> On Aug 11, 2021, at 8:37 AM, Richard Biener <rguent...@suse.de> wrote:
>
> On Wed, 11 Aug 2021, Qing Zhao wrote:
>
>>
>>
>>> On Aug 11, 2021, at 2:02 AM, Richard Biener <rguent...@suse.de> wrote:
>>>
>>> On Tue, 10 Aug 2021, Qing Zhao wrote:
>>>
>>>>
>>>>
>>>>> On Aug 10, 2021, at 3:16 PM, Qing Zhao via Gcc-patches
>>>>> <gcc-patches@gcc.gnu.org> wrote:
>>>>>
>>>>> Hi, Richard,
>>>>>
>>>>>> On Aug 10, 2021, at 10:22 AM, Richard Biener <rguent...@suse.de> wrote:
>>>>>>>>
>>>>>>>> Especially in the VLA case but likely also in general (though unlikely
>>>>>>>> since usually the receiver of initializations are simple enough). I'd
>>>>>>>> expect the VLA case end up as
>>>>>>>>
>>>>>>>> *ptr_to_decl = .DEFERRED_INIT (...);
>>>>>>>>
>>>>>>>> where *ptr_to_decl is the DECL_VALUE_EXPR of the decl.
>>>>>>>
>>>>>>> So, for the following small testing case:
>>>>>>>
>>>>>>> ====
>>>>>>> extern void bar (int);
>>>>>>>
>>>>>>> void foo(int n)
>>>>>>> {
>>>>>>> int arr[n];
>>>>>>> bar (arr[2]);
>>>>>>> return;
>>>>>>> }
>>>>>>> =====
>>>>>>>
>>>>>>> If I compile it with -ftrivial-auto-var-init=zero -fdump-tree-gimple -S
>>>>>>> -o auto-init-11.s -fdump-rtl-expand, the *.gimple dump is:
>>>>>>>
>>>>>>> =====
>>>>>>> void foo (int n)
>>>>>>> {
>>>>>>> int n.0;
>>>>>>> sizetype D.1950;
>>>>>>> bitsizetype D.1951;
>>>>>>> sizetype D.1952;
>>>>>>> bitsizetype D.1953;
>>>>>>> sizetype D.1954;
>>>>>>> int[0:D.1950] * arr.1;
>>>>>>> void * saved_stack.2;
>>>>>>> int arr[0:D.1950] [value-expr: *arr.1];
>>>>>>>
>>>>>>> saved_stack.2 = __builtin_stack_save ();
>>>>>>> try
>>>>>>> {
>>>>>>> n.0 = n;
>>>>>>> _1 = (long int) n.0;
>>>>>>> _2 = _1 + -1;
>>>>>>> _3 = (sizetype) _2;
>>>>>>> D.1950 = _3;
>>>>>>> _4 = (sizetype) n.0;
>>>>>>> _5 = (bitsizetype) _4;
>>>>>>> _6 = _5 * 32;
>>>>>>> D.1951 = _6;
>>>>>>> _7 = (sizetype) n.0;
>>>>>>> _8 = _7 * 4;
>>>>>>> D.1952 = _8;
>>>>>>> _9 = (sizetype) n.0;
>>>>>>> _10 = (bitsizetype) _9;
>>>>>>> _11 = _10 * 32;
>>>>>>> D.1953 = _11;
>>>>>>> _12 = (sizetype) n.0;
>>>>>>> _13 = _12 * 4;
>>>>>>> D.1954 = _13;
>>>>>>> arr.1 = __builtin_alloca_with_align (D.1954, 32);
>>>>>>> arr = .DEFERRED_INIT (D.1952, 2, 1);
>>>>>>> _14 = (*arr.1)[2];
>>>>>>> bar (_14);
>>>>>>> return;
>>>>>>> }
>>>>>>> finally
>>>>>>> {
>>>>>>> __builtin_stack_restore (saved_stack.2);
>>>>>>> }
>>>>>>> }
>>>>>>>
>>>>>>> ====
>>>>>>>
>>>>>>> You think that the above .DEFEERED_INIT is not correct?
>>>>>>> It should be:
>>>>>>>
>>>>>>> *arr.1 = .DEFERRED_INIT (D.1952. 2, 1);
>>>>>>>
>>>>>>> ?
>>>>>>
>>>>>> Yes.
>>>>>>
>>>>>
>>>>> I updated gimplify.c for VLA and now it emits the call to .DEFERRED_INIT
>>>>> as:
>>>>>
>>>>> arr.1 = __builtin_alloca_with_align (D.1954, 32);
>>>>> *arr.1 = .DEFERRED_INIT (D.1952, 2, 1);
>>>>>
>>>>> However, this call triggered the assertion failure in verify_gimple_call
>>>>> of tree-cfg.c because the LHS is not a valid LHS.
