'omp scan' struct block seq update for OpenMP 5.x

While OpenMP 5.0 required a single structured block before and after the
'omp scan' directive, OpenMP 5.1 changed this to a 'structured block sequence,
denoting 2 or more executable statements in OpenMP 5.1 (whoops!) and zero or
more in OpenMP 5.2. This commit updates C/C++ to accept zero statements (but
till requires the '{' ... '}' for the final-loop-body) and updates Fortran
to accept zero or more than one statements.

If there is no preceeding or succeeding executable statement, a warning is
shown.

gcc/c/ChangeLog:

	* c-parser.cc (c_parser_omp_scan_loop_body): Handle
	zero exec statements before/after 'omp scan'.

gcc/cp/ChangeLog:

	* parser.cc (cp_parser_omp_scan_loop_body): Handle
	zero exec statements before/after 'omp scan'.

gcc/fortran/ChangeLog:

	* openmp.cc (gfc_resolve_omp_do_blocks): Handle zero
	or more than one exec statements before/after 'omp scan'.
	* trans-openmp.cc (gfc_trans_omp_do): Likewise.

libgomp/ChangeLog:

	* testsuite/libgomp.c-c++-common/scan-1.c: New test.
	* testsuite/libgomp.c/scan-23.c: New test.
	* testsuite/libgomp.fortran/scan-2.f90: New test.

gcc/testsuite/ChangeLog:

	* g++.dg/gomp/attrs-7.C: Update dg-error/dg-warning.
	* gfortran.dg/gomp/loop-2.f90: Likewise.
	* gfortran.dg/gomp/reduction5.f90: Likewise.
	* gfortran.dg/gomp/reduction6.f90: Likewise.
	* gfortran.dg/gomp/scan-1.f90: Likewise.
	* gfortran.dg/gomp/taskloop-2.f90: Likewise.
	* c-c++-common/gomp/scan-6.c: New test.
	* gfortran.dg/gomp/scan-8.f90: New test.

