GAS: DWARF-5: Ensure that the 0'th entry in the directory table contains the current working directory.

* dwarf2dbg.c (get_directory_table_entry): Ensure that dir[0]
	contains current working directory.
	(out_dir_and_file_list): Likewise.
	* testsuite/gas/elf/dwarf-5-dir0.s: New test source file.
	* testsuite/gas/elf/dwarf-5-dir0.d: New test driver.
	* testsuite/gas/elf/elf.exp: Run the new test.
	* testsuite/gas/elf/dwarf-5-file0.d: Adjust expected output.
	* testsuite/gas/i386/dwarf5-line-1.d: Likewise.
	* testsuite/gas/i386/dwarf5-line-2.d: Likewise.

gas/ChangeLog

@@ -1,3 +1,15 @@
+2021-08-09  Nick Clifton  <nickc@redhat.com>
+
+	* dwarf2dbg.c (get_directory_table_entry): Ensure that dir[0]
+	contains current working directory.
+	(out_dir_and_file_list): Likewise.
+	* testsuite/gas/elf/dwarf-5-dir0.s: New test source file.
+	* testsuite/gas/elf/dwarf-5-dir0.d: New test driver.
+	* testsuite/gas/elf/elf.exp: Run the new test.
+	* testsuite/gas/elf/dwarf-5-file0.d: Adjust expected output.
+	* testsuite/gas/i386/dwarf5-line-1.d: Likewise.
+	* testsuite/gas/i386/dwarf5-line-2.d: Likewise.
+
 2021-07-14  Alan Modra  <amodra@gmail.com>
 
 	* write.c (TC_VALIDATE_FIX_SUB): Default to 0.

gas/dwarf2dbg.c

@@ -620,16 +620,31 @@ get_directory_table_entry (const char *dirname,
   if (can_use_zero)
     {
       if (dirs == NULL || dirs[0] == NULL)
+	{
+	  const char * pwd = getpwd ();
+
+	  if (dwarf_level >= 5 && strcmp (dirname, pwd) != 0)
+	    {
+	      /* In DWARF-5 the 0 entry in the directory table is expected to be
+		 the same as the DW_AT_comp_dir (which is set to the current build
+		 directory).  Since we are about to create a directory entry that
+		 is not the same, allocate the current directory first.
+		 FIXME: Alternatively we could generate an error message here.  */
+	      (void) get_directory_table_entry (pwd, strlen (pwd), true);
+	      d = 1;
+	    }
+	  else
 	    d = 0;
 	}
+    }
   else if (d == 0)
     d = 1;
 
   if (d >= dirs_allocated)
     {
       unsigned int old = dirs_allocated;
-
+#define DIR_TABLE_INCREMENT 32
-      dirs_allocated = d + 32;
+      dirs_allocated = d + DIR_TABLE_INCREMENT;
       dirs = XRESIZEVEC (char *, dirs, dirs_allocated);
       memset (dirs + old, 0, (dirs_allocated - old) * sizeof (char *));
     }
@@ -779,7 +794,7 @@ allocate_filename_to_slot (const char *dirname,
 	    {
 	      if (dirs == NULL)
 		{
-		  dirs_allocated = files[num].dir + 32;
+		  dirs_allocated = files[num].dir + DIR_TABLE_INCREMENT;
 		  dirs = XCNEWVEC (char *, dirs_allocated);
 		}
 	      
@@ -807,7 +822,7 @@ allocate_filename_to_slot (const char *dirname,
 		{
 		  if (dirs == NULL)
 		    {
-		      dirs_allocated = files[num].dir + 32;
+		      dirs_allocated = files[num].dir + DIR_TABLE_INCREMENT;
 		      dirs = XCNEWVEC (char *, dirs_allocated);
 		    }
 
@@ -2082,7 +2097,12 @@ out_dir_and_file_list (segT line_seg, int sizeof_offset)
 	 Otherwise use pwd as main file directory.  */
       if (dirs_in_use > 0 && dirs != NULL && dirs[0] != NULL)
 	dir = remap_debug_filename (dirs[0]);
-      else if (dirs_in_use > 1 && dirs != NULL && dirs[1] != NULL)
+      else if (dirs_in_use > 1
+	       && dirs != NULL
+	       && dirs[1] != NULL
+	       /* DWARF-5 directory tables expect dir[0] to be the same as
+		  DW_AT_comp_dir, which is the same as pwd.  */
+	       && dwarf_level < 5)
 	dir = remap_debug_filename (dirs[1]);
       else
 	dir = remap_debug_filename (getpwd ());
@@ -2185,7 +2205,7 @@ out_dir_and_file_list (segT line_seg, int sizeof_offset)
 	     uses slot zero, but that is only set explicitly using a
 	     .file 0 directive.  If that isn't used, but file 1 is,
 	     then use that as main file name.  */
-	  if (DWARF2_LINE_VERSION >= 5 && i == 0 && files_in_use >= 1)
+	  if (DWARF2_LINE_VERSION >= 5 && i == 0 && files_in_use >= 1 && files[0].filename == NULL)
 	    files[0].filename = files[1].filename;
 	  else
 	    files[i].filename = "";

