haifa-sched.c (reemit_other_notes): New.

        * haifa-sched.c (reemit_other_notes): New.
        (schedule_block): Use it.
        * sched-ebb.c (schedule_ebbs): Call remove_unnecessary_notes.
        * sched-rgn.c (schedule_insns): Likewise.
        * cfglayout.c (remove_scope_notes): Handle removing note at
        the end of the insn chain.
        * function.c (debug_find_var_in_block_tree): New.

        * gcc.dg/debug-1.c, gcc.dg/debug-2.c: New.

From-SVN: r48333

9 files changed, 138 insertions, 19 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index e42d64be1ff..c6c6b921e2a 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,13 @@
+2001-12-27  Richard Henderson  <rth@redhat.com>
+
+	* haifa-sched.c (reemit_other_notes): New.
+	(schedule_block): Use it.
+	* sched-ebb.c (schedule_ebbs): Call remove_unnecessary_notes.
+	* sched-rgn.c (schedule_insns): Likewise.
+	* cfglayout.c (remove_scope_notes): Handle removing note at
+	the end of the insn chain.
+	* function.c (debug_find_var_in_block_tree): New.
+
 2001-12-27  Alan Modra  <amodra@bigpond.net.au>
 	    David Edelsohn  <edelsohn@gnu.org>
 
diff --git a/gcc/cfglayout.c b/gcc/cfglayout.c
index 14f08eb39ef..e0adb53c71a 100644
--- a/gcc/cfglayout.c
+++ b/gcc/cfglayout.c
@@ -540,7 +540,8 @@ remove_scope_notes ()
 	  if (PREV_INSN (x))
 	    {
 	      NEXT_INSN (PREV_INSN (x)) = next;
-	      PREV_INSN (next) = PREV_INSN (x);
+	      if (next)
+	        PREV_INSN (next) = PREV_INSN (x);
 
               NEXT_INSN (x) = NULL;
               PREV_INSN (x) = NULL;
diff --git a/gcc/function.c b/gcc/function.c
index f5a3102bf4d..097aea44684 100644
--- a/gcc/function.c
+++ b/gcc/function.c
@@ -277,6 +277,7 @@ static void reorder_fix_fragments PARAMS ((tree));
 static tree blocks_nreverse	PARAMS ((tree));
 static int all_blocks		PARAMS ((tree, tree *));
 static tree *get_block_vector   PARAMS ((tree, int *));
+extern tree debug_find_var_in_block_tree PARAMS ((tree, tree));
 /* We always define `record_insns' even if its not used so that we
    can always export `prologue_epilogue_contains'.  */
 static void record_insns	PARAMS ((rtx, varray_type *)) ATTRIBUTE_UNUSED;
@@ -6051,6 +6052,29 @@ number_blocks (fn)
 
   return;
 }
+
+/* If VAR is present in a subblock of BLOCK, return the subblock.  */
+
+tree
+debug_find_var_in_block_tree (var, block)
+     tree var;
+     tree block;
+{
+  tree t;
+
+  for (t = BLOCK_VARS (block); t; t = TREE_CHAIN (t))
+    if (t == var)
+      return block;
+
+  for (t = BLOCK_SUBBLOCKS (block); t; t = TREE_CHAIN (t))
+    {
+      tree ret = debug_find_var_in_block_tree (var, t);
+      if (ret)
+	return ret;
+    }
+
+  return NULL_TREE;
+}
 
 /* Allocate a function structure and reset its contents to the defaults.  */
 
diff --git a/gcc/haifa-sched.c b/gcc/haifa-sched.c
index 7b9a2e82126..ca6cfbb1d4f 100644
--- a/gcc/haifa-sched.c
+++ b/gcc/haifa-sched.c
@@ -319,6 +319,7 @@ static void adjust_priority PARAMS ((rtx));
 static rtx unlink_other_notes PARAMS ((rtx, rtx));
 static rtx unlink_line_notes PARAMS ((rtx, rtx));
 static rtx reemit_notes PARAMS ((rtx, rtx));
+static rtx reemit_other_notes PARAMS ((rtx, rtx));
 
 static rtx *ready_lastpos PARAMS ((struct ready_list *));
 static void ready_sort PARAMS ((struct ready_list *));
@@ -1575,6 +1576,60 @@ reemit_notes (insn, last)
   return retval;
 }
 
