DWARFv5: Handle DW_MACRO_define_strx and DW_MACRO_undef_strx macro entries.

GDB complaints "During symbol reading: unrecognized DW_MACFINO
opcode 0xb" with the testcase given below. Clang is emitting
DW_MACRO_define_strx and DW_MACRO_undef_strx entries in .debug_macro
section which are not supported in GDB. This patch handles them.

DW_MACRO_define_strx and DW_MACRO_undef_strx are added in DWARFv5.
They have two operands. The first operand encodes the line number of
the #define or #undef macro directive. The second operand identifies
a string; it is represented using an unsigned LEB128 encoded value,
which is interpreted as a zero-based index into an array of offsets
in the .debug_str_offsets section. This is as per the section 6.3.2.1
of Dwarf Debugging Information Format Version 5.

Test case used:
 #define MAX_SIZE 10
int main(void)
{
   int size = 0;
   size = size + MAX_SIZE;

   printf("\n The value of size is [%d]\n",size);

   return 0;
}

clang -gdwarf-5 -fdebug-macro  macro.c -o macro.out

Before the patch:

gdb/new_gdb/binutils-gdb/build/bin/gdb -q macro.out -ex "set complaints 1" -ex "start"
Reading symbols from macro.out...
During symbol reading: unrecognized DW_MACFINO opcode 0xb
Temporary breakpoint 1 at 0x4004df: file macro.c, line 7.
Starting program: /home/nitika/workspace/macro.out

Temporary breakpoint 1, main () at macro.c:7
7          int size = 0;
(gdb)

Tested by running the testsuite before and after the patch with
 -gdwarf-5 and there is no increase in the number of test cases
that fails. Used clang 11.0.0.

gdb/ChangeLog:

	* dwarf2/macro.c (dwarf_decode_macro_bytes): Handle DW_MACRO_define_strx
	and DW_MACRO_undef_strx.
	(dwarf_decode_macros): Likewise
	* dwarf2/read.c (dwarf_decode_macros): Pass str_offsets_base in the parameters
	which is the value of DW_AT_str_offsets_base.
	* dwarf2/macro.h (dwarf_decode_macros): Modify the definition to include
	str_offsets_base.

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 8081081b8d097d25950dc24fe0f917b19d7a12c8..9dd2123d60e64417275f4693d3f6bd93ab6f664e 100644 (file)
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,13 @@
+2020-10-02  Nitika Achra  <Nitika.Achra@amd.com>
+
+       * dwarf2/macro.c (dwarf_decode_macro_bytes): Handle DW_MACRO_define_strx
+       and DW_MACRO_undef_strx.
+       (dwarf_decode_macros): Likewise
+       * dwarf2/read.c (dwarf_decode_macros): Pass str_offsets_base in the parameters
+       which is the value of DW_AT_str_offsets_base.
+        * dwarf2/macro.h (dwarf_decode_macros): Modify the definition to include
+       str_offsets_base.
+
 2020-10-01  Kamil Rytarowski  <n54@gmx.com>
 
        * i386-tdep.h (i386nbsd_sc_reg_offset): Remove.

diff --git a/gdb/dwarf2/macro.c b/gdb/dwarf2/macro.c
index d047d806f884b34f97dca2736927413b1f67f9f3..92086145643467fe5e277db7de40e7f5e1885635 100644 (file)
--- a/gdb/dwarf2/macro.c
+++ b/gdb/dwarf2/macro.c
@@ -427,6 +427,9 @@ dwarf_decode_macro_bytes (dwarf2_per_objfile *per_objfile,
                          const struct dwarf2_section_info *section,
                          int section_is_gnu, int section_is_dwz,
                          unsigned int offset_size,
+                         struct dwarf2_section_info *str_section,
+                         struct dwarf2_section_info *str_offsets_section,
+                         ULONGEST str_offsets_base,
                          htab_t include_hash)
 {
   struct objfile *objfile = per_objfile->objfile;
@@ -561,6 +564,53 @@ dwarf_decode_macro_bytes (dwarf2_per_objfile *per_objfile,
           }
           break;
 
