Fix debug metadata for arrays with negative bounds

For Fortran array with negative bounds, the ACON here is
a sptr + offset address constant, sptr is the base symbol
representing the array and need not adding the positive
offset to the !DIExpression of the array variable.

Author: gklimowicz

tools/flang2/flang2exe/cgmain.cpp

@@ -11669,8 +11669,13 @@ gen_acon_expr(int ilix, LL_Type *expected_type)
     return make_constval_op(make_int_lltype(ptrbits), val[1], val[0]);
   }
   sym_is_refd(sptr);
-  process_sptr_offset(sptr, variable_offset_in_aggregate(
-                                sptr, ACONOFFG(opnd) < 0 ? 0 : ACONOFFG(opnd)));
+  /* In case of non-struct, e.g. a Fortran array may have ACON as sptr + offset,
+   * the "offset" works with "bound" and "index" together to calculate the 
+   * addresses of array elements. However, when generating debug metadata, the
+   * "offset" is not needed in the !DIExpression of the array variable. The
+   * array variable's location always starts from the beginning/first element. */
+  idx = (STYPEG(sptr) == ST_ARRAY || ACONOFFG(opnd) < 0) ? 0 : ACONOFFG(opnd);
+  process_sptr_offset(sptr, variable_offset_in_aggregate(sptr, idx));
   idx = ACONOFFG(opnd); /* byte offset */
 
   ty1 = make_lltype_from_dtype(DT_ADDR);