Remove sym_fns::sym_read_psymbols

Partial symbols are read via the sym_fns::sym_read_psymbols function
pointer.  In order to separate the partial symbols from the objfile,
this must instead be done via a virtual method on
quick_symbol_functions.  This patch implements this change.

gdb/ChangeLog
2021-03-20  Tom Tromey  <tom@tromey.com>

	* xcoffread.c (xcoff_sym_fns): Update.
	* symfile.h (struct sym_fns) <sym_read_psymbols>: Remove.
	* symfile-debug.c (objfile::has_partial_symbols): Use
	can_lazily_read_symbols.
	(debug_sym_read_psymbols): Remove.
	(debug_sym_fns, install_symfile_debug_logging): Update.
	* quick-symbol.h (struct quick_symbol_functions)
	<can_lazily_read_symbols, read_partial_symbols>: New methods.
	* psymtab.c (require_partial_symbols): Use new 'qf' methods.
	* mipsread.c (ecoff_sym_fns): Update.
	* machoread.c (macho_sym_fns): Update.
	* elfread.c (struct lazy_dwarf_reader): New.
	(elf_symfile_read): Update.
	(read_psyms): Now a method of lazy_dwarf_reader.
	(elf_sym_fns): Update.
	(elf_sym_fns_lazy_psyms): Remove.
	* dbxread.c (aout_sym_fns): Update.
	* coffread.c (coff_sym_fns): Update.

11 files changed, 59 insertions, 61 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 9eba43c..1640270 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,26 @@
 2021-03-20  Tom Tromey  <tom@tromey.com>
 
+	* xcoffread.c (xcoff_sym_fns): Update.
+	* symfile.h (struct sym_fns) <sym_read_psymbols>: Remove.
+	* symfile-debug.c (objfile::has_partial_symbols): Use
+	can_lazily_read_symbols.
+	(debug_sym_read_psymbols): Remove.
+	(debug_sym_fns, install_symfile_debug_logging): Update.
+	* quick-symbol.h (struct quick_symbol_functions)
+	<can_lazily_read_symbols, read_partial_symbols>: New methods.
+	* psymtab.c (require_partial_symbols): Use new 'qf' methods.
+	* mipsread.c (ecoff_sym_fns): Update.
+	* machoread.c (macho_sym_fns): Update.
+	* elfread.c (struct lazy_dwarf_reader): New.
+	(elf_symfile_read): Update.
+	(read_psyms): Now a method of lazy_dwarf_reader.
+	(elf_sym_fns): Update.
+	(elf_sym_fns_lazy_psyms): Remove.
+	* dbxread.c (aout_sym_fns): Update.
+	* coffread.c (coff_sym_fns): Update.
+
+2021-03-20  Tom Tromey  <tom@tromey.com>
+
 	* symfile.c (syms_from_objfile_1): Call reset_psymtabs.
 	(reread_symbols): Move reset_psymtabs call later.
 	* objfiles.c (objfile::objfile): Don't initialize
diff --git a/gdb/coffread.c b/gdb/coffread.c
index 676deec..b527f93 100644
--- a/gdb/coffread.c
+++ b/gdb/coffread.c
@@ -2168,7 +2168,6 @@ static const struct sym_fns coff_sym_fns =
 				   for sym_read() */
   coff_symfile_read,		/* sym_read: read a symbol file into
 				   symtab */
-  NULL,				/* sym_read_psymbols */
   coff_symfile_finish,		/* sym_finish: finished with file,
 				   cleanup */
   default_symfile_offsets,	/* sym_offsets: xlate external to
diff --git a/gdb/dbxread.c b/gdb/dbxread.c
index 9a470bf..e0cc259 100644
--- a/gdb/dbxread.c
+++ b/gdb/dbxread.c
@@ -3131,7 +3131,6 @@ static const struct sym_fns aout_sym_fns =
   dbx_new_init,			/* init anything gbl to entire symtab */
   dbx_symfile_init,		/* read initial info, setup for sym_read() */
   dbx_symfile_read,		/* read a symbol file into symtab */
-  NULL,				/* sym_read_psymbols */
   dbx_symfile_finish,		/* finished with file, cleanup */
   default_symfile_offsets, 	/* parse user's offsets to internal form */
   default_symfile_segments,	/* Get segment information from a file.  */
diff --git a/gdb/elfread.c b/gdb/elfread.c
index 4ca1f4d..157a071 100644
--- a/gdb/elfread.c
+++ b/gdb/elfread.c
@@ -53,7 +53,24 @@
 #include "debuginfod-support.h"
 #include "dwarf2/public.h"
 
-/* Forward declarations.  */
+/* A subclass of psymbol_functions that arranges to read the DWARF
+   partial symbols when needed.  */
+struct lazy_dwarf_reader : public psymbol_functions
+{
+  using psymbol_functions::psymbol_functions;
+
+  bool can_lazily_read_symbols () override
+  {
+    return true;
+  }
+
+  void read_partial_symbols (struct objfile *objfile) override
+  {
+    if (dwarf2_has_info (objfile, nullptr))
+      dwarf2_build_psymtabs (objfile);
+  }
+};
+
 extern const struct sym_fns elf_sym_fns_lazy_psyms;
 
