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From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug sanitizer/64265] [5 Regression] r217669 broke tsan
Date: Fri, 12 Dec 2014 13:36:00 -0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64265

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
static void
instrument_func_entry (void)
{
  basic_block succ_bb;
  gimple_stmt_iterator gsi;
  tree ret_addr, builtin_decl;
  gimple g;

  succ_bb = single_succ (ENTRY_BLOCK_PTR_FOR_FN (cfun));
  gsi = gsi_after_labels (succ_bb);

indeed.

It should do

  succ_bb = split_edge (single_succ_edge (ENTRY_BLOCK_PTR_FOR_FN (cfun)));
  gsi = gsi_after_labels (succ_bb);

instead for example.  Or use gsi_insert_on_edge_immediate () and insert
on the edge (that avoids splitting the edge if not necessary).