/* The negative-index vtable initializers built up so far. These
are in order from least negative index to most negative index. */
tree inits;
- /* The last (i.e., most negative entry in INITS. */
+ /* The last (i.e., most negative) entry in INITS. */
tree* last_init;
/* The binfo for the virtual base for which we're building
vcall offset initializers. */
static tree get_vfield_name PARAMS ((tree));
static void finish_struct_anon PARAMS ((tree));
static tree build_vbase_pointer PARAMS ((tree, tree));
-static tree build_vtable_entry PARAMS ((tree, tree, tree, int));
+static tree build_vtable_entry PARAMS ((tree, tree, tree));
static tree get_vtable_name PARAMS ((tree));
-static tree get_derived_offset PARAMS ((tree, tree));
static tree get_basefndecls PARAMS ((tree, tree));
static int build_primary_vtable PARAMS ((tree, tree));
static int build_secondary_vtable PARAMS ((tree, tree));
return mangle_vtt_for_type (type);
}
-/* Return the offset to the main vtable for a given base BINFO. */
-
-tree
-get_vfield_offset (binfo)
- tree binfo;
-{
- return
- size_binop (PLUS_EXPR, byte_position (TYPE_VFIELD (BINFO_TYPE (binfo))),
- BINFO_OFFSET (binfo));
-}
-
-/* Get the offset to the start of the original binfo that we derived
- this binfo from. If we find TYPE first, return the offset only
- that far. The shortened search is useful because the this pointer
- on method calling is expected to point to a DECL_CONTEXT (fndecl)
- object, and not a baseclass of it. */
-
-static tree
-get_derived_offset (binfo, type)
- tree binfo, type;
-{
- tree offset1 = get_vfield_offset (TYPE_BINFO (BINFO_TYPE (binfo)));
- tree offset2;
-
- while (!same_type_p (BINFO_TYPE (binfo), type))
- binfo = get_primary_binfo (binfo);
-
- offset2 = get_vfield_offset (TYPE_BINFO (BINFO_TYPE (binfo)));
- return size_binop (MINUS_EXPR, offset1, offset2);
-}
-
/* Create a VAR_DECL for a primary or secondary vtable for CLASS_TYPE.
(For a secondary vtable for B-in-D, CLASS_TYPE should be D, not B.)
Use NAME for the name of the vtable, and VTABLE_TYPE for its type. */
{
BV_VCALL_INDEX (t) = NULL_TREE;
BV_USE_VCALL_INDEX_P (t) = 0;
- BV_GENERATE_THUNK_WITH_VTABLE_P (t) = 0;
}
return copies;
{
if (binfo == TYPE_BINFO (t))
/* In this case, it is *type*'s vtable we are modifying. We start
- with the approximation that it's vtable is that of the
+ with the approximation that its vtable is that of the
immediate base class. */
- return build_primary_vtable (TYPE_BINFO (DECL_CONTEXT (TYPE_VFIELD (t))),
+ /* ??? This actually passes TYPE_BINFO (t), not the primary base binfo,
+ since we've updated DECL_CONTEXT (TYPE_VFIELD (t)) by now. */
+ return build_primary_vtable (TYPE_BINFO (DECL_CONTEXT (TYPE_VFIELD (t))),
t);
else
/* This is our very own copy of `basetype' to play with. Later,
BV_FN (v) = fndecl;
/* Now assign virtual dispatch information, if unset. We can
- dispatch this, through any overridden base function. */
+ dispatch this through any overridden base function.
+
+ FIXME this can choose a secondary vtable if the primary is not
+ also lexically first, leading to useless conversions.
