coroutines: Use cp_build_init_expr consistently.

Message ID 20221011215831.67154-1-iain@sandoe.co.uk
State Accepted, archived
Headers
Series coroutines: Use cp_build_init_expr consistently. |

Checks

Context Check Description
snail/gcc-patch-check success Github commit url

Commit Message

Iain Sandoe Oct. 11, 2022, 9:58 p.m. UTC
  Tested on x86_64-darwin19, OK for master?
thanks
Iain

-- >8 --

Now we have the TARGET_EXPR_ELIDING_P flag, it is important to ensure it
is set properly on target exprs.  The code here has a mixture of APIs used
to build inits.  This patch changes that to use cp_build_init_expr() where
possible, since that handles setting the flag.
---
 gcc/cp/coroutines.cc | 25 ++++++++-----------------
 1 file changed, 8 insertions(+), 17 deletions(-)
  

Comments

Jason Merrill Oct. 11, 2022, 10:06 p.m. UTC | #1
On 10/11/22 17:58, Iain Sandoe wrote:
> Tested on x86_64-darwin19, OK for master?
> thanks
> Iain
> 
> -- >8 --
> 
> Now we have the TARGET_EXPR_ELIDING_P flag, it is important to ensure it
> is set properly on target exprs.  The code here has a mixture of APIs used
> to build inits.  This patch changes that to use cp_build_init_expr() where
> possible, since that handles setting the flag.

Hmm, I wouldn't expect this to be necessary, since cp_build_modify_expr 
calls cp_build_init_expr for INIT_EXPR.  Perhaps the similarity of the 
function names is a trap...

> ---
>   gcc/cp/coroutines.cc | 25 ++++++++-----------------
>   1 file changed, 8 insertions(+), 17 deletions(-)
> 
> diff --git a/gcc/cp/coroutines.cc b/gcc/cp/coroutines.cc
> index 01a3e831ee5..20d309445eb 100644
> --- a/gcc/cp/coroutines.cc
> +++ b/gcc/cp/coroutines.cc
> @@ -1025,8 +1025,7 @@ build_co_await (location_t loc, tree a, suspend_point_kind suspend_kind)
>     else
>       {
>         e_proxy = get_awaitable_var (suspend_kind, o_type);
> -      o = cp_build_modify_expr (loc, e_proxy, INIT_EXPR, o,
> -				tf_warning_or_error);
> +      o = cp_build_init_expr (loc, e_proxy, o);
>       }
>   
>     /* I suppose we could check that this is contextually convertible to bool.  */
> @@ -2889,8 +2888,7 @@ flatten_await_stmt (var_nest_node *n, hash_set<tree> *promoted,
>   	  gcc_checking_assert (!already_present);
>   	  tree inner = TREE_OPERAND (init, 1);
>   	  gcc_checking_assert (TREE_CODE (inner) != COND_EXPR);
> -	  init = cp_build_modify_expr (input_location, var, INIT_EXPR, init,
> -				       tf_warning_or_error);
> +	  init = cp_build_init_expr (var, init);
>   	  /* Simplify for the case that we have an init containing the temp
>   	     alone.  */
>   	  if (t == n->init && n->var == NULL_TREE)
> @@ -3656,8 +3654,7 @@ await_statement_walker (tree *stmt, int *do_subtree, void *d)
>   	    if (TREE_CODE (cond_inner) == CLEANUP_POINT_EXPR)
>   	      cond_inner = TREE_OPERAND (cond_inner, 0);
>   	    location_t sloc = EXPR_LOCATION (SWITCH_STMT_COND (sw_stmt));
> -	    tree new_s = cp_build_init_expr (sloc, newvar,
> -				     cond_inner);
> +	    tree new_s = cp_build_init_expr (sloc, newvar, cond_inner);
>   	    finish_expr_stmt (new_s);
>   	    SWITCH_STMT_COND (sw_stmt) = newvar;
>   	    /* Now add the switch statement with the condition re-
> @@ -4902,9 +4899,8 @@ morph_fn_to_coro (tree orig, tree *resumer, tree *destroyer)
>   	      if (flag_exceptions)
>   		{
>   		  /* This var is now live.  */
> -		  r = build_modify_expr (fn_start, parm.guard_var,
> -					 boolean_type_node, INIT_EXPR, fn_start,
> -					 boolean_true_node, boolean_type_node);
> +		  r = cp_build_init_expr (fn_start, parm.guard_var,
> +					  boolean_true_node);
>   		  finish_expr_stmt (r);
>   		}
>   	    }
> @@ -4948,9 +4944,7 @@ morph_fn_to_coro (tree orig, tree *resumer, tree *destroyer)
>         r = coro_build_cvt_void_expr_stmt (r, fn_start);
>         finish_expr_stmt (r);
>   
> -      r = build_modify_expr (fn_start, coro_promise_live, boolean_type_node,
> -			     INIT_EXPR, fn_start, boolean_true_node,
> -			     boolean_type_node);
> +      r = cp_build_init_expr (fn_start, coro_promise_live, boolean_true_node);
>         finish_expr_stmt (r);
>   
>         promise_dtor
> @@ -5031,8 +5025,7 @@ morph_fn_to_coro (tree orig, tree *resumer, tree *destroyer)
>   				       NULL_TREE);
>         add_decl_expr (gro);
>         gro_bind_vars = gro;
> -      r = cp_build_modify_expr (input_location, gro, INIT_EXPR, get_ro,
> -				tf_warning_or_error);
> +      r = cp_build_init_expr (gro, get_ro);
>         /* The constructed object might require a cleanup.  */
>         if (TYPE_HAS_NONTRIVIAL_DESTRUCTOR (gro_type))
>   	{
> @@ -5053,9 +5046,7 @@ morph_fn_to_coro (tree orig, tree *resumer, tree *destroyer)
>        cleanup.  */
>     if (gro_ret_dtor)
>       {
> -       r = build_modify_expr (fn_start, coro_gro_live, boolean_type_node,
> -			      INIT_EXPR, fn_start, boolean_true_node,
> -			      boolean_type_node);
> +       r = cp_build_init_expr (fn_start, coro_gro_live, boolean_true_node);
>         finish_expr_stmt (r);
>       }
>     /* Initialize the resume_idx_var to 0, meaning "not started".  */
  
