void
finish_thunk (tree thunk)
{
tree function, name;
tree fixed_offset = ssize_int (THUNK_FIXED_OFFSET (thunk));
tree virtual_offset = THUNK_VIRTUAL_OFFSET (thunk);
gcc_assert (!DECL_NAME (thunk) && DECL_THUNK_P (thunk));
if (virtual_offset && DECL_RESULT_THUNK_P (thunk))
virtual_offset = BINFO_VPTR_FIELD (virtual_offset);
function = THUNK_TARGET (thunk);
name = mangle_thunk (function, DECL_THIS_THUNK_P (thunk),
fixed_offset, virtual_offset);
/* We can end up with declarations of (logically) different
covariant thunks, that do identical adjustments. The two thunks
will be adjusting between within different hierarchies, which
happen to have the same layout. We must nullify one of them to
refer to the other. */
if (DECL_RESULT_THUNK_P (thunk))
{
tree cov_probe;
for (cov_probe = DECL_THUNKS (function);
cov_probe; cov_probe = TREE_CHAIN (cov_probe))
if (DECL_NAME (cov_probe) == name)
{
gcc_assert (!DECL_THUNKS (thunk));
THUNK_ALIAS (thunk) = (THUNK_ALIAS (cov_probe)
? THUNK_ALIAS (cov_probe) : cov_probe);
break;
}
}
DECL_NAME (thunk) = name;
SET_DECL_ASSEMBLER_NAME (thunk, name);
}
tree
make_thunk (tree function, bool this_adjusting,
tree fixed_offset, tree virtual_offset)
{
HOST_WIDE_INT d;
tree thunk;
gcc_assert (TREE_CODE (function) == FUNCTION_DECL);
/* We can have this thunks to covariant thunks, but not vice versa. */
gcc_assert (!DECL_THIS_THUNK_P (function));
gcc_assert (!DECL_RESULT_THUNK_P (function) || this_adjusting);
/* Scale the VIRTUAL_OFFSET to be in terms of bytes. */
if (this_adjusting && virtual_offset)
virtual_offset
= size_binop (MULT_EXPR,
virtual_offset,
convert (ssizetype,
TYPE_SIZE_UNIT (vtable_entry_type)));
d = tree_low_cst (fixed_offset, 0);
/* See if we already have the thunk in question. For this_adjusting
thunks VIRTUAL_OFFSET will be an INTEGER_CST, for covariant thunks it
will be a BINFO. */
for (thunk = DECL_THUNKS (function); thunk; thunk = TREE_CHAIN (thunk))
if (DECL_THIS_THUNK_P (thunk) == this_adjusting
&& THUNK_FIXED_OFFSET (thunk) == d
&& !virtual_offset == !THUNK_VIRTUAL_OFFSET (thunk)
&& (!virtual_offset
|| (this_adjusting
? tree_int_cst_equal (THUNK_VIRTUAL_OFFSET (thunk),
virtual_offset)
: THUNK_VIRTUAL_OFFSET (thunk) == virtual_offset)))
return thunk;
/* All thunks must be created before FUNCTION is actually emitted;
the ABI requires that all thunks be emitted together with the
function to which they transfer control. */
gcc_assert (!TREE_ASM_WRITTEN (function));
/* Likewise, we can only be adding thunks to a function declared in
the class currently being laid out. */
gcc_assert (TYPE_SIZE (DECL_CONTEXT (function))
&& TYPE_BEING_DEFINED (DECL_CONTEXT (function)));
thunk = build_decl (FUNCTION_DECL, NULL_TREE, TREE_TYPE (function));
DECL_LANG_SPECIFIC (thunk) = DECL_LANG_SPECIFIC (function);
cxx_dup_lang_specific_decl (thunk);
DECL_THUNKS (thunk) = NULL_TREE;
DECL_CONTEXT (thunk) = DECL_CONTEXT (function);
TREE_READONLY (thunk) = TREE_READONLY (function);
TREE_THIS_VOLATILE (thunk) = TREE_THIS_VOLATILE (function);
TREE_PUBLIC (thunk) = TREE_PUBLIC (function);
SET_DECL_THUNK_P (thunk, this_adjusting);
THUNK_TARGET (thunk) = function;
THUNK_FIXED_OFFSET (thunk) = d;
THUNK_VIRTUAL_OFFSET (thunk) = virtual_offset;
THUNK_ALIAS (thunk) = NULL_TREE;
/* The thunk itself is not a constructor or destructor, even if
the thing it is thunking to is. */
DECL_INTERFACE_KNOWN (thunk) = 1;
DECL_NOT_REALLY_EXTERN (thunk) = 1;
DECL_SAVED_FUNCTION_DATA (thunk) = NULL;
