[PATCH v2 1/2] DWARFv5: Handle DW_MACRO_define_strx and DW_MACRO_undef_strx macro entries.

[PATCH v2 1/2] DWARFv5: Handle DW_MACRO_define_strx and DW_MACRO_undef_strx macro entries.

[nitachra]

Hi Tom,

Thanks for the review.

>>> +        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));

>>I think that, in addition to issuing a complaint, this code should probably not try to read the string.  This is going to be an out-of-bounds read.

Done

>>> +        ULONGEST str_offset;
>>> +        if (offset_size == 4)
>>> +          str_offset = bfd_get_32 (abfd, info_ptr);
>>> +        else
>>> +          str_offset = bfd_get_64 (abfd, info_ptr);

>>I think this can use read_offset.
Done

>>>  /* Return the .debug_loc section to use for CU.
>>> diff --git a/gdb/macrotab.c b/gdb/macrotab.c index 
>>> 9ada436eaf..4ffb2d67cb 100644
>>> --- a/gdb/macrotab.c
>>> +++ b/gdb/macrotab.c
>>> @@ -507,7 +507,8 @@ struct macro_source_file *  
>>> macro_lookup_inclusion (struct macro_source_file *source, const char 
>>> *name)  {
>>>    /* Is SOURCE itself named NAME?  */
>>> -  if (filename_cmp (name, source->filename) == 0)
>>> +  if (filename_cmp (name, source->filename) == 0 ||
>>> +      filename_cmp (basename (name), basename (source->filename)) == 
>>> + 0)
>>>      return source;

>>This seems to be an unrelated change.

I have divided the patch in two. Please have a look.

Regards,
Nitika

---
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.
---
 gdb/dwarf2/macro.c | 71 ++++++++++++++++++++++++++++++++++++++++++++--
 gdb/dwarf2/macro.h |  3 ++
 gdb/dwarf2/read.c  | 21 +++++++++++++-
 3 files changed, 91 insertions(+), 4 deletions(-)

diff --git a/gdb/dwarf2/macro.c b/gdb/dwarf2/macro.c
index d047d806f8..9208614564 100644
--- 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 d874068947..0a7ac55fc0 100644
--- 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 558fad74f8..845adb0325 100644
--- a/gdb/dwarf2/read.c
+++ b/gdb/dwarf2/read.c
@@ -23350,8 +23350,27 @@ 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.
-- 
2.17.1

[PATCH v2 2/2] DWARFv5: Fix for the filename complaint when printing macro

[nitachra]

GDB complaints "During symbol reading: symtab found for 'macro.c',
but that file is not covered in the compilation unit's macro information.
No symbol "MAX_SIZE" in the current context" when printing the macro with
the testcase file macro.c given below. This patch fixes this and prints
the correct value.

When gdb reads file number from DW_MACRO_start_file data in .debug_macro
section, it will do name lookup in file_names and include_directories
index table of .debug_line section. Prior to DWARFv5 include_directories[0]
has no info, so a lookup at that index will return NULL and we have file name
"macro.c". But in dwarfv5 current directory is explicitly represented at index 0
(as shown in the snippet below), hence after lookup you get "PATH/macro.c".
A snippet of .debug_line is as follows-

include_directories[  0] = "/home/nitika/workspace"
include_directories[  1] = "/usr/include"
include_directories[  2] = "/usr/include/x86_64-linux-gnu/bits"
include_directories[  3] = "/usr/include/x86_64-linux-gnu/sys"
include_directories[  4] = "/usr/include/x86_64-linux-gnu/gnu"
include_directories[  5] = "up_llvm/llvm-project/build/lib/clang/11.0.0/include"
include_directories[  6] = "/usr/include/x86_64-linux-gnu/bits/types"

file_names[  0]:
           name: "macro.c"
      dir_index: 0
   md5_checksum: 0ee310711170f2dd9844b522e844207d

Test case used (macro.c):

 #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 -q  macro.out -ex "start" -ex "set complaints 1"  -ex "p MAX_SIZE"
Reading symbols from macro.out...
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;
During symbol reading: symtab found for 'macro.c',
but that file is not covered in the compilation unit's macro information
No symbol "MAX_SIZE" in current context.

After the patch:

gdb -q  macro.out -ex "start" -ex "p MAX_SIZE"
Reading symbols from macro.out...
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;
$1 = 10

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:

	* macrotab.c (macro_lookup_inclusion): In DWARF version 5 filename includes
	the full directory path.
---
 gdb/macrotab.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/gdb/macrotab.c b/gdb/macrotab.c
index 9ada436eaf..4ffb2d67cb 100644
--- a/gdb/macrotab.c
+++ b/gdb/macrotab.c
@@ -507,7 +507,8 @@ struct macro_source_file *
 macro_lookup_inclusion (struct macro_source_file *source, const char *name)
 {
   /* Is SOURCE itself named NAME?  */
-  if (filename_cmp (name, source->filename) == 0)
+  if (filename_cmp (name, source->filename) == 0 ||
+      filename_cmp (basename (name), basename (source->filename)) == 0)
     return source;
 
   /* It's not us.  Try all our children, and return the lowest.  */
-- 
2.17.1

Re: [PATCH v2 1/2] DWARFv5: Handle DW_MACRO_define_strx and DW_MACRO_undef_strx macro entries.

