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Random cleanups [3/4]: zero out DECL_VINDEX field

Message ID Pine.LNX.4.64.1103310322500.19760@wotan.suse.de
State New
Headers show

Commit Message

Michael Matz March 31, 2011, 1:32 a.m. UTC 
Hi,

I noticed this while working on early-merging LTO.  The DECL_VINDEX slot 
of FUNCTION_DECLs is supposed to hold the numeric index of the vtable 
slot if it's a virtual function.  During parsing the C++ frontend uses it 
to hold a reference to itself, which then later is supposed to be 
transformed into the real index.  Sometimes the C++ frontend copies 
function_decls, leaving the old one reachable via various means (but not 
as a reachable function, merely in scopes and the like), but fixes up 
only the copy.

Instead of diddling with the frontend we can just as well zero out 
meaningless DECL_VINDEX slots (i.e. when they're not an integer).  It's 
used for debug info generation (when it's an integer) and as a flag ala 
"this function is a virtual method" by the middle-end.

Regstrapped on x86_64-linux with the other three cleanups.  Okay for 
trunk?


Ciao,
Michael.

Comments

Diego Novillo March 31, 2011, 1:44 a.m. UTC | #1 
On Wed, Mar 30, 2011 at 21:32, Michael Matz <matz@suse.de> wrote:

>        * tree.c (free_lang_data_in_decl): Zero DECL_VINDEX if it's not
>        an integer.
>        * tree.h (tree_decl_non_common.vindex): Adjust comment.

OK.


Diego.
diff mbox

Patch

Index: tree.c
===================================================================
--- tree.c	(revision 171537)
+++ tree.c	(working copy)
@@ -4647,6 +4647,13 @@  free_lang_data_in_decl (tree decl)
 	  && RECORD_OR_UNION_TYPE_P
 	       (DECL_CONTEXT (DECL_ABSTRACT_ORIGIN (decl))))
 	DECL_ABSTRACT_ORIGIN (decl) = NULL_TREE;
+
+      /* Sometimes the C++ frontend doesn't manage to transform a temporary
+         DECL_VINDEX referring to itself into a vtable slot number as it
+	 should.  Happens with functions that are copied and then forgotten
+	 about.  Just clear it, it won't matter anymore.  */
+      if (DECL_VINDEX (decl) && !host_integerp (DECL_VINDEX (decl), 0))
+	DECL_VINDEX (decl) = NULL_TREE;
     }
   else if (TREE_CODE (decl) == VAR_DECL)
     {
Index: tree.h
===================================================================
--- tree.h	(revision 171537)
+++ tree.h	(working copy)
@@ -3228,7 +3233,7 @@  struct GTY(())
   tree arguments;
   /* Almost all FE's use this.  */
   tree result;
-  /* C++ uses this in namespaces.  */
+  /* C++ uses this in namespaces and function_decls.  */
   tree vindex;
 };