openmp: For min/max omp atomic compare forms verify arg types with build_binary_op...

The MIN_EXPR/MAX_EXPR handling in *build_binary_op is minimal (especially
for C FE), because min/max aren't expressions the languages contain directly.
I'm using those for the
  #pragma omp atomic
  x = x < y ? y : x;
forms, but e.g. for the attached testcase we normally reject _Complex int vs. int
comparisons, in C++ due to MIN/MAX_EXPR we were diagnosing it as invalid types
for <unknown> while in C we accept it and ICEd later on.

The following patch will try build_binary_op with LT_EXPR on the operands first
to get needed diagnostics and fail if it returns error_mark_node.

2022-02-16  Jakub Jelinek  <jakub@redhat.com>

	PR c/104531
	* c-omp.cc (c_finish_omp_atomic): For MIN_EXPR/MAX_EXPR, try first
	build_binary_op with LT_EXPR and only if that doesn't return
	error_mark_node call build_modify_expr.

	* c-c++-common/gomp/atomic-31.c: New test.

diff --git a/gcc/c-family/c-omp.cc b/gcc/c-family/c-omp.cc
index f5314d6..cd9d866 100644 (file)
--- a/gcc/c-family/c-omp.cc
+++ b/gcc/c-family/c-omp.cc
@@ -353,8 +353,13 @@ c_finish_omp_atomic (location_t loc, enum tree_code code,
     }
   bool save = in_late_binary_op;
   in_late_binary_op = true;
-  x = build_modify_expr (loc, blhs ? blhs : lhs, NULL_TREE, opcode,
-                        loc, rhs, NULL_TREE);
+  if ((opcode == MIN_EXPR || opcode == MAX_EXPR)
+      && build_binary_op (loc, LT_EXPR, blhs ? blhs : lhs, rhs,
+                         true) == error_mark_node)
+    x = error_mark_node;
+  else
+    x = build_modify_expr (loc, blhs ? blhs : lhs, NULL_TREE, opcode,
+                          loc, rhs, NULL_TREE);
   in_late_binary_op = save;
   if (x == error_mark_node)
     return error_mark_node;

diff --git a/gcc/testsuite/c-c++-common/gomp/atomic-31.c b/gcc/testsuite/c-c++-common/gomp/atomic-31.c
new file mode 100644 (file)
index 0000000..9ec3140
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/gomp/atomic-31.c
@@ -0,0 +1,11 @@
+/* c/104531 */
+/* { dg-do compile } */
+
+int x;
+
+void
+foo (_Complex int y)
+{
+  #pragma omp atomic compare   /* { dg-error "invalid operands" } */
+  x = x > y ? y : x;
+}