[Tom Tromey]

> 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.

Thank you.  This is ok.

Tom

Re: [PATCH v2 2/2] DWARFv5: Fix for the filename complaint when printing macro

[Simon Marchi]

On 2020-08-10 11:06 a.m., nitachra wrote:
> GDB complaints "During symbol reading: symtab found for 'macro.c',
> but that file is not covered in the compilation unit's macro information.
> No symbol "MAX_SIZE" in the current context" when printing the macro with
> the testcase file macro.c given below. This patch fixes this and prints
> the correct value.
>
> When gdb reads file number from DW_MACRO_start_file data in .debug_macro
> section, it will do name lookup in file_names and include_directories
> index table of .debug_line section. Prior to DWARFv5 include_directories[0]
> has no info, so a lookup at that index will return NULL and we have file name
> "macro.c". But in dwarfv5 current directory is explicitly represented at index 0
> (as shown in the snippet below), hence after lookup you get "PATH/macro.c".
> A snippet of .debug_line is as follows-
>
> include_directories[  0] = "/home/nitika/workspace"
> include_directories[  1] = "/usr/include"
> include_directories[  2] = "/usr/include/x86_64-linux-gnu/bits"
> include_directories[  3] = "/usr/include/x86_64-linux-gnu/sys"
> include_directories[  4] = "/usr/include/x86_64-linux-gnu/gnu"
> include_directories[  5] = "up_llvm/llvm-project/build/lib/clang/11.0.0/include"
> include_directories[  6] = "/usr/include/x86_64-linux-gnu/bits/types"
>
> file_names[  0]:
>            name: "macro.c"
>       dir_index: 0
>    md5_checksum: 0ee310711170f2dd9844b522e844207d
>
> Test case used (macro.c):
>
>  #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 -q  macro.out -ex "start" -ex "set complaints 1"  -ex "p MAX_SIZE"
> Reading symbols from macro.out...
> 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;
> During symbol reading: symtab found for 'macro.c',
> but that file is not covered in the compilation unit's macro information
> No symbol "MAX_SIZE" in current context.
>
> After the patch:
>
> gdb -q  macro.out -ex "start" -ex "p MAX_SIZE"
> Reading symbols from macro.out...
> 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;
> $1 = 10
>
> 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.

But... is there an increase in number of test that pass?  Shouldn't some
macro-related test catch this somehow?  If not, it would be really good
to add a test for this.


>
> gdb/ChangeLog:
>
> 	* macrotab.c (macro_lookup_inclusion): In DWARF version 5 filename includes
> 	the full directory path.
> ---
>  gdb/macrotab.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/gdb/macrotab.c b/gdb/macrotab.c
> index 9ada436eaf..4ffb2d67cb 100644
> --- a/gdb/macrotab.c
> +++ b/gdb/macrotab.c
> @@ -507,7 +507,8 @@ struct macro_source_file *
>  macro_lookup_inclusion (struct macro_source_file *source, const char *name)
>  {
>    /* Is SOURCE itself named NAME?  */
> -  if (filename_cmp (name, source->filename) == 0)
> +  if (filename_cmp (name, source->filename) == 0 ||
> +      filename_cmp (basename (name), basename (source->filename)) == 0)
>      return source;

I'm not sure what the best solution is, since I don't really know this
code, but comparing just the basename sounds dangerous.  Let's say I
debug a file "foo.c" that includes a file "generated/foo.c", won't there
be confusion between the two files?

Simon

[PATCH v2 1/2] DWARFv5: Handle DW_MACRO_define_strx and DW_MACRO_undef_strx macro entries.

[nitachra]

>> 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.

>Thank you.  This is ok.

>Tom

Hi Tom,

Thanks for the review. Could you please push this patch for me? All the
Changelogs are in place. Or can you tell me the procedure to add myself in
the list of contributors so that I can push it myself?

Regards,
Nitika

---
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.
---
 gdb/ChangeLog      | 10 +++++++
 gdb/dwarf2/macro.c | 71 ++++++++++++++++++++++++++++++++++++++++++++--
 gdb/dwarf2/macro.h |  3 ++
 gdb/dwarf2/read.c  | 21 +++++++++++++-
 4 files changed, 101 insertions(+), 4 deletions(-)

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index ce9cef5f51..7b431d275e 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,13 @@
+2020-09-24  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.
+
 2020-09-21  Tom Tromey  <tromey@adacore.com>
 
 	* sparc-tdep.c (sparc32_skip_prologue): Use
diff --git a/gdb/dwarf2/macro.c b/gdb/dwarf2/macro.c
index d047d806f8..9208614564 100644
--- 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 d874068947..0a7ac55fc0 100644
--- 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 a339141ce0..0729b6a413 100644
--- a/gdb/dwarf2/read.c
+++ b/gdb/dwarf2/read.c
@@ -23878,8 +23878,27 @@ 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.
-- 
2.17.1