[PATCH] PR 63721 IPA ICF cause atomic-comp-swap-release-acquire.c ICE

[Jiong Wang <jiong dot wang at arm dot com>]

the same ICE will happen on x86-64, if compile with -O2 -fPIC.

the reason is for the following two functions, they are identical, so 
IPA-ICF
pass try to transform the second function to call the first one directly.

int
atomic_compare_exchange_STRONG_RELEASE_ACQUIRE (int a, int b)
{
  return __atomic_compare_exchange (&v, &a, &b,
                    STRONG, __ATOMIC_RELEASE,
                    __ATOMIC_ACQUIRE);
}

int
atomic_compare_exchange_n_STRONG_RELEASE_ACQUIRE (int a, int b)
{
  return __atomic_compare_exchange_n (&v, &a, b,
                      STRONG, __ATOMIC_RELEASE,
                      __ATOMIC_ACQUIRE);
}

while during this transformation, looks like there are something wrong 
with the
function argument handling. take "a" for example, because later there 
are "&a",
so it's marked as addressable. while after transformation, if we turn the
second function into

int atomic_compare_exchange_n_STRONG_RELEASE_ACQUIRE (int a, int b)
{
  return atomic_compare_exchange_STRONG_RELEASE_ACQUIRE (a, b)
}

then argument a is no longer addressable.

so, in cgraph_node::release_body, when making the wrapper, except 
clearing the
function body, we should also clear the addressable flag for function args
because they are decided by the function body which is cleared.

bootstrap ok on x86-64 and no regression.
bootstrap ok on aarch64 juno.
ICE gone away on arm & x86-64

ok for trunk?

gcc/

  PR  tree-optimization/63721
  * cgraph.c (cgraph_node::release_body): Clear addressable flag for function args.

diff --git a/gcc/cgraph.c b/gcc/cgraph.c
index d430bc5..7ac0b2a 100644
--- a/gcc/cgraph.c
+++ b/gcc/cgraph.c
@@ -1668,6 +1668,7 @@ release_function_body (tree decl)
 void
 cgraph_node::release_body (bool keep_arguments)
 {
+  tree arg_p;
   ipa_transforms_to_apply.release ();
   if (!used_as_abstract_origin && symtab->state != PARSING)
     {
@@ -1676,6 +1677,10 @@ cgraph_node::release_body (bool keep_arguments)
       if (!keep_arguments)
 	DECL_ARGUMENTS (decl) = NULL;
     }
+
+  for (arg_p = DECL_ARGUMENTS (decl); arg_p; arg_p = DECL_CHAIN (arg_p))
+    TREE_ADDRESSABLE (arg_p) = 0;
+
   /* If the node is abstract and needed, then do not clear DECL_INITIAL
      of its associated function function declaration because it's
      needed to emit debug info later.  */