[PATCH] Add cgraph edge for early fixup_cfg inserted __builtin_unreachable (PR target/71910)

[Jakub Jelinek]

Hi!

In cross to mingw we ICE on the following testcase, because fixup_cfg pass
adds __builtin_unreachable call without adding corresponding cgraph_edge
(the body of the parallel region doesn't return, so while GOMP_parallel
isn't a noreturn function, it will actually never return).

Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

Or is there a better check on when we care about the cgraph edges being
maintained?

2016-08-08  Jakub Jelinek  <ja...@redhat.com>

        PR target/71910
        * tree-cfg.c (execute_fixup_cfg): Add node variable, use it.  Before 
inlining,
        add cgraph edge for the added __builtin_unreachable call.

        * g++.dg/gomp/pr71910.C: New test.

--- gcc/tree-cfg.c.jj   2016-07-14 20:28:33.000000000 +0200
+++ gcc/tree-cfg.c      2016-08-08 10:38:52.124012808 +0200
@@ -8987,16 +8987,14 @@ execute_fixup_cfg (void)
   gcov_type count_scale;
   edge e;
   edge_iterator ei;
+  cgraph_node *node = cgraph_node::get (current_function_decl);
 
   count_scale
-      = GCOV_COMPUTE_SCALE (cgraph_node::get (current_function_decl)->count,
-                           ENTRY_BLOCK_PTR_FOR_FN (cfun)->count);
+    = GCOV_COMPUTE_SCALE (node->count, ENTRY_BLOCK_PTR_FOR_FN (cfun)->count);
 
-  ENTRY_BLOCK_PTR_FOR_FN (cfun)->count =
-                           cgraph_node::get (current_function_decl)->count;
-  EXIT_BLOCK_PTR_FOR_FN (cfun)->count =
-                           apply_scale (EXIT_BLOCK_PTR_FOR_FN (cfun)->count,
-                                       count_scale);
+  ENTRY_BLOCK_PTR_FOR_FN (cfun)->count = node->count;
+  EXIT_BLOCK_PTR_FOR_FN (cfun)->count
+    = apply_scale (EXIT_BLOCK_PTR_FOR_FN (cfun)->count, count_scale);
 
   FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR_FOR_FN (cfun)->succs)
     e->count = apply_scale (e->count, count_scale);
@@ -9089,10 +9087,19 @@ execute_fixup_cfg (void)
            {
              if (stmt && is_gimple_call (stmt))
                gimple_call_set_ctrl_altering (stmt, false);
-             stmt = gimple_build_call
-                 (builtin_decl_implicit (BUILT_IN_UNREACHABLE), 0);
+             tree fndecl = builtin_decl_implicit (BUILT_IN_UNREACHABLE);
+             stmt = gimple_build_call (fndecl, 0);
              gimple_stmt_iterator gsi = gsi_last_bb (bb);
              gsi_insert_after (&gsi, stmt, GSI_NEW_STMT);
+             if (!cfun->after_inlining)
+               {
+                 gcall *call_stmt = dyn_cast <gcall *> (stmt);
+                 int freq
+                   = compute_call_stmt_bb_frequency (current_function_decl,
+                                                     bb);
+                 node->create_edge (cgraph_node::get_create (fndecl),
+                                    call_stmt, bb->count, freq);
+               }
            }
        }
     }
--- gcc/testsuite/g++.dg/gomp/pr71910.C.jj      2016-08-08 10:39:57.810197176 
+0200
+++ gcc/testsuite/g++.dg/gomp/pr71910.C 2016-08-08 10:40:22.608886749 +0200
@@ -0,0 +1,13 @@
+// PR target/71910
+// { dg-do compile }
+// { dg-additional-options "-O2" }
+
+#include <vector>
+
+int
+main ()
+{
+  std::vector<double> vec(10);
+#pragma omp parallel
+  __builtin_exit (0);
+}

        Jakub