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RFC: cache the CRC in the BFD


Right now gdb may cache a CRC on an objfile.

However, the CRC is actually a property of the BFD.  It seems better to
me to cache it there instead.  This patch implements that.

Built and regtested on x86-64 Fedora 16.

Tom

	* gdb_bfd.c (struct gdb_bfd_data) <crc_computed, crc>:
	New fields.
	(get_file_crc): Move from symfile.c.
	(gdb_bfd_crc): New function.
	* gdb_bfd.h (gdb_bfd_crc): Declare.
	* objfiles.h (struct objfile) <crc32, crc32_p>: Remove.
	* symfile.c (get_file_crc): Move to gdb_bfd.c.
	(separate_debug_file_exists): Use gdb_bfd_crc.
---
 gdb/gdb_bfd.c  |   58 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 gdb/gdb_bfd.h  |    6 +++++
 gdb/objfiles.h |    5 ----
 gdb/symfile.c  |   51 +++++++-----------------------------------------
 4 files changed, 72 insertions(+), 48 deletions(-)

diff --git a/gdb/gdb_bfd.c b/gdb/gdb_bfd.c
index ae561d3..f8d985d 100644
--- a/gdb/gdb_bfd.c
+++ b/gdb/gdb_bfd.c
@@ -81,6 +81,12 @@ struct gdb_bfd_data
   /* The mtime of the BFD at the point the cache entry was made.  */
   time_t mtime;
 
+  /* This is true if we have successfully computed the file's CRC.  */
+  unsigned int crc_computed : 1;
+
+  /* The file's CRC.  */
+  unsigned long crc;
+
   /* If the BFD comes from an archive, this points to the archive's
      BFD.  Otherwise, this is NULL.  */
   bfd *archive_bfd;
@@ -414,6 +420,58 @@ gdb_bfd_map_section (asection *sectp, bfd_size_type *size)
   return descriptor->data;
 }
 
+/* Return 32-bit CRC for ABFD.  If successful store it to *FILE_CRC_RETURN and
+   return 1.  Otherwise print a warning and return 0.  ABFD seek position is
+   not preserved.  */
+
+static int
+get_file_crc (bfd *abfd, unsigned long *file_crc_return)
+{
+  unsigned long file_crc = 0;
+
+  if (bfd_seek (abfd, 0, SEEK_SET) != 0)
+    {
+      warning (_("Problem reading \"%s\" for CRC: %s"),
+	       bfd_get_filename (abfd), bfd_errmsg (bfd_get_error ()));
+      return 0;
+    }
+
+  for (;;)
+    {
+      gdb_byte buffer[8 * 1024];
+      bfd_size_type count;
+
+      count = bfd_bread (buffer, sizeof (buffer), abfd);
+      if (count == (bfd_size_type) -1)
+	{
+	  warning (_("Problem reading \"%s\" for CRC: %s"),
+		   bfd_get_filename (abfd), bfd_errmsg (bfd_get_error ()));
+	  return 0;
+	}
+      if (count == 0)
+	break;
+      file_crc = bfd_calc_gnu_debuglink_crc32 (file_crc, buffer, count);
+    }
+
+  *file_crc_return = file_crc;
+  return 1;
+}
+
+/* See gdb_bfd.h.  */
+
+int
+gdb_bfd_crc (struct bfd *abfd, unsigned long *crc_out)
+{
+  struct gdb_bfd_data *gdata = bfd_usrdata (abfd);
+
+  if (!gdata->crc_computed)
+    gdata->crc_computed = get_file_crc (abfd, &gdata->crc);
+
+  if (gdata->crc_computed)
+    *crc_out = gdata->crc;
+  return gdata->crc_computed;
+}
+
 
 
 /* See gdb_bfd.h.  */
diff --git a/gdb/gdb_bfd.h b/gdb/gdb_bfd.h
index f3ee9ff..1e74bfe 100644
--- a/gdb/gdb_bfd.h
+++ b/gdb/gdb_bfd.h
@@ -70,6 +70,12 @@ void gdb_bfd_mark_parent (bfd *child, bfd *parent);
 
 const gdb_byte *gdb_bfd_map_section (asection *section, bfd_size_type *size);
 