+ In the V3 ABI, there's no reason for DECL_VIRTUAL_CONTEXT to
+ ever be different from DECL_CONTEXT. */
if (TREE_CODE (DECL_VINDEX (fndecl)) != INTEGER_CST)
{
DECL_VINDEX (fndecl) = DECL_VINDEX (base_fndecl);
return base_binfo;
}
-/* If BINFO is an unmarked virtual binfo for a class with a primary
+/* If BINFO is an unmarked virtual binfo for a class with a primary virtual
base, then BINFO has no primary base in this graph. Called from
mark_primary_bases. */
void *data ATTRIBUTE_UNUSED;
{
if (TREE_VIA_VIRTUAL (binfo) && !BINFO_MARKED (binfo)
- && CLASSTYPE_HAS_PRIMARY_BASE_P (BINFO_TYPE (binfo)))
+ && CLASSTYPE_HAS_PRIMARY_BASE_P (BINFO_TYPE (binfo))
+ && TREE_VIA_VIRTUAL (CLASSTYPE_PRIMARY_BINFO (BINFO_TYPE (binfo))))
BINFO_LOST_PRIMARY_P (binfo) = 1;
CLEAR_BINFO_MARKED (binfo);
path;
path = TREE_CHAIN (path))
{
- for (method = TYPE_METHODS (BINFO_TYPE (TREE_VALUE (path)));
- method;
- method = TREE_CHAIN (method))
- if (DECL_VIRTUAL_P (method)
- && same_signature_p (method, ffod->fn))
- break;
-
+ method = look_for_overrides_here (BINFO_TYPE (TREE_VALUE (path)),
+ ffod->fn);
if (method)
break;
}
struct T : virtual public R { virtual void f (); };
struct U : public S, public T { };
- is not -- there's no way to decide whether to put `S::f' or
+ is not -- there's no way to decide whether to put `S::f' or
`T::f' in the vtable for `R'.
The solution is to look at all paths to BINFO. If we find
/* If there was no winner, issue an error message. */
if (!ffod.overriding_fn)
- cp_error ("no unique final overrider for `%D' in `%T'", fn, t);
+ {
+ cp_error ("no unique final overrider for `%D' in `%T'", fn, t);
+ return error_mark_node;
+ }
return build_tree_list (ffod.overriding_fn, ffod.overriding_base);
}
-/* Update a entry in the vtable for BINFO, which is in the hierarchy
- dominated by T. FN has been overridden in BINFO; VIRTUALS points
- to the corresponding position in the BINFO_VIRTUALS list. */
+#if 0
+/* Returns the function from the BINFO_VIRTUALS entry in T which matches
+ the signature of FUNCTION_DECL FN, or NULL_TREE if none. In other words,
+ the function that the slot in T's primary vtable points to. */
+
+static tree get_matching_virtual PARAMS ((tree, tree));
+static tree
+get_matching_virtual (t, fn)
+ tree t, fn;
+{
+ tree f;
+
+ for (f = BINFO_VIRTUALS (TYPE_BINFO (t)); f; f = TREE_CHAIN (f))
+ if (same_signature_p (BV_FN (f), fn))
+ return BV_FN (f);
+ return NULL_TREE;
+}
+#endif
+
+/* Update an entry in the vtable for BINFO, which is in the hierarchy
+ dominated by T. FN has been overriden in BINFO; VIRTUALS points to the
+ corresponding position in the BINFO_VIRTUALS list. */
static void
update_vtable_entry_for_fn (t, binfo, fn, virtuals)
tree overrider;
tree delta;
tree virtual_base;
- int generate_thunk_with_vtable_p;
+ tree first_defn;
- /* Find the function which originally caused this vtable
- entry to be present. */
- b = binfo;
- while (1)
+ /* Find the nearest primary base (possibly binfo itself) which defines
+ this function; this is the class the caller will convert to when
+ calling FN through BINFO. */
+ for (b = binfo; ; b = get_primary_binfo (b))
{
- tree primary_base;
- tree f;
-
- primary_base = get_primary_binfo (b);
- if (!primary_base)
+ if (look_for_overrides_here (BINFO_TYPE (b), fn))
break;
-
- for (f = BINFO_VIRTUALS (TYPE_BINFO (BINFO_TYPE (primary_base)));
- f;
- f = TREE_CHAIN (f))
- if (same_signature_p (BV_FN (f), fn))
- break;
-
- if (!f)
- break;
-
- fn = BV_FN (f);
- b = primary_base;
}
+ first_defn = b;
/* Find the final overrider. */
overrider = find_final_overrider (t, b, fn);
if (overrider == error_mark_node)
return;
- /* Compute the constant adjustment to the `this' pointer. The
- `this' pointer, when this function is called, will point at the