Iain Sandoe Oct. 11, 2022, 10:17 p.m. UTC | #2
Hi Jason

> On 11 Oct 2022, at 23:06, Jason Merrill <jason@redhat.com> wrote:
> 
> On 10/11/22 17:58, Iain Sandoe wrote:
>> Tested on x86_64-darwin19, OK for master?
>> thanks
>> Iain
>> -- >8 --
>> Now we have the TARGET_EXPR_ELIDING_P flag, it is important to ensure it
>> is set properly on target exprs.  The code here has a mixture of APIs used
>> to build inits.  This patch changes that to use cp_build_init_expr() where
>> possible, since that handles setting the flag.
> 
> Hmm, I wouldn't expect this to be necessary, since cp_build_modify_expr calls cp_build_init_expr for INIT_EXPR.

It seems that path is only taken if the init is a CONSTRUCTOR.

>  Perhaps the similarity of the function names is a trap...

not sure exactly what trap you mean.

It seems that on my local set of additional tests (for some of the open prs) there are some
progressions from this change, I will have to track down which change is the cause.

thanks
Iain

> 
>> ---
>>  gcc/cp/coroutines.cc | 25 ++++++++-----------------
>>  1 file changed, 8 insertions(+), 17 deletions(-)
>> diff --git a/gcc/cp/coroutines.cc b/gcc/cp/coroutines.cc
>> index 01a3e831ee5..20d309445eb 100644
>> --- a/gcc/cp/coroutines.cc
>> +++ b/gcc/cp/coroutines.cc
>> @@ -1025,8 +1025,7 @@ build_co_await (location_t loc, tree a, suspend_point_kind suspend_kind)
>>    else
>>      {
>>        e_proxy = get_awaitable_var (suspend_kind, o_type);
>> -      o = cp_build_modify_expr (loc, e_proxy, INIT_EXPR, o,
>> -				tf_warning_or_error);
>> +      o = cp_build_init_expr (loc, e_proxy, o);
>>      }
>>      /* I suppose we could check that this is contextually convertible to bool.  */
>> @@ -2889,8 +2888,7 @@ flatten_await_stmt (var_nest_node *n, hash_set<tree> *promoted,
>>  	  gcc_checking_assert (!already_present);
>>  	  tree inner = TREE_OPERAND (init, 1);
>>  	  gcc_checking_assert (TREE_CODE (inner) != COND_EXPR);
>> -	  init = cp_build_modify_expr (input_location, var, INIT_EXPR, init,
>> -				       tf_warning_or_error);
>> +	  init = cp_build_init_expr (var, init);
>>  	  /* Simplify for the case that we have an init containing the temp
>>  	     alone.  */
>>  	  if (t == n->init && n->var == NULL_TREE)
>> @@ -3656,8 +3654,7 @@ await_statement_walker (tree *stmt, int *do_subtree, void *d)
>>  	    if (TREE_CODE (cond_inner) == CLEANUP_POINT_EXPR)
>>  	      cond_inner = TREE_OPERAND (cond_inner, 0);
>>  	    location_t sloc = EXPR_LOCATION (SWITCH_STMT_COND (sw_stmt));
>> -	    tree new_s = cp_build_init_expr (sloc, newvar,
>> -				     cond_inner);
>> +	    tree new_s = cp_build_init_expr (sloc, newvar, cond_inner);
>>  	    finish_expr_stmt (new_s);
>>  	    SWITCH_STMT_COND (sw_stmt) = newvar;
>>  	    /* Now add the switch statement with the condition re-
>> @@ -4902,9 +4899,8 @@ morph_fn_to_coro (tree orig, tree *resumer, tree *destroyer)
>>  	      if (flag_exceptions)
>>  		{
>>  		  /* This var is now live.  */
>> -		  r = build_modify_expr (fn_start, parm.guard_var,
>> -					 boolean_type_node, INIT_EXPR, fn_start,
>> -					 boolean_true_node, boolean_type_node);
>> +		  r = cp_build_init_expr (fn_start, parm.guard_var,
>> +					  boolean_true_node);
>>  		  finish_expr_stmt (r);
>>  		}
>>  	    }
>> @@ -4948,9 +4944,7 @@ morph_fn_to_coro (tree orig, tree *resumer, tree *destroyer)
>>        r = coro_build_cvt_void_expr_stmt (r, fn_start);
>>        finish_expr_stmt (r);
>>  -      r = build_modify_expr (fn_start, coro_promise_live, boolean_type_node,
>> -			     INIT_EXPR, fn_start, boolean_true_node,
>> -			     boolean_type_node);
>> +      r = cp_build_init_expr (fn_start, coro_promise_live, boolean_true_node);
>>        finish_expr_stmt (r);
>>          promise_dtor
>> @@ -5031,8 +5025,7 @@ morph_fn_to_coro (tree orig, tree *resumer, tree *destroyer)
>>  				       NULL_TREE);
>>        add_decl_expr (gro);
>>        gro_bind_vars = gro;
>> -      r = cp_build_modify_expr (input_location, gro, INIT_EXPR, get_ro,
>> -				tf_warning_or_error);
>> +      r = cp_build_init_expr (gro, get_ro);
>>        /* The constructed object might require a cleanup.  */
>>        if (TYPE_HAS_NONTRIVIAL_DESTRUCTOR (gro_type))
>>  	{
>> @@ -5053,9 +5046,7 @@ morph_fn_to_coro (tree orig, tree *resumer, tree *destroyer)
>>       cleanup.  */
>>    if (gro_ret_dtor)
>>      {
>> -       r = build_modify_expr (fn_start, coro_gro_live, boolean_type_node,
>> -			      INIT_EXPR, fn_start, boolean_true_node,
>> -			      boolean_type_node);
>> +       r = cp_build_init_expr (fn_start, coro_gro_live, boolean_true_node);
>>        finish_expr_stmt (r);
>>      }
>>    /* Initialize the resume_idx_var to 0, meaning "not started".  */
>
  
