From patchwork Sat Feb  9 20:36:55 2013
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Subject: C++ PATCH to decls_match to improve efficiency of version checking
Date: Sat, 09 Feb 2013 10:36:55 -0000
From: Jason Merrill <jason@redhat.com>
X-Patchwork-Id: 219445
Message-Id: <5116B367.2040401@redhat.com>
To: gcc-patches List <gcc-patches@gcc.gnu.org>

While looking at 56247 I noticed that the new multiversioning code was 
unnecessarily duplicating the calls to compare parameter and return 
types of a function.  Fixed by moving the version code a little later.

Tested x86_64-pc-linux-gnu, applying to trunk.


commit 3c47969eacbc63b68740e48c0e9dae06b20ddf08
Author: Jason Merrill <jason@redhat.com>
Date:   Fri Feb 8 18:37:58 2013 -0500

    	* decl.c (decls_match): Check versions later.

diff --git a/gcc/cp/decl.c b/gcc/cp/decl.c
index 5317fcf..5a9ad2c 100644
--- a/gcc/cp/decl.c
+++ b/gcc/cp/decl.c
@@ -976,36 +976,6 @@ decls_match (tree newdecl, tree olddecl)
       if (t1 != t2)
 	return 0;
 
-      /* The decls dont match if they correspond to two different versions
-	 of the same function.   Disallow extern "C" functions to be
-	 versions for now.  */
-      if (compparms (p1, p2)
-	  && same_type_p (TREE_TYPE (f1), TREE_TYPE (f2))
-	  && !DECL_EXTERN_C_P (newdecl)
-	  && !DECL_EXTERN_C_P (olddecl)
-	  && targetm.target_option.function_versions (newdecl, olddecl))
-	{
-	  /* Mark functions as versions if necessary.  Modify the mangled decl
-	     name if necessary.  */
-	  if (DECL_FUNCTION_VERSIONED (newdecl)
-	      && DECL_FUNCTION_VERSIONED (olddecl))
-	    return 0;
-	  if (!DECL_FUNCTION_VERSIONED (newdecl))
-	    {
-	      DECL_FUNCTION_VERSIONED (newdecl) = 1;
-	      if (DECL_ASSEMBLER_NAME_SET_P (newdecl))
-	        mangle_decl (newdecl);
-	    }
-	  if (!DECL_FUNCTION_VERSIONED (olddecl))
-	    {
-	      DECL_FUNCTION_VERSIONED (olddecl) = 1;
-	      if (DECL_ASSEMBLER_NAME_SET_P (olddecl))
-	       mangle_decl (olddecl);
-	    }
-	  record_function_versions (olddecl, newdecl);
-	  return 0;
-	}
-
       if (CP_DECL_CONTEXT (newdecl) != CP_DECL_CONTEXT (olddecl)
 	  && ! (DECL_EXTERN_C_P (newdecl)
 		&& DECL_EXTERN_C_P (olddecl)))
@@ -1063,6 +1033,35 @@ decls_match (tree newdecl, tree olddecl)
 	}
       else
 	types_match = 0;
+
+      /* The decls dont match if they correspond to two different versions
+	 of the same function.   Disallow extern "C" functions to be
+	 versions for now.  */
+      if (types_match
+	  && !DECL_EXTERN_C_P (newdecl)
+	  && !DECL_EXTERN_C_P (olddecl)
+	  && targetm.target_option.function_versions (newdecl, olddecl))
+	{
+	  /* Mark functions as versions if necessary.  Modify the mangled decl
+	     name if necessary.  */
+	  if (DECL_FUNCTION_VERSIONED (newdecl)
+	      && DECL_FUNCTION_VERSIONED (olddecl))
+	    return 0;
+	  if (!DECL_FUNCTION_VERSIONED (newdecl))
+	    {
+	      DECL_FUNCTION_VERSIONED (newdecl) = 1;
+	      if (DECL_ASSEMBLER_NAME_SET_P (newdecl))
+	        mangle_decl (newdecl);
+	    }
+	  if (!DECL_FUNCTION_VERSIONED (olddecl))
+	    {
+	      DECL_FUNCTION_VERSIONED (olddecl) = 1;
+	      if (DECL_ASSEMBLER_NAME_SET_P (olddecl))
+	       mangle_decl (olddecl);
+	    }
+	  record_function_versions (olddecl, newdecl);
+	  return 0;
+	}
     }
   else if (TREE_CODE (newdecl) == TEMPLATE_DECL)
     {