https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94874
Bug ID: 94874
Summary: [OpenMP] Unhelpful 'defaultmap(none)' diagnostic for
'DECL_ARTIFICIAL': 'error: ‘array_li.0’ not specified
in enclosing ‘target’'
Product: gcc
Version: 10.0
Status: UNCONFIRMED
Keywords: openmp
Severity: normal
Priority: P3
Component: middle-end
Assignee: unassigned at gcc dot gnu.org
Reporter: tschwinge at gcc dot gnu.org
CC: burnus at gcc dot gnu.org, jakub at gcc dot gnu.org
Target Milestone: ---
Created attachment 48417
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=48417&action=edit
'gcc/testsuite/c-c++-common/gomp/pr.c'
[...]/pr.c:24:37: error: ‘array_li.0’ not specified in enclosing ‘target’
24 | array_so_openmp_target = sizeof array;
| ~~~~~~~^~~~~
I suppose for all such compiler-generated ('DECL_ARTIFICIAL') objects, we
shouldn't generate 'default(none)'/'defaultmap(none)' diagnostics, but instead
make them available on the offloading device in the "best possible" way. (...,
which probably defaults to 'firstprivate' given that these are typically
small-size objects?) (Regarding the latter, see also
'gcc/gimplify.c:omp_shared_to_firstprivate_optimizable_decl_p', which applies
similar rationale regarding "large decls".)
Also, for conceptual simplicity, I suppose any such compiler-generated
('DECL_ARTIFICIAL') objects should in some way be marked up with 'firstprivate'
clauses "explicitly by the compiler" when they are created, instead of having
'omp_default_clause' etc. do that. (I have not studied that in detail.) My
inclination would be to put an 'gcc_assert (!DECL_ARTIFICIAL(decl))' there?
But maybe that's too hard. Also need to sort out how that relates to
'lang_hooks.decls.omp_predetermined_sharing' etc.
Back to the diagnostic here, for '-x c++' we get, worse:
[...]/pr.c:24:28: error: ‘’ not specified in enclosing ‘target’
24 | array_so_openmp_target = sizeof array;
| ~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~
(Notice the empty '‘’'.) Per GDB:
Breakpoint 1, omp_notice_variable (ctx=0x2d2fc10,
decl=decl@entry=0x7ffff7feee10, in_code=in_code@entry=true) at
[...]/source-gcc/gcc/gimplify.c:7487
7487 error ("%qE not specified in enclosing
%<target%>",
(gdb) print d
$1 = (tree) 0x7ffff7feee10
(gdb) call debug_tree(d)
<var_decl 0x7ffff7feee10 D.2560
type <integer_type 0x7ffff67c3150 ssizetype public DI
size <integer_cst 0x7ffff67a5e70 constant 64>
unit-size <integer_cst 0x7ffff67a5e88 constant 8>
align:64 warn_if_not_align:0 symtab:0 alias-set -1 canonical-type
0x7ffff67c3150 precision:64 min <integer_cst 0x7ffff67a5000
-9223372036854775808> max <integer_cst 0x7ffff67a5f00 9223372036854775807>>
used ignored DI [...]/pr.c:8:23 size <integer_cst 0x7ffff67a5e70 64>
unit-size <integer_cst 0x7ffff67a5e88 8>
align:64 warn_if_not_align:0 context <function_decl 0x7ffff6933d00
vla>>
(gdb) print d.decl_minimal.name
$2 = (tree) 0x0
Doing something like 'gcc/fortran/trans-openmp.c:gfc_omp_report_decl' doesn't
easily help here, because:
(gdb) print d.decl_common.artificial_flag
$3 = 1
(gdb) print d.decl_common.lang_specific
$4 = (lang_decl *) 0x0