+/* Compute the CRC for ABFD.  The CRC is used to find and verify
+   separate debug files.  When successful, this fills in *CRC_OUT and
+   returns 1.  Otherwise, this issues a warning and returns 0.  */
+
+int gdb_bfd_crc (struct bfd *abfd, unsigned long *crc_out);
+
 
 
 /* A wrapper for bfd_fopen that initializes the gdb-specific reference
diff --git a/gdb/objfiles.h b/gdb/objfiles.h
index 6d29084..54ac646 100644
--- a/gdb/objfiles.h
+++ b/gdb/objfiles.h
@@ -259,11 +259,6 @@ struct objfile
 
     long mtime;
 
-    /* Cached 32-bit CRC as computed by gnu_debuglink_crc32.  CRC32 is valid
-       iff CRC32_P.  */
-    unsigned long crc32;
-    int crc32_p;
-
     /* Obstack to hold objects that should be freed when we load a new symbol
        table from this object file.  */
 
diff --git a/gdb/symfile.c b/gdb/symfile.c
index 4d65889..eef3128 100644
--- a/gdb/symfile.c
+++ b/gdb/symfile.c
@@ -1348,43 +1348,6 @@ symbol_file_clear (int from_tty)
     printf_unfiltered (_("No symbol file now.\n"));
 }
 
-/* Return 32-bit CRC for ABFD.  If successful store it to *FILE_CRC_RETURN and
-   return 1.  Otherwise print a warning and return 0.  ABFD seek position is
-   not preserved.  */
-
-static int
-get_file_crc (bfd *abfd, unsigned long *file_crc_return)
-{
-  unsigned long file_crc = 0;
-
-  if (bfd_seek (abfd, 0, SEEK_SET) != 0)
-    {
-      warning (_("Problem reading \"%s\" for CRC: %s"),
-	       bfd_get_filename (abfd), bfd_errmsg (bfd_get_error ()));
-      return 0;
-    }
-
-  for (;;)
-    {
-      gdb_byte buffer[8 * 1024];
-      bfd_size_type count;
-
-      count = bfd_bread (buffer, sizeof (buffer), abfd);
-      if (count == (bfd_size_type) -1)
-	{
-	  warning (_("Problem reading \"%s\" for CRC: %s"),
-		   bfd_get_filename (abfd), bfd_errmsg (bfd_get_error ()));
-	  return 0;
-	}
-      if (count == 0)
-	break;
-      file_crc = bfd_calc_gnu_debuglink_crc32 (file_crc, buffer, count);
-    }
-
-  *file_crc_return = file_crc;
-  return 1;
-}
-
 static int
 separate_debug_file_exists (const char *name, unsigned long crc,
 			    struct objfile *parent_objfile)
@@ -1434,7 +1397,7 @@ separate_debug_file_exists (const char *name, unsigned long crc,
   else
     verified_as_different = 0;
 
-  file_crc_p = get_file_crc (abfd, &file_crc);
+  file_crc_p = gdb_bfd_crc (abfd, &file_crc);
 
   gdb_bfd_unref (abfd);
 
@@ -1443,19 +1406,21 @@ separate_debug_file_exists (const char *name, unsigned long crc,
 
   if (crc != file_crc)
     {
+      unsigned long parent_crc;
+      int parent_crc_p;
+
       /* If one (or both) the files are accessed for example the via "remote:"
 	 gdbserver way it does not support the bfd_stat operation.  Verify
 	 whether those two files are not the same manually.  */
 
-      if (!verified_as_different && !parent_objfile->crc32_p)
+      if (!verified_as_different)
 	{
-	  parent_objfile->crc32_p = get_file_crc (parent_objfile->obfd,
-						  &parent_objfile->crc32);
-	  if (!parent_objfile->crc32_p)
+	  parent_crc_p = gdb_bfd_crc (parent_objfile->obfd, &parent_crc);
+	  if (!parent_crc_p)
 	    return 0;
 	}
 
-      if (verified_as_different || parent_objfile->crc32 != file_crc)
+      if (verified_as_different || parent_crc != file_crc)
 	warning (_("the debug information found in \"%s\""
 		   " does not match \"%s\" (CRC mismatch).\n"),
 		 name, parent_objfile->name);
-- 
1.7.7.6


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