Backported from mainline

	2017-09-14  Jakub Jelinek  <jakub@redhat.com>
 
	PR target/81325
	* cfgbuild.c (find_bb_boundaries): Ignore debug insns in decisions
	if and where to split a bb, except for splitting before debug insn
	sequences followed by non-label real insn.  Delete debug insns
	in between basic blocks.

	* g++.dg/cpp0x/pr81325.C: New test.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/branches/gcc-7-branch@252805 138bc75d-0d04-0410-961f-82ee72b054a4

4 files changed, 138 insertions, 12 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 0cdc16860df..67ca1a75ed3 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,6 +1,14 @@
 2017-09-15  Jakub Jelinek  <jakub@redhat.com>
 
 	Backported from mainline
+	2017-09-14  Jakub Jelinek  <jakub@redhat.com>
+ 
+	PR target/81325
+	* cfgbuild.c (find_bb_boundaries): Ignore debug insns in decisions
+	if and where to split a bb, except for splitting before debug insn
+	sequences followed by non-label real insn.  Delete debug insns
+	in between basic blocks.
+
 	2017-09-12  Jakub Jelinek  <jakub@redhat.com>
 
 	PR target/82112
diff --git a/gcc/cfgbuild.c b/gcc/cfgbuild.c
index 69ca1282c37..238954a1cfa 100644
--- a/gcc/cfgbuild.c
+++ b/gcc/cfgbuild.c
@@ -442,9 +442,10 @@ find_bb_boundaries (basic_block bb)
   rtx_insn *end = BB_END (bb), *x;
   rtx_jump_table_data *table;
   rtx_insn *flow_transfer_insn = NULL;
+  rtx_insn *debug_insn = NULL;
   edge fallthru = NULL;
 
-  if (insn == BB_END (bb))
+  if (insn == end)
     return;
 
   if (LABEL_P (insn))
@@ -455,27 +456,49 @@ find_bb_boundaries (basic_block bb)
     {
       enum rtx_code code = GET_CODE (insn);
 
+      if (code == DEBUG_INSN)
+	{
+	  if (flow_transfer_insn && !debug_insn)
+	    debug_insn = insn;
+	}
       /* In case we've previously seen an insn that effects a control
 	 flow transfer, split the block.  */
-      if ((flow_transfer_insn || code == CODE_LABEL)
-	  && inside_basic_block_p (insn))
+      else if ((flow_transfer_insn || code == CODE_LABEL)
+	       && inside_basic_block_p (insn))
 	{
-	  fallthru = split_block (bb, PREV_INSN (insn));
+	  rtx_insn *prev = PREV_INSN (insn);
+
+	  /* If the first non-debug inside_basic_block_p insn after a control
+	     flow transfer is not a label, split the block before the debug
+	     insn instead of before the non-debug insn, so that the debug
+	     insns are not lost.  */
+	  if (debug_insn && code != CODE_LABEL && code != BARRIER)
+	    prev = PREV_INSN (debug_insn);
+	  fallthru = split_block (bb, prev);
 	  if (flow_transfer_insn)
 	    {
 	      BB_END (bb) = flow_transfer_insn;
 
+	      rtx_insn *next;
 	      /* Clean up the bb field for the insns between the blocks.  */
 	      for (x = NEXT_INSN (flow_transfer_insn);
 		   x != BB_HEAD (fallthru->dest);
-		   x = NEXT_INSN (x))
-		if (!BARRIER_P (x))
-		  set_block_for_insn (x, NULL);
+		   x = next)
+		{
+		  next = NEXT_INSN (x);
+		  /* Debug insns should not be in between basic blocks,
+		     drop them on the floor.  */
+		  if (DEBUG_INSN_P (x))
+		    delete_insn (x);
+		  else if (!BARRIER_P (x))
+		    set_block_for_insn (x, NULL);
+		}
 	    }
 
 	  bb = fallthru->dest;
 	  remove_edge (fallthru);
 	  flow_transfer_insn = NULL;
+	  debug_insn = NULL;
 	  if (code == CODE_LABEL && LABEL_ALT_ENTRY_P (insn))
 	    make_edge (ENTRY_BLOCK_PTR_FOR_FN (cfun), bb, 0);
 	}
@@ -498,17 +521,23 @@ find_bb_boundaries (basic_block bb)
   /* In case expander replaced normal insn by sequence terminating by
      return and barrier, or possibly other sequence not behaving like
      ordinary jump, we need to take care and move basic block boundary.  */
-  if (flow_transfer_insn)
+  if (flow_transfer_insn && flow_transfer_insn != end)
     {
       BB_END (bb) = flow_transfer_insn;
 
