[PATCH] DWARFv5: Fix for the filename complaint when printing macro.

[Nitika.Achra@amd.com]

From: nitachra <Nitika.Achra@amd.com>

GDB complaints "During symbol reading: symtab found for file,
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.

A snippet of .debug_macro is as follows-

DW_MACRO_start_file - lineno: 0 filenum: 1
  DW_MACRO_define_strx - lineno: 3 macro: MAX_SIZE 10
DW_MACRO_end_file

Index of the file for the lookup in file_names table in .debug_line is (filenum - 1)

A snippet of .debug_line is as follows-

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

dir_index will be used to lookup the path in include_directories table-

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"

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 above), hence after lookup you get "/home/nitika/workspace/macro.c".
(compilation directory is /home/nitika/workspace)

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, macro
	filename includes the full directory path. Changing the if condition
	to include the comparison for full filename.
	* macrotab.h (macro_lookup_inclusion): Changing the definition,
	symtab as parameter instead of only the filename.
	* macroscope.c (sal_macro_scope): Passing the symtab instead of
	filename while calling macro_lookup_inclusion.
	* dwarf2/line-header.c (file_file_name): As per the comment in
	its definition in line-header.h, it should return file name
	relative to the compilation directory of file number I in this
	object's file name table.
---
 gdb/dwarf2/line-header.c | 8 --------
 gdb/macroscope.c         | 2 +-
 gdb/macrotab.c           | 7 ++++---
 gdb/macrotab.h           | 2 +-
 4 files changed, 6 insertions(+), 13 deletions(-)

diff --git a/gdb/dwarf2/line-header.c b/gdb/dwarf2/line-header.c
index 7575297f96..8975a03285 100644
--- a/gdb/dwarf2/line-header.c
+++ b/gdb/dwarf2/line-header.c
@@ -69,14 +69,6 @@ line_header::file_file_name (int file) const
     {
       const file_entry *fe = file_name_at (file);
 
-      if (!IS_ABSOLUTE_PATH (fe->name))
-	{
-	  const char *dir = fe->include_dir (this);
-	  if (dir != NULL)
-	    return gdb::unique_xmalloc_ptr<char> (concat (dir, SLASH_STRING,
-							  fe->name,
-							  (char *) NULL));
-	}
       return make_unique_xstrdup (fe->name);
     }
   else
diff --git a/gdb/macroscope.c b/gdb/macroscope.c
index e2abdd1bdd..a994068003 100644
--- a/gdb/macroscope.c
+++ b/gdb/macroscope.c
@@ -50,7 +50,7 @@ sal_macro_scope (struct symtab_and_line sal)
   gdb::unique_xmalloc_ptr<struct macro_scope> ms (XNEW (struct macro_scope));
 
   main_file = macro_main (COMPUNIT_MACRO_TABLE (cust));
-  inclusion = macro_lookup_inclusion (main_file, sal.symtab->filename);
+  inclusion = macro_lookup_inclusion (main_file, sal.symtab);
 
   if (inclusion)
     {
diff --git a/gdb/macrotab.c b/gdb/macrotab.c
index 96b29e345a..fae14b3c3c 100644
--- a/gdb/macrotab.c
+++ b/gdb/macrotab.c
@@ -504,10 +504,11 @@ macro_include (struct macro_source_file *source,
 
 
 struct macro_source_file *
-macro_lookup_inclusion (struct macro_source_file *source, const char *name)
+macro_lookup_inclusion (struct macro_source_file *source, struct symtab *symtab)
 {
   /* Is SOURCE itself named NAME?  */
-  if (filename_cmp (name, source->filename) == 0)
+  if (filename_cmp (symtab->filename, source->filename) == 0 ||
+      filename_cmp (symtab->fullname, macro_source_fullname(source).c_str()) == 0)
     return source;
 
   /* It's not us.  Try all our children, and return the lowest.  */
@@ -519,7 +520,7 @@ macro_lookup_inclusion (struct macro_source_file *source, const char *name)
     for (child = source->includes; child; child = child->next_included)
       {
 	struct macro_source_file *result
-	  = macro_lookup_inclusion (child, name);
+	  = macro_lookup_inclusion (child, symtab);
 
 	if (result)
 	  {
diff --git a/gdb/macrotab.h b/gdb/macrotab.h
index ea539e872e..6cbd3bc474 100644
--- a/gdb/macrotab.h
+++ b/gdb/macrotab.h
@@ -235,7 +235,7 @@ void macro_define_special (struct macro_table *table);
    least-nested inclusion --- the one closest to the main source file.  */
 struct macro_source_file *macro_lookup_inclusion
 			  (struct macro_source_file *source,
-			   const char *name);
+			   struct symtab *symtab);
 
 
 /* Record an object-like #definition (i.e., one with no parameter list).
-- 
2.17.1