Blame SOURCES/gcc8-rh2117838.patch

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diff --git a/gcc/testsuite/g++.dg/torture/phi-1.C b/gcc/testsuite/g++.dg/torture/phi-1.C
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new file mode 100644
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index 00000000000..69fb3d7ba38
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--- /dev/null
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+++ b/gcc/testsuite/g++.dg/torture/phi-1.C
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@@ -0,0 +1,28 @@
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+// { dg-do compile { target c++11 } }
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+// { dg-options "--param early-inlining-insns=14" }
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+
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+struct Element;
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+template <int _Nm> struct __array_traits { typedef Element _Type[_Nm]; };
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+template <int _Nm> struct array {
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+  typename __array_traits<_Nm>::_Type _M_elems;
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+};
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+bool logLevel();
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+struct LogCapture {
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+  void stream();
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+};
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+struct Element {
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+  Element();
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+  long data_;
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+};
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+using ElementArray = array<6>;
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+struct ElementManager {
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+  ElementManager();
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+  ElementArray array_;
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+};
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+static ElementArray makeArray() {
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+  if (logLevel())
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+    LogCapture().stream();
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+  ElementArray foo;
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+  return foo;
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+}
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+ElementManager::ElementManager() : array_(makeArray()) {}
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diff --git a/gcc/tree-cfg.c b/gcc/tree-cfg.c
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index 84e58e66628..78c0c6a4189 100644
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--- a/gcc/tree-cfg.c
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+++ b/gcc/tree-cfg.c
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@@ -2944,35 +2944,6 @@ last_and_only_stmt (basic_block bb)
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     return NULL;
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 }
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-/* Reinstall those PHI arguments queued in OLD_EDGE to NEW_EDGE.  */
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-
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-static void
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-reinstall_phi_args (edge new_edge, edge old_edge)
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-{
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-  edge_var_map *vm;
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-  int i;
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-  gphi_iterator phis;
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-
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-  vec<edge_var_map> *v = redirect_edge_var_map_vector (old_edge);
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-  if (!v)
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-    return;
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-
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-  for (i = 0, phis = gsi_start_phis (new_edge->dest);
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-       v->iterate (i, &vm) && !gsi_end_p (phis);
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-       i++, gsi_next (&phis))
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-    {
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-      gphi *phi = phis.phi ();
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-      tree result = redirect_edge_var_map_result (vm);
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-      tree arg = redirect_edge_var_map_def (vm);
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-
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-      gcc_assert (result == gimple_phi_result (phi));
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-
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-      add_phi_arg (phi, arg, new_edge, redirect_edge_var_map_location (vm));
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-    }
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-
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-  redirect_edge_var_map_clear (old_edge);
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-}
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-
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 /* Returns the basic block after which the new basic block created
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    by splitting edge EDGE_IN should be placed.  Tries to keep the new block
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    near its "logical" location.  This is of most help to humans looking
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@@ -3012,11 +2983,24 @@ gimple_split_edge (edge edge_in)
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   new_bb = create_empty_bb (after_bb);
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   new_bb->count = edge_in->count ();
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-  e = redirect_edge_and_branch (edge_in, new_bb);
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-  gcc_assert (e == edge_in);
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-
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+  /* We want to avoid re-allocating PHIs when we first
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+     add the fallthru edge from new_bb to dest but we also
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+     want to avoid changing PHI argument order when
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+     first redirecting edge_in away from dest.  The former
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+     avoids changing PHI argument order by adding them
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+     last and then the redirection swapping it back into
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+     place by means of unordered remove.
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+     So hack around things by temporarily removing all PHIs
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+     from the destination during the edge redirection and then
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+     making sure the edges stay in order.  */
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+  gimple_seq saved_phis = phi_nodes (dest);
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+  unsigned old_dest_idx = edge_in->dest_idx;
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+  set_phi_nodes (dest, NULL);
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   new_edge = make_single_succ_edge (new_bb, dest, EDGE_FALLTHRU);
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-  reinstall_phi_args (new_edge, e);
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+  e = redirect_edge_and_branch (edge_in, new_bb);
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+  gcc_assert (e == edge_in && new_edge->dest_idx == old_dest_idx);
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+  /* set_phi_nodes sets the BB of the PHI nodes, so do it manually here.  */
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+  dest->il.gimple.phi_nodes = saved_phis;
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   return new_bb;
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 }