else.
>>>
>>
>> Ah, sorry, this is of course wrong, (I forgot to complete the sentence,
>> and later forgot to check it again)....
>>
>>
>> This is what I actually wanted to say:
>>
>> 2019-09-03 Bernd Edlinger <[email protected]>
>>
>> PR middle-end/91603
>> PR middle-end/91612
>> PR middle-end/91613
>> * expr.c (expand_expr_real_1): Handle unaligned decl_rtl
>> and SSA_NAME referring to CONSTANT_P correctly.
>>
>> testsuite:
>> 2019-09-03 Bernd Edlinger <[email protected]>
>>
>> PR middle-end/91603
>> * testsuite/gcc.target/arm/pr91603.c: New test.
>
> @@ -10062,7 +10062,43 @@ expand_expr_real_1 (tree exp, rtx target,
> machine_
> {
> if (exp && MEM_P (temp) && REG_P (XEXP (temp, 0)))
> mark_reg_pointer (XEXP (temp, 0), DECL_ALIGN (exp));
> + }
> + else if (MEM_P (decl_rtl))
> + temp = decl_rtl;
>
> + if (temp != 0)
> + {
> + if (MEM_P (temp)
> + && modifier != EXPAND_WRITE
> + && modifier != EXPAND_MEMORY
> + && modifier != EXPAND_INITIALIZER
> + && modifier != EXPAND_CONST_ADDRESS
> + && modifier != EXPAND_SUM
> + && !inner_reference_p
> + && mode != BLKmode
> + && MEM_ALIGN (temp) < GET_MODE_ALIGNMENT (mode))
>
> So other places ([TARGET_]MEM_REF cases) use "just"
>
Yes, interesting all of them do slightly different things.
I started with cloning the MEM_REF case, but it ran immediately
into issues with this assert here:
result = expand_expr (exp, target, tmode,
modifier == EXPAND_INITIALIZER
? EXPAND_INITIALIZER : EXPAND_CONST_ADDRESS);
/* If the DECL isn't in memory, then the DECL wasn't properly
marked TREE_ADDRESSABLE, which will be either a front-end
or a tree optimizer bug. */
gcc_assert (MEM_P (result));
result = XEXP (result, 0);
which implies that I need to add EXPAND_INITIALIZER and EXPAND_CONST_ADDRESS,
but since the code immediately above also has an exception of EXPAND_SUM:
else if (MEM_P (decl_rtl) && modifier != EXPAND_INITIALIZER)
{
if (alt_rtl)
*alt_rtl = decl_rtl;
decl_rtl = use_anchored_address (decl_rtl);
if (modifier != EXPAND_CONST_ADDRESS
&& modifier != EXPAND_SUM
I thought it I need to add also an exception for EXPAND_SUM.
Probably there is a reason why TARGET_MEM_REF does not need the
extract_bit_field stuff, when I read the comment here:
/* If the target does not have special handling for unaligned
loads of mode then it can use regular moves for them. */
&& ((icode = optab_handler (movmisalign_optab, mode))
!= CODE_FOR_nothing))
it is just, I don't really believe it.
> if (modifier != EXPAND_WRITE
> && modifier != EXPAND_MEMORY
> && !inner_reference_p
> && mode != BLKmode
> && align < GET_MODE_ALIGNMENT (mode))
>
> I also wonder if you can split out all this common code to
> a function (the actual unaligned expansion, that is) and call
> it from those places (where the TARGET_MEM_REF case misses the
> slow_unaligned_access case - presumably wanting to "assert"
> that this doesn't happen.
>
> /* If the target does not have special handling for unaligned
> loads of mode then it can use regular moves for them. */
>
Actually there is still a small difference to the MEM_REF expansion,
see the alt_rtl and the EXPAND_STACK_PARAM:
temp = extract_bit_field (temp, GET_MODE_BITSIZE (mode),
0, TYPE_UNSIGNED (TREE_TYPE (exp)),
(modifier == EXPAND_STACK_PARM
? NULL_RTX : target),
mode, mode, false, alt_rtl);
TARGET_MEM_REF does not do extract_bit_field at all,
while I think ignoring target and alt_rtl in the DECL_P case is safe,
target, because it is at most a missed optimization, and
alt_rtl because it should already be handled above?
But if I pass target I cannot simply ignore alt_rtl any more?
Well, I could pass target and alt_rtl differently each time.
should I still try to factor that into a single function, it will have
around 7 parameters?
Bernd.
