openmp: Optimize DECL_IN_CONSTANT_POOL vars in target regions

DECL_IN_CONSTANT_POOL are shared and thus don't really get emitted in the
BLOCK where they are used, so for OpenMP target regions that have initializers
gimplified into copying from them we actually map them at runtime from host to
offload devices.  This patch instead marks them as "omp declare target", so
that they are on the target device from the beginning and don't need to be
copied there.

2020-02-09  Jakub Jelinek  <jakub@redhat.com>

	* gimplify.c (gimplify_adjust_omp_clauses_1): Promote
	DECL_IN_CONSTANT_POOL variables into "omp declare target" to avoid
	copying them around between host and target.

	* testsuite/libgomp.c/target-38.c: New test.

2 files changed, 32 insertions, 0 deletions

diff --git a/libgomp/ChangeLog b/libgomp/ChangeLog
index ba14005c6ea..0740df8b2a1 100644
--- a/libgomp/ChangeLog
+++ b/libgomp/ChangeLog
@@ -1,3 +1,7 @@
+2020-02-09  Jakub Jelinek  <jakub@redhat.com>
+
+	* testsuite/libgomp.c/target-38.c: New test.
+
 2020-02-06  Jakub Jelinek  <jakub@redhat.com>
 
 	PR libgomp/93515
diff --git a/libgomp/testsuite/libgomp.c/target-38.c b/libgomp/testsuite/libgomp.c/target-38.c
new file mode 100644
index 00000000000..81699720526
--- /dev/null
+++ b/libgomp/testsuite/libgomp.c/target-38.c
@@ -0,0 +1,28 @@
+#define A(n) n##0, n##1, n##2, n##3, n##4, n##5, n##6, n##7, n##8, n##9
+#define B(n) A(n##0), A(n##1), A(n##2), A(n##3), A(n##4), A(n##5), A(n##6), A(n##7), A(n##8), A(n##9)
+
+int
+foo (int x)
+{
+  int b[] = { B(4), B(5), B(6) };
+  return b[x];
+}
+
+int v[] = { 1, 2, 3, 4, 5, 6 };
+#pragma omp declare target to (foo, v)
+
+int
+main ()
+{
+  int i = 5;
+  asm ("" : "+g" (i));
+  #pragma omp target map(tofrom:i)
+  {
+    int a[] = { B(1), B(2), B(3) };
+    asm ("" : : "m" (a) : "memory");
+    i = a[i] + foo (i) + v[i & 63];
+  }
+  if (i != 105 + 405 + 6)
+    __builtin_abort ();
+  return 0;
+}