+       case DW_MACRO_define_strx:
+       case DW_MACRO_undef_strx:
+         {
+           unsigned int bytes_read;
+
+           int line = read_unsigned_leb128 (abfd, mac_ptr, &bytes_read);
+           mac_ptr += bytes_read;
+           int offset_index = read_unsigned_leb128 (abfd, mac_ptr, &bytes_read);
+           mac_ptr += bytes_read;
+
+           str_offsets_section->read (objfile);
+           const gdb_byte *info_ptr = (str_offsets_section->buffer
+                                       + str_offsets_base
+                                       + offset_index * offset_size);
+
+           const char *macinfo_str = (macinfo_type == DW_MACRO_define_strx ?
+                                      "DW_MACRO_define_strx" : "DW_MACRO_undef_strx");
+
+           if (str_offsets_base + offset_index * offset_size
+               >= str_offsets_section->size)
+             {
+               complaint (_("%s pointing outside of .debug_str_offsets section "
+                            "[in module %s]"), macinfo_str, objfile_name (objfile));
+               break;
+             }
+
+           ULONGEST str_offset = read_offset (abfd, info_ptr, offset_size);
+
+           const char *body = str_section->read_string (objfile, str_offset,
+                                                        macinfo_str);
+           if (current_file == nullptr)
+             {
+               /* DWARF violation as no main source is present.  */
+               complaint (_("debug info with no main source gives macro %s "
+                            "on line %d: %s"),
+                            macinfo_type == DW_MACRO_define_strx ? _("definition")
+                            : _("undefinition"), line, body);
+               break;
+             }
+
+           if (macinfo_type == DW_MACRO_define_strx)
+             parse_macro_definition (current_file, line, body);
+           else
+             macro_undef (current_file, line, body);
+          }
+          break;
+
         case DW_MACRO_start_file:
           {
             unsigned int bytes_read;
@@ -671,7 +721,8 @@ dwarf_decode_macro_bytes (dwarf2_per_objfile *per_objfile,
                                          new_mac_ptr, include_mac_end,
                                          current_file, lh, section,
                                          section_is_gnu, is_dwz, offset_size,
-                                         include_hash);
+                                         str_section, str_offsets_section,
+                                         str_offsets_base, include_hash);
 
                htab_remove_elt (include_hash, (void *) new_mac_ptr);
              }
@@ -712,7 +763,9 @@ dwarf_decode_macros (dwarf2_per_objfile *per_objfile,
                     buildsym_compunit *builder,
                     const dwarf2_section_info *section,
                     const struct line_header *lh, unsigned int offset_size,
-                    unsigned int offset, int section_is_gnu)
+                    unsigned int offset, struct dwarf2_section_info *str_section,
+                    struct dwarf2_section_info *str_offsets_section,
+                    ULONGEST str_offsets_base, int section_is_gnu)
 {
   bfd *abfd;
   const gdb_byte *mac_ptr, *mac_end;
@@ -814,6 +867,17 @@ dwarf_decode_macros (dwarf2_per_objfile *per_objfile,
            mac_ptr += offset_size;
          }
          break;
+       case DW_MACRO_define_strx:
+       case DW_MACRO_undef_strx:
+         {
+           unsigned int bytes_read;
+
+           read_unsigned_leb128 (abfd, mac_ptr, &bytes_read);
+           mac_ptr += bytes_read;
+           read_unsigned_leb128 (abfd, mac_ptr, &bytes_read);
+           mac_ptr += bytes_read;
+         }
+         break;
 
        case DW_MACRO_import:
        case DW_MACRO_import_sup:
@@ -861,5 +925,6 @@ dwarf_decode_macros (dwarf2_per_objfile *per_objfile,
   *slot = (void *) mac_ptr;
   dwarf_decode_macro_bytes (per_objfile, builder, abfd, mac_ptr, mac_end,
                            current_file, lh, section, section_is_gnu, 0,
-                           offset_size, include_hash.get ());
+                           offset_size, str_section, str_offsets_section,
+                           str_offsets_base, include_hash.get ());
 }

diff --git a/gdb/dwarf2/macro.h b/gdb/dwarf2/macro.h
index d874068947069cf12d710671e820a991079b031d..0a7ac55fc0c7be4fc63bdcd5fbfc0ddb0ca6a61f 100644 (file)
--- a/gdb/dwarf2/macro.h
+++ b/gdb/dwarf2/macro.h
@@ -28,6 +28,9 @@ extern void dwarf_decode_macros (dwarf2_per_objfile *per_objfile,
                                 const struct line_header *lh,
                                 unsigned int offset_size,
                                 unsigned int offset,
+                                dwarf2_section_info *str_section,
+                                dwarf2_section_info *str_offsets_section,
+                                ULONGEST str_offsets_base,
                                 int section_is_gnu);
 
 #endif /* GDB_DWARF2_MACRO_H */

diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
index 973a375641e8b7d064899d187841750dd3b7634d..eedfea112d96223d37e13642f67006c5a7d8f5e4 100644 (file)
--- a/gdb/dwarf2/read.c
+++ b/gdb/dwarf2/read.c
@@ -23900,8 +23900,27 @@ dwarf_decode_macros (struct dwarf2_cu *cu, unsigned int offset,
 
   buildsym_compunit *builder = cu->get_builder ();
 
+  struct dwarf2_section_info *str_offsets_section;
+  struct dwarf2_section_info *str_section;
+  ULONGEST str_offsets_base;
+
+  if (cu->dwo_unit != nullptr)
+    {
+      str_offsets_section = &cu->dwo_unit->dwo_file
+                              ->sections.str_offsets;
+      str_section = &cu->dwo_unit->dwo_file->sections.str;
+      str_offsets_base = cu->header.addr_size;
+    }
+  else
+    {
+      str_offsets_section = &per_objfile->per_bfd->str_offsets;
+      str_section = &per_objfile->per_bfd->str;
+      str_offsets_base = *cu->str_offsets_base;
+    }
+
   dwarf_decode_macros (per_objfile, builder, section, lh,
-                      offset_size, offset, section_is_gnu);
+                      offset_size, offset, str_section, str_offsets_section,
+                      str_offsets_base, section_is_gnu);
 }
 
 /* Return the .debug_loc section to use for CU.