Jason Merrill Oct. 11, 2022, 11:19 p.m. UTC | #3
On 10/11/22 18:17, Iain Sandoe wrote:
> Hi Jason
> 
>> On 11 Oct 2022, at 23:06, Jason Merrill <jason@redhat.com> wrote:
>>
>> On 10/11/22 17:58, Iain Sandoe wrote:
>>> Tested on x86_64-darwin19, OK for master?
>>> thanks
>>> Iain
>>> -- >8 --
>>> Now we have the TARGET_EXPR_ELIDING_P flag, it is important to ensure it
>>> is set properly on target exprs.  The code here has a mixture of APIs used
>>> to build inits.  This patch changes that to use cp_build_init_expr() where
>>> possible, since that handles setting the flag.
>>
>> Hmm, I wouldn't expect this to be necessary, since cp_build_modify_expr calls cp_build_init_expr for INIT_EXPR.
> 
> It seems that path is only taken if the init is a CONSTRUCTOR.

If it's not a CONSTRUCTOR it builds a constructor call, which should end 
up having the same effect.  Certainly cp_build_init_expr is simpler if 
it works, so the patch is OK, but if it's necessary that indicates a bug 
that should be fixed.

>>   Perhaps the similarity of the function names is a trap...
> 
> not sure exactly what trap you mean.

The names are close, but cp_build_modify_expr is a lot more complicated; 
it handles conversions and overloaded operators.

> It seems that on my local set of additional tests (for some of the open prs) there are some
> progressions from this change, I will have to track down which change is the cause.
> 
> thanks
> Iain
> 
>>
>>> ---
>>>   gcc/cp/coroutines.cc | 25 ++++++++-----------------
>>>   1 file changed, 8 insertions(+), 17 deletions(-)
>>> diff --git a/gcc/cp/coroutines.cc b/gcc/cp/coroutines.cc
>>> index 01a3e831ee5..20d309445eb 100644
>>> --- a/gcc/cp/coroutines.cc
>>> +++ b/gcc/cp/coroutines.cc
>>> @@ -1025,8 +1025,7 @@ build_co_await (location_t loc, tree a, suspend_point_kind suspend_kind)
>>>     else
>>>       {
>>>         e_proxy = get_awaitable_var (suspend_kind, o_type);
>>> -      o = cp_build_modify_expr (loc, e_proxy, INIT_EXPR, o,
>>> -				tf_warning_or_error);
>>> +      o = cp_build_init_expr (loc, e_proxy, o);
>>>       }
>>>       /* I suppose we could check that this is contextually convertible to bool.  */
>>> @@ -2889,8 +2888,7 @@ flatten_await_stmt (var_nest_node *n, hash_set<tree> *promoted,
>>>   	  gcc_checking_assert (!already_present);
>>>   	  tree inner = TREE_OPERAND (init, 1);
>>>   	  gcc_checking_assert (TREE_CODE (inner) != COND_EXPR);
>>> -	  init = cp_build_modify_expr (input_location, var, INIT_EXPR, init,
>>> -				       tf_warning_or_error);
>>> +	  init = cp_build_init_expr (var, init);
>>>   	  /* Simplify for the case that we have an init containing the temp
