lto: Fix up lto_fixup_prevailing_type [PR108910]

Without LTO, TYPE_POINTER_TO/TYPE_REFERENCE_TO chains are only maintained
inside of build_{pointer,reference}_type_for_mode and those routines
ensure that the pointer/reference type added to the chain is really
without any user attributes (unless something would modify the types
in place, but that would be wrong).

Now, LTO adds stuff to these chains in lto_fixup_prevailing_type but
doesn't guarantee that.  The testcase in the PR (which I'm not including
for testsuite because when (I hope) the aarch64 backend bug will be fixed,
the testcase would work either way) shows a case where user has
TYPE_USER_ALIGN type with very high alignment, as there aren't enough
pointers to float in the code left that one becomes the prevailing one
(because types with attributes are created with build_distinct_type_copy
and thus their own TYPE_MAIN_VARIANTs), lto_fixup_prevailing_type puts
it into the TYPE_POINTER_TO chain of float and later on during expansion
of __builtin_cexpif expander uses build_pointer_type (float_type_node)
to emit a sincosf call and instead of getting a normal pointer type gets
this non-standard one.

The following patch fixes that by not adding into those chains
types with TYPE_ATTRIBUTES, and for REFERENCE_TYPEs not even with
TYPE_REF_IS_RVALUE - while the C++ FE adds those into those chains,
it always ensures such a type goes immediately after the corresponding
non-TYPE_REF_IS_RVALUE REFERENCE_TYPE with the same
mode/TYPE_REF_CAN_ALIAS_ALL, so LTO would need to ensure that too, but
TYPE_REF_IS_RVALUE types are looked that way only in the C++ FE.

2023-03-01  Jakub Jelinek  <jakub@redhat.com>

	PR target/108910
	* lto-common.cc (lto_fixup_prevailing_type): Don't add t to
	TYPE_POINTER_TO or TYPE_REFERENCE_TO chain if it has
	TYPE_ATTRIBUTES or is TYPE_REF_IS_RVALUE.

1 files changed, 19 insertions, 15 deletions

diff --git a/gcc/lto/lto-common.cc b/gcc/lto/lto-common.cc
index b166d17..882dd89 100644
--- a/gcc/lto/lto-common.cc
+++ b/gcc/lto/lto-common.cc
@@ -984,21 +984,25 @@ lto_fixup_prevailing_type (tree t)
       TYPE_NEXT_VARIANT (t) = TYPE_NEXT_VARIANT (mv);
       TYPE_NEXT_VARIANT (mv) = t;
     }
-
-  /* The following reconstructs the pointer chains
-     of the new pointed-to type if we are a main variant.  We do
-     not stream those so they are broken before fixup.  */
-  if (TREE_CODE (t) == POINTER_TYPE
-      && TYPE_MAIN_VARIANT (t) == t)
-    {
-      TYPE_NEXT_PTR_TO (t) = TYPE_POINTER_TO (TREE_TYPE (t));
-      TYPE_POINTER_TO (TREE_TYPE (t)) = t;
-    }
-  else if (TREE_CODE (t) == REFERENCE_TYPE
-	   && TYPE_MAIN_VARIANT (t) == t)
-    {
-      TYPE_NEXT_REF_TO (t) = TYPE_REFERENCE_TO (TREE_TYPE (t));
-      TYPE_REFERENCE_TO (TREE_TYPE (t)) = t;
+  else if (!TYPE_ATTRIBUTES (t))
+    {
+      /* The following reconstructs the pointer chains
+	 of the new pointed-to type if we are a main variant.  We do
+	 not stream those so they are broken before fixup.
+	 Don't add it if despite being main variant it has
+	 attributes (then it was created with build_distinct_type_copy).
+	 Similarly don't add TYPE_REF_IS_RVALUE REFERENCE_TYPEs.
+	 Don't add it if there is something in the chain already.  */
+      if (TREE_CODE (t) == POINTER_TYPE)
+	{
+	  TYPE_NEXT_PTR_TO (t) = TYPE_POINTER_TO (TREE_TYPE (t));
+	  TYPE_POINTER_TO (TREE_TYPE (t)) = t;
+	}
+      else if (TREE_CODE (t) == REFERENCE_TYPE && !TYPE_REF_IS_RVALUE (t))
+	{
+	  TYPE_NEXT_REF_TO (t) = TYPE_REFERENCE_TO (TREE_TYPE (t));
+	  TYPE_REFERENCE_TO (TREE_TYPE (t)) = t;
+	}
     }
 }