Re: [PATCH] Replace more DEBUG_EXPR_DECL creations with build_debug_expr_decl

Richard Biener rguenther@suse.de
Fri Nov 12 19:17:51 GMT 2021


On November 12, 2021 3:39:56 PM GMT+01:00, Martin Jambor <mjambor@suse.cz> wrote:
>Hi,
>
>On Tue, Nov 09 2021, Richard Biener wrote:
>> On Mon, 8 Nov 2021, Martin Jambor wrote:
>>> this patch introduces a helper function build_debug_expr_decl to build
>>> DEBUG_EXPR_DECL tree nodes in the most common way and replaces with a
>>> call of this function all code pieces which build such a DECL itself
>>> and sets its mode to the TYPE_MODE of its type.
>>> 
>>> There still remain 11 instances of open-coded creation of a
>>> DEBUG_EXPR_DECL which set the mode of the DECL to something else.  It
>>> would probably be a good idea to figure out that has any effect and if
>>> not, convert them to calls of build_debug_expr_decl too.  But this
>>> patch deliberately does not introduce any functional changes.
>>> 
>>> Bootstrapped and tested on x86_64-linux, OK for trunk?
>>
>> OK (the const_tree suggestion is a good one).
>>
>> For the remaining cases I'd simply use
>>
>> decl = build_debug_expr_decl (type);
>> SET_DECL_MODE (decl) = ...;
>>
>> and thus override the mode afterwards, maybe adding a comment to
>> check whether that's necessary.  As said, the only case where it
>> might matter is when we create a debug decl replacement for a FIELD_DECL,
>> so maybe for those SRA things we create for DWARF "piece" info?
>>
>
>Like this?  This patch replaces all but one remaining open coded
>constructions of DEBUG_EXPR_DECL with calls to build_debug_expr_decl,
>even if - in order not to introduce any functional change - the mode of
>the constructed decl is then overwritten.
>
>It is not clear if changing the mode has any effect in practice and
>therefore I have added a FIXME note to code which does it, as
>requested.
>
>After this patch, DEBUG_EXPR_DECLs are created only by
>build_debug_expr_decl and make_debug_expr_from_rtl which looks like
>it should be left alone.
>
>Bootstrapped and tested on x86_64-linux.  OK for trunk?

Yes. 

Thanks, 
Richard. 

>I have also compared the generated DWARF (with readelf -w) of cc1plus
>generated by a compiler with this patch and one with the mode setting
>removed (on top of this patch) and there were no differences
>whatsoever.  So perhaps we can just remove it?  I have not
>bootstrapped that patch yet, though.

I guess that for one case it mattered and we might have a testcase to show that and other cases were just cut and pasted from the "wrong" place... 

Richard. 

