ipa-devirt: Fix crash in obj_type_ref_class [PR95114]

The testcase has failed since r9-5035, because obj_type_ref_class
tries to look up an ODR type when no ODR type information is
available.  (The information was available earlier in the
compilation, but was freed during pass_ipa_free_lang_data.)
We then crash dereferencing the null get_odr_type result.

The test passes with -O2.  However, it fails again if -fdump-tree-all
is used, since obj_type_ref_class is called indirectly from the
dump routines.

Other code creates ODR type entries on the fly by passing “true”
as the insert parameter.  But obj_type_ref_class can't do that
unconditionally, since it should have no side-effects when used
from the dumping code.

Following a suggestion from Honza, this patch adds parameters
to say whether the routines are being called from dump routines
and uses those to derive the insert parameter.

gcc/
	PR middle-end/95114
	* tree.h (virtual_method_call_p): Add a default-false parameter
	that indicates whether the function is being called from dump
	routines.
	(obj_type_ref_class): Likewise.
	* tree.c (virtual_method_call_p): Likewise.
	* ipa-devirt.c (obj_type_ref_class): Likewise.  Lazily add ODR
	type information for the type when the parameter is false.
	* tree-pretty-print.c (dump_generic_node): Update calls to
	virtual_method_call_p and obj_type_ref_class accordingly.

gcc/testsuite/
	PR middle-end/95114
	* g++.target/aarch64/pr95114.C: New test.

1 files changed, 6 insertions, 3 deletions

diff --git a/gcc/ipa-devirt.c b/gcc/ipa-devirt.c
index 0340dec..3ab7049 100644
--- a/gcc/ipa-devirt.c
+++ b/gcc/ipa-devirt.c
@@ -1883,10 +1883,11 @@ add_type_duplicate (odr_type val, tree type)
   return build_bases;
 }
 
-/* REF is OBJ_TYPE_REF, return the class the ref corresponds to.  */
+/* REF is OBJ_TYPE_REF, return the class the ref corresponds to.
+   FOR_DUMP_P is true when being called from the dump routines.  */
 
 tree
-obj_type_ref_class (const_tree ref)
+obj_type_ref_class (const_tree ref, bool for_dump_p)
 {
   gcc_checking_assert (TREE_CODE (ref) == OBJ_TYPE_REF);
   ref = TREE_TYPE (ref);
@@ -1902,8 +1903,10 @@ obj_type_ref_class (const_tree ref)
   tree ret = TREE_TYPE (ref);
   if (!in_lto_p && !TYPE_STRUCTURAL_EQUALITY_P (ret))
     ret = TYPE_CANONICAL (ret);
+  else if (odr_type ot = get_odr_type (ret, !for_dump_p))
+    ret = ot->type;
   else
-    ret = get_odr_type (ret)->type;
+    gcc_assert (for_dump_p);
   return ret;
 }