> Now we have it spelled out 4 times ... makes sense to create a new
> macro for it? (though I cannot think of a good name...
> UNACCESSIBLE_TYPE_P ()?)
Yep, actually I already made that version of patch yesterday but then got
hooked by beers. This is better version (also with more sensible comments).
I will commit it at afternoon if you have no further comments.
* lto.c (hash_canonical_type): Be sure we hash only types that
need alias set.
(gimple_register_canonical_type_1): Do not produce canonical
types for types that do not need alias sets.
* tree.c (gimple_canonical_types_compatible_p): Sanity check that
we do not try to compute canonical type for type that does not need
alias set.
(verify_type): Drop FIXME for METHOD_TYPE, update FIXME for
FUNCITON_TYPE.
* tree.h (type_with_alias_set_p): New.
Index: lto/lto.c
===================================================================
--- lto/lto.c (revision 223508)
+++ lto/lto.c (working copy)
@@ -309,6 +309,12 @@ hash_canonical_type (tree type)
{
inchash::hash hstate;
+ /* We compute alias sets only for types that needs them.
+ Be sure we do not recurse to something else as we can not hash incomplete
+ types in a way they would have same hash value as compatible complete
+ types. */
+ gcc_checking_assert (type_with_alias_set_p (type));
+
/* Combine a few common features of types so that types are grouped into
smaller sets; when searching for existing matching types to merge,
only existing types having the same features as the new type will be
@@ -493,7 +495,7 @@ gimple_register_canonical_type_1 (tree t
static void
gimple_register_canonical_type (tree t)
{
- if (TYPE_CANONICAL (t))
+ if (TYPE_CANONICAL (t) || !type_with_alias_set_p (t))
return;
gimple_register_canonical_type_1 (t, hash_canonical_type (t));
Index: tree.c
===================================================================
--- tree.c (revision 223508)
+++ tree.c (working copy)
@@ -12720,6 +12720,23 @@ gimple_canonical_types_compatible_p (con
if (t1 == NULL_TREE || t2 == NULL_TREE)
return false;
+ /* We consider complete types always compatible with incomplete type.
+ This does not make sense for canonical type calculation and thus we
+ need to ensure that we are never called on it.
+
+ FIXME: For more correctness the function probably should have three modes
+ 1) mode assuming that types are complete mathcing their structure
+ 2) mode allowing incomplete types but producing equivalence classes
+ and thus ignoring all info from complete types
+ 3) mode allowing incomplete types to match complete but checking
+ compatibility between complete types.
+
+ 1 and 2 can be used for canonical type calculation. 3 is the real
+ definition of type compatibility that can be used i.e. for warnings during
+ declaration merging. */
+
+ gcc_assert (!trust_type_canonical
+ || (type_with_alias_set_p (t1) && type_with_alias_set_p (t2)));
/* If the types have been previously registered and found equal
they still are. */
if (TYPE_CANONICAL (t1) && TYPE_CANONICAL (t2)
@@ -12939,10 +12953,9 @@ verify_type (const_tree t)
/* Method and function types can not be used to address memory and thus
TYPE_CANONICAL really matters only for determining useless conversions.
- FIXME: C++ FE does not agree with gimple_canonical_types_compatible_p
- here. gimple_canonical_types_compatible_p calls comp_type_attributes
- while for C++ FE the attributes does not make difference. */
- else if (TREE_CODE (t) == FUNCTION_TYPE || TREE_CODE (t) == METHOD_TYPE)
+ FIXME: C++ FE produce declarations of builtin functions that are not
+ compatible with main variants. */
+ else if (TREE_CODE (t) == FUNCTION_TYPE)
;
else if (t != ct
/* FIXME: gimple_canonical_types_compatible_p can not compare types
Index: tree.h
===================================================================
--- tree.h (revision 223508)
+++ tree.h (working copy)
@@ -5090,6 +5090,26 @@ int_bit_position (const_tree field)
+ wi::to_offset (DECL_FIELD_BIT_OFFSET (field))).to_shwi ();
}
+/* Return true if it makes sense to consider alias set for a type T. */
+
+inline bool
+type_with_alias_set_p (const_tree t)
+{
+ /* Function and method types are never accessed as memory locations. */
+ if (TREE_CODE (t) == FUNCTION_TYPE || TREE_CODE (t) == METHOD_TYPE)
+ return false;
+
+ if (COMPLETE_TYPE_P (t))
+ return true;
+
+ /* Incomplete types can not be accessed in general except for arrays
+ where we can fetch its element despite we have no array bounds. */
+ if (TREE_CODE (t) == ARRAY_TYPE && COMPLETE_TYPE_P (TREE_TYPE (t)))
+ return true;
+
+ return false;
+}
+
extern void gt_ggc_mx (tree &);
extern void gt_pch_nx (tree &);
extern void gt_pch_nx (tree &, gt_pointer_operator, void *);