 /* The struct elfinfo is available only during ELF symbol table and
@@ -1283,7 +1300,8 @@ elf_symfile_read (struct objfile *objfile, symfile_add_flags symfile_flags)
 	     partial symbols, because OBJF_PSYMTABS_READ has not been
 	     set, and so our lazy reader function will still be called
 	     when needed.  */
-	  objfile_set_sym_fns (objfile, &elf_sym_fns_lazy_psyms);
+	  objfile->qf.reset
+	    (new lazy_dwarf_reader (objfile->partial_symtabs));
 	}
     }
   /* If the file has its own symbol tables it has no separate debug
@@ -1353,15 +1371,6 @@ elf_symfile_read (struct objfile *objfile, symfile_add_flags symfile_flags)
     }
 }
 
-/* Callback to lazily read psymtabs.  */
-
-static void
-read_psyms (struct objfile *objfile)
-{
-  if (dwarf2_has_info (objfile, NULL))
-    dwarf2_build_psymtabs (objfile);
-}
-
 /* Initialize anything that needs initializing when a completely new symbol
    file is specified (not just adding some symbols from another file, e.g. a
    shared library).  */
@@ -1428,24 +1437,6 @@ static const struct sym_fns elf_sym_fns =
   elf_new_init,			/* init anything gbl to entire symtab */
   elf_symfile_init,		/* read initial info, setup for sym_read() */
   elf_symfile_read,		/* read a symbol file into symtab */
-  NULL,				/* sym_read_psymbols */
-  elf_symfile_finish,		/* finished with file, cleanup */
-  default_symfile_offsets,	/* Translate ext. to int. relocation */
-  elf_symfile_segments,		/* Get segment information from a file.  */
-  NULL,
-  default_symfile_relocate,	/* Relocate a debug section.  */
-  &elf_probe_fns,		/* sym_probe_fns */
-};
-
-/* The same as elf_sym_fns, but not registered and lazily reads
-   psymbols.  */
-
-const struct sym_fns elf_sym_fns_lazy_psyms =
-{
-  elf_new_init,			/* init anything gbl to entire symtab */
-  elf_symfile_init,		/* read initial info, setup for sym_read() */
-  elf_symfile_read,		/* read a symbol file into symtab */
-  read_psyms,			/* sym_read_psymbols */
   elf_symfile_finish,		/* finished with file, cleanup */
   default_symfile_offsets,	/* Translate ext. to int. relocation */
   elf_symfile_segments,		/* Get segment information from a file.  */
diff --git a/gdb/machoread.c b/gdb/machoread.c
index 44baaa2..17aa9ce 100644
--- a/gdb/machoread.c
+++ b/gdb/machoread.c
@@ -951,7 +951,6 @@ static const struct sym_fns macho_sym_fns = {
   macho_new_init,               /* init anything gbl to entire symtab */
   macho_symfile_init,           /* read initial info, setup for sym_read() */
   macho_symfile_read,           /* read a symbol file into symtab */
-  NULL,				/* sym_read_psymbols */
   macho_symfile_finish,         /* finished with file, cleanup */
   macho_symfile_offsets,        /* xlate external to internal form */
   default_symfile_segments,	/* Get segment information from a file.  */
diff --git a/gdb/mipsread.c b/gdb/mipsread.c
index 3f0697b..b51af3e 100644
--- a/gdb/mipsread.c
+++ b/gdb/mipsread.c
@@ -369,7 +369,6 @@ static const struct sym_fns ecoff_sym_fns =
   mipscoff_new_init,		/* init anything gbl to entire symtab */
   mipscoff_symfile_init,	/* read initial info, setup for sym_read() */
   mipscoff_symfile_read,	/* read a symbol file into symtab */
-  NULL,				/* sym_read_psymbols */
   mipscoff_symfile_finish,	/* finished with file, cleanup */
   default_symfile_offsets,	/* dummy FIXME til implem sym reloc */
   default_symfile_segments,	/* Get segment information from a file.  */
diff --git a/gdb/psymtab.c b/gdb/psymtab.c
index 1549ead..b5ddef9 100644
--- a/gdb/psymtab.c
+++ b/gdb/psymtab.c
@@ -84,13 +84,12 @@ require_partial_symbols (struct objfile *objfile, bool verbose)
     {
       objfile->flags |= OBJF_PSYMTABS_READ;
 