+
+/* NOTE_LIST is the end of a chain of notes previously found among the
+   insns.  Insert them at the beginning of the insns.  Actually, insert
+   NOTE_INSN_BLOCK_END notes at the end of the insns.  Doing otherwise
+   tends to collapse lexical blocks into empty regions, which is somewhat
+   less than useful.  */
+/* ??? Ideally we'd mark each insn with the block it originated from,
+   and preserve that information.  This requires some moderately
+   sophisticated block reconstruction code, since block nestings must
+   be preserved.  */
+
+static rtx
+reemit_other_notes (head, tail)
+     rtx head, tail;
+{
+  bool saw_block_beg = false;
+
+  while (note_list)
+    {
+      rtx note_tail = note_list;
+      note_list = PREV_INSN (note_tail);
+
+      if (NOTE_LINE_NUMBER (note_tail) == NOTE_INSN_BLOCK_END
+	  /* We can only extend the lexical block while we havn't
+	     seen a BLOCK_BEG note.  Otherwise we risk mis-nesting
+	     the notes.  */
+	  && ! saw_block_beg)
+	{
+	  rtx insert_after = tail;
+	  if (GET_CODE (NEXT_INSN (tail)) == BARRIER)
+	    insert_after = NEXT_INSN (tail);
+
+	  PREV_INSN (note_tail) = insert_after;
+	  NEXT_INSN (note_tail) = NEXT_INSN (insert_after);
+	  if (NEXT_INSN (insert_after))
+	    PREV_INSN (NEXT_INSN (insert_after)) = note_tail;
+	  NEXT_INSN (insert_after) = note_tail;
+	}
+      else
+	{
+	  if (NOTE_LINE_NUMBER (note_tail) == NOTE_INSN_BLOCK_BEG)
+	    saw_block_beg = true;
+
+	  PREV_INSN (note_tail) = PREV_INSN (head);
+	  NEXT_INSN (PREV_INSN (head)) = note_tail;
+	  NEXT_INSN (note_tail) = head;
+	  PREV_INSN (head) = note_tail;
+	  head = note_tail;
+	}
+    }
+
+  return head;
+}
+
 /* Move INSN, and all insns which should be issued before it,
    due to SCHED_GROUP_P flag.  Reemit notes if needed.
 
@@ -1800,24 +1855,7 @@ schedule_block (b, rgn_n_insns)
   head = NEXT_INSN (prev_head);
   tail = last;
 
-  /* Restore-other-notes: NOTE_LIST is the end of a chain of notes
-     previously found among the insns.  Insert them at the beginning
-     of the insns.  */
-  if (note_list != 0)
-    {
-      rtx note_head = note_list;
-
-      while (PREV_INSN (note_head))
-	{
-	  note_head = PREV_INSN (note_head);
-	}
-
-      PREV_INSN (note_head) = PREV_INSN (head);
-      NEXT_INSN (PREV_INSN (head)) = note_head;
-      PREV_INSN (head) = note_list;
-      NEXT_INSN (note_list) = head;
-      head = note_head;
-    }
+  head = reemit_other_notes (head, tail);
 
   /* Debugging.  */
   if (sched_verbose)
diff --git a/gcc/sched-ebb.c b/gcc/sched-ebb.c
index d4a9f777653..13b9fe6602d 100644
--- a/gcc/sched-ebb.c
+++ b/gcc/sched-ebb.c
@@ -285,6 +285,10 @@ schedule_ebbs (dump_file)
   if (n_basic_blocks == 0)
     return;
 
+  /* Remove lexical block notes for empty regions.  These get shuffled
+     about during scheduling and confuse the debugging issue.  */
+  remove_unnecessary_notes ();
+
   sched_init (dump_file);
 
   current_sched_info = &ebb_sched_info;
diff --git a/gcc/sched-rgn.c b/gcc/sched-rgn.c
index ab5adee8159..68242046221 100644
--- a/gcc/sched-rgn.c
+++ b/gcc/sched-rgn.c
@@ -2896,6 +2896,10 @@ schedule_insns (dump_file)
   if (n_basic_blocks == 0)
     return;
 
+  /* Remove lexical block notes for empty regions.  These get shuffled
+     about during scheduling and confuse the debugging issue.  */
+  remove_unnecessary_notes ();
+
   nr_inter = 0;
   nr_spec = 0;
 
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 698296b87a0..915a148a432 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,7 @@
+2001-12-27  Richard Henderson  <rth@redhat.com>
+
+	* gcc.dg/debug-1.c, gcc.dg/debug-2.c: New.
+
 2001-12-26  Nathan Sidwell  <nathan@codesourcery.com>
 
 	* g++.dg/eh/ctor1.C: New test.
diff --git a/gcc/testsuite/gcc.dg/debug-1.c b/gcc/testsuite/gcc.dg/debug-1.c
new file mode 100644
index 00000000000..1e53b14eb5c
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/debug-1.c
@@ -0,0 +1,14 @@
+/* Verify that the scheduler does not discard the lexical block.  */
+/* { dg-do compile } */
+/* { dg-options "-O2 -g -dA" } */
+/* { dg-final { scan-assembler "xyzzy" } } */
+
+long foo(long p)
+{
+  {
+    long xyzzy = 0;
+    if (p)
+      xyzzy = 2;
+    return xyzzy;
+  }
+}
diff --git a/gcc/testsuite/gcc.dg/debug-2.c b/gcc/testsuite/gcc.dg/debug-2.c
new file mode 100644
index 00000000000..4305059ba7b
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/debug-2.c
@@ -0,0 +1,20 @@
+/* Verify that the scheduler does not discard the lexical block.  */
+/* { dg-do compile } */
+/* { dg-options "-O2 -g -dA" } */
+/* { dg-final { scan-assembler "xyzzy" } } */
+
+long foo(long p)
+{
+  if (1)
+    {
+      long xyzzy = 0;
+      if (p)
+        xyzzy = 2;
+      return xyzzy;
+    }
+  else
+    {
+      int x = 0;
+      return x;
+    }
+}