Re: [PATCH] Fix ICE with statement frontiers (PR debug/83645)

[Richard Biener <rguenther at suse dot de>]

On January 3, 2018 9:42:01 PM GMT+01:00, Jakub Jelinek <jakub@redhat.com> wrote:
>Hi!
>
>When var-tracking pass isn't done (e.g. with -O2 -g -fno-var-tracking
>or -O2 -gstatement-frontiers), rest_of_handle_final calls
>variable_tracking_main in order to perform delete_vta_debug_insns
>- replace the debug marker insns with notes.  The problem with that is
>that final pass is after freeing cfg, so using
>FOR_EACH_BB/FOR_BB_INSNS_SAFE
>is incorrect as the attached patch shows, e.g. the barriers pass swaps
>a
>barrier with the statement notes and nothing updates the bb boundaries.
>
>Fixed by doing the replacements on the raw insn stream when called from
>final.c.  Bootstrapped/regtested on x86_64-linux and i686-linux, ok for
>trunk?

OK. 

Richard. 

>2018-01-03  Jakub Jelinek  <jakub@redhat.com>
>
>	PR debug/83645
>	* var-tracking.c (delete_vta_debug_insn): New inline function.
>	(delete_vta_debug_insns): Add USE_CFG argument, if true, walk just
>	insns from get_insns () to NULL instead of each bb separately.
>	Use delete_vta_debug_insn.  No longer static.
>	(vt_debug_insns_local, variable_tracking_main_1): Adjust
>	delete_vta_debug_insns callers.
>	* rtl.h (delete_vta_debug_insns): Declare.
>	* final.c (rest_of_handle_final): Call delete_vta_debug_insns
>	instead of variable_tracking_main.
>
>	* gcc.dg/pr83645.c: New test.
>
>--- gcc/var-tracking.c.jj	2018-01-03 10:19:54.385533834 +0100
>+++ gcc/var-tracking.c	2018-01-03 16:01:48.608217538 +0100
>@@ -10271,11 +10271,40 @@ vt_initialize (void)
> 
> static int debug_label_num = 1;
> 
>+/* Remove from the insn stream a single debug insn used for
>+   variable tracking at assignments.  */
>+
>+static inline void
>+delete_vta_debug_insn (rtx_insn *insn)
>+{
>+  if (DEBUG_MARKER_INSN_P (insn))
>+    {
>+      reemit_marker_as_note (insn);
>+      return;
>+    }
>+
>+  tree decl = INSN_VAR_LOCATION_DECL (insn);
>+  if (TREE_CODE (decl) == LABEL_DECL
>+      && DECL_NAME (decl)
>+      && !DECL_RTL_SET_P (decl))
>+    {
>+      PUT_CODE (insn, NOTE);
>+      NOTE_KIND (insn) = NOTE_INSN_DELETED_DEBUG_LABEL;
>+      NOTE_DELETED_LABEL_NAME (insn)
>+	= IDENTIFIER_POINTER (DECL_NAME (decl));
>+      SET_DECL_RTL (decl, insn);
>+      CODE_LABEL_NUMBER (insn) = debug_label_num++;
>+    }
>+  else
>+    delete_insn (insn);
>+}
>+
> /* Remove from the insn stream all debug insns used for variable
>-   tracking at assignments.  */
>+   tracking at assignments.  USE_CFG should be false if the cfg is no
>+   longer usable.  */
> 
>-static void
>-delete_vta_debug_insns (void)
>+void
>+delete_vta_debug_insns (bool use_cfg)
> {
>   basic_block bb;
>   rtx_insn *insn, *next;
>@@ -10283,33 +10312,20 @@ delete_vta_debug_insns (void)
>   if (!MAY_HAVE_DEBUG_INSNS)
>     return;
> 
>-  FOR_EACH_BB_FN (bb, cfun)
>-    {
>-      FOR_BB_INSNS_SAFE (bb, insn, next)
>+  if (use_cfg)
>+    FOR_EACH_BB_FN (bb, cfun)
>+      {
