In the latest PR95551, the issue came up with a Fortran array
constructor ("if ((any (array /= [(-i, i=1, 10)])") used
in a target section within a host procedure. The constructor
is converted into a static local variable
A.10 = [-1, -2, ...]
ends up in omp-offload.c's offload_vars.
With -O3 optimization, the variable is optimized away on the
host side but it is still in the .gnu.offload_vars (→ host_table,
target_data), causing link errors.
* * *
I think there is a wider issue (→PR 95551 and others) regarding the
consistency between host and target variables and optimizations, but
I wonder why such a variables has to appear at all in the offload_vars
table.
Hence, I am thinking of the attached patch which does not add TREE_READONLY
variables to .gnu.offload_vars; I additionally require TREE_ARTIFICIAL as I
am thinking of the case such as Fortran parameter to which one an create a
pointer to – which might require the mapping information (is_device_{addr,ptr}).
[The question is whether more needs to be excluded, e.g. to exclude
virtual tables from the exlusion? For instance by requiring
TREE_CODE (DECL_CONTEXT (decl)) == FUNCTION_DECL ?]
For the test case, with -O3, the variable (A.10.3) is optimized away and
seemingly also not streamed out as it also does not appear with -foffload="-O0".
Thoughts?
Tobias
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openmp: don't add aritificial const decl to offload table (PRs 94848 + 95551)
gcc/ChangeLog:
PR lto/94848
PR middle-end/95551
* lto-cgraph.c (output_offload_tables): Skip readonly
aritificial variables.
* omp-offload.c (add_decls_addresses_to_decl_constructor,
omp_finish_file): Likewise
libgomp/ChangeLog:
PR lto/94848
PR middle-end/95551
* testsuite/libgomp.fortran/target-var.f90: New test.
gcc/lto-cgraph.c | 4 +++
gcc/omp-offload.c | 7 +++++-
libgomp/testsuite/libgomp.fortran/target-var.f90 | 32 ++++++++++++++++++++++++
3 files changed, 42 insertions(+), 1 deletion(-)
diff --git a/gcc/lto-cgraph.c b/gcc/lto-cgraph.c
index a671c671fa7..747d44c9f84 100644
--- a/gcc/lto-cgraph.c
+++ b/gcc/lto-cgraph.c
@@ -1077,6 +1077,10 @@ output_offload_tables (void)
for (unsigned i = 0; i < vec_safe_length (offload_vars); i++)
{
+ if (TREE_READONLY ((*offload_vars)[i])
+ && DECL_ARTIFICIAL ((*offload_vars)[i]))
+ continue;
+
streamer_write_enum (ob->main_stream, LTO_symtab_tags,
LTO_symtab_last_tag, LTO_symtab_variable);
lto_output_var_decl_ref (ob->decl_state, ob->main_stream,
diff --git a/gcc/omp-offload.c b/gcc/omp-offload.c
index b2df91a5724..2f6c55d8667 100644
--- a/gcc/omp-offload.c
+++ b/gcc/omp-offload.c
@@ -125,6 +125,9 @@ add_decls_addresses_to_decl_constructor (vec<tree, va_gc> *v_decls,
#endif
&& lookup_attribute ("omp declare target link", DECL_ATTRIBUTES (it));
+ if (is_var && TREE_READONLY (it) && DECL_ARTIFICIAL (it))
+ continue;
+
tree size = NULL_TREE;
if (is_var)
size = fold_convert (const_ptr_type_node, DECL_SIZE_UNIT (it));
@@ -341,7 +344,7 @@ omp_finish_file (void)
add_decls_addresses_to_decl_constructor (offload_vars, v_v);
tree vars_decl_type = build_array_type_nelts (pointer_sized_int_node,
- num_vars * 2);
+ vec_safe_length (v_v));
tree funcs_decl_type = build_array_type_nelts (pointer_sized_int_node,
num_funcs);
SET_TYPE_ALIGN (vars_decl_type, TYPE_ALIGN (pointer_sized_int_node));
@@ -381,6 +384,8 @@ omp_finish_file (void)
for (unsigned i = 0; i < num_vars; i++)
{
tree it = (*offload_vars)[i];
+ if (TREE_READONLY (it) && DECL_ARTIFICIAL (it))
+ continue;
#ifdef ACCEL_COMPILER
if (DECL_HAS_VALUE_EXPR_P (it)
&& lookup_attribute ("omp declare target link",
diff --git a/libgomp/testsuite/libgomp.fortran/target-var.f90 b/libgomp/testsuite/libgomp.fortran/target-var.f90
new file mode 100644
index 00000000000..5e5ccd47c96
--- /dev/null
+++ b/libgomp/testsuite/libgomp.fortran/target-var.f90
@@ -0,0 +1,32 @@
+! { dg-additional-options "-O3" }
+!
+! With -O3 the static local variable A.10 generated for
+! the array constructor [-2, -4, ..., -20] is optimized
+! away - which has to be handled in the offload_vars table.
+!
+program main
+ implicit none (type, external)
+ integer :: j
+ integer, allocatable :: A(:)
+
+ A = [(3*j, j=1, 10)]
+ call bar (A)
+ deallocate (A)
+contains
+ subroutine bar (array)
+ integer :: i
+ integer :: array(:)
+
+ !$omp target map(from:array)
+ !$acc parallel copyout(array)
+ array = [(-2*i, i = 1, size(array))]
+ !$omp do private(array)
+ !$acc loop gang private(array)
+ do i = 1, 10
+ array(i) = 9*i
+ end do
+ if (any (array /= [(-2*i, i = 1, 10)])) error stop 2
+ !$omp end target
+ !$acc end parallel
+ end subroutine bar
+end