>>>   	     alone.  */
>>>   	  if (t == n->init && n->var == NULL_TREE)
>>> @@ -3656,8 +3654,7 @@ await_statement_walker (tree *stmt, int *do_subtree, void *d)
>>>   	    if (TREE_CODE (cond_inner) == CLEANUP_POINT_EXPR)
>>>   	      cond_inner = TREE_OPERAND (cond_inner, 0);
>>>   	    location_t sloc = EXPR_LOCATION (SWITCH_STMT_COND (sw_stmt));
>>> -	    tree new_s = cp_build_init_expr (sloc, newvar,
>>> -				     cond_inner);
>>> +	    tree new_s = cp_build_init_expr (sloc, newvar, cond_inner);
>>>   	    finish_expr_stmt (new_s);
>>>   	    SWITCH_STMT_COND (sw_stmt) = newvar;
>>>   	    /* Now add the switch statement with the condition re-
>>> @@ -4902,9 +4899,8 @@ morph_fn_to_coro (tree orig, tree *resumer, tree *destroyer)
>>>   	      if (flag_exceptions)
>>>   		{
>>>   		  /* This var is now live.  */
>>> -		  r = build_modify_expr (fn_start, parm.guard_var,
>>> -					 boolean_type_node, INIT_EXPR, fn_start,
>>> -					 boolean_true_node, boolean_type_node);
>>> +		  r = cp_build_init_expr (fn_start, parm.guard_var,
>>> +					  boolean_true_node);
>>>   		  finish_expr_stmt (r);
>>>   		}
>>>   	    }
>>> @@ -4948,9 +4944,7 @@ morph_fn_to_coro (tree orig, tree *resumer, tree *destroyer)
>>>         r = coro_build_cvt_void_expr_stmt (r, fn_start);
>>>         finish_expr_stmt (r);
>>>   -      r = build_modify_expr (fn_start, coro_promise_live, boolean_type_node,
>>> -			     INIT_EXPR, fn_start, boolean_true_node,
>>> -			     boolean_type_node);
>>> +      r = cp_build_init_expr (fn_start, coro_promise_live, boolean_true_node);
>>>         finish_expr_stmt (r);
>>>           promise_dtor
>>> @@ -5031,8 +5025,7 @@ morph_fn_to_coro (tree orig, tree *resumer, tree *destroyer)
>>>   				       NULL_TREE);
>>>         add_decl_expr (gro);
>>>         gro_bind_vars = gro;
>>> -      r = cp_build_modify_expr (input_location, gro, INIT_EXPR, get_ro,
>>> -				tf_warning_or_error);
>>> +      r = cp_build_init_expr (gro, get_ro);
>>>         /* The constructed object might require a cleanup.  */
>>>         if (TYPE_HAS_NONTRIVIAL_DESTRUCTOR (gro_type))
>>>   	{
>>> @@ -5053,9 +5046,7 @@ morph_fn_to_coro (tree orig, tree *resumer, tree *destroyer)
>>>        cleanup.  */
>>>     if (gro_ret_dtor)
>>>       {
>>> -       r = build_modify_expr (fn_start, coro_gro_live, boolean_type_node,
>>> -			      INIT_EXPR, fn_start, boolean_true_node,
>>> -			      boolean_type_node);
>>> +       r = cp_build_init_expr (fn_start, coro_gro_live, boolean_true_node);
>>>         finish_expr_stmt (r);
>>>       }
>>>     /* Initialize the resume_idx_var to 0, meaning "not started".  */
>>
>
  
