Make it possible for the a.out BFD back-end to merge read-only

sections with .text if the following 3 conditions are true:

1. Section has file contents and is read-only.
2. The VMA of the section is after the end of .text and before
   the start of .data.
3. The image is demand-pageable (otherwise, a_text in the header
   will not reflect the gap between .text and .data).

Fixes PR 19164.

gnu/dist/toolchain/bfd/aoutnbsd.h

@@ -1222,11 +1222,17 @@ NAME(aout,set_section_contents) (abfd, section, location, offset, count)
   if (section != obj_textsec (abfd)
       && section != obj_datasec (abfd))
     {
-      (*_bfd_error_handler)
-	("%s: can not represent section `%s' in a.out object file format",
-	 bfd_get_filename (abfd), bfd_get_section_name (abfd, section));
-      bfd_set_error (bfd_error_nonrepresentable_section);
-      return false;
+      if (aout_section_merge_with_text_p (abfd, section))
+	section->filepos = obj_textsec (abfd)->filepos +
+			   (section->vma - obj_textsec (abfd)->vma);
+      else
+	{
+          (*_bfd_error_handler)
+	    ("%s: can not represent section `%s' in a.out object file format",
+	     bfd_get_filename (abfd), bfd_get_section_name (abfd, section));
+          bfd_set_error (bfd_error_nonrepresentable_section);
+          return false;
+	}
     }
 
   if (count != 0)
@@ -1540,11 +1546,16 @@ translate_to_native_sym_flags (abfd, cache_ptr, sym_pointer)
     sym_pointer->e_type[0] = N_UNDF | N_EXT;
   else
     {
-      (*_bfd_error_handler)
-	("%s: can not represent section `%s' in a.out object file format",
-	 bfd_get_filename (abfd), bfd_get_section_name (abfd, sec));
-      bfd_set_error (bfd_error_nonrepresentable_section);
-      return false;
+      if (aout_section_merge_with_text_p (abfd, sec))
+	sym_pointer->e_type[0] |= N_TEXT;
+      else
+	{
+          (*_bfd_error_handler)
+	    ("%s: can not represent section `%s' in a.out object file format",
+	     bfd_get_filename (abfd), bfd_get_section_name (abfd, sec));
+          bfd_set_error (bfd_error_nonrepresentable_section);
+          return false;
+	}
     }
 
   /* Turn the symbol from section relative to absolute again */

gnu/dist/toolchain/bfd/aoutx.h

@@ -1266,11 +1266,17 @@ NAME(aout,set_section_contents) (abfd, section, location, offset, count)
   if (section != obj_textsec (abfd)
       && section != obj_datasec (abfd))
     {
-      (*_bfd_error_handler)
-	(_("%s: can not represent section `%s' in a.out object file format"),
-	 bfd_get_filename (abfd), bfd_get_section_name (abfd, section));
-      bfd_set_error (bfd_error_nonrepresentable_section);
-      return false;
+      if (aout_section_merge_with_text_p (abfd, section))
+	section->filepos = obj_textsec (abfd)->filepos +
+			   (section->vma - obj_textsec (abfd)->vma);
+      else
+	{
+          (*_bfd_error_handler)
+	    (_("%s: can not represent section `%s' in a.out object file format"),
+	     bfd_get_filename (abfd), bfd_get_section_name (abfd, section));
+          bfd_set_error (bfd_error_nonrepresentable_section);
+          return false;
+	}
     }
 
   if (count != 0)
@@ -1694,11 +1700,16 @@ translate_to_native_sym_flags (abfd, cache_ptr, sym_pointer)
     sym_pointer->e_type[0] = N_UNDF | N_EXT;
   else
     {
-      (*_bfd_error_handler)
-	(_("%s: can not represent section `%s' in a.out object file format"),
-	 bfd_get_filename (abfd), bfd_get_section_name (abfd, sec));
-      bfd_set_error (bfd_error_nonrepresentable_section);
-      return false;
+      if (aout_section_merge_with_text_p (abfd, sec))
+	sym_pointer->e_type[0] |= N_TEXT;
+      else
+	{
+          (*_bfd_error_handler)
+	    (_("%s: can not represent section `%s' in a.out object file format"),
+	     bfd_get_filename (abfd), bfd_get_section_name (abfd, sec));
+          bfd_set_error (bfd_error_nonrepresentable_section);
+          return false;
+	}
     }
 
   /* Turn the symbol from section relative to absolute again */

gnu/dist/toolchain/bfd/libaout.h

@@ -649,4 +649,23 @@ NAME(aout,bfd_free_cached_info) PARAMS ((bfd *));
       }									      
 #endif
 
+/* Test if a read-only section can be merged with .text.  This is
+   possible if:
+
+   1. Section has file contents and is read-only.
+   2. The VMA of the section is after the end of .text and before
+      the start of .data.
+   3. The image is demand-pageable (otherwise, a_text in the header
+      will not reflect the gap between .text and .data).  */
+
+#define aout_section_merge_with_text_p(abfd, sec)			\
+  (((sec)->flags & (SEC_HAS_CONTENTS|SEC_READONLY)) ==			\
+      (SEC_HAS_CONTENTS|SEC_READONLY)					\
+   && obj_textsec (abfd) != NULL					\
+   && obj_datasec (abfd) != NULL					\
+   && (sec)->vma >= (obj_textsec (abfd)->vma +				\
+		    obj_textsec (abfd)->_cooked_size)			\
+   && ((sec)->vma + (sec)->_cooked_size) <= obj_datasec (abfd)->vma	\
+   && ((abfd)->flags & D_PAGED) != 0)
+
 #endif /* ! defined (LIBAOUT_H) */

gnu/dist/toolchain/bfd/netbsd.h

@@ -391,11 +391,16 @@ netbsd_translate_to_native_sym_flags (abfd, cache_ptr, sym_pointer)
     sym_pointer->e_type[0] = N_UNDF | N_EXT;
   else
     {
-      (*_bfd_error_handler)
-	("%s: can not represent section `%s' in a.out object file format",
-	 bfd_get_filename (abfd), bfd_get_section_name (abfd, sec));
-      bfd_set_error (bfd_error_nonrepresentable_section);
-      return false;
+      if (aout_section_merge_with_text_p (abfd, sec))
+	sym_pointer->e_type[0] |= N_TEXT;
+      else
+	{
+          (*_bfd_error_handler)
+	    ("%s: n2 can not represent section `%s' in a.out object file format",
+	     bfd_get_filename (abfd), bfd_get_section_name (abfd, sec));
+          bfd_set_error (bfd_error_nonrepresentable_section);
+          return false;
+	}
     }
 
   /* Turn the symbol from section relative to absolute again */