[libgomp, testsuite, nvptx] Limit recursion in declare_target-{1,2}.f90

When running testcases libgomp.fortran/examples-4/declare_target-{1,2}.f90 on
an RTX A2000 (sm_86) with driver 510.60.02 and with GOMP_NVPTX_JIT=-O0 I run
into:
...
FAIL: libgomp.fortran/examples-4/declare_target-1.f90 -O0 \
  -DGOMP_NVPTX_JIT=-O0 execution test
FAIL: libgomp.fortran/examples-4/declare_target-2.f90 -O0 \
  -DGOMP_NVPTX_JIT=-O0 execution test
...

Fix this by further limiting recursion depth in the test-cases for nvptx.

Furthermore, make the recursion depth limiting nvptx-specific.

Tested on x86_64 with nvptx accelerator.

libgomp/ChangeLog:

2022-04-01  Tom de Vries  <tdevries@suse.de>

	* testsuite/libgomp.fortran/examples-4/declare_target-1.f90: Define
	and use REC_DEPTH.
	* testsuite/libgomp.fortran/examples-4/declare_target-2.f90: Same.

2 files changed, 27 insertions, 11 deletions

diff --git a/libgomp/testsuite/libgomp.fortran/examples-4/declare_target-1.f90 b/libgomp/testsuite/libgomp.fortran/examples-4/declare_target-1.f90
index b761979ecde..03c5c53ed67 100644
--- a/libgomp/testsuite/libgomp.fortran/examples-4/declare_target-1.f90
+++ b/libgomp/testsuite/libgomp.fortran/examples-4/declare_target-1.f90
@@ -1,4 +1,16 @@
 ! { dg-do run }
+! { dg-additional-options "-cpp" }
+! Reduced from 25 to 23, otherwise execution runs out of thread stack on
+! Nvidia Titan V.
+! Reduced from 23 to 22, otherwise execution runs out of thread stack on
+! Nvidia T400 (2GB variant), when run with GOMP_NVPTX_JIT=-O0.
+! Reduced from 22 to 20, otherwise execution runs out of thread stack on
+! Nvidia RTX A2000 (6GB variant), when run with GOMP_NVPTX_JIT=-O0.
+! { dg-additional-options "-DREC_DEPTH=20" { target { offload_target_nvptx } } } */
+
+#ifndef REC_DEPTH
+#define REC_DEPTH 25
+#endif
 
 module e_53_1_mod
   integer :: THRESHOLD = 20
@@ -27,9 +39,5 @@ end module
 program e_53_1
   use e_53_1_mod, only : fib, fib_wrapper
   if (fib (15) /= fib_wrapper (15)) stop 1
-  ! Reduced from 25 to 23, otherwise execution runs out of thread stack on
-  ! Nvidia Titan V.
-  ! Reduced from 23 to 22, otherwise execution runs out of thread stack on
-  ! Nvidia T400 (2GB variant), when run with GOMP_NVPTX_JIT=-O0.
-  if (fib (22) /= fib_wrapper (22)) stop 2
+  if (fib (REC_DEPTH) /= fib_wrapper (REC_DEPTH)) stop 2
 end program
diff --git a/libgomp/testsuite/libgomp.fortran/examples-4/declare_target-2.f90 b/libgomp/testsuite/libgomp.fortran/examples-4/declare_target-2.f90
index f576c25ba39..0e8bea578a8 100644
--- a/libgomp/testsuite/libgomp.fortran/examples-4/declare_target-2.f90
+++ b/libgomp/testsuite/libgomp.fortran/examples-4/declare_target-2.f90
@@ -1,16 +1,24 @@
 ! { dg-do run }
+! { dg-additional-options "-cpp" }
+! Reduced from 25 to 23, otherwise execution runs out of thread stack on
+! Nvidia Titan V.
+! Reduced from 23 to 22, otherwise execution runs out of thread stack on
+! Nvidia T400 (2GB variant), when run with GOMP_NVPTX_JIT=-O0.
+! Reduced from 22 to 18, otherwise execution runs out of thread stack on
+! Nvidia RTX A2000 (6GB variant), when run with GOMP_NVPTX_JIT=-O0.
+! { dg-additional-options "-DREC_DEPTH=18" { target { offload_target_nvptx } } } */
+
+#ifndef REC_DEPTH
+#define REC_DEPTH 25
+#endif
 
 program e_53_2
   !$omp declare target (fib)
   integer :: x, fib
   !$omp target map(from: x)
-    ! Reduced from 25 to 23, otherwise execution runs out of thread stack on
-    ! Nvidia Titan V.
-    ! Reduced from 23 to 22, otherwise execution runs out of thread stack on
-    ! Nvidia T400 (2GB variant), when run with GOMP_NVPTX_JIT=-O0.
-    x = fib (22)
+    x = fib (REC_DEPTH)
   !$omp end target
-  if (x /= fib (22)) stop 1
+  if (x /= fib (REC_DEPTH)) stop 1
 end program
 
 integer recursive function fib (n) result (f)