Patchwork Improve debug info if tree DCE removes stores (PR debug/50317, fallout)

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Submitter Jakub Jelinek
Date Dec. 2, 2011, 7:28 p.m.
Message ID <20111202192848.GH27242@tyan-ft48-01.lab.bos.redhat.com>
Download mbox | patch
Permalink /patch/128945/
State New
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Comments

Jakub Jelinek - Dec. 2, 2011, 7:28 p.m.
On Fri, Dec 02, 2011 at 02:27:40PM +0100, Richard Guenther wrote:
> This change seems wrong.  We are turning valid gimple
> 
> # DEBUG D#2 => transfer.0  [with addres taken]
> 
> into invalid one
> 
> # DEBUG D#2 => transfer.0  [without address taken]
> 
> once you update that stmt with update_stmt you'll get an SSA operand
> for transfer.0 which is not in SSA form because you fail to rewrite it
> into.
> 
> Why do this in remove_unused_locals and not in update_address_taken?
> Or, why do it at all?
> 
> I have a SSA operand checking patch that catches this now ...

Here is a fix for that.  Instead of clearing TREE_ADDRESSABLE for
unreferenced vars we allow them in target_for_debug_bind if they aren't
referenced vars (thus we don't risk mixing VALUE tracking with the
old style REG_EXPR/MEM_EXPR tracking of these variables).

Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

2011-12-02  Jakub Jelinek  <jakub@redhat.com>

	PR debug/50317
	* tree-ssa.c (target_for_debug_bind): Also allow is_gimple_reg_type
	vars that aren't referenced.
	(tree-ssa-live.c (remove_unused_locals): Don't clear TREE_ADDRESSABLE
	of unreferenced local vars.
	* cfgexpand.c (expand_debug_expr): For DEBUG_IMPLICIT_PTR allow also
	TREE_ADDRESSABLE vars that satisfy target_for_debug_bind.



	Jakub
Richard Guenther - Dec. 3, 2011, 3:20 p.m.
On Fri, Dec 2, 2011 at 8:28 PM, Jakub Jelinek <jakub@redhat.com> wrote:
> On Fri, Dec 02, 2011 at 02:27:40PM +0100, Richard Guenther wrote:
>> This change seems wrong.  We are turning valid gimple
>>
>> # DEBUG D#2 => transfer.0  [with addres taken]
>>
>> into invalid one
>>
>> # DEBUG D#2 => transfer.0  [without address taken]
>>
>> once you update that stmt with update_stmt you'll get an SSA operand
>> for transfer.0 which is not in SSA form because you fail to rewrite it
>> into.
>>
>> Why do this in remove_unused_locals and not in update_address_taken?
>> Or, why do it at all?
>>
>> I have a SSA operand checking patch that catches this now ...
>
> Here is a fix for that.  Instead of clearing TREE_ADDRESSABLE for
> unreferenced vars we allow them in target_for_debug_bind if they aren't
> referenced vars (thus we don't risk mixing VALUE tracking with the
> old style REG_EXPR/MEM_EXPR tracking of these variables).
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

Ok.  (Note that the outcome of target_for_debug_bind may change during
compilation, but only from false to true as far as I can see, so that
should be ok)

Thanks,
Richard.