- class whose vtable this is. */
- delta = size_binop (PLUS_EXPR,
- get_derived_offset (binfo,
- DECL_VIRTUAL_CONTEXT (fn)),
- BINFO_OFFSET (binfo));
-
/* Assume that we will produce a thunk that convert all the way to
the final overrider, and not to an intermediate virtual base. */
virtual_base = NULL_TREE;
- /* Assume that we will always generate thunks with the vtables that
- reference them. */
- generate_thunk_with_vtable_p = 1;
-
/* Under the new ABI, we will convert to an intermediate virtual
base first, and then use the vcall offset located there to finish
the conversion. */
while (b)
{
- /* If we find BINFO, then the final overrider is in a class
- derived from BINFO, so the thunks can be generated with
- the final overrider. */
- if (!virtual_base
- && same_type_p (BINFO_TYPE (b), BINFO_TYPE (binfo)))
- generate_thunk_with_vtable_p = 0;
-
- /* If we find the final overrider, then we can stop
- walking. */
+ /* If we find the final overrider, then we can stop
+ walking. */
if (same_type_p (BINFO_TYPE (b),
BINFO_TYPE (TREE_VALUE (overrider))))
break;
- /* If we find a virtual base, and we haven't yet found the
- overrider, then there is a virtual base between the
- declaring base and the final overrider. */
+ /* If we find a virtual base, and we haven't yet found the
+ overrider, then there is a virtual base between the
+ declaring base (first_defn) and the final overrider. */
if (!virtual_base && TREE_VIA_VIRTUAL (b))
- {
- generate_thunk_with_vtable_p = 1;
- virtual_base = b;
- }
+ virtual_base = b;
b = BINFO_INHERITANCE_CHAIN (b);
}
+ /* Compute the constant adjustment to the `this' pointer. The
+ `this' pointer, when this function is called, will point at BINFO
+ (or one of its primary bases, which are at the same offset). */
+
if (virtual_base)
/* The `this' pointer needs to be adjusted to the nearest virtual
base. */
- delta = size_diffop (BINFO_OFFSET (virtual_base), delta);
+ delta = size_diffop (BINFO_OFFSET (virtual_base),
+ BINFO_OFFSET (binfo));
else
- /* The `this' pointer needs to be adjusted from pointing to
- BINFO to pointing at the base where the final overrider
- appears. */
- delta = size_diffop (BINFO_OFFSET (TREE_VALUE (overrider)), delta);
+ {
+ /* The `this' pointer needs to be adjusted from pointing to
+ BINFO to pointing at the base where the final overrider
+ appears. */
+ delta = size_diffop (BINFO_OFFSET (TREE_VALUE (overrider)),
+ BINFO_OFFSET (binfo));
+
+#if 0
+ /* Disable this optimization pending an ABI change, or until
+ we can force emission of the non-virtual thunk even if we don't
+ use it. */
+ if (! integer_zerop (delta))
+ {
+ /* We'll need a thunk. But if we have a (perhaps formerly)
+ primary virtual base, we have a vcall slot for this function,
+ so we can use it rather than create a non-virtual thunk. */
+
+ b = get_primary_binfo (first_defn);
+ for (; b; b = get_primary_binfo (b))
+ {
+ tree f = get_matching_virtual (BINFO_TYPE (b), fn);
+ if (!f)
+ /* b doesn't have this function; no suitable vbase. */
+ break;
+ if (TREE_VIA_VIRTUAL (b))
+ {
+ /* Found one; we can treat ourselves as a virtual base. */
+ virtual_base = binfo;
+ delta = size_zero_node;
+ break;
+ }
+ }
+ }
+#endif
+ }
modify_vtable_entry (t,
binfo,
if (virtual_base)
BV_USE_VCALL_INDEX_P (*virtuals) = 1;
- if (generate_thunk_with_vtable_p)
- BV_GENERATE_THUNK_WITH_VTABLE_P (*virtuals) = 1;
}
/* Called from modify_all_vtables via dfs_walk. */
void *data;
{
if (/* There's no need to modify the vtable for a non-virtual
- primary base; we're not going to use that vtable anyhow
- (virtual primary bases can become non-primary in a
- class derivation of this one.) */
+ primary base; we're not going to use that vtable anyhow.