>>>>> Then I modify tree-cfg.c as:
>>>>>
>>>>> diff --git a/gcc/tree-cfg.c b/gcc/tree-cfg.c
>>>>> index 330eb7dd89bf..180d4f1f9e32 100644
>>>>> --- a/gcc/tree-cfg.c
>>>>> +++ b/gcc/tree-cfg.c
>>>>> @@ -3375,7 +3375,11 @@ verify_gimple_call (gcall *stmt)
>>>>> }
>>>>>
>>>>> tree lhs = gimple_call_lhs (stmt);
>>>>> + /* For .DEFERRED_INIT call, the LHS might be an indirection of
>>>>> + a pointer for the VLA variable, which is not a valid LHS of
>>>>> + a gimple call, we ignore the asssertion on this. */
>>>>> if (lhs
>>>>> + && (!gimple_call_internal_p (stmt, IFN_DEFERRED_INIT))
>>>>> && (!is_gimple_reg (lhs)
>>>>> && (!is_gimple_lvalue (lhs)
>>>>> || verify_types_in_gimple_reference
>>>>>
>>>>> The assertion failure in tree-cfg.c got resolved, but I got another
>>>>> assertion failure in operands_scanner::get_expr_operands (tree *expr_p,
>>>>> int flags), line 945:
>>>>>
>>>>> 939 /* If we get here, something has gone wrong. */
>>>>> 940 if (flag_checking)
>>>>> 941 {
>>>>> 942 fprintf (stderr, "unhandled expression in
>>>>> get_expr_operands():\n");
>>>>> 943 debug_tree (expr);
>>>>> 944 fputs ("\n", stderr);
>>>>> 945 gcc_unreachable ();
>>>>> 946 }
>>>>>
>>>>> Looks like that the gimple statement:
>>>>> *arr.1 = .DEFERRED_INIT (D.1952, 2, 1);
>>>>>
>>>>> Is not valid. i.e, the LHS should not be an indirection to a pointer.
>>>>>
>>>>> How to resolve this issue?
>>>
>>> It sounds like the LHS is an INDIRECT_REF maybe? That means it's
>>> still not properly gimplified because it should end up as a MEM_REF
>>> instead.
>>>
>>> But I'm just guessing here ... if you are in a debugger then you can
>>> invoke debug_tree (lhs) in the inferior to see what it exactly is
>>> at the point of the failure.
>>
>> Yes, it’s an INDIRECT_REF at the point of the failure even though I added a
>>
>> gimplify_var_or_parm_decl (lhs)
>
> I think the easiest is to build the .DEFERRED_INIT as GENERIC
> and use gimplify_assign () to gimplify and add the result
> to the sequence. Thus, build a GENERIC CALL_EXPR and then
> gimplify_assign (lhs, call_expr, seq);
Which utility routine is used to build an Internal generic call?
Currently, I used “gimple_build_call_internal” to build this internal gimple
call.
For the generic call, shall I use “build_call_expr_loc” ?
Qing
>
> Richard.
>
>> Qing
>>
>>>
>>>> I came up with the following solution:
>>>>
>>>> Define the IFN_DEFERRED_INIT function as:
>>>>
>>>> LHS = DEFERRED_INIT (SIZE of the DECL, INIT_TYPE, IS_VLA);
>>>>
>>>> if IS_VLA is false, the LHS is the DECL itself,
>>>> if IS_VLA is true, the LHS is the pointer to this DECL that created by
>>>> gimplify_vla_decl.
>>>>
>>>>
>>>> The benefit of this solution are:
>>>>
>>>> 1. Resolved the invalid IR issue;
>>>> 2. The call stmt carries the address of the VLA natually;
>>>>
>>>> The issue with this solution is:
>>>>
>>>> For VLA and non-VLA, the LHS will be different,
>>>>
>>>> Do you see any other potential issues with this solution?
>>>>
>>>> thanks.
>>>>
>>>> Qing
>>>>
>>>>
>>>>
>>>>
>>>>
>>>
>>> --
>>> Richard Biener <rguent...@suse.de>
>>> SUSE Software Solutions Germany GmbH, Maxfeldstrasse 5, 90409 Nuernberg,
>>> Germany; GF: Felix Imendörffer; HRB 36809 (AG Nuernberg)
>>
>>
>
> --
> Richard Biener <rguent...@suse.de>
> SUSE Software Solutions Germany GmbH, Maxfeldstrasse 5, 90409 Nuernberg,
> Germany; GF: Felix Imendörffer; HRB 36809 (AG Nuernberg)