>Thanks,
>
>Martin
>
>
>gcc/ChangeLog:
>
>2021-11-11  Martin Jambor  <mjambor@suse.cz>
>
>	* cfgexpand.c (expand_gimple_basic_block): Use build_debug_expr_decl,
>	add a fixme note about the mode assignment perhaps being unnecessary.
>	* ipa-param-manipulation.c (ipa_param_adjustments::modify_call):
>	Likewise.
>	(ipa_param_body_adjustments::mark_dead_statements): Likewise.
>	(ipa_param_body_adjustments::reset_debug_stmts): Likewise.
>	* tree-inline.c (remap_ssa_name): Likewise.
>	(tree_function_versioning): Likewise.
>	* tree-into-ssa.c (rewrite_debug_stmt_uses): Likewise.
>	* tree-ssa-loop-ivopts.c (remove_unused_ivs): Likewise.
>	* tree-ssa.c (insert_debug_temp_for_var_def): Likewise.
>---
> gcc/cfgexpand.c              |  5 ++---
> gcc/ipa-param-manipulation.c | 17 +++++++----------
> gcc/tree-inline.c            | 17 +++++++----------
> gcc/tree-into-ssa.c          |  7 +++----
> gcc/tree-ssa-loop-ivopts.c   |  5 ++---
> gcc/tree-ssa.c               |  5 ++---
> 6 files changed, 23 insertions(+), 33 deletions(-)
>
>diff --git a/gcc/cfgexpand.c b/gcc/cfgexpand.c
>index 55ff75bd78e..eb6466f4be6 100644
>--- a/gcc/cfgexpand.c
>+++ b/gcc/cfgexpand.c
>@@ -5898,18 +5898,17 @@ expand_gimple_basic_block (basic_block bb, bool disable_tail_calls)
> 		       temporary.  */
> 		    gimple *debugstmt;
> 		    tree value = gimple_assign_rhs_to_tree (def);
>-		    tree vexpr = make_node (DEBUG_EXPR_DECL);
>+		    tree vexpr = build_debug_expr_decl (TREE_TYPE (value));
> 		    rtx val;
> 		    machine_mode mode;
> 
> 		    set_curr_insn_location (gimple_location (def));
> 
>-		    DECL_ARTIFICIAL (vexpr) = 1;
>-		    TREE_TYPE (vexpr) = TREE_TYPE (value);
> 		    if (DECL_P (value))
> 		      mode = DECL_MODE (value);
> 		    else
> 		      mode = TYPE_MODE (TREE_TYPE (value));
>+		    /* FIXME: Is setting the mode really necessary? */
> 		    SET_DECL_MODE (vexpr, mode);
> 
> 		    val = gen_rtx_VAR_LOCATION
>diff --git a/gcc/ipa-param-manipulation.c b/gcc/ipa-param-manipulation.c
>index ae3149718ca..a230735d71e 100644
>--- a/gcc/ipa-param-manipulation.c
>+++ b/gcc/ipa-param-manipulation.c
>@@ -831,9 +831,8 @@ ipa_param_adjustments::modify_call (cgraph_edge *cs,
> 	      }
> 	  if (ddecl == NULL)
> 	    {
>-	      ddecl = make_node (DEBUG_EXPR_DECL);
>-	      DECL_ARTIFICIAL (ddecl) = 1;
>-	      TREE_TYPE (ddecl) = TREE_TYPE (origin);
>+	      ddecl = build_debug_expr_decl (TREE_TYPE (origin));
>+	      /* FIXME: Is setting the mode really necessary? */
> 	      SET_DECL_MODE (ddecl, DECL_MODE (origin));
> 
> 	      vec_safe_push (*debug_args, origin);
>@@ -1063,9 +1062,8 @@ ipa_param_body_adjustments::mark_dead_statements (tree dead_param,
>       return;
>     }
> 
>-  tree dp_ddecl = make_node (DEBUG_EXPR_DECL);
>-  DECL_ARTIFICIAL (dp_ddecl) = 1;
>-  TREE_TYPE (dp_ddecl) = TREE_TYPE (dead_param);
>+  tree dp_ddecl = build_debug_expr_decl (TREE_TYPE (dead_param));
>+  /* FIXME: Is setting the mode really necessary? */
>   SET_DECL_MODE (dp_ddecl, DECL_MODE (dead_param));
>   m_dead_ssa_debug_equiv.put (parm_ddef, dp_ddecl);
> }
>@@ -2217,11 +2215,10 @@ ipa_param_body_adjustments::reset_debug_stmts ()
> 	    gcc_assert (is_gimple_debug (stmt));
> 	    if (vexpr == NULL && gsip != NULL)
> 	      {
>-		vexpr = make_node (DEBUG_EXPR_DECL);
>-		def_temp = gimple_build_debug_source_bind (vexpr, decl, NULL);
>-		DECL_ARTIFICIAL (vexpr) = 1;
>-		TREE_TYPE (vexpr) = TREE_TYPE (name);
>+		vexpr = build_debug_expr_decl (TREE_TYPE (name));
>+		/* FIXME: Is setting the mode really necessary? */
> 		SET_DECL_MODE (vexpr, DECL_MODE (decl));
>+		def_temp = gimple_build_debug_source_bind (vexpr, decl, NULL);
> 		gsi_insert_before (gsip, def_temp, GSI_SAME_STMT);
> 	      }
> 	    if (vexpr)
>diff --git a/gcc/tree-inline.c b/gcc/tree-inline.c
>index 53d664ec2e4..8c108d8e4e7 100644
>--- a/gcc/tree-inline.c
>+++ b/gcc/tree-inline.c
>@@ -193,7 +193,6 @@ remap_ssa_name (tree name, copy_body_data *id)
> 	  && id->entry_bb == NULL
> 	  && single_succ_p (ENTRY_BLOCK_PTR_FOR_FN (cfun)))
> 	{
>-	  tree vexpr = make_node (DEBUG_EXPR_DECL);
> 	  gimple *def_temp;