DECL_DESTRUCTOR_P (thunk) = 0;
DECL_CONSTRUCTOR_P (thunk) = 0;
DECL_EXTERNAL (thunk) = 1;
DECL_ARTIFICIAL (thunk) = 1;
/* Even if this thunk is a member of a local class, we don't
need a static chain. */
DECL_NO_STATIC_CHAIN (thunk) = 1;
/* The THUNK is not a pending inline, even if the FUNCTION is. */
DECL_PENDING_INLINE_P (thunk) = 0;
DECL_INLINE (thunk) = 0;
DECL_DECLARED_INLINE_P (thunk) = 0;
/* Nor has it been deferred. */
DECL_DEFERRED_FN (thunk) = 0;
/* Nor is it a template instantiation. */
DECL_USE_TEMPLATE (thunk) = 0;
DECL_TEMPLATE_INFO (thunk) = NULL;
/* Add it to the list of thunks associated with FUNCTION. */
TREE_CHAIN (thunk) = DECL_THUNKS (function);
DECL_THUNKS (function) = thunk;
return thunk;
}
void
use_thunk (tree thunk_fndecl, bool emit_p)
{
tree a, t, function, alias;
tree virtual_offset;
HOST_WIDE_INT fixed_offset, virtual_value;
bool this_adjusting = DECL_THIS_THUNK_P (thunk_fndecl);
/* We should have called finish_thunk to give it a name. */
gcc_assert (DECL_NAME (thunk_fndecl));
/* We should never be using an alias, always refer to the
aliased thunk. */
gcc_assert (!THUNK_ALIAS (thunk_fndecl));
if (TREE_ASM_WRITTEN (thunk_fndecl))
return;
function = THUNK_TARGET (thunk_fndecl);
if (DECL_RESULT (thunk_fndecl))
/* We already turned this thunk into an ordinary function.
There's no need to process this thunk again. */
return;
if (DECL_THUNK_P (function))
/* The target is itself a thunk, process it now. */
use_thunk (function, emit_p);
/* Thunks are always addressable; they only appear in vtables. */
TREE_ADDRESSABLE (thunk_fndecl) = 1;
/* Figure out what function is being thunked to. It's referenced in
this translation unit. */
TREE_ADDRESSABLE (function) = 1;
mark_used (function);
if (!emit_p)
return;
if (TARGET_USE_LOCAL_THUNK_ALIAS_P (function))
alias = make_alias_for_thunk (function);
else
alias = function;
fixed_offset = THUNK_FIXED_OFFSET (thunk_fndecl);
virtual_offset = THUNK_VIRTUAL_OFFSET (thunk_fndecl);
if (virtual_offset)
{
if (!this_adjusting)
virtual_offset = BINFO_VPTR_FIELD (virtual_offset);
virtual_value = tree_low_cst (virtual_offset, /*pos=*/0);
gcc_assert (virtual_value);
}
else
virtual_value = 0;
/* And, if we need to emit the thunk, it's used. */
mark_used (thunk_fndecl);
/* This thunk is actually defined. */
DECL_EXTERNAL (thunk_fndecl) = 0;
/* The linkage of the function may have changed. FIXME in linkage
rewrite. */
TREE_PUBLIC (thunk_fndecl) = TREE_PUBLIC (function);
DECL_VISIBILITY (thunk_fndecl) = DECL_VISIBILITY (function);
DECL_VISIBILITY_SPECIFIED (thunk_fndecl)
= DECL_VISIBILITY_SPECIFIED (function);
if (DECL_ONE_ONLY (function))
make_decl_one_only (thunk_fndecl);
if (flag_syntax_only)
{
TREE_ASM_WRITTEN (thunk_fndecl) = 1;
return;
}
push_to_top_level ();
if (TARGET_USE_LOCAL_THUNK_ALIAS_P (function)
&& targetm.have_named_sections)
{
resolve_unique_section (function, 0, flag_function_sections);
if (DECL_SECTION_NAME (function) != NULL && DECL_ONE_ONLY (function))
{
resolve_unique_section (thunk_fndecl, 0, flag_function_sections);
/* Output the thunk into the same section as function. */
DECL_SECTION_NAME (thunk_fndecl) = DECL_SECTION_NAME (function);
}
}
/* The back-end expects DECL_INITIAL to contain a BLOCK, so we
create one. */
DECL_INITIAL (thunk_fndecl) = make_node (BLOCK);
/* Set up cloned argument trees for the thunk. */
t = NULL_TREE;
for (a = DECL_ARGUMENTS (function); a; a = TREE_CHAIN (a))
{
tree x = copy_node (a);
TREE_CHAIN (x) = t;