gas/testsuite/gas/elf/dwarf-5-dir0.d

@@ -0,0 +1,20 @@
+#as: --gdwarf-5
+#name: DWARF5 dir[0]
+#readelf: -wl
+
+#...
+ The Directory Table \(offset 0x.*, lines 4, columns 1\):
+  Entry	Name
+  0	\(indirect line string, offset: 0x0\): .*/gas/testsuite
+  1	\(indirect line string, offset: 0x.*\): ../not-the-build-directory
+  2	\(indirect line string, offset: 0x.*\): secondary directory
+  3	\(indirect line string, offset: 0x.*\): /tmp
+
+ The File Name Table \(offset 0x.*, lines 3, columns 3\):
+  Entry	Dir	MD5				Name
+  0	1 0x0	\(indirect line string, offset: 0x.*\): master-source-file.c
+  1	2 0x0	\(indirect line string, offset: 0x.*\): secondary source file
+  2	3 0x95828e8bc4f7404dbf7526fb7bd0f192	\(indirect line string, offset: 0x.*\): foo.c
+#pass
+
+

gas/testsuite/gas/elf/dwarf-5-dir0.s

@@ -0,0 +1,19 @@
+	.section	.debug_info,"",%progbits
+	.4byte	0x8a
+	.2byte  0x2
+	.4byte	.Ldebug_abbrev0
+	.byte	0x4
+	.uleb128 0x1
+
+	.file 0 "../not-the-build-directory/master-source-file.c"
+	.line 1
+	.text
+	.octa 0x12345678901234567890123456789012
+
+	.file 1 "secondary directory/secondary source file"
+	.line 2
+	.word 2
+
+	.file 2 "/tmp" "foo.c" md5 0x95828e8bc4f7404dbf7526fb7bd0f192
+	.line 5
+	.word 6

gas/testsuite/gas/elf/dwarf-5-file0.d

@@ -3,17 +3,18 @@
 #readelf: -wl
 
 #...
- The Directory Table \(offset 0x.*, lines 3, columns 1\):
+ The Directory Table \(offset 0x.*, lines 4, columns 1\):
   Entry	Name
-  0	\(indirect line string, offset: 0x.*\): master directory
+#...
-  1	\(indirect line string, offset: 0x.*\): secondary directory
+  1	\(indirect line string, offset: 0x.*\): master directory
-  2	\(indirect line string, offset: 0x.*\): /tmp
+  2	\(indirect line string, offset: 0x.*\): secondary directory
+  3	\(indirect line string, offset: 0x.*\): /tmp
 
  The File Name Table \(offset 0x.*, lines 3, columns 3\):
   Entry	Dir	MD5				Name
-  0	0 0x0	\(indirect line string, offset: 0x.*\): master source file
+  0	1 0x0	\(indirect line string, offset: 0x.*\): master source file
-  1	1 0x0	\(indirect line string, offset: 0x.*\): secondary source file
+  1	2 0x0	\(indirect line string, offset: 0x.*\): secondary source file
-  2	2 0x95828e8bc4f7404dbf7526fb7bd0f192	\(indirect line string, offset: 0x.*\): foo.c
+  2	3 0x95828e8bc4f7404dbf7526fb7bd0f192	\(indirect line string, offset: 0x.*\): foo.c
 #pass
 
 

gas/testsuite/gas/elf/elf.exp

@@ -297,6 +297,7 @@ if { [is_elf_format] } then {
     run_dump_test "dwarf2-19" $dump_opts
     run_dump_test "dwarf2-20" $dump_opts
     run_dump_test "dwarf-5-file0" $dump_opts
+    run_dump_test "dwarf-5-dir0" $dump_opts
     run_dump_test "dwarf-4-cu" $dump_opts
     run_dump_test "dwarf-5-cu" $dump_opts
     run_dump_test "dwarf-5-nop-for-line-table" $dump_opts

gas/testsuite/gas/i386/dwarf5-line-1.d

@@ -33,7 +33,7 @@ Raw dump of debug contents of section \.z?debug_line:
 
  The Directory Table \(offset 0x.*, lines 2, columns 1\):
   Entry	Name
-  0	\(indirect line string, offset: 0x.*\): .*/gas/testsuite/gas/i386
+  0	\(indirect line string, offset: 0x.*\): .*/gas/testsuite
   1	\(indirect line string, offset: 0x.*\): .*/gas/testsuite/gas/i386
 
  The File Name Table \(offset 0x.*, lines 2, columns 3\):

gas/testsuite/gas/i386/dwarf5-line-2.d

@@ -33,7 +33,7 @@ Raw dump of debug contents of section \.z?debug_line:
 
  The Directory Table \(offset 0x.*, lines 2, columns 1\):
   Entry	Name
-  0	\(indirect line string, offset: 0x.*\): .*/gas/testsuite/gas/i386
+  0	\(indirect line string, offset: 0x.*\): .*/gas/testsuite
   1	\(indirect line string, offset: 0x.*\): .*/gas/testsuite/gas/i386
 
  The File Name Table \(offset 0x.*, lines 1, columns 3\):