> 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?
2. Could the routine “expand_builtin_memset” be applied on the memset call
whose “DEST” is
an address expression on SSA_NAME?
3. Within “expand_DEFERRED_INIT”, can I call “expand_builtin_memset” to expand
.DEFERRED_INIT?
I suspect that one of the above 3 might be the issue, but not sure which one?
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)