-      if (objfile->sf != nullptr
-	  && objfile->sf->sym_read_psymbols)
+      if (objfile->qf->can_lazily_read_symbols ())
 	{
 	  if (verbose)
 	    printf_filtered (_("Reading symbols from %s...\n"),
 			     objfile_name (objfile));
-	  (*objfile->sf->sym_read_psymbols) (objfile);
+	  objfile->qf->read_partial_symbols (objfile);
 
 	  if (verbose && !objfile_has_symbols (objfile))
 	    printf_filtered (_("(No debugging symbols found in %s)\n"),
diff --git a/gdb/quick-symbol.h b/gdb/quick-symbol.h
index 315a97a..dd2b896 100644
--- a/gdb/quick-symbol.h
+++ b/gdb/quick-symbol.h
@@ -237,6 +237,20 @@ struct quick_symbol_functions
   {
     /* Do nothing.  */
   }
+
+  /* Return true if this class can lazily read the symbols.  This may
+     only return true if there are in fact symbols to be read, because
+     this is used in the implementation of 'has_partial_symbols'.  */
+  virtual bool can_lazily_read_symbols ()
+  {
+    return false;
+  }
+
+  /* Read the partial symbols for OBJFILE.  This will only ever be
+     called if can_lazily_read_symbols returns true.  */
+  virtual void read_partial_symbols (struct objfile *objfile)
+  {
+  }
 };
 
 typedef std::unique_ptr<quick_symbol_functions> quick_symbol_functions_up;
diff --git a/gdb/symfile-debug.c b/gdb/symfile-debug.c
index 406eac0..94559c7 100644
--- a/gdb/symfile-debug.c
+++ b/gdb/symfile-debug.c
@@ -81,8 +81,8 @@ objfile::has_partial_symbols ()
      this function the symbols may have been already read in but they also may
      not be present in this objfile.  */
   if ((flags & OBJF_PSYMTABS_READ) == 0
-      && sf != nullptr
-      && sf->sym_read_psymbols != NULL)
+      && qf != nullptr
+      && qf->can_lazily_read_symbols ())
     retval = true;
   else if (qf != nullptr)
     retval = qf->has_symbols (this);
@@ -421,18 +421,6 @@ debug_sym_read (struct objfile *objfile, symfile_add_flags symfile_flags)
 }
 
 static void
-debug_sym_read_psymbols (struct objfile *objfile)
-{
-  const struct debug_sym_fns_data *debug_data
-    = symfile_debug_objfile_data_key.get (objfile);
-
-  fprintf_filtered (gdb_stdlog, "sf->sym_read_psymbols (%s)\n",
-		    objfile_debug_name (objfile));
-
-  debug_data->real_sf->sym_read_psymbols (objfile);
-}
-
-static void
 debug_sym_finish (struct objfile *objfile)
 {
   const struct debug_sym_fns_data *debug_data
@@ -508,7 +496,6 @@ static const struct sym_fns debug_sym_fns =
   debug_sym_new_init,
   debug_sym_init,
   debug_sym_read,
-  debug_sym_read_psymbols,
   debug_sym_finish,
   debug_sym_offsets,
   debug_sym_segments,
@@ -543,8 +530,6 @@ install_symfile_debug_logging (struct objfile *objfile)
   COPY_SF_PTR (real_sf, debug_data, sym_new_init, debug_sym_new_init);
   COPY_SF_PTR (real_sf, debug_data, sym_init, debug_sym_init);
   COPY_SF_PTR (real_sf, debug_data, sym_read, debug_sym_read);
-  COPY_SF_PTR (real_sf, debug_data, sym_read_psymbols,
-	       debug_sym_read_psymbols);
   COPY_SF_PTR (real_sf, debug_data, sym_finish, debug_sym_finish);
   COPY_SF_PTR (real_sf, debug_data, sym_offsets, debug_sym_offsets);
   COPY_SF_PTR (real_sf, debug_data, sym_segments, debug_sym_segments);
diff --git a/gdb/symfile.h b/gdb/symfile.h
index 2c37f88..bae2a79 100644
--- a/gdb/symfile.h
+++ b/gdb/symfile.h
@@ -137,13 +137,6 @@ struct sym_fns
 
   void (*sym_read) (struct objfile *, symfile_add_flags);
 
-  /* Read the partial symbols for an objfile.  This may be NULL, in which case
-     gdb has to check other ways if this objfile has any symbols.  This may
-     only be non-NULL if the objfile actually does have debuginfo available.
-     */
-
-  void (*sym_read_psymbols) (struct objfile *);
-
   /* Called when we are finished with an objfile.  Should do all
      cleanup that is specific to the object file format for the
      particular objfile.  */
diff --git a/gdb/xcoffread.c b/gdb/xcoffread.c
index 711d893..7f2fee3 100644
--- a/gdb/xcoffread.c
+++ b/gdb/xcoffread.c
@@ -3005,7 +3005,6 @@ static const struct sym_fns xcoff_sym_fns =
   xcoff_new_init,		/* init anything gbl to entire symtab */
   xcoff_symfile_init,		/* read initial info, setup for sym_read() */
   xcoff_initial_scan,		/* read a symbol file into symtab */
-  NULL,				/* sym_read_psymbols */
   xcoff_symfile_finish,		/* finished with file, cleanup */
   xcoff_symfile_offsets,	/* xlate offsets ext->int form */
   default_symfile_segments,	/* Get segment information from a file.  */