> 2011-12-02  Jakub Jelinek  <jakub@redhat.com>
>
>        PR debug/50317
>        * tree-ssa.c (target_for_debug_bind): Also allow is_gimple_reg_type
>        vars that aren't referenced.
>        (tree-ssa-live.c (remove_unused_locals): Don't clear TREE_ADDRESSABLE
>        of unreferenced local vars.
>        * cfgexpand.c (expand_debug_expr): For DEBUG_IMPLICIT_PTR allow also
>        TREE_ADDRESSABLE vars that satisfy target_for_debug_bind.
>
> --- gcc/tree-ssa.c.jj   2011-11-29 08:58:52.000000000 +0100
> +++ gcc/tree-ssa.c      2011-12-02 15:04:03.494148642 +0100
> @@ -264,7 +264,12 @@ target_for_debug_bind (tree var)
>     return NULL_TREE;
>
>   if (!is_gimple_reg (var))
> -    return NULL_TREE;
> +    {
> +      if (is_gimple_reg_type (TREE_TYPE (var))
> +         && referenced_var_lookup (cfun, DECL_UID (var)) == NULL_TREE)
> +       return var;
> +      return NULL_TREE;
> +    }
>
>   return var;
>  }
> --- gcc/tree-ssa-live.c.jj      2011-12-02 01:52:27.000000000 +0100
> +++ gcc/tree-ssa-live.c 2011-12-02 15:04:59.601816335 +0100
> @@ -814,15 +814,7 @@ remove_unused_locals (void)
>              bitmap_set_bit (global_unused_vars, DECL_UID (var));
>            }
>          else
> -           {
> -             /* For unreferenced local vars drop TREE_ADDRESSABLE
> -                bit in case it is referenced from debug stmts.  */
> -             if (DECL_CONTEXT (var) == current_function_decl
> -                 && TREE_ADDRESSABLE (var)
> -                 && is_gimple_reg_type (TREE_TYPE (var)))
> -               TREE_ADDRESSABLE (var) = 0;
> -             continue;
> -           }
> +           continue;
>        }
>       else if (TREE_CODE (var) == VAR_DECL
>               && DECL_HARD_REGISTER (var)
> --- gcc/cfgexpand.c.jj  2011-12-02 01:52:27.000000000 +0100
> +++ gcc/cfgexpand.c     2011-12-02 15:24:37.982327507 +0100
> @@ -3325,7 +3325,8 @@ expand_debug_expr (tree exp)
>          if ((TREE_CODE (TREE_OPERAND (exp, 0)) == VAR_DECL
>               || TREE_CODE (TREE_OPERAND (exp, 0)) == PARM_DECL
>               || TREE_CODE (TREE_OPERAND (exp, 0)) == RESULT_DECL)
> -             && !TREE_ADDRESSABLE (TREE_OPERAND (exp, 0)))
> +             && (!TREE_ADDRESSABLE (TREE_OPERAND (exp, 0))
> +                 || target_for_debug_bind (TREE_OPERAND (exp, 0))))
>            return gen_rtx_DEBUG_IMPLICIT_PTR (mode, TREE_OPERAND (exp, 0));
>
>          if (handled_component_p (TREE_OPERAND (exp, 0)))
> @@ -3337,7 +3338,8 @@ expand_debug_expr (tree exp)
>              if ((TREE_CODE (decl) == VAR_DECL
>                   || TREE_CODE (decl) == PARM_DECL
>                   || TREE_CODE (decl) == RESULT_DECL)
> -                 && !TREE_ADDRESSABLE (decl)
> +                 && (!TREE_ADDRESSABLE (decl)
> +                     || target_for_debug_bind (decl))
>                  && (bitoffset % BITS_PER_UNIT) == 0
>                  && bitsize > 0
>                  && bitsize == maxsize)
>
>
>        Jakub

Patch

--- gcc/tree-ssa.c.jj	2011-11-29 08:58:52.000000000 +0100
+++ gcc/tree-ssa.c	2011-12-02 15:04:03.494148642 +0100
@@ -264,7 +264,12 @@  target_for_debug_bind (tree var)
     return NULL_TREE;
 
   if (!is_gimple_reg (var))
-    return NULL_TREE;
+    {
+      if (is_gimple_reg_type (TREE_TYPE (var))
+	  && referenced_var_lookup (cfun, DECL_UID (var)) == NULL_TREE)
+	return var;
+      return NULL_TREE;
+    }
 
   return var;
 }
--- gcc/tree-ssa-live.c.jj	2011-12-02 01:52:27.000000000 +0100
+++ gcc/tree-ssa-live.c	2011-12-02 15:04:59.601816335 +0100
@@ -814,15 +814,7 @@  remove_unused_locals (void)
 	      bitmap_set_bit (global_unused_vars, DECL_UID (var));
 	    }
 	  else
-	    {
-	      /* For unreferenced local vars drop TREE_ADDRESSABLE
-		 bit in case it is referenced from debug stmts.  */
-	      if (DECL_CONTEXT (var) == current_function_decl
-		  && TREE_ADDRESSABLE (var)
-		  && is_gimple_reg_type (TREE_TYPE (var)))
-		TREE_ADDRESSABLE (var) = 0;
-	      continue;
-	    }
+	    continue;
 	}
       else if (TREE_CODE (var) == VAR_DECL
 	       && DECL_HARD_REGISTER (var)
--- gcc/cfgexpand.c.jj	2011-12-02 01:52:27.000000000 +0100
+++ gcc/cfgexpand.c	2011-12-02 15:24:37.982327507 +0100
@@ -3325,7 +3325,8 @@  expand_debug_expr (tree exp)
 	  if ((TREE_CODE (TREE_OPERAND (exp, 0)) == VAR_DECL
 	       || TREE_CODE (TREE_OPERAND (exp, 0)) == PARM_DECL
 	       || TREE_CODE (TREE_OPERAND (exp, 0)) == RESULT_DECL)
-	      && !TREE_ADDRESSABLE (TREE_OPERAND (exp, 0)))
+	      && (!TREE_ADDRESSABLE (TREE_OPERAND (exp, 0))
+		  || target_for_debug_bind (TREE_OPERAND (exp, 0))))
 	    return gen_rtx_DEBUG_IMPLICIT_PTR (mode, TREE_OPERAND (exp, 0));
 
 	  if (handled_component_p (TREE_OPERAND (exp, 0)))
@@ -3337,7 +3338,8 @@  expand_debug_expr (tree exp)
 	      if ((TREE_CODE (decl) == VAR_DECL
 		   || TREE_CODE (decl) == PARM_DECL
 		   || TREE_CODE (decl) == RESULT_DECL)
-		  && !TREE_ADDRESSABLE (decl)
+		  && (!TREE_ADDRESSABLE (decl)
+		      || target_for_debug_bind (decl))
 		  && (bitoffset % BITS_PER_UNIT) == 0
 		  && bitsize > 0
 		  && bitsize == maxsize)