> On Aug 19, 2021, at 4:00 AM, Richard Biener <rguent...@suse.de> wrote:
>
> On Wed, 18 Aug 2021, Qing Zhao wrote:
>
>>
>>
>>> On Aug 18, 2021, at 2:15 AM, Richard Biener <rguent...@suse.de> wrote:
>>>
>>> On Tue, 17 Aug 2021, Qing Zhao wrote:
>>>
>>>>
>>>>
>>>>> On Aug 17, 2021, at 9:50 AM, Qing Zhao via Gcc-patches
>>>>> <gcc-patches@gcc.gnu.org> wrote:
>>>>>
>>>>>
>>>>>
>>>>>> On Aug 17, 2021, at 3:29 AM, Richard Biener <rguent...@suse.de> wrote:
>>>>>>
>>>>>> On Mon, 16 Aug 2021, Qing Zhao wrote:
>>>>>>
>>>>>>> My current code for expand_DEFERRED_INIT is like the following, could
>>>>>>> you check and see whether there is any issue for it:
>>>>>>>
>>>>>>> #define INIT_PATTERN_VALUE 0xFE
>>>>>>> static void
>>>>>>> expand_DEFERRED_INIT (internal_fn, gcall *stmt)
>>>>>>> {
>>>>>>> tree lhs = gimple_call_lhs (stmt);
>>>>>>> tree var_size = gimple_call_arg (stmt, 0);
>>>>>>> enum auto_init_type init_type
>>>>>>> = (enum auto_init_type) TREE_INT_CST_LOW (gimple_call_arg (stmt, 1));
>>>>>>> bool is_vla = (bool) TREE_INT_CST_LOW (gimple_call_arg (stmt, 2));
>>>>>>>
>>>>>>> tree var_type = TREE_TYPE (lhs);
>>>>>>> gcc_assert (init_type > AUTO_INIT_UNINITIALIZED);
>>>>>>>
>>>>>>> if (is_vla || (!use_register_for_decl (lhs)))
>>>>>>> {
>>>>>>> if (TREE_CODE (lhs) == SSA_NAME)
>>>>>>> lhs = SSA_NAME_VAR (lhs);
>>>>>>
>>>>>> this should not be necessary (in fact you shouldn't see a SSA_NAME
>>>>>> here, if you do then using SSA_NAME_VAR is wrong)
>>>>> You mean during RTL expansion phase, all SSA_NAMEs are gone already?
>>>>
>>>> Actually, the lhs could be SSA_NAME here,
>>>>
>>>> Breakpoint 1, expand_DEFERRED_INIT (stmt=0x7fffe96ae348) at
>>>> ../../latest-gcc/gcc/internal-fn.c:3021
>>>> 3021 mark_addressable (lhs);
>>>> (gdb) call debug_tree(lhs)
>>>> <ssa_name 0x7fffe9584e58
>>>> type <real_type 0x7fffe959b2a0 float sizes-gimplified SF
>>>> size <integer_cst 0x7fffe9579f48 constant 32>
>>>> unit-size <integer_cst 0x7fffe9579f60 constant 4>
>>>> align:32 warn_if_not_align:0 symtab:0 alias-set 2 canonical-type
>>>> 0x7fffe959b2a0 precision:32
>>>> pointer_to_this <pointer_type 0x7fffe959b7e0>>
>>>> visited var <var_decl 0x7ffff7ff7bd0 temp1>
>>>> def_stmt temp1_5 = .DEFERRED_INIT (4, 2, 0, &"temp1"[0]);
>>>> version:5>
>>>>
>>>> when I deleted:
>>>>
>>>> if (TREE_CODE (lhs) == SSA_NAME
>>>> lhs = SSA_NAME_VAR (lhs);
>>>
>>> but then using SSA_NAME_VAR is broken. I suspect use_register_for_decl
>>> isn't the correct thing to look at. I think we need to look at what
>>> the LHS expanded to if it is a SSA_VAR_P (that includes SSA names
>>> but also plain DECLs but not what we get from VLAs where we'd see
>>> *ptr). So sth like
>>>
>>> bool reg_lhs;
>>> if (SSA_VAR_P (lhs))
>>> {
>>> rtx tem = expand_expr (lhs, NULL_RTX, VOIDmode, EXPAND_WRITE);
>>> reg_lhs = !MEM_P (tem);
>>> /* If not MEM_P reg_lhs should be REG_P or SUBREG_P (but maybe
>>> also CONCAT or lowpart...?) */
>>> }
>>> else
>>> {
>>> gcc_assert (is_vla);
>>> reg_lhs = false;
>>> }
>>>
>>> if (!reg_lhs)
>>> memset path
>>> else
>>> expand_assignment path
>>
>> After making the following change:
>>
>> + bool reg_lhs = true;
>>
>> tree var_type = TREE_TYPE (lhs);
>> gcc_assert (init_type > AUTO_INIT_UNINITIALIZED);
>>
>> - if (is_vla || (!use_register_for_decl (lhs)))
>> + if (SSA_VAR_P (lhs))
>> + {
>> + rtx tem = expand_expr (lhs, NULL_RTX, VOIDmode, EXPAND_WRITE);
>> + reg_lhs = !MEM_P (tem);
>> + }
>> + else
>> + {
>> + gcc_assert (is_vla);
>> + reg_lhs = false;
>> + }
>> +
>> + if (!reg_lhs)
>> {
>>
>> I got exactly the same internal error that failed at expr.c:
>>
>> 8436 /* We must have made progress. */
>> 8437 gcc_assert (inner != exp);
>>
>>
>> Looks like for the following code:
>>
>> 3026 if (!reg_lhs)
>> 3027 {
>> 3028 /* If this is a VLA or the variable is not in register,
>> 3029 expand to a memset to initialize it. */
>> 3030 mark_addressable (lhs);
>> 3031 tree var_addr = build_fold_addr_expr (lhs);
>> 3032
>> 3033 tree value = (init_type == AUTO_INIT_PATTERN) ?
