Re: [PATCH] c++: End lifetime of objects in constexpr after destructor call [PR71093]

[Jakub Jelinek <jakub@redhat.com>]

On Mon, Dec 11, 2023 at 05:00:50PM -0500, Jason Merrill wrote:
> In discussion of PR71093 it came up that more clobber_kind options would be
> useful within the C++ front-end.
> 
> gcc/ChangeLog:
> 
> 	* tree-core.h (enum clobber_kind): Rename CLOBBER_EOL to
> 	CLOBBER_STORAGE_END.  Add CLOBBER_STORAGE_BEGIN,
> 	CLOBBER_OBJECT_BEGIN, CLOBBER_OBJECT_END.
> 	* gimple-lower-bitint.cc
> 	* gimple-ssa-warn-access.cc
> 	* gimplify.cc
> 	* tree-inline.cc
> 	* tree-ssa-ccp.cc: Adjust for rename.

I doubt the above style will make it through the pre-commit hook, but I
might be wrong.

> --- a/gcc/gimple-lower-bitint.cc
> +++ b/gcc/gimple-lower-bitint.cc
> @@ -806,7 +806,7 @@ bitint_large_huge::handle_operand (tree op, tree idx)
>  	  && m_after_stmt
>  	  && bitmap_bit_p (m_single_use_names, SSA_NAME_VERSION (op)))
>  	{
> -	  tree clobber = build_clobber (TREE_TYPE (m_vars[p]), CLOBBER_EOL);
> +	  tree clobber = build_clobber (TREE_TYPE (m_vars[p]), CLOBBER_STORAGE_END);

This needs line wrapping I think.

> @@ -2100,7 +2100,7 @@ bitint_large_huge::handle_operand_addr (tree op, gimple *stmt,
>  	      ret = build_fold_addr_expr (var);
>  	      if (!stmt_ends_bb_p (gsi_stmt (m_gsi)))
>  		{
> -		  tree clobber = build_clobber (m_limb_type, CLOBBER_EOL);
> +		  tree clobber = build_clobber (m_limb_type, CLOBBER_STORAGE_END);

This too.

>  	      && flag_stack_reuse != SR_NONE)
>  	    {
> -	      tree clobber = build_clobber (TREE_TYPE (t), CLOBBER_EOL);
> +	      tree clobber = build_clobber (TREE_TYPE (t), CLOBBER_STORAGE_END);
>  	      gimple *clobber_stmt;
>  	      clobber_stmt = gimple_build_assign (t, clobber);
>  	      gimple_set_location (clobber_stmt, end_locus);
> @@ -7417,7 +7417,7 @@ gimplify_target_expr (tree *expr_p, gimple_seq *pre_p, gimple_seq *post_p)
>  	{
>  	  if (flag_stack_reuse == SR_ALL)
>  	    {
> -	      tree clobber = build_clobber (TREE_TYPE (temp), CLOBBER_EOL);
> +	      tree clobber = build_clobber (TREE_TYPE (temp), CLOBBER_STORAGE_END);
>  	      clobber = build2 (MODIFY_EXPR, TREE_TYPE (temp), temp, clobber);
>  	      gimple_push_cleanup (temp, clobber, false, pre_p, true);
>  	    }

These too.

> diff --git a/gcc/tree-inline.cc b/gcc/tree-inline.cc
> index a4fc839a22d..cca3227fa89 100644
> --- a/gcc/tree-inline.cc
> +++ b/gcc/tree-inline.cc
> @@ -5136,7 +5136,7 @@ expand_call_inline (basic_block bb, gimple *stmt, copy_body_data *id,
>  	      && !is_gimple_reg (*varp)
>  	      && !(id->debug_map && id->debug_map->get (p)))
>  	    {
> -	      tree clobber = build_clobber (TREE_TYPE (*varp), CLOBBER_EOL);
> +	      tree clobber = build_clobber (TREE_TYPE (*varp), CLOBBER_STORAGE_END);
>  	      gimple *clobber_stmt;
>  	      clobber_stmt = gimple_build_assign (*varp, clobber);
>  	      gimple_set_location (clobber_stmt, gimple_location (stmt));
> @@ -5208,7 +5208,7 @@ expand_call_inline (basic_block bb, gimple *stmt, copy_body_data *id,
>  	  && !is_gimple_reg (id->retvar)
>  	  && !stmt_ends_bb_p (stmt))
>  	{
> -	  tree clobber = build_clobber (TREE_TYPE (id->retvar), CLOBBER_EOL);
> +	  tree clobber = build_clobber (TREE_TYPE (id->retvar), CLOBBER_STORAGE_END);
>  	  gimple *clobber_stmt;
>  	  clobber_stmt = gimple_build_assign (id->retvar, clobber);
>  	  gimple_set_location (clobber_stmt, gimple_location (old_stmt));

And these.

Otherwise LGTM.

	Jakub