Patchwork patch: remove is_gimple_non_addressable

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Submitter Aldy Hernandez
Date Jan. 9, 2012, 2:57 p.m.
Message ID <4F0B0068.9050204@redhat.com>
Download mbox | patch
Permalink /patch/135033/
State New
Headers show

Comments

Aldy Hernandez - Jan. 9, 2012, 2:57 p.m.
> Ok with simply excluding SSA_NAMEs like
>
> @@ -4411,16 +4411,27 @@ gimplify_modify_expr_rhs (tree *expr_p,
>   		/* It's OK to use the target directly if it's being
>   		   initialized. */
>   		use_target = true;
> -	      else if (TREE_CODE (*to_p) != SSA_NAME
>                           &&  ....)
> -		/* Don't use the original target if it's already addressable;
> -		   if its address escapes, and the called function uses the
> -		   NRV optimization, a conforming program could see *to_p
> -		   change before the called function returns; see c++/19317.
> -		   When optimizing, the return_slot pass marks more functions
> -		   as safe after we have escape info.  */
> -		use_target = false;
> - 	      else
> -		use_target = true;
>
> as SSA_NAMEs can never become addressable during gimplification.

Ok, since I'm never quite 100% sure I'm following your suggestions... 
I'm posting the final patch here.  If tests pass, I'll commit.

Thanks again.
* gimple.c (is_gimple_non_addressable): Remove.
	* gimple.h: Remove is_gimple_non_addressable.
	* gimplify.c (gimplify_modify_expr_rhs): Use is_gimple_reg instead of
	is_gimple_non_addressable.
	* trans-mem.c (expand_assign_tm): Same.
Richard Guenther - Jan. 9, 2012, 3:46 p.m.
On Mon, Jan 9, 2012 at 3:57 PM, Aldy Hernandez <aldyh@redhat.com> wrote:
>
>> Ok with simply excluding SSA_NAMEs like
>>
>> @@ -4411,16 +4411,27 @@ gimplify_modify_expr_rhs (tree *expr_p,
>>                /* It's OK to use the target directly if it's being
>>                   initialized. */
>>                use_target = true;
>> -             else if (TREE_CODE (*to_p) != SSA_NAME
>>                          &&  ....)
>> -               /* Don't use the original target if it's already
>> addressable;
>> -                  if its address escapes, and the called function uses
>> the
>> -                  NRV optimization, a conforming program could see *to_p
>> -                  change before the called function returns; see
>> c++/19317.
>> -                  When optimizing, the return_slot pass marks more
>> functions
>> -                  as safe after we have escape info.  */
>> -               use_target = false;
>> -             else
>> -               use_target = true;
>>
>> as SSA_NAMEs can never become addressable during gimplification.
>
>
> Ok, since I'm never quite 100% sure I'm following your suggestions... I'm
> posting the final patch here.  If tests pass, I'll commit.

Yes, that looks fine.

Thanks,
Richard.

> Thanks again.

Patch

Index: trans-mem.c
===================================================================
--- trans-mem.c	(revision 182908)
+++ trans-mem.c	(working copy)
@@ -2184,7 +2184,7 @@  expand_assign_tm (struct tm_region *regi
       /* ??? Figure out if there's any possible overlap between the LHS
 	 and the RHS and if not, use MEMCPY.  */
 
-      if (load_p && is_gimple_non_addressable (lhs))
+      if (load_p && is_gimple_reg (lhs))
 	{
 	  tmp = create_tmp_var (TREE_TYPE (lhs), NULL);
 	  lhs_addr = build_fold_addr_expr (tmp);
Index: gimplify.c
===================================================================
--- gimplify.c	(revision 182848)
+++ gimplify.c	(working copy)
@@ -4411,7 +4411,9 @@  gimplify_modify_expr_rhs (tree *expr_p,
 		/* It's OK to use the target directly if it's being
 		   initialized. */
 		use_target = true;
-	      else if (!is_gimple_non_addressable (*to_p))
+	      else if (TREE_CODE (*to_p) != SSA_NAME
+		      && (!is_gimple_variable (*to_p)
+			  || needs_to_live_in_memory (*to_p)))
 		/* Don't use the original target if it's already addressable;
 		   if its address escapes, and the called function uses the
 		   NRV optimization, a conforming program could see *to_p
Index: gimple.c
===================================================================
--- gimple.c	(revision 182848)
+++ gimple.c	(working copy)
@@ -2963,17 +2963,6 @@  is_gimple_reg (tree t)
 }
 
 
-/* Return true if T is a GIMPLE variable whose address is not needed.  */
-
-bool
-is_gimple_non_addressable (tree t)
-{
-  if (TREE_CODE (t) == SSA_NAME)
-    t = SSA_NAME_VAR (t);
-
-  return (is_gimple_variable (t) && ! needs_to_live_in_memory (t));
-}
-
 /* Return true if T is a GIMPLE rvalue, i.e. an identifier or a constant.  */
 
 bool
Index: gimple.h
===================================================================
--- gimple.h	(revision 182848)
+++ gimple.h	(working copy)
@@ -1006,9 +1006,6 @@  extern bool is_gimple_mem_rhs (tree);
 /* Returns true iff T is a valid if-statement condition.  */
 extern bool is_gimple_condexpr (tree);
 
-/* Returns true iff T is a variable that does not need to live in memory.  */
-extern bool is_gimple_non_addressable (tree t);
-
 /* Returns true iff T is a valid call address expression.  */
 extern bool is_gimple_call_addr (tree);