>+	FOR_BB_INSNS_SAFE (bb, insn, next)
>+	  if (DEBUG_INSN_P (insn))
>+	    delete_vta_debug_insn (insn);
>+      }
>+  else
>+    for (insn = get_insns (); insn; insn = next)
>+      {
>+	next = NEXT_INSN (insn);
> 	if (DEBUG_INSN_P (insn))
>-	  {
>-	    if (DEBUG_MARKER_INSN_P (insn))
>-	      {
>-		reemit_marker_as_note (insn);
>-		continue;
>-	      }
>-
>-	    tree decl = INSN_VAR_LOCATION_DECL (insn);
>-	    if (TREE_CODE (decl) == LABEL_DECL
>-		&& DECL_NAME (decl)
>-		&& !DECL_RTL_SET_P (decl))
>-	      {
>-		PUT_CODE (insn, NOTE);
>-		NOTE_KIND (insn) = NOTE_INSN_DELETED_DEBUG_LABEL;
>-		NOTE_DELETED_LABEL_NAME (insn)
>-		  = IDENTIFIER_POINTER (DECL_NAME (decl));
>-		SET_DECL_RTL (decl, insn);
>-		CODE_LABEL_NUMBER (insn) = debug_label_num++;
>-	      }
>-	    else
>-	      delete_insn (insn);
>-	  }
>-    }
>+	  delete_vta_debug_insn (insn);
>+      }
> }
> 
> /* Run a fast, BB-local only version of var tracking, to take care of
>@@ -10322,7 +10338,7 @@ static void
> vt_debug_insns_local (bool skipped ATTRIBUTE_UNUSED)
> {
>   /* ??? Just skip it all for now.  */
>-  delete_vta_debug_insns ();
>+  delete_vta_debug_insns (true);
> }
> 
> /* Free the data structures needed for variable tracking.  */
>@@ -10395,7 +10411,7 @@ variable_tracking_main_1 (void)
> 	 any pseudos at this point.  */
>       || targetm.no_register_allocation)
>     {
>-      delete_vta_debug_insns ();
>+      delete_vta_debug_insns (true);
>       return 0;
>     }
> 
>@@ -10423,7 +10439,7 @@ variable_tracking_main_1 (void)
>     {
>       vt_finalize ();
> 
>-      delete_vta_debug_insns ();
>+      delete_vta_debug_insns (true);
> 
>       /* This is later restored by our caller.  */
>       flag_var_tracking_assignments = 0;
>--- gcc/rtl.h.jj	2018-01-03 10:19:55.184533962 +0100
>+++ gcc/rtl.h	2018-01-03 15:56:13.089080504 +0100
>@@ -4254,6 +4254,7 @@ extern GTY(()) rtx stack_limit_rtx;
> 
> /* In var-tracking.c */
> extern unsigned int variable_tracking_main (void);
>+extern void delete_vta_debug_insns (bool);
> 
> /* In stor-layout.c.  */
> extern void get_mode_bounds (scalar_int_mode, int,
>--- gcc/final.c.jj	2018-01-03 10:19:54.049533777 +0100
>+++ gcc/final.c	2018-01-03 15:56:48.509091487 +0100
>@@ -4544,7 +4544,7 @@ rest_of_handle_final (void)
>   /* Turn debug markers into notes if the var-tracking pass has not
>      been invoked.  */
>   if (!flag_var_tracking && MAY_HAVE_DEBUG_MARKER_INSNS)
>-    variable_tracking_main ();
>+    delete_vta_debug_insns (false);
> 
>   assemble_start_function (current_function_decl, fnname);
>   final_start_function (get_insns (), asm_out_file, optimize);
>--- gcc/testsuite/gcc.dg/pr83645.c.jj	2018-01-03 15:57:37.669106731
>+0100
>+++ gcc/testsuite/gcc.dg/pr83645.c	2018-01-03 15:57:06.575097090 +0100
>@@ -0,0 +1,14 @@
>+/* PR debug/83645 */
>+/* { dg-do compile } */
>+/* { dg-options "-O2 -g -fno-var-tracking" } */
>+
>+int a, b, c[1];
>+
>+void
>+foo (void)
>+{
>+  int i = 0;
>+  b = a;
>+  for (;;)
>+    c[i++] = 7;
>+}
>
>	Jakub