Support for DWARF5 location lists entries

This patch handles DW_LLE_base_addressx, DW_LLE_startx_length and
DW_LLE_start_length.

Tested by running the testsuite before and after the patch and there is
no increase in the number of test cases that fails. Tested with both
-gdwarf-4 and -gdwarf-5 flags. Also tested -gslit-dwarf along with
-gdwarf-4 as well as -gdwarf5 flags.

This is an effort to support DWARF5 in gdb.

gdb/ChangeLog:

	* dwarf2loc.c (decode_debug_loclists_addresses): Handle
	DW_LLE_base_addressx, DW_LLE_startx_length, DW_LLE_start_length.

2 files changed, 44 insertions, 0 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index cd89a44..5513bea 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,8 @@
+2020-01-16  Nitika Achra  <Nitika.Achra@amd.com>
+
+	* dwarf2loc.c (decode_debug_loclists_addresses): Handle
+	DW_LLE_base_addressx, DW_LLE_startx_length, DW_LLE_start_length.
+
 2020-01-15  Simon Marchi  <simon.marchi@efficios.com>
 
 	* infcmd.c (post_create_inferior): Use get_thread_regcache
diff --git a/gdb/dwarf2loc.c b/gdb/dwarf2loc.c
index 1fe6829..405b239 100644
--- a/gdb/dwarf2loc.c
+++ b/gdb/dwarf2loc.c
@@ -173,6 +173,41 @@ decode_debug_loclists_addresses (struct dwarf2_per_cu_data *per_cu,
 
   switch (*loc_ptr++)
     {
+    case DW_LLE_base_addressx:
+      *low = 0;
+      loc_ptr = gdb_read_uleb128 (loc_ptr, buf_end, &u64);
+      if (loc_ptr == NULL)
+	 return DEBUG_LOC_BUFFER_OVERFLOW;
+      *high = dwarf2_read_addr_index (per_cu, u64);
+      *new_ptr = loc_ptr;
+      return DEBUG_LOC_BASE_ADDRESS;
+    case DW_LLE_startx_length:
+      loc_ptr = gdb_read_uleb128 (loc_ptr, buf_end, &u64);
+      if (loc_ptr == NULL)
+	 return DEBUG_LOC_BUFFER_OVERFLOW;
+      *low = dwarf2_read_addr_index (per_cu, u64);
+      *high = *low;
+      loc_ptr = gdb_read_uleb128 (loc_ptr, buf_end, &u64);
+      if (loc_ptr == NULL)
+	 return DEBUG_LOC_BUFFER_OVERFLOW;
+      *high += u64;
+      *new_ptr = loc_ptr;
+      return DEBUG_LOC_START_LENGTH;
+    case DW_LLE_start_length:
+      if (buf_end - loc_ptr < addr_size)
+	 return DEBUG_LOC_BUFFER_OVERFLOW;
+      if (signed_addr_p)
+	 *low = extract_signed_integer (loc_ptr, addr_size, byte_order);
+      else
+	 *low = extract_unsigned_integer (loc_ptr, addr_size, byte_order);
+      loc_ptr += addr_size;
+      *high = *low;
+      loc_ptr = gdb_read_uleb128 (loc_ptr, buf_end, &u64);
+      if (loc_ptr == NULL)
+	 return DEBUG_LOC_BUFFER_OVERFLOW;
+      *high += u64;
+      *new_ptr = loc_ptr;
+      return DEBUG_LOC_START_LENGTH;
     case DW_LLE_end_of_list:
       *new_ptr = loc_ptr;
       return DEBUG_LOC_END_OF_LIST;
@@ -197,6 +232,10 @@ decode_debug_loclists_addresses (struct dwarf2_per_cu_data *per_cu,
       *high = u64;
       *new_ptr = loc_ptr;
       return DEBUG_LOC_START_END;
+    /* Following cases are not supported yet.  */
+    case DW_LLE_startx_endx:
+    case DW_LLE_start_end:
+    case DW_LLE_default_location:
     default:
       return DEBUG_LOC_INVALID_ENTRY;
     }