DECL_CONTEXT (x) = thunk_fndecl;
SET_DECL_RTL (x, NULL_RTX);
DECL_HAS_VALUE_EXPR_P (x) = 0;
t = x;
}
a = nreverse (t);
DECL_ARGUMENTS (thunk_fndecl) = a;
BLOCK_VARS (DECL_INITIAL (thunk_fndecl)) = a;
if (this_adjusting
&& targetm.asm_out.can_output_mi_thunk (thunk_fndecl, fixed_offset,
virtual_value, alias))
{
const char *fnname;
current_function_decl = thunk_fndecl;
DECL_RESULT (thunk_fndecl)
= build_decl (RESULT_DECL, 0, integer_type_node);
fnname = XSTR (XEXP (DECL_RTL (thunk_fndecl), 0), 0);
init_function_start (thunk_fndecl);
current_function_is_thunk = 1;
assemble_start_function (thunk_fndecl, fnname);
targetm.asm_out.output_mi_thunk (asm_out_file, thunk_fndecl,
fixed_offset, virtual_value, alias);
assemble_end_function (thunk_fndecl, fnname);
init_insn_lengths ();
current_function_decl = 0;
cfun = 0;
TREE_ASM_WRITTEN (thunk_fndecl) = 1;
}
else
{
/* If this is a covariant thunk, or we don't have the necessary
code for efficient thunks, generate a thunk function that
just makes a call to the real function. Unfortunately, this
doesn't work for varargs. */
if (varargs_function_p (function))
error ("generic thunk code fails for method %q#D which uses %<...%>",
function);
DECL_RESULT (thunk_fndecl) = NULL_TREE;
start_preparsed_function (thunk_fndecl, NULL_TREE, SF_PRE_PARSED);
/* We don't bother with a body block for thunks. */
/* There's no need to check accessibility inside the thunk body. */
push_deferring_access_checks (dk_no_check);
t = a;
if (this_adjusting)
t = thunk_adjust (t, /*this_adjusting=*/1,
fixed_offset, virtual_offset);
/* Build up the call to the real function. */
t = tree_cons (NULL_TREE, t, NULL_TREE);
for (a = TREE_CHAIN (a); a; a = TREE_CHAIN (a))
t = tree_cons (NULL_TREE, a, t);
t = nreverse (t);
t = build_call (alias, t);
CALL_FROM_THUNK_P (t) = 1;
if (VOID_TYPE_P (TREE_TYPE (t)))
finish_expr_stmt (t);
else
{
if (!this_adjusting)
{
tree cond = NULL_TREE;
if (TREE_CODE (TREE_TYPE (t)) == POINTER_TYPE)
{
/* If the return type is a pointer, we need to
protect against NULL. We know there will be an
adjustment, because that's why we're emitting a
thunk. */
t = save_expr (t);
cond = cp_convert (boolean_type_node, t);
}
t = thunk_adjust (t, /*this_adjusting=*/0,
fixed_offset, virtual_offset);
if (cond)
t = build3 (COND_EXPR, TREE_TYPE (t), cond, t,
cp_convert (TREE_TYPE (t), integer_zero_node));
}
if (IS_AGGR_TYPE (TREE_TYPE (t)))
t = build_cplus_new (TREE_TYPE (t), t);
finish_return_stmt (t);
}
/* Since we want to emit the thunk, we explicitly mark its name as
referenced. */
mark_decl_referenced (thunk_fndecl);
/* But we don't want debugging information about it. */
DECL_IGNORED_P (thunk_fndecl) = 1;
/* Re-enable access control. */
pop_deferring_access_checks ();
thunk_fndecl = finish_function (0);
tree_lowering_passes (thunk_fndecl);
expand_body (thunk_fndecl);
}
pop_from_top_level ();
}
void
use_thunk (tree thunk_fndecl, bool emit_p)
{
tree a, t, function, alias;
tree virtual_offset;
HOST_WIDE_INT fixed_offset, virtual_value;
bool this_adjusting = DECL_THIS_THUNK_P (thunk_fndecl);
/* We should have called finish_thunk to give it a name. */
gcc_assert (DECL_NAME (thunk_fndecl));
/* We should never be using an alias, always refer to the
aliased thunk. */
gcc_assert (!THUNK_ALIAS (thunk_fndecl));
if (TREE_ASM_WRITTEN (thunk_fndecl))
return;
function = THUNK_TARGET (thunk_fndecl);
if (DECL_RESULT (thunk_fndecl))
/* We already turned this thunk into an ordinary function.
