[PATCH, OpenMP] PR103642 - Fix omp-low ICE for indirect references based off component access

[Chung-Lin Tang]

This issue was triggered after the patch extending syntax for component access
in map clauses
(https://gcc.gnu.org/git/gitweb.cgi?p=gcc.git;h=0ab29cf0bb68960c)

In gimplify_scan_omp_clauses, the case for handling indirect accesses (which 
creates
firstprivate ptr and zero-length array section map for such decls) was 
erroneously
went into for non-pointer cases (here being the base struct decl), so added the
appropriate checks there.

Added new testcase is a compile only test for the ICE. The original omptests 
t-partial-struct
test actually should not execute correctly, because for map(t.s->a[:N]), 
map(t.s[:1])
is not implicitly mapped, thus the entire offloaded access does not work as is.
(fixing that omptests test is out of scope here)

Tested without regressions, okay for trunk?

Thanks,
Chung-Lin

2022-01-03  Chung-Lin Tang  <clt...@codesourcery.com>

gcc/ChangeLog:

        PR middle-end/103642
        * gimplify.c (gimplify_scan_omp_clauses): Do not do indir_p handling
        for non-pointer or non-reference-to-pointer cases.

gcc/testsuite/ChangeLog:

        * c-c++-common/gomp/pr103642.c: New test.




        
diff --git a/gcc/gimplify.c b/gcc/gimplify.c
index b118c72f62c..bdc8189c2a7 100644
--- a/gcc/gimplify.c
+++ b/gcc/gimplify.c
@@ -9543,7 +9543,10 @@ gimplify_scan_omp_clauses (tree *list_p, gimple_seq 
*pre_p,
                          == REFERENCE_TYPE))
                    decl = TREE_OPERAND (decl, 0);
                }
-             if (decl != orig_decl && DECL_P (decl) && indir_p)
+             if (decl != orig_decl && DECL_P (decl) && indir_p
+                 && (TREE_CODE (TREE_TYPE (decl)) == POINTER_TYPE
+                     || (decl_ref
+                         && TREE_CODE (TREE_TYPE (decl_ref)) == POINTER_TYPE)))
                {
                  gomp_map_kind k
                    = ((code == OACC_EXIT_DATA || code == OMP_TARGET_EXIT_DATA)
diff --git a/gcc/testsuite/c-c++-common/gomp/pr103642.c 
b/gcc/testsuite/c-c++-common/gomp/pr103642.c
new file mode 100644
index 00000000000..c5451596b69
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/gomp/pr103642.c
@@ -0,0 +1,31 @@
+/* PR middle-end/103642 */
+/* { dg-do compile } */
+
+#include <stdlib.h>
+
+typedef struct
+{
+  int *a;
+} S;
+
+typedef struct
+{
+  S *s;
+  int *ptr;
+} T;
+
+#define N 10
+
+int main (void)
+{
+  T t;
+  t.s = (S *) malloc (sizeof (S));
+  t.s->a = (int *) malloc (sizeof(int) * N);
+
+  #pragma omp target map(from: t.s->a[:N])
+  {
+    t.s->a[0] = 1;
+  }
+
+  return 0;
+}