+ We do still need to do this for virtual primary bases, as they
+ could become non-primary in a construction vtable. */
(!BINFO_PRIMARY_P (binfo) || TREE_VIA_VIRTUAL (binfo))
/* Similarly, a base without a vtable needs no modification. */
&& CLASSTYPE_VFIELDS (BINFO_TYPE (binfo)))
layout_class_type (t, &empty, &vfuns,
&new_virtuals, &overridden_virtuals);
- /* Set up the DECL_FIELD_BITPOS of the vfield if we need to, as we
- might need to know it for setting up the offsets in the vtable
- (or in thunks) below. */
+ /* Make sure that we get our own copy of the vfield FIELD_DECL. */
vfield = TYPE_VFIELD (t);
if (vfield != NULL_TREE
&& DECL_FIELD_CONTEXT (vfield) != t)
tree rtti_binfo;
int *non_fn_entries_p;
{
- tree v;
+ tree v, b;
tree vfun_inits;
tree vbase;
vtbl_init_data vid;
tree fn;
tree pfn;
tree init;
- int generate_with_vtable_p = BV_GENERATE_THUNK_WITH_VTABLE_P (v);
/* Pull the offset for `this', and the function to call, out of
the list. */
vcall_index = BV_VCALL_INDEX (v);
my_friendly_assert (vcall_index != NULL_TREE, 20000621);
}
- else if (vid.ctor_vtbl_p && BV_VCALL_INDEX (v))
- {
- /* In the original, we did not need to use the vcall index, even
- though there was one, but in a ctor vtable things might be
- different (a primary virtual base might have moved). Be
- conservative and use a vcall adjusting thunk. */
- vcall_index = BV_VCALL_INDEX (v);
- generate_with_vtable_p = 1;
- }
else
vcall_index = NULL_TREE;
pfn = build1 (ADDR_EXPR, vfunc_ptr_type_node, fn);
/* The address of a function can't change. */
TREE_CONSTANT (pfn) = 1;
+
/* Enter it in the vtable. */
- init = build_vtable_entry (delta, vcall_index, pfn,
- generate_with_vtable_p);
+ init = build_vtable_entry (delta, vcall_index, pfn);
+
+ /* If the only definition of this function signature along our
+ primary base chain is from a lost primary, this vtable slot will
+ never be used, so just zero it out. This is important to avoid
+ requiring extra thunks which cannot be generated with the function.
