re PR debug/83084 (-fcompare-debug failure on ppc64le)

	PR debug/83084
	* valtrack.c (propagate_for_debug_subst, propagate_for_debug): Reset
	debug insns if they would contain UNSPEC_VOLATILE or volatile asm.
	(dead_debug_insert_temp): Likewise, but also ignore even non-volatile
	asm.

	* g++.dg/opt/pr83084.C: New test.

From-SVN: r255051

gcc/ChangeLog

 2017-11-22  Jakub Jelinek  <jakub@redhat.com>
 
+	PR debug/83084
+	* valtrack.c (propagate_for_debug_subst, propagate_for_debug): Reset
+	debug insns if they would contain UNSPEC_VOLATILE or volatile asm.
+	(dead_debug_insert_temp): Likewise, but also ignore even non-volatile
+	asm.
+
 	PR middle-end/82875
 	* optabs.c (expand_doubleword_mult, expand_binop): Before calling
 	expand_binop with *mul_widen_optab, make sure at least one of the

gcc/testsuite/ChangeLog

 2017-11-22  Jakub Jelinek  <jakub@redhat.com>
 
+	PR debug/83084
+	* g++.dg/opt/pr83084.C: New test.
+
 	PR middle-end/82875
 	* gcc.dg/pr82875.c: New test.
 	* gcc.c-torture/compile/pr82875.c: New test.
 
-2017-11-22  Jakub Jelinek  <jakub@redhat.com>
-
 	PR debug/83034
 	* gcc.dg/pr83034.c: New test.
 

gcc/testsuite/g++.dg/opt/pr83084.C

+// PR debug/83084
+// { dg-do compile }
+// { dg-options "-O2 -fcompare-debug -Wno-return-type" }
+
+enum E { F };
+template <E = F> struct A {
+  bool foo ();
+  int b;
+};
+template <> bool A<>::foo () {
+  int a;
+  do
+    if (a)
+      return false;
+  while (__atomic_compare_exchange_n (&b, &a, 0, 1, 4, 0));
+}

gcc/valtrack.c

@@ -171,10 +171,13 @@ propagate_for_debug_subst (rtx from, const_rtx old_rtx, void *data)
 	if (REG_P (*iter) && ++cnt > 1)
 	  {
 	    rtx dval = make_debug_expr_from_rtl (old_rtx);
+	    rtx to = pair->to;
+	    if (volatile_insn_p (to))
+	      to = gen_rtx_UNKNOWN_VAR_LOC ();
 	    /* Emit a debug bind insn.  */
 	    rtx bind
 	      = gen_rtx_VAR_LOCATION (GET_MODE (old_rtx),
-				      DEBUG_EXPR_TREE_DECL (dval), pair->to,
+				      DEBUG_EXPR_TREE_DECL (dval), to,
 				      VAR_INIT_STATUS_INITIALIZED);
 	    rtx_insn *bind_insn = emit_debug_insn_before (bind, pair->insn);
 	    df_insn_rescan (bind_insn);
@@ -217,6 +220,8 @@ propagate_for_debug (rtx_insn *insn, rtx_insn *last, rtx dest, rtx src,
 					 dest, propagate_for_debug_subst, &p);
 	  if (loc == INSN_VAR_LOCATION_LOC (insn))
 	    continue;
+	  if (volatile_insn_p (loc))
+	    loc = gen_rtx_UNKNOWN_VAR_LOC ();
 	  INSN_VAR_LOCATION_LOC (insn) = loc;
 	  df_insn_rescan (insn);
 	}
@@ -660,6 +665,12 @@ dead_debug_insert_temp (struct dead_debug_local *debug, unsigned int uregno,
 		}
 	      return 0;
 	    }
+	  /* Asm in DEBUG_INSN is never useful, we can't emit debug info for
+	     that.  And for volatile_insn_p, it is actually harmful
+	     - DEBUG_INSNs shouldn't have any side-effects.  */
+	  else if (GET_CODE (src) == ASM_OPERANDS
+		   || volatile_insn_p (src))
+	    set = NULL_RTX;
 	}
 
       /* ??? Should we try to extract it from a PARALLEL?  */