>> 3034 build_int_cst (integer_type_node,
>> 3035 INIT_PATTERN_VALUE) :
>> 3036 integer_zero_node;
>> 3037 tree m_call = build_call_expr (builtin_decl_implicit
>> (BUILT_IN_MEMSET),
>> 3038 3, var_addr, value, var_size);
>> 3039 /* Expand this memset call. */
>> 3040 expand_builtin_memset (m_call, NULL_RTX, TYPE_MODE (var_type));
>> 3041 }
>>
>> At line 3030, “lhs” could be a SSA_NAME.
>>
>> My questions are:
>>
>> 1. Could the routine “mark_addressable” and “build_fold_addr_expr” be
>> applied on SSA_NAME?
>
> No.
>
>> 2. Could the routine “expand_builtin_memset” be applied on the memset call
>> whose “DEST” is
>> an address expression on SSA_NAME?
>
> No.
>
>> 3. Within “expand_DEFERRED_INIT”, can I call “expand_builtin_memset” to
>> expand .DEFERRED_INIT?
>
> Well, not with "invalid" GENERIC I fear (address of a SSA name).
>
>> I suspect that one of the above 3 might be the issue, but not sure which one?
>
> All of the above ;) So while reg_lhs is now precise as to how the
> variable will end up (the SSA name will end up as a stack variable in this
> case, for whatever reason), expansion via memcpy only works when
> working on the RTL representation. The usual "workaround" (ugh)
> is to use make_tree (), so in the !reg_lhs path you'd do
>
> /* Get a new GENERIC representation for the RTL. That's necesary
> in case LHS is an SSA name. */
> lhs = make_tree (TREE_TYPE (lhs), tem);
This resolved the issue.
Another question,
Previously, I used
if (TREE_CODE (lhs) == SSA_NAME)
lhs = SSA_NAME_VAR (lhs);
To resolve this issue. The purpose looks like the same as “make_tree”, just get
an generic tree for the LHS.
Why you said using SSA_NAME_VAR is broken? Is it because SSA_NAME_VAR will not
always return a valid TREE?
I should use as following
If (TREE_CODE (lhs) == SSA_NAME) && SSA_NAME_VAR (lhs))
Lhs = SSA_NAME_VAR (lhs)
?
>
> alternatively you could maybe do
>
> if (DECL_P (lhs))
> {
> + rtx tem = expand_expr (lhs, NULL_RTX, VOIDmode, EXPAND_WRITE);
> + reg_lhs = !MEM_P (tem);
> }
> else if (TREE_CODE (lhs) == SSA_NAME)
> reg_lhs = true;
> else
> reg_lhs = false;
>
> thus treat SSA names as register storage always (even if it will end
> up on the stack).
My question here, for a complicate structure SSA_NAME, will expanding through
memset better than expand_asssignment?
Qing
>
> Richard.
>
>> Thanks a lot.
>>
>> Qing
>>
>>
>>
>>> bool reg_lhs;
>>> if (SSA_VAR_P (lhs))
>>> {
>>> rtx tem = expand_expr (lhs, NULL_RTX, VOIDmode, EXPAND_WRITE);
>>> reg_lhs = !MEM_P (tem);
>>> /* If not MEM_P reg_lhs should be REG_P or SUBREG_P (but maybe
>>> also CONCAT or lowpart...?) */
>>> }
>>> else
>>> {
>>> gcc_assert (is_vla);
>>> reg_lhs = false;
>>> }
>>
>>
>>>
>>>> Many testing cases failed with internal compiler error:
>>>>
>>>> /home/opc/Work/GCC/latest-gcc/gcc/testsuite/c-c++-common/auto-init-3.c:9:9:
>>>> internal compiler error: in expand_expr_addr_expr_1, at expr.c:8437
>>>> 0xe237aa expand_expr_addr_expr_1
>>>> ../../latest-gcc/gcc/expr.c:8437
>>>> 0xe24059 expand_expr_addr_expr
>>>> ../../latest-gcc/gcc/expr.c:8525
>>>> 0xe32b56 expand_expr_real_1(tree_node*, rtx_def*, machine_mode,
>>>> expand_modifier, rtx_def**, bool)
>>>> ../../latest-gcc/gcc/expr.c:11741
>>>> 0xe2da52 expand_expr_real_1(tree_node*, rtx_def*, machine_mode,
>>>> expand_modifier, rtx_def**, bool)
>>>> ../../latest-gcc/gcc/expr.c:10777
>>>> 0xe24706 expand_expr_real(tree_node*, rtx_def*, machine_mode,
>>>> expand_modifier, rtx_def**, bool)
>>>> ../../latest-gcc/gcc/expr.c:8713
>>>> 0xc13f15 expand_expr
>>>> ../../latest-gcc/gcc/expr.h:301
>>>> 0xc17acb get_memory_rtx
>>>> ../../latest-gcc/gcc/builtins.c:1370
>>>> 0xc2223d expand_builtin_memset_args
>>>> ../../latest-gcc/gcc/builtins.c:4102
>>>> 0xc21a20 expand_builtin_memset(tree_node*, rtx_def*, machine_mode)
>>>> ../../latest-gcc/gcc/builtins.c:3886
>>>> 0xfb5c85 expand_DEFERRED_INIT
>>>> ../../latest-gcc/gcc/internal-fn.c:3031
>>>>
>>>>
>>>> So, did I do anything wrong?
>>>>
>>>> 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)