+
+ We could also handle this in update_vtable_entry_for_fn; doing it
+ here means we zero out unused slots in ctor vtables as well,
+ rather than filling them with erroneous values (though harmless,
+ apart from relocation costs). */
+ if (fn != abort_fndecl)
+ for (b = binfo; ; b = get_primary_binfo (b))
+ {
+ /* We found a defn before a lost primary; go ahead as normal. */
+ if (look_for_overrides_here (BINFO_TYPE (b), fn))
+ break;
+
+ /* The nearest definition is from a lost primary; clear the
+ slot. */
+ if (BINFO_LOST_PRIMARY_P (b))
+ {
+ init = size_zero_node;
+ break;
+ }
+ }
+
/* And add it to the chain of initializers. */
vfun_inits = tree_cons (NULL_TREE, init, vfun_inits);
}
return chainon (vid.inits, vfun_inits);
}
-/* Sets vid->inits to be the initializers for the vbase and vcall
+/* Adds to vid->inits the initializers for the vbase and vcall
offsets in BINFO, which is in the hierarchy dominated by T. */
static void
}
/* Adds the initializers for the vcall offset entries in the vtable
- for BINFO (which is part of the class hierarchy dominated by T) to
- VID->INITS. */
+ for BINFO (which is part of the class hierarchy dominated by VID->DERIVED)
+ to VID->INITS. */
static void
build_vcall_offset_vtbl_entries (binfo, vid)
vtable. For example:
class A { virtual void f (); };
- class B : virtual public A { };
- class C: virtual public A, public B {};
-
- Now imagine:
-
- B* b = new C;
- b->f();
-
- The location of `A' is not at a fixed offset relative to `B'; the
- offset depends on the complete object derived from `B'. So,
- `B' vtable contains an entry for `f' that indicates by what
- amount the `this' pointer for `B' needs to be adjusted to arrive
- at `A'.
+ class B1 : virtual public A { virtual void f (); };
+ class B2 : virtual public A { virtual void f (); };
+ class C: public B1, public B2 { virtual void f (); };
+
+ A C object has a primary base of B1, which has a primary base of A. A
+ C also has a secondary base of B2, which no longer has a primary base
+ of A. So the B2-in-C construction vtable needs a secondary vtable for
+ A, which will adjust the A* to a B2* to call f. We have no way of
+ knowing what (or even whether) this offset will be when we define B2,
+ so we store this "vcall offset" in the A sub-vtable and look it up in
+ a "virtual thunk" for B2::f.
We need entries for all the functions in our primary vtable and
- in our non-virtual bases vtables. */
+ in our non-virtual bases' secondary vtables. */
vid->vbase = binfo;
/* Now, walk through the non-virtual bases, adding vcall offsets. */
add_vcall_offset_vtbl_entries_r (binfo, vid);
tree primary_binfo;
/* Don't walk into virtual bases -- except, of course, for the
- virtual base for which we are building vcall offsets. */
+ virtual base for which we are building vcall offsets. Any
+ primary virtual base will have already had its offsets generated
+ through the recursion in build_vcall_and_vbase_vtbl_entries. */
if (TREE_VIA_VIRTUAL (binfo) && vid->vbase != binfo)
return;
tree base_virtuals;
tree orig_virtuals;
tree binfo_inits;
- int lost_primary = 0;
- /* If BINFO is a primary base, this is the least derived class of
- BINFO that is not a primary base. */
+ /* If BINFO is a primary base, the most derived class which has BINFO as
+ a primary base; otherwise, just BINFO. */
tree non_primary_binfo;
binfo_inits = NULL_TREE;
- /* We might be a primary base class. Go up the inheritance
- hierarchy until we find the class of which we are a primary base:
+ /* We might be a primary base class. Go up the inheritance hierarchy
+ until we find the most derived class of which we are a primary base:
it is the BINFO_VIRTUALS there that we need to consider. */
non_primary_binfo = binfo;
