2010-12-16  Andi Kleen	<ak@linux.intel.com>
	    H.J. Lu  <hongjiu.lu@intel.com>

	* varasm.c (section_flags_string): New.
	(get_section): Print more details on conflicting section flags.

diff --git a/gcc/varasm.c b/gcc/varasm.c
index ed44610..d91497c 100644
--- a/gcc/varasm.c
+++ b/gcc/varasm.c
@@ -268,6 +268,47 @@ get_noswitch_section (unsigned int flags, noswitch_section_callback callback)
   return sect;
 }
 
+/* Return a string for section flags F.  */
+
+static char *
+section_flags_string (unsigned int f)
+{
+  static const struct section_flag
+    {
+      const char *name;
+      unsigned int flag;
+    }
+  section_flags[] =
+    {
+	{ "code", SECTION_CODE },
+	{ "write", SECTION_WRITE },
+	{ "debug", SECTION_DEBUG },
+	{ "linkonce", SECTION_LINKONCE },
+	{ "small", SECTION_SMALL },
+	{ "bss", SECTION_BSS },
+	{ "forget", SECTION_FORGET },
+	{ "merge", SECTION_MERGE },
+	{ "strings", SECTION_STRINGS },
+	{ "override", SECTION_OVERRIDE },
+	{ "tls", SECTION_TLS },
+	{ "common", SECTION_COMMON },
+	{ "unnamed", SECTION_UNNAMED},
+	{ "named", SECTION_NAMED },
+	{ "noswitch", SECTION_NOSWITCH }
+    };
+  unsigned int i;
+  char *flag = NULL;
+  for (i = 0; i < ARRAY_SIZE (section_flags); i++)
+    if ((f & section_flags[i].flag) != 0)
+      {
+	if (flag)
+	  flag = concat (flag, " ", section_flags[i].name, NULL);
+	else
+	  flag = concat (section_flags[i].name, NULL);
+      }
+  return flag;
+}
+
 /* Return the named section structure associated with NAME.  Create
    a new section with the given fields if no such structure exists.  */
 
@@ -290,15 +331,24 @@ get_section (const char *name, unsigned int flags, tree decl)
     }
   else
     {
+      unsigned int oflags;
+
       sect = *slot;
-      if ((sect->common.flags & ~SECTION_DECLARED) != flags
+      oflags = sect->common.flags & ~SECTION_DECLARED;
+      if (oflags != flags
 	  && ((sect->common.flags | flags) & SECTION_OVERRIDE) == 0)
 	{
+	  char *str;
 	  /* Sanity check user variables for flag changes.  */
 	  if (decl == 0)
 	    decl = sect->named.decl;
 	  gcc_assert (decl);
 	  error ("%+D causes a section type conflict", decl);
+	  flags = (oflags ^ flags) & ~SECTION_OVERRIDE;
+	  str = section_flags_string (flags);
+	  inform (DECL_SOURCE_LOCATION (decl), 
+		  "new section declaration differs in: %s", str);
+	  free (str);
 	}
     }
   return sect;