https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115637
Bug ID: 115637
Summary: gimple_regimplify_operands doesn't handle VALUE_EXPR
inside a MEM_REF / OpenMP declare target link
Product: gcc
Version: 15.0
Status: UNCONFIRMED
Keywords: openmp, wrong-code
Severity: normal
Priority: P3
Component: middle-end
Assignee: unassigned at gcc dot gnu.org
Reporter: burnus at gcc dot gnu.org
CC: jakub at gcc dot gnu.org
Target Milestone: ---
Created attachment 58511
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=58511&action=edit
Fortran testcase – requires '-fopenmp' and configured offloading - and patch
for PR115559
gimple_regimplify_operands doesn't expand the value expression of 'arr2' in:
MEM <uint128_t> [(c_char * {ref-all})&arr2]
with arr2 having the value expression:
value-expr <mem_ref 0x7ffff72ed9d8 type <array_type 0x7ffff72e9540>
arg:0 <var_decl 0x7ffff72f21b0 arr2$13$linkptr>
arg:1 <integer_cst 0x7ffff72d8ac8 constant 0>>>
The code is produced for the attached code, which requires offloading, -fopenmp
and the patch for PR fortran/115559.
While 'omp declare target link(arr2)' has no direct effect on the host code, it
replaces on the device a variable such as
int arr[4];
by
int *arr$linkptr;
and all user of arr by (arr$linkref[0]). On the device side, the following code
is produced:
MEM <uint128_t> [(c_char * {ref-all})&arr2] = _7;
_2 = arr2[_1];
the replacement of the latter works:
_20 = arr2.13.linkptr;
but the 'MEM <uint128_t> [(c_char * {ref-all})&arr2] = _7;' remains and causes
later the link error:
ld: error: undefined symbol: arr2.13
for the offload side.
* * *
The replacement is done via omp-offload.cc's pass_omp_target_link::execute.
Here,
gimple_regimplify_operands (gsi_stmt (gsi), &gsi);
is then called for the MEMREF - which starts some regimplification, in
particular, the following is then reached:
gimplify.cc's gimplify_expr
...
/* We arrive here through the various re-gimplifcation paths. */
case MEM_REF:
/* First try re-folding the whole thing. */
tmp = fold_binary (MEM_REF, TREE_TYPE (*expr_p),
TREE_OPERAND (*expr_p, 0),
TREE_OPERAND (*expr_p, 1));
if (tmp)
… (tmp == NULL) …
break;
}
/* Avoid re-gimplifying the address operand if it is already
in suitable form. Re-gimplifying would mark the address
operand addressable. Always gimplify when not in SSA form
as we still may have to gimplify decls with value-exprs. */
if (!gimplify_ctxp || !gimple_in_ssa_p (cfun)
|| !is_gimple_mem_ref_addr (TREE_OPERAND (*expr_p, 0)))
{
ret = gimplify_expr (&TREE_OPERAND (*expr_p, 0), pre_p, post_p,
is_gimple_mem_ref_addr, fb_rvalue);
if (ret == GS_ERROR)
break;
}
recalculate_side_effects (*expr_p);
* * *
Full 'debug_tree':
<mem_ref 0x7ffff72edd98
type <integer_type 0x7ffff72e9bd0 unsigned TI
size <integer_cst 0x7ffff7202798 constant 128>
unit-size <integer_cst 0x7ffff72027b0 constant 16>
user align:32 warn_if_not_align:0 symtab:0 alias-set -1 canonical-type
0x7ffff720ba80 precision:128 min <integer_cst 0x7ffff72d8a20 0> max
<integer_cst 0x7ffff72ed758 340282366920938463463374607431768211455>>
arg:0 <addr_expr 0x7ffff72dcb20
type <pointer_type 0x7ffff72e9dc8 type <array_type 0x7ffff72e9540>
public unsigned DI
size <integer_cst 0x7ffff7202468 constant 64>
unit-size <integer_cst 0x7ffff7202480 constant 8>
align:64 warn_if_not_align:0 symtab:0 alias-set -1
structural-equality>
constant
arg:0 <var_decl 0x7ffff72f2090 arr2 type <array_type 0x7ffff72e9540>
addressable static nonlocal TI declare-target-link.f90:3:28 size
<integer_cst 0x7ffff7202798 128> unit-size <integer_cst 0x7ffff72027b0 16>
align:128 warn_if_not_align:0 context <function_decl 0x7ffff72ecf00
sub>
attributes <tree_list 0x7ffff72ed578
purpose <identifier_node 0x7ffff72ed550 omp declare target
link>>
value-expr <mem_ref 0x7ffff72ed9d8 type <array_type 0x7ffff72e9540>
arg:0 <var_decl 0x7ffff72f21b0 arr2$13$linkptr>
arg:1 <integer_cst 0x7ffff72d8ac8 constant 0>>>
declare-target-link.f90:29:24 start: declare-target-link.f90:29:24
finish: declare-target-link.f90:29:24>
arg:1 <integer_cst 0x7ffff72d8b40 type <pointer_type 0x7ffff72e9d20>
constant 0>>
