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

Jakub Jelinek jakub@redhat.com
Wed Jan 3 20:42:00 GMT 2018


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?

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



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