There's no need to process this thunk again. */
return;
if (DECL_THUNK_P (function))
/* The target is itself a thunk, process it now. */
use_thunk (function, emit_p);
/* Thunks are always addressable; they only appear in vtables. */
TREE_ADDRESSABLE (thunk_fndecl) = 1;
/* Figure out what function is being thunked to. It's referenced in
this translation unit. */
TREE_ADDRESSABLE (function) = 1;
mark_used (function);
if (!emit_p)
return;
if (0 && TARGET_USE_LOCAL_THUNK_ALIAS_P (function))
alias = make_alias_for_thunk (function);
else
alias = function;
fixed_offset = THUNK_FIXED_OFFSET (thunk_fndecl);
virtual_offset = THUNK_VIRTUAL_OFFSET (thunk_fndecl);
if (virtual_offset)
{
if (!this_adjusting)
virtual_offset = BINFO_VPTR_FIELD (virtual_offset);
virtual_value = tree_low_cst (virtual_offset, /*pos=*/0);
gcc_assert (virtual_value);
}
else
virtual_value = 0;
/* And, if we need to emit the thunk, it's used. */
mark_used (thunk_fndecl);
/* This thunk is actually defined. */
DECL_EXTERNAL (thunk_fndecl) = 0;
/* The linkage of the function may have changed. FIXME in linkage
rewrite. */
TREE_PUBLIC (thunk_fndecl) = TREE_PUBLIC (function);
DECL_VISIBILITY (thunk_fndecl) = DECL_VISIBILITY (function);
DECL_VISIBILITY_SPECIFIED (thunk_fndecl)
= DECL_VISIBILITY_SPECIFIED (function);
if (DECL_ONE_ONLY (function) || DECL_WEAK (function))
make_decl_one_only (thunk_fndecl, cxx_comdat_group (thunk_fndecl));
if (flag_syntax_only)
{
TREE_ASM_WRITTEN (thunk_fndecl) = 1;
return;
}
push_to_top_level ();
if (TARGET_USE_LOCAL_THUNK_ALIAS_P (function)
&& targetm.have_named_sections)
{
resolve_unique_section (function, 0, flag_function_sections);
if (DECL_SECTION_NAME (function) != NULL && DECL_ONE_ONLY (function))
{
resolve_unique_section (thunk_fndecl, 0, flag_function_sections);
/* Output the thunk into the same section as function. */
DECL_SECTION_NAME (thunk_fndecl) = DECL_SECTION_NAME (function);
}
}
/* Set up cloned argument trees for the thunk. */
t = NULL_TREE;
for (a = DECL_ARGUMENTS (function); a; a = TREE_CHAIN (a))
{
tree x = copy_node (a);
TREE_CHAIN (x) = t;
DECL_CONTEXT (x) = thunk_fndecl;
SET_DECL_RTL (x, NULL_RTX);
DECL_HAS_VALUE_EXPR_P (x) = 0;
t = x;
}
a = nreverse (t);
DECL_ARGUMENTS (thunk_fndecl) = a;
TREE_ASM_WRITTEN (thunk_fndecl) = 1;
cgraph_add_thunk (thunk_fndecl, function,
this_adjusting, fixed_offset, virtual_value,
virtual_offset, alias);
if (!this_adjusting
|| !targetm.asm_out.can_output_mi_thunk (thunk_fndecl, fixed_offset,
virtual_value, alias))
{
/* If this is a covariant thunk, or we don't have the necessary
code for efficient thunks, generate a thunk function that
just makes a call to the real function. Unfortunately, this
doesn't work for varargs. */
if (varargs_function_p (function))
error ("generic thunk code fails for method %q#D which uses %<...%>",
function);
}
pop_from_top_level ();
}
