From patchwork Wed Jun 30 13:25:41 2010
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Subject: [rfa] Fix PR44699: bootstrap problem
Date: Wed, 30 Jun 2010 03:25:41 -0000
From: Michael Matz <matz@suse.de>
X-Patchwork-Id: 57411
Message-Id: <Pine.LNX.4.64.1006301522080.18619@wotan.suse.de>
To: Richard Guenther <richard.guenther@gmail.com>
Cc: gcc-patches@gcc.gnu.org

Hi,

On Tue, 29 Jun 2010, Richard Guenther wrote:

> On Tue, Jun 29, 2010 at 5:45 PM, Michael Matz <matz@suse.de> wrote:
> > Hello,
> >
> > Allocating an array of length num_ssa_names, then doing foldings or other
> > transformations that can create new SSA names, and then iterating that
> > array again as if it had num_ssa_names elements is not a good idea.
> >
> > This fixes the testcase.  I'm going to regstrap this, once the
> > function_arg_advance brokenness is fixed.  Okay, assuming this will work?
> 
> Ok.

While it fixes the testcase (and regstraps on linux) it still breaks on 
Darwin.  We also need to be careful to not attach VDEFs to the generated 
new 'lhs = tmp' assignment if LHS is a gimple reg.  Those VDEFs would be 
removed fairly quickly breaking the vdef/vuse chains again (that was 
pre-existing breakage).

So I'd like to add this hunk to the patch (whole patch regstrapping again 
on x86_64-linux).  Okay for trunk?


Ciao,
Michael.


Index: gimple-fold.c
===================================================================
--- gimple-fold.c	(revision 161602)
+++ gimple-fold.c	(working copy)
@@ -1150,7 +1150,14 @@ gimplify_and_update_call_from_tree (gimp
 	  gsi_insert_before (si_p, last, GSI_NEW_STMT);
 	  gsi_next (si_p);
 	}
-      if (laststore)
+      if (laststore && is_gimple_reg (lhs))
+	{
+	  gimple_set_vdef (laststore, gimple_vdef (stmt));
+	  update_stmt (laststore);
+	  move_ssa_defining_stmt_for_defs (laststore, stmt);
+	  laststore = NULL;
+	}
+      else if (laststore)
 	{
 	  reaching_vuse = make_ssa_name (gimple_vop (cfun), laststore);
 	  gimple_set_vdef (laststore, reaching_vuse);
@@ -1158,9 +1165,13 @@ gimplify_and_update_call_from_tree (gimp
 	  laststore = NULL;
 	}
       new_stmt = gimple_build_assign (lhs, tmp);
-      gimple_set_vuse (new_stmt, reaching_vuse);
-      gimple_set_vdef (new_stmt, gimple_vdef (stmt));
-      move_ssa_defining_stmt_for_defs (new_stmt, stmt);
+      if (!is_gimple_reg (tmp))
+	gimple_set_vuse (new_stmt, reaching_vuse);
+      if (!is_gimple_reg (lhs))
+	{
+	  gimple_set_vdef (new_stmt, gimple_vdef (stmt));
+	  move_ssa_defining_stmt_for_defs (new_stmt, stmt);
+	}
     }
 
   gimple_set_location (new_stmt, gimple_location (stmt));