[C++] Protect call to copy_attributes_to_builtin (PR91505)

[thirdparty/gcc.git] / gcc / mode-switching.c

diff --git a/gcc/mode-switching.c b/gcc/mode-switching.c
index c391c0b123876e69719e3c7de579d22f27d594b5..2ff21a400813f4be4cc2ae2dde651a4f02f40ec4 100644 (file)
--- a/gcc/mode-switching.c
+++ b/gcc/mode-switching.c
@@ -1,5 +1,5 @@
 /* CPU mode switching
-   Copyright (C) 1998-2017 Free Software Foundation, Inc.
+   Copyright (C) 1998-2019 Free Software Foundation, Inc.
 
 This file is part of GCC.
 
@@ -248,8 +248,22 @@ create_pre_exit (int n_entities, int *entity_map, const int *num_modes)
        gcc_assert (!pre_exit);
        /* If this function returns a value at the end, we have to
           insert the final mode switch before the return value copy
-          to its hard register.  */
-       if (EDGE_COUNT (EXIT_BLOCK_PTR_FOR_FN (cfun)->preds) == 1
+          to its hard register.
+
+          x86 targets use mode-switching infrastructure to
+          conditionally insert vzeroupper instruction at the exit
+          from the function where there is no need to switch the
+          mode before the return value copy.  The vzeroupper insertion
+          pass runs after reload, so use !reload_completed as a stand-in
+          for x86 to skip the search for the return value copy insn.
+
+          N.b.: the code below assumes that the return copy insn
+          immediately precedes its corresponding use insn.  This
+          assumption does not hold after reload, since sched1 pass
+          can schedule the return copy insn away from its
+          corresponding use insn.  */
+       if (!reload_completed
+           && EDGE_COUNT (EXIT_BLOCK_PTR_FOR_FN (cfun)->preds) == 1
            && NONJUMP_INSN_P ((last_insn = BB_END (src_bb)))
            && GET_CODE (PATTERN (last_insn)) == USE
            && GET_CODE ((ret_reg = XEXP (PATTERN (last_insn), 0))) == REG)
@@ -842,7 +856,10 @@ optimize_mode_switching (void)
     commit_edge_insertions ();
 
   if (targetm.mode_switching.entry && targetm.mode_switching.exit)
-    cleanup_cfg (CLEANUP_NO_INSN_DEL);
+    {
+      free_dominance_info (CDI_DOMINATORS);
+      cleanup_cfg (CLEANUP_NO_INSN_DEL);
+    }
   else if (!need_commit && !emitted)
     return 0;