c-pch.c: Include flags.h.

	* c-pch.c: Include flags.h.  Add comments to routines.
	(struct c_pch_validity): New.
	(get_ident): Update PCH file version number.
	(pch_init): Output current debugging type.
	(c_common_valid_pch): Check debugging type.
	* Makefile.in (c-pch.o): Update dependencies.
	* flags.h (debug_type_names): Declare.
	* toplev.c (debug_type_names): Move out of decode_g_option.

From-SVN: r65499

1 files changed, 72 insertions, 25 deletions

diff --git a/gcc/c-pch.c b/gcc/c-pch.c
index 27a299f..a7fa879 100644
--- a/gcc/c-pch.c
+++ b/gcc/c-pch.c
@@ -23,6 +23,7 @@ Boston, MA 02111-1307, USA.  */
 #include "coretypes.h"
 #include "cpplib.h"
 #include "tree.h"
+#include "flags.h"
 #include "c-common.h"
 #include "output.h"
 #include "toplev.h"
@@ -31,6 +32,11 @@ Boston, MA 02111-1307, USA.  */
 #include "ggc.h"
 #include "langhooks.h"
 
+struct c_pch_validity
+{
+  unsigned char debug_info_type;
+};
+
 struct c_pch_header 
 {
   unsigned long asm_size;
@@ -45,11 +51,16 @@ static long asm_file_startpos;
 
 static const char * get_ident PARAMS((void));
 
+/* Compute an appropriate 8-byte magic number for the PCH file, so that
+   utilities like file(1) can identify it, and so that GCC can quickly
+   ignore non-PCH files and PCH files that are of a completely different
+   format.  */
+
 static const char *
 get_ident()
 {
   static char result[IDENT_LENGTH];
-  static const char template[IDENT_LENGTH] = "gpch.010";
+  static const char template[IDENT_LENGTH] = "gpch.011";
   
   memcpy (result, template, IDENT_LENGTH);
   if (c_language == clk_c)
@@ -61,36 +72,45 @@ get_ident()
   return result;
 }
 
+/* Prepare to write a PCH file.  This is called at the start of 
+   compilation.  */
+
 void
 pch_init ()
 {
   FILE *f;
+  struct c_pch_validity v;
   
-  if (pch_file)
-    {
-      f = fopen (pch_file, "w+b");
-      if (f == NULL)
-	fatal_io_error ("can't open %s", pch_file);
-      pch_outfile = f;
-      
-      if (fwrite (get_ident(), IDENT_LENGTH, 1, f) != 1)
-	fatal_io_error ("can't write to %s", pch_file);
-
-      /* We need to be able to re-read the output.  */
-      /* The driver always provides a valid -o option.  */
-      if (asm_file_name == NULL
-	  || strcmp (asm_file_name, "-") == 0)
-	fatal_error ("`%s' is not a valid output file", asm_file_name);
-
-      asm_file_startpos = ftell (asm_out_file);
-      
-      /* Let the debugging format deal with the PCHness.  */
-      (*debug_hooks->handle_pch) (0);
-
-      cpp_save_state (parse_in, f);
-    }
+  if (! pch_file)
+    return;
+  
+  f = fopen (pch_file, "w+b");
+  if (f == NULL)
+    fatal_io_error ("can't open %s", pch_file);
+  pch_outfile = f;
+  
+  v.debug_info_type = write_symbols;
+  if (fwrite (get_ident(), IDENT_LENGTH, 1, f) != 1
+      || fwrite (&v, sizeof (v), 1, f) != 1)
+    fatal_io_error ("can't write to %s", pch_file);
+
+  /* We need to be able to re-read the output.  */
+  /* The driver always provides a valid -o option.  */
+  if (asm_file_name == NULL
+      || strcmp (asm_file_name, "-") == 0)
+    fatal_error ("`%s' is not a valid output file", asm_file_name);
+  
+  asm_file_startpos = ftell (asm_out_file);
+  
+  /* Let the debugging format deal with the PCHness.  */
+  (*debug_hooks->handle_pch) (0);
+  
+  cpp_save_state (parse_in, f);
 }
 
+/* Write the PCH file.  This is called at the end of a compilation which
+   will produce a PCH file.  */
+
 void
 c_common_write_pch ()
 {
@@ -134,6 +154,9 @@ c_common_write_pch ()
   fclose (pch_outfile);
 }
 
+/* Check the PCH file called NAME, open on FD, to see if it can be used
+   in this compilation.  */
+
 int
 c_common_valid_pch (pfile, name, fd)
      cpp_reader *pfile;
@@ -144,12 +167,13 @@ c_common_valid_pch (pfile, name, fd)
   int result;
   char ident[IDENT_LENGTH];
   const char *pch_ident;
+  struct c_pch_validity v;
 
   if (! allow_pch)
     return 2;
 
   /* Perform a quick test of whether this is a valid
-     precompiled header for C.  */
+     precompiled header for the current language.  */
 
   sizeread = read (fd, ident, IDENT_LENGTH);
   if (sizeread == -1)
@@ -181,6 +205,26 @@ c_common_valid_pch (pfile, name, fd)
       return 2;
     }
 
+  if (read (fd, &v, sizeof (v)) != sizeof (v))
+    {
+      fatal_io_error ("can't read %s", name);
+      return 2;
+    }
+
+  /* The allowable debug info combinations are that either the PCH file
+     was built with the same as is being used now, or the PCH file was
+     built for some kind of debug info but now none is in use.  */
+  if (v.debug_info_type != write_symbols
+      && write_symbols != NO_DEBUG)
+    {
+      if (cpp_get_options (pfile)->warn_invalid_pch)
+	cpp_error (pfile, DL_WARNING, 
+		   "%s: created with -g%s, but used with -g%s", name,
+		   debug_type_names[v.debug_info_type],
+		   debug_type_names[write_symbols]);
+      return 2;
+    }
+
   /* Check the preprocessor macros are the same as when the PCH was
      generated.  */
   
@@ -191,6 +235,9 @@ c_common_valid_pch (pfile, name, fd)
     return result == 0;
 }
 
+/* Load in the PCH file NAME, open on FD.  It was originally searched for
+   by ORIG_NAME.  */
+
 void
 c_common_read_pch (pfile, name, fd, orig_name)
      cpp_reader *pfile;