3 files changed, 248 insertions, 0 deletions

diff --git a/libgomp/testsuite/libgomp.c-c++-common/scan-1.c b/libgomp/testsuite/libgomp.c-c++-common/scan-1.c
new file mode 100644
index 0000000..d1951a3
--- /dev/null
+++ b/libgomp/testsuite/libgomp.c-c++-common/scan-1.c
@@ -0,0 +1,68 @@
+#define N 30
+#define M 3
+
+int a[N][M], b[N][M], c[N][M];
+
+int
+main()
+{
+  int x, y, shift;
+  int j = 0;
+  for (int i = 0; i < N; i++)
+    {
+      a[i][0] = (i+1)*32;
+      a[i][1] = (i+1)*17;
+      a[i][2] = (i+1)*11;
+      b[i][0] = (i+1)*7;
+      b[i][1] = (i+1)*5;
+      b[i][2] = (i+1)*3;
+    }
+
+  x = 0;
+  #pragma omp parallel for simd collapse(2) reduction(inscan,+: x) private(shift)
+  for (int i = 0; i < N; i++)
+    for (int j = 0; j < M; j++)
+      {
+	x += a[i][j];
+	x += b[i][j];
+        #pragma omp scan inclusive(x)
+        shift = i + 29*j;
+        c[i][j] = x + shift;
+      }
+
+  y = 0;
+  for (int i = 0; i < N; i++)
+    for (int j = 0; j < M; j++)
+      {
+	y += a[i][j] + b[i][j];
+	if (c[i][j] != y + i + 29*j)
+	  __builtin_abort ();
+      }
+  if (x != y)
+    __builtin_abort ();
+
+  x = 0;
+  #pragma omp parallel for simd collapse(2) reduction(inscan,+: x) private(shift)
+  for (int i = 0; i < N; i++)
+    for (int j = 0; j < M; j++)
+      {
+	shift = i + 29*j;
+	c[i][j] = x + shift;
+	#pragma omp scan exclusive(x)
+	x += a[i][j];
+	x += b[i][j];
+      }
+
+  y = 0;
+  for (int i = 0; i < N; i++)
+    for (int j = 0; j < M; j++)
+      {
+	if (c[i][j] != y + i + 29*j)
+	  __builtin_abort ();
+	y += a[i][j] + b[i][j];
+      }
+  if (x != y)
+    __builtin_abort ();
+
+  return 0;
+}
diff --git a/libgomp/testsuite/libgomp.c/scan-23.c b/libgomp/testsuite/libgomp.c/scan-23.c
new file mode 100644
index 0000000..e7681ad
--- /dev/null
+++ b/libgomp/testsuite/libgomp.c/scan-23.c
@@ -0,0 +1,121 @@
+/* { dg-require-effective-target size32plus } */
+/* Same as scan-9.c, instead of using { ... } it simply uses multiple
+   executable stmt before 'omp scan'.  */
+
+extern void abort (void);
+int r, a[1024], b[1024], x, y, z;
+
+__attribute__((noipa)) void
+foo (int *a, int *b)
+{
+  #pragma omp for reduction (inscan, +:r) lastprivate (conditional: z) firstprivate (x) private (y)
+  for (int i = 0; i < 1024; i++)
+    {
+      y = a[i];
+      r += y + x + 12;
+      #pragma omp scan inclusive(r)
+      b[i] = r;
+      if ((i & 1) == 0 && i < 937)
+        z = r;
+    }
+}
+
+__attribute__((noipa)) int
+bar (void)
+{
+  int s = 0;
+  #pragma omp parallel
+  #pragma omp for reduction (inscan, +:s) firstprivate (x) private (y) lastprivate (z)
+  for (int i = 0; i < 1024; i++)
+    {
+      y = 2 * a[i]; s += y; z = y;
+      #pragma omp scan inclusive(s)
+      y = s; b[i] = y + x + 12;
+    }
+  return s;
+}
+
+__attribute__((noipa)) void
+baz (int *a, int *b)
+{
+  #pragma omp parallel for reduction (inscan, +:r) firstprivate (x) lastprivate (x)
+  for (int i = 0; i < 1024; i++)
+    {
+      r += a[i] + x + 12; if (i == 1023) x = 29;
+      #pragma omp scan inclusive(r)
+      b[i] = r;
+    }
+}
+
+__attribute__((noipa)) int
+qux (void)
+{
+  int s = 0;
+  #pragma omp parallel for reduction (inscan, +:s) lastprivate (conditional: x, y)
+  for (int i = 0; i < 1024; i++)
+    {
+      s += 2 * a[i]; if ((a[i] & 1) == 1 && i < 825) x = a[i];
+      #pragma omp scan inclusive(s)
+      b[i] = s; if ((a[i] & 1) == 0 && i < 829) y = a[i];
+    }
+  return s;
+}
+
+int
+main ()
+{
+  int s = 0;
+  x = -12;
+  for (int i = 0; i < 1024; ++i)
+    {
+      a[i] = i;
+      b[i] = -1;
+      asm ("" : "+g" (i));
+    }
+  #pragma omp parallel
+  foo (a, b);
+  if (r != 1024 * 1023 / 2 || x != -12 || z != b[936])
+    abort ();
+  for (int i = 0; i < 1024; ++i)
+    {
+      s += i;
+      if (b[i] != s)
+	abort ();
+      else
+	b[i] = 25;
+    }
+  if (bar () != 1024 * 1023 || x != -12 || z != 2 * 1023)
+    abort ();
+  s = 0;
+  for (int i = 0; i < 1024; ++i)
+    {
+      s += 2 * i;
+      if (b[i] != s)
+	abort ();
+      else
+	b[i] = -1;
+    }
+  r = 0;
+  baz (a, b);
+  if (r != 1024 * 1023 / 2 || x != 29)
+    abort ();
+  s = 0;
+  for (int i = 0; i < 1024; ++i)
+    {
+      s += i;
+      if (b[i] != s)
+	abort ();
+      else
+	b[i] = -25;
+    }
+  if (qux () != 1024 * 1023 || x != 823 || y != 828)
+    abort ();
+  s = 0;
+  for (int i = 0; i < 1024; ++i)
+    {
+      s += 2 * i;
+      if (b[i] != s)
+	abort ();
+    }
+  return 0;
+}
diff --git a/libgomp/testsuite/libgomp.fortran/scan-2.f90 b/libgomp/testsuite/libgomp.fortran/scan-2.f90
new file mode 100644
index 0000000..2815ec7
--- /dev/null
+++ b/libgomp/testsuite/libgomp.fortran/scan-2.f90
@@ -0,0 +1,59 @@
+implicit none
+integer, parameter :: N = 30
+integer, parameter :: M = 3
+
+integer :: a(M,N), b(M,N), c(M,N)
+integer :: x, y, shift
+integer :: i, j
+
+do i = 1, N
+  a(1,i) = i*32
+  a(2,i) = i*17
+  a(3,i) = i*11
+  b(1,i) = i*7
+  b(2,i) = i*5
+  b(3,i) = i*3
+end do
+
+x = 0
+!$omp parallel do simd collapse(2) reduction(inscan,+: x) private(shift)
+do i = 1, N
+  do j = 1, M
+    x = x + a(j,i)
+    x = x + b(j,i)
+    !$omp scan inclusive(x)
+    shift = i + 29*j
+    c(j,i) = x + shift;
+  end do
+end do
+
+y = 0
+do i = 1, N
+  do j = 1, M
+    y = y +  a(j,i) + b(j,i)
+    if (c(j,i) /= y + i + 29*j) error stop 1
+  end do
+end do
+if (x /= y) error stop 2
+
+x = 0
+!$omp parallel do simd collapse(2) reduction(inscan,+: x) private(shift)
+do i = 1, N
+  do j = 1, M
+    shift = i + 29*j
+    c(j,i) = x + shift;
+    !$omp scan exclusive(x)
+    x = x + a(j,i)
+    x = x + b(j,i)
+  end do
+end do
+
+y = 0
+do i = 1, N
+  do j = 1, M
+    if (c(j,i) /= y + i + 29*j) error stop 1
+    y = y + a(j,i) + b(j,i)
+  end do
+end do
+if (x /= y) error stop 2
+end