> 	  gimple_stmt_iterator gsi;
> 	  tree val = SSA_NAME_VAR (name);
>@@ -210,10 +209,10 @@ remap_ssa_name (tree name, copy_body_data *id)
> 	  n = id->decl_map->get (val);
> 	  if (n && TREE_CODE (*n) == DEBUG_EXPR_DECL)
> 	    return *n;
>-	  def_temp = gimple_build_debug_source_bind (vexpr, val, NULL);
>-	  DECL_ARTIFICIAL (vexpr) = 1;
>-	  TREE_TYPE (vexpr) = TREE_TYPE (name);
>+	  tree vexpr = build_debug_expr_decl (TREE_TYPE (name));
>+	  /* FIXME: Is setting the mode really necessary? */
> 	  SET_DECL_MODE (vexpr, DECL_MODE (SSA_NAME_VAR (name)));
>+	  def_temp = gimple_build_debug_source_bind (vexpr, val, NULL);
> 	  gsi = gsi_after_labels (single_succ (ENTRY_BLOCK_PTR_FOR_FN (cfun)));
> 	  gsi_insert_before (&gsi, def_temp, GSI_SAME_STMT);
> 	  insert_decl_map (id, val, vexpr);
>@@ -6450,9 +6449,8 @@ tree_function_versioning (tree old_decl, tree new_decl,
> 	      debug_args = decl_debug_args_insert (new_decl);
> 	      len = vec_safe_length (*debug_args);
> 	    }
>-	  ddecl = make_node (DEBUG_EXPR_DECL);
>-	  DECL_ARTIFICIAL (ddecl) = 1;
>-	  TREE_TYPE (ddecl) = TREE_TYPE (parm);
>+	  ddecl = build_debug_expr_decl (TREE_TYPE (parm));
>+	  /* FIXME: Is setting the mode really necessary? */
> 	  SET_DECL_MODE (ddecl, DECL_MODE (parm));
> 	  vec_safe_push (*debug_args, DECL_ORIGIN (parm));
> 	  vec_safe_push (*debug_args, ddecl);
>@@ -6488,9 +6486,8 @@ tree_function_versioning (tree old_decl, tree new_decl,
> 		  vexpr = *d;
> 	      if (!vexpr)
> 		{
>-		  vexpr = make_node (DEBUG_EXPR_DECL);
>-		  DECL_ARTIFICIAL (vexpr) = 1;
>-		  TREE_TYPE (vexpr) = TREE_TYPE (parm);
>+		  vexpr = build_debug_expr_decl (TREE_TYPE (parm));
>+		  /* FIXME: Is setting the mode really necessary? */
> 		  SET_DECL_MODE (vexpr, DECL_MODE (parm));
> 		}
> 	      def_temp = gimple_build_debug_bind (var, vexpr, NULL);
>diff --git a/gcc/tree-into-ssa.c b/gcc/tree-into-ssa.c
>index 8045e34df26..265dcc5d42f 100644
>--- a/gcc/tree-into-ssa.c
>+++ b/gcc/tree-into-ssa.c
>@@ -1284,11 +1284,10 @@ rewrite_debug_stmt_uses (gimple *stmt)
> 	      if (def == NULL_TREE)
> 		{
> 		  gimple *def_temp;
>-		  def = make_node (DEBUG_EXPR_DECL);
>-		  def_temp = gimple_build_debug_source_bind (def, var, NULL);
>-		  DECL_ARTIFICIAL (def) = 1;
>-		  TREE_TYPE (def) = TREE_TYPE (var);
>+		  def = build_debug_expr_decl (TREE_TYPE (var));
>+		  /* FIXME: Is setting the mode really necessary? */
> 		  SET_DECL_MODE (def, DECL_MODE (var));
>+		  def_temp = gimple_build_debug_source_bind (def, var, NULL);
> 		  gsi =
> 		 gsi_after_labels (single_succ (ENTRY_BLOCK_PTR_FOR_FN (cfun)));
> 		  gsi_insert_before (&gsi, def_temp, GSI_SAME_STMT);
>diff --git a/gcc/tree-ssa-loop-ivopts.c b/gcc/tree-ssa-loop-ivopts.c
>index 4a498abe3b0..5a7fd305d91 100644
>--- a/gcc/tree-ssa-loop-ivopts.c
>+++ b/gcc/tree-ssa-loop-ivopts.c
>@@ -7742,9 +7742,8 @@ remove_unused_ivs (struct ivopts_data *data, bitmap toremove)
> 	      comp = unshare_expr (comp);
> 	      if (count > 1)
> 		{
>-		  tree vexpr = make_node (DEBUG_EXPR_DECL);
>-		  DECL_ARTIFICIAL (vexpr) = 1;
>-		  TREE_TYPE (vexpr) = TREE_TYPE (comp);
>+		  tree vexpr = build_debug_expr_decl (TREE_TYPE (comp));
>+		  /* FIXME: Is setting the mode really necessary? */
> 		  if (SSA_NAME_VAR (def))
> 		    SET_DECL_MODE (vexpr, DECL_MODE (SSA_NAME_VAR (def)));
> 		  else
>diff --git a/gcc/tree-ssa.c b/gcc/tree-ssa.c
>index 3f25d654d3f..1565e21d983 100644
>--- a/gcc/tree-ssa.c
>+++ b/gcc/tree-ssa.c
>@@ -434,14 +434,13 @@ insert_debug_temp_for_var_def (gimple_stmt_iterator *gsi, tree var)
>       else
> 	{
> 	  gdebug *def_temp;
>-	  tree vexpr = make_node (DEBUG_EXPR_DECL);
>+	  tree vexpr = build_debug_expr_decl (TREE_TYPE (value));
> 
> 	  def_temp = gimple_build_debug_bind (vexpr,
> 					      unshare_expr (value),
> 					      def_stmt);
> 
>-	  DECL_ARTIFICIAL (vexpr) = 1;
>-	  TREE_TYPE (vexpr) = TREE_TYPE (value);
>+	  /* FIXME: Is setting the mode really necessary? */
> 	  if (DECL_P (value))
> 	    SET_DECL_MODE (vexpr, DECL_MODE (value));
> 	  else



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