while (BINFO_INHERITANCE_CHAIN (non_primary_binfo))
{
tree b;
- /* If we have reached a virtual base, then it must be the
- virtual base for which we are building vcall offsets. In
- turn, the virtual base must be a (possibly indirect) primary
- base of the class that we are initializing, or we wouldn't
- care about its vtable offsets. */
+ /* If we have reached a virtual base, then it must be vid->vbase,
+ because we ignore other virtual bases in
+ add_vcall_offset_vtbl_entries_r. In turn, it must be a primary
+ base (possibly multi-level) of vid->binfo, or we wouldn't
+ have called build_vcall_and_vbase_vtbl_entries for it. But it
+ might be a lost primary, so just skip down to vid->binfo. */
if (TREE_VIA_VIRTUAL (non_primary_binfo))
{
- if (vid->ctor_vtbl_p)
- {
- tree probe;
-
- for (probe = vid->binfo;
- probe != non_primary_binfo;
- probe = get_primary_binfo (probe))
- {
- if (BINFO_LOST_PRIMARY_P (probe))
- {
- lost_primary = 1;
- break;
- }
- }
- }
+ if (non_primary_binfo != vid->vbase)
+ abort ();
non_primary_binfo = vid->binfo;
break;
}
tree vcall_offset;
/* Find the declaration that originally caused this function to
- be present. */
+ be present in BINFO_TYPE (binfo). */
orig_fn = BV_FN (orig_virtuals);
- /* We do not need an entry if this function is declared in a
- virtual base (or one of its virtual bases), and not
- overridden in the section of the hierarchy dominated by the
- virtual base for which we are building vcall offsets. */
+ /* When processing BINFO, we only want to generate vcall slots for
+ function slots introduced in BINFO. So don't try to generate
+ one if the function isn't even defined in BINFO. */
if (!same_type_p (DECL_CONTEXT (orig_fn), BINFO_TYPE (binfo)))
continue;
if (i != VARRAY_ACTIVE_SIZE (vid->fns))
continue;
- /* The FN comes from BASE. So, we must calculate the adjustment
- from the virtual base that derived from BINFO to BASE. */
+ /* The FN comes from BASE. So, we must calculate the adjustment from
+ vid->vbase to BASE. We can just look for BASE in the complete
+ object because we are converting from a virtual base, so if there
+ were multiple copies, there would not be a unique final overrider
+ and vid->derived would be ill-formed. */
base = DECL_CONTEXT (fn);
base_binfo = get_binfo (base, vid->derived, /*protect=*/0);
/* Compute the vcall offset. */
- vcall_offset = BINFO_OFFSET (vid->vbase);
- if (lost_primary)
- vcall_offset = size_binop (PLUS_EXPR, vcall_offset,
- BINFO_OFFSET (vid->binfo));
+ /* As mentioned above, the vbase we're working on is a primary base of
+ vid->binfo. But it might be a lost primary, so its BINFO_OFFSET
+ might be wrong, so we just use the BINFO_OFFSET from vid->binfo. */
+ vcall_offset = BINFO_OFFSET (vid->binfo);
vcall_offset = size_diffop (BINFO_OFFSET (base_binfo),
vcall_offset);
vcall_offset = fold (build1 (NOP_EXPR, vtable_entry_type,
/* Keep track of the vtable index where this vcall offset can be
found. For a construction vtable, we already made this
- annotation when we build the original vtable. */
+ annotation when we built the original vtable. */
if (!vid->ctor_vtbl_p)
BV_VCALL_INDEX (derived_virtuals) = vid->index;
ABI.) */
static tree
-build_vtable_entry (delta, vcall_index, entry, generate_with_vtable_p)
+build_vtable_entry (delta, vcall_index, entry)
tree delta;
tree vcall_index;
tree entry;
- int generate_with_vtable_p;
{
if (flag_vtable_thunks)
{
if ((!integer_zerop (delta) || vcall_index != NULL_TREE)
&& fn != abort_fndecl)
{
- entry = make_thunk (entry, delta, vcall_index,
- generate_with_vtable_p);
+ entry = make_thunk (entry, delta, vcall_index);
entry = build1 (ADDR_EXPR, vtable_entry_type, entry);
TREE_READONLY (entry) = 1;
TREE_CONSTANT (entry) = 1;
projects / gcc.git / commitdiff