> On Aug 11, 2021, at 8:58 AM, Richard Biener <rguent...@suse.de> wrote:
>
> On Wed, 11 Aug 2021, Qing Zhao wrote:
>
>>
>>
>>> 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” ?
>
> For example look at build_asan_poison_call_expr which does such thing
> for ASAN poison internal function call insertion at gimplification time.
Okay, got it.
Will try.
Qing
>
> Richard.
>
>> 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)
>>
>>
>
> --
> Richard Biener <rguent...@suse.de>
> SUSE Software Solutions Germany GmbH, Maxfeldstrasse 5, 90409 Nuernberg,
> Germany; GF: Felix Imendörffer; HRB 36809 (AG Nuernberg)