       /* Clean up the bb field for the insns that do not belong to BB.  */
-      x = flow_transfer_insn;
-      while (x != end)
+      rtx_insn *next;
+      for (x = NEXT_INSN (flow_transfer_insn); ; x = next)
 	{
-	  x = NEXT_INSN (x);
-	  if (!BARRIER_P (x))
+	  next = NEXT_INSN (x);
+	  /* Debug insns should not be in between basic blocks,
+	     drop them on the floor.  */
+	  if (DEBUG_INSN_P (x))
+	    delete_insn (x);
+	  else if (!BARRIER_P (x))
 	    set_block_for_insn (x, NULL);
+	  if (x == end)
+	    break;
 	}
     }
 
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index c2eaa6296ab..b8b5f2eacff 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,6 +1,11 @@
 2017-09-15  Jakub Jelinek  <jakub@redhat.com>
 
 	Backported from mainline
+	2017-09-14  Jakub Jelinek  <jakub@redhat.com>
+ 
+	PR target/81325
+	* g++.dg/cpp0x/pr81325.C: New test.
+
 	2017-09-12  Jakub Jelinek  <jakub@redhat.com>
 
 	PR target/82112
diff --git a/gcc/testsuite/g++.dg/cpp0x/pr81325.C b/gcc/testsuite/g++.dg/cpp0x/pr81325.C
new file mode 100644
index 00000000000..11f0900caa2
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/pr81325.C
@@ -0,0 +1,84 @@
+// PR target/81325
+// { dg-do compile { target c++11 } }
+// { dg-options "-O2 -fcompare-debug" }
+
+struct A { A(const char *, const int & = 0); };
+template <typename> struct B;
+template <typename> struct C {
+  int _M_i;
+  void m_fn1() { __atomic_fetch_add(&_M_i, 0, __ATOMIC_RELAXED); }
+};
+struct D {
+  int *Data;
+  long Length = 0;
+  D(int) : Data() {}
+};
+template <> struct B<int> : C<int> {};
+struct F {
+  B<int> RefCount;
+  void m_fn2() { RefCount.m_fn1(); }
+};
+struct G {
+  F *Obj;
+  G(const G &p1) : Obj(p1.Obj) {
+    if (Obj) {
+      F *a = 0;
+      a->m_fn2();
+    }
+  }
+};
+struct H {
+  int CPlusPlus : 1;
+};
+struct I {
+  enum {} KindId;
+};
+template <typename ResultT, typename ArgT> struct J {
+  void operator()();
+  ResultT operator()(ArgT) {}
+};
+struct K {
+  int AllowBind;
+  I SupportedKind;
+  I RestrictKind;
+  G Implementation;
+};
+struct L {
+  L(int) : Implementation(Implementation) {}
+  K Implementation;
+};
+struct M {
+  int Param1;
+};
+struct N {
+  N(int, L &p2) : Param2(p2) {}
+  L Param2;
+};
+struct O {
+  L m_fn3();
+};
+L ignoringImpCasts(L);
+J<O, L> b;
+L hasName(const A &);
+M hasOverloadedOperatorName(D);
+J<O, int> c;
+struct P {
+  void m_fn4(L, int);
+};
+struct Q {
+  void m_fn5(P *);
+};
+H d;
+void Q::m_fn5(P *p1) {
+  if (!d.CPlusPlus) {
+    c();
+    L e = 0, f = ignoringImpCasts(e);
+    b(ignoringImpCasts(f)).m_fn3();
+  }
+  hasOverloadedOperatorName(0);
+  hasName("");
+  L g = 0;
+  N(0, g);
+  L h(0);
+  p1->m_fn4(h, 0);
+}