re PR tree-optimization/84960 (ICE in GIMPLE pass: isolate-paths)

	PR tree-optimization/84960
	* tree-cfg.c (remove_bb): Don't move forced labels into bb->prev_bb
	if it is ENTRY block, move them into single succ of ENTRY in that case.

	* gcc.c-torture/compile/pr84960.c: New test.

From-SVN: r258744

gcc/ChangeLog

+2018-03-21  Jakub Jelinek  <jakub@redhat.com>
+
+	PR tree-optimization/84960
+	* tree-cfg.c (remove_bb): Don't move forced labels into bb->prev_bb
+	if it is ENTRY block, move them into single succ of ENTRY in that case.
+
 2018-03-21  Richard Sandiford  <richard.sandiford@linaro.org>
 
 	PR tree-optimization/84811

gcc/testsuite/ChangeLog

+2018-03-21  Jakub Jelinek  <jakub@redhat.com>
+
+	PR tree-optimization/84960
+	* gcc.c-torture/compile/pr84960.c: New test.
+
 2018-03-21  Richard Sandiford  <richard.sandiford@linaro.org>
 
 	PR tree-optimization/84811

gcc/testsuite/gcc.c-torture/compile/pr84960.c

+/* PR tree-optimization/84960 */
+/* { dg-do compile { target indirect_jumps } } */
+
+void
+foo (unsigned int a, float b, void *c)
+{
+lab:
+  if ((b - (a %= 0) < 1U) * -1U)
+    ;
+  else
+    {
+      unsigned int f = a;
+      __builtin_unreachable ();
+      c = &&lab;
+    }
+  goto *c;
+}

gcc/tree-cfg.c

@@ -2301,6 +2301,12 @@ remove_bb (basic_block bb)
 		}
 
 	      new_bb = bb->prev_bb;
+	      /* Don't move any labels into ENTRY block.  */
+	      if (new_bb == ENTRY_BLOCK_PTR_FOR_FN (cfun))
+		{
+		  new_bb = single_succ (new_bb);
+		  gcc_assert (new_bb != bb);
+		}
 	      new_gsi = gsi_start_bb (new_bb);
 	      gsi_remove (&i, false);
 	      gsi_insert_before (&new_gsi, stmt, GSI_NEW_STMT);