[Patch] Fortran: OpenMP/OpenACC avoid uninit access in size calc for mapping

[Tobias Burnus <tobias@codesourcery.com>]

[-- Attachment #1: Type: text/plain, Size: 1470 bytes --]

Hi Thomas & Jakub,

found when working on the deep-mapping patch* with OpenMP code
(and part of that patch) but it already shows up in an existing
OpenACC testcase. I think it makes sense to fix it already for GCC 12.

Problem: Also for unallocated allocatables, their size was
calculated - the 'if(desc.data == NULL)' check was only added
for pointers.

Result after the patch: When compiling with -O (which is the default
for goacc.exp), the warning now disappears. Thus, I now use '-O0'
and the previous "is uninitialized" is now "may be uninitialized".

Unrelated to the patch and the testcase, I added some
'allocate'**/'if(allocated())' to the testcase - as otherwise
uninit vars would be accessed. (Not relevant for the warning
or the patch - but I prefer no invalid code in testcases,
if it can be avoided.)

OK for mainline?

Tobias
* https://gcc.gnu.org/pipermail/gcc-patches/2022-March/591144.html

** I am actually not sure whether 'acc update(b)' will/should map a
previous allocated variable - or whether it should. But that's
unrelated to this bug fix. See also: https://gcc.gnu.org/PR96668
for the re-mapping in OpenMP (works for arrays but not scalars).
-----------------
Siemens Electronic Design Automation GmbH; Anschrift: Arnulfstraße 201, 80634 München; Gesellschaft mit beschränkter Haftung; Geschäftsführer: Thomas Heurung, Frank Thürauf; Sitz der Gesellschaft: München; Registergericht München, HRB 106955

[-- Attachment #2: uninit-map.diff --]
[-- Type: text/x-patch, Size: 3885 bytes --]

Fortran: OpenMP/OpenACC avoid uninit access in size calc for mapping

gcc/fortran/ChangeLog:

	* trans-openmp.cc (gfc_trans_omp_clauses, gfc_omp_finish_clause):
	Obtain size for mapping only if allocatable array is allocated.

gcc/testsuite/ChangeLog:

	* gfortran.dg/goacc/array-with-dt-1.f90: Run with -O0 and
	update dg-warning.
	* gfortran.dg/goacc/pr93464.f90: Likewise.

 gcc/fortran/trans-openmp.cc                         |  6 ++++--
 gcc/testsuite/gfortran.dg/goacc/array-with-dt-1.f90 | 12 +++++++++---
 gcc/testsuite/gfortran.dg/goacc/pr93464.f90         |  8 ++++----
 3 files changed, 17 insertions(+), 9 deletions(-)

diff --git a/gcc/fortran/trans-openmp.cc b/gcc/fortran/trans-openmp.cc
index 4d56a771349..fad76a4791f 100644
--- a/gcc/fortran/trans-openmp.cc
+++ b/gcc/fortran/trans-openmp.cc
@@ -1597,7 +1597,8 @@ gfc_omp_finish_clause (tree c, gimple_seq *pre_p, bool openacc)
       tree size = create_tmp_var (gfc_array_index_type);
       tree elemsz = TYPE_SIZE_UNIT (gfc_get_element_type (type));
       elemsz = fold_convert (gfc_array_index_type, elemsz);
-      if (GFC_TYPE_ARRAY_AKIND (type) == GFC_ARRAY_POINTER
+      if (GFC_TYPE_ARRAY_AKIND (type) == GFC_ARRAY_ALLOCATABLE
+	  || GFC_TYPE_ARRAY_AKIND (type) == GFC_ARRAY_POINTER
 	  || GFC_TYPE_ARRAY_AKIND (type) == GFC_ARRAY_POINTER_CONT)
 	{
 	  stmtblock_t cond_block;
@@ -3208,7 +3209,8 @@ gfc_trans_omp_clauses (stmtblock_t *block, gfc_omp_clauses *clauses,
 
 		      /* We have to check for n->sym->attr.dimension because
 			 of scalar coarrays.  */
-		      if (n->sym->attr.pointer && n->sym->attr.dimension)
+		      if ((n->sym->attr.pointer || n->sym->attr.allocatable)
+			  && n->sym->attr.dimension)
 			{
 			  stmtblock_t cond_block;
 			  tree size
diff --git a/gcc/testsuite/gfortran.dg/goacc/array-with-dt-1.f90 b/gcc/testsuite/gfortran.dg/goacc/array-with-dt-1.f90
index 136e42acd59..f6880238c89 100644
--- a/gcc/testsuite/gfortran.dg/goacc/array-with-dt-1.f90
+++ b/gcc/testsuite/gfortran.dg/goacc/array-with-dt-1.f90
@@ -1,4 +1,4 @@
-! { dg-additional-options -Wuninitialized }
+! { dg-additional-options "-Wuninitialized -O0" }
 
 type t
    integer, allocatable :: A(:,:)
@@ -8,9 +8,15 @@ type(t), allocatable :: b(:)
 ! { dg-note {'b' declared here} {} { target *-*-* } .-1 }
 
 !$acc update host(b)
-! { dg-warning {'b\.dim\[0\]\.ubound' is used uninitialized} {} { target *-*-* } .-1 }
-! { dg-warning {'b\.dim\[0\]\.lbound' is used uninitialized} {} { target *-*-* } .-2 }
+! { dg-warning {'b\.dim\[0\]\.ubound' may be used uninitialized} {} { target *-*-* } .-1 }
+! { dg-warning {'b\.dim\[0\]\.lbound' may be used uninitialized} {} { target *-*-* } .-2 }
+
+allocate(b(1))
+!$acc update host(b)
 !$acc update host(b(:))
+
+!$acc update host(b(1)%A)
+allocate(b(1)%A(1,1))
 !$acc update host(b(1)%A)
 !$acc update host(b(1)%A(:,:))
 end
diff --git a/gcc/testsuite/gfortran.dg/goacc/pr93464.f90 b/gcc/testsuite/gfortran.dg/goacc/pr93464.f90
index c92f1d3d8b2..18531abdf77 100644
--- a/gcc/testsuite/gfortran.dg/goacc/pr93464.f90
+++ b/gcc/testsuite/gfortran.dg/goacc/pr93464.f90
@@ -2,17 +2,17 @@
 !
 ! Contributed by G. Steinmetz
 
-! { dg-additional-options -Wuninitialized }
+! { dg-additional-options "-Wuninitialized -O0" }
 
 program p
    character :: c(2) = 'a'
    character, allocatable :: z(:)
    ! { dg-note {'z' declared here} {} { target *-*-* } .-1 }
    !$acc parallel
-   ! { dg-warning {'z\.dim\[0\]\.ubound' is used uninitialized} {} { target *-*-* } .-1 }
-   ! { dg-warning {'z\.dim\[0\]\.lbound' is used uninitialized} {} { target *-*-* } .-2 }
+   ! { dg-warning {'z\.dim\[0\]\.ubound' may be used uninitialized} {} { target *-*-* } .-1 }
+   ! { dg-warning {'z\.dim\[0\]\.lbound' may be used uninitialized} {} { target *-*-* } .-2 }
    !$omp target
-   z = c
+   if (allocated(z)) z = c
    !$acc end parallel
    !$omp end target
    print *, z