Iain Sandoe Oct. 12, 2022, 6:34 a.m. UTC | #4
> On 12 Oct 2022, at 00:19, Jason Merrill <jason@redhat.com> wrote:
> 
> On 10/11/22 18:17, Iain Sandoe wrote:
>> Hi Jason
>>> On 11 Oct 2022, at 23:06, Jason Merrill <jason@redhat.com> wrote:
>>> 
>>> On 10/11/22 17:58, Iain Sandoe wrote:

>>>> Now we have the TARGET_EXPR_ELIDING_P flag, it is important to ensure it
>>>> is set properly on target exprs.  The code here has a mixture of APIs used
>>>> to build inits.  This patch changes that to use cp_build_init_expr() where
>>>> possible, since that handles setting the flag.
>>> 
>>> Hmm, I wouldn't expect this to be necessary, since cp_build_modify_expr calls cp_build_init_expr for INIT_EXPR.

You are, of course, right..

>>>  Perhaps the similarity of the function names is a trap...
>> not sure exactly what trap you mean.
> 
> The names are close, but cp_build_modify_expr is a lot more complicated; it handles conversions and overloaded operators.

This is one of the tricky parts about synthesizing AST from scratch - knowing which API is the “right one” to use in each case - e.g. here:  cp_build_modify_expr or  cp_build_init_expr or even build2 (INIT_EXPR..

So, it seems that where there could be a mismatch to be diagnosed, I should use cp_build_modify_expr, but maybe in some of the cases where there is no checking needed (e.g. set a guard var to true) it would be appropriate to use one of the simpler forms.

