openmp: Allow non-rectangular loops with pointer iterators

This patch handles pointer iterators for non-rectangular loops.  They are
more limited than integral iterators of non-rectangular loops, in particular
only var-outer, var-outer + a2, a2 + var-outer or var-outer - a2 can appear
in lb or ub where a2 is some integral loop invariant expression, so no e.g.
multiplication etc.

2021-10-27  Jakub Jelinek  <jakub@redhat.com>

gcc/
	* omp-expand.c (expand_omp_for_init_counts): Handle non-rectangular
	iterators with pointer types.
	(expand_omp_for_init_vars, extract_omp_for_update_vars): Likewise.
gcc/c-family/
	* c-omp.c (c_omp_check_loop_iv_r): Don't clear 3rd bit for
	POINTER_PLUS_EXPR.
	(c_omp_check_nonrect_loop_iv): Handle POINTER_PLUS_EXPR.
	(c_omp_check_loop_iv): Set kind even if the iterator is non-integral.
gcc/testsuite/
	* c-c++-common/gomp/loop-8.c: New test.
	* c-c++-common/gomp/loop-9.c: New test.
libgomp/
	* testsuite/libgomp.c/loop-26.c: New test.
	* testsuite/libgomp.c/loop-27.c: New test.

2 files changed, 48 insertions, 0 deletions

diff --git a/gcc/testsuite/c-c++-common/gomp/loop-8.c b/gcc/testsuite/c-c++-common/gomp/loop-8.c
new file mode 100644
index 0000000..d66bbcd
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/gomp/loop-8.c
@@ -0,0 +1,10 @@
+void
+foo (void)
+{
+  int a[1024];
+  int *p, *q;
+  #pragma omp parallel for collapse(2)
+  for (p = &a[0]; p < &a[512]; p++)
+    for (q = p + 64; q < p + 128; q++)
+      ;
+}
diff --git a/gcc/testsuite/c-c++-common/gomp/loop-9.c b/gcc/testsuite/c-c++-common/gomp/loop-9.c
new file mode 100644
index 0000000..a64ad98
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/gomp/loop-9.c
@@ -0,0 +1,38 @@
+int *qux (int *);
+
+void
+foo (void)
+{
+  int a[1024];
+  int *p;
+  short *q;
+  __PTRDIFF_TYPE__ r;
+  #pragma omp parallel for collapse(2)
+  for (p = &a[0]; p < &a[512]; p++)
+    for (q = (short *) p + 64; q < (short *) p + 128; q++)	/* { dg-error "outer iteration variable 'p' used in initializer expression has type other than 'short int ?\\\*'" } */
+      ;
+  #pragma omp parallel for collapse(2)
+  for (p = &a[0]; p < &a[512]; p++)
+    for (r = &a[32] - p; r < 32; r++)				/* { dg-error "initializer expression refers to iteration variable 'p'" } */
+      ;
+  #pragma omp parallel for collapse(2)
+  for (r = 0; r < 64; r++)
+    for (p = &a[0] + r; p < &a[32] + 3 * r; p++)		/* { dg-error "initializer expression refers to iteration variable 'r'" } */
+      ;
+}
+
+void
+bar (void)
+{
+  int a[1024];
+  int *p, *q, *r;
+  #pragma omp parallel for collapse(2)
+  for (p = &a[0]; p < &a[512]; p++)
+    for (q = p + (&a[16] - qux (p)); q < &a[32]; q++)		/* { dg-error "initializer expression refers to iteration variable 'p'" } */
+      ;
+  #pragma omp parallel for collapse(3)
+  for (p = &a[0]; p < &a[512]; p++)
+    for (q = &a[0]; q < &a[512]; q++)
+      for (r = p; r < q + 32; r++)				/* { dg-error "two different outer iteration variables 'p' and 'q' used in a single loop" } */
+	;
+}