>> It seems that on my local set of additional tests (for some of the open prs) there are some
>> progressions from this change,

That’s a spurious observation, because cp_build_init_expr does not do the diagnostics.

patch withdrawn.
thanks for the explanations,
Iain
  

Patch

diff --git a/gcc/cp/coroutines.cc b/gcc/cp/coroutines.cc
index 01a3e831ee5..20d309445eb 100644
--- a/gcc/cp/coroutines.cc
+++ b/gcc/cp/coroutines.cc
@@ -1025,8 +1025,7 @@  build_co_await (location_t loc, tree a, suspend_point_kind suspend_kind)
   else
     {
       e_proxy = get_awaitable_var (suspend_kind, o_type);
-      o = cp_build_modify_expr (loc, e_proxy, INIT_EXPR, o,
-				tf_warning_or_error);
+      o = cp_build_init_expr (loc, e_proxy, o);
     }
 
   /* I suppose we could check that this is contextually convertible to bool.  */
@@ -2889,8 +2888,7 @@  flatten_await_stmt (var_nest_node *n, hash_set<tree> *promoted,
 	  gcc_checking_assert (!already_present);
 	  tree inner = TREE_OPERAND (init, 1);
 	  gcc_checking_assert (TREE_CODE (inner) != COND_EXPR);
-	  init = cp_build_modify_expr (input_location, var, INIT_EXPR, init,
-				       tf_warning_or_error);
+	  init = cp_build_init_expr (var, init);
 	  /* Simplify for the case that we have an init containing the temp
 	     alone.  */
 	  if (t == n->init && n->var == NULL_TREE)
@@ -3656,8 +3654,7 @@  await_statement_walker (tree *stmt, int *do_subtree, void *d)
 	    if (TREE_CODE (cond_inner) == CLEANUP_POINT_EXPR)
 	      cond_inner = TREE_OPERAND (cond_inner, 0);
 	    location_t sloc = EXPR_LOCATION (SWITCH_STMT_COND (sw_stmt));
-	    tree new_s = cp_build_init_expr (sloc, newvar,
-				     cond_inner);
+	    tree new_s = cp_build_init_expr (sloc, newvar, cond_inner);
 	    finish_expr_stmt (new_s);
 	    SWITCH_STMT_COND (sw_stmt) = newvar;
 	    /* Now add the switch statement with the condition re-
@@ -4902,9 +4899,8 @@  morph_fn_to_coro (tree orig, tree *resumer, tree *destroyer)
 	      if (flag_exceptions)
 		{
 		  /* This var is now live.  */
-		  r = build_modify_expr (fn_start, parm.guard_var,
-					 boolean_type_node, INIT_EXPR, fn_start,
-					 boolean_true_node, boolean_type_node);
+		  r = cp_build_init_expr (fn_start, parm.guard_var,
+					  boolean_true_node);
 		  finish_expr_stmt (r);
 		}
 	    }
@@ -4948,9 +4944,7 @@  morph_fn_to_coro (tree orig, tree *resumer, tree *destroyer)
       r = coro_build_cvt_void_expr_stmt (r, fn_start);
       finish_expr_stmt (r);
 
-      r = build_modify_expr (fn_start, coro_promise_live, boolean_type_node,
-			     INIT_EXPR, fn_start, boolean_true_node,
-			     boolean_type_node);
+      r = cp_build_init_expr (fn_start, coro_promise_live, boolean_true_node);
       finish_expr_stmt (r);
 
       promise_dtor
@@ -5031,8 +5025,7 @@  morph_fn_to_coro (tree orig, tree *resumer, tree *destroyer)
 				       NULL_TREE);
       add_decl_expr (gro);
       gro_bind_vars = gro;
-      r = cp_build_modify_expr (input_location, gro, INIT_EXPR, get_ro,
-				tf_warning_or_error);
+      r = cp_build_init_expr (gro, get_ro);
       /* The constructed object might require a cleanup.  */
       if (TYPE_HAS_NONTRIVIAL_DESTRUCTOR (gro_type))
 	{
@@ -5053,9 +5046,7 @@  morph_fn_to_coro (tree orig, tree *resumer, tree *destroyer)
      cleanup.  */
   if (gro_ret_dtor)
     {
-       r = build_modify_expr (fn_start, coro_gro_live, boolean_type_node,
-			      INIT_EXPR, fn_start, boolean_true_node,
-			      boolean_type_node);
+       r = cp_build_init_expr (fn_start, coro_gro_live, boolean_true_node);
       finish_expr_stmt (r);
     }
   /* Initialize the resume_idx_var to 0, meaning "not started".  */