This is the mail archive of the
gcc-patches@gcc.gnu.org
mailing list for the GCC project.
Re: C++ PATCH: Remove THUNK_DECLs
>>>>> "Jason" == Jason Merrill <jason@cygnus.com> writes:
Jason> I don't think this is safe. The reason for using a
Jason> THUNK_DECL in the first place was because we wanted to
Jason> store information in it that is wrong for a FUNCTION_DECL:
Here's a patch that should avoid the DECL_SAVED_INSNS and DECL_INITIAL
overlaps which were by far the most troubling. (See an earlier post
on DECL_FRAME_SIZE for why that one doesn't worry me.) It follows
both of your excellent suggestions: use DECL_LANG_SPECIFIC for this
stuff, and make generic thunks into something that looks like an
ordinary function before giving it to the back-end.
Thanks for pointing out the dangers, and for suggesting fixes.
Tested (both -fnew-abi and not) on i686-pc-linux-gnu.
--
Mark Mitchell mark@codesourcery.com
CodeSourcery, LLC http://www.codesourcery.com
2000-05-04 Mark Mitchell <mark@codesourcery.com>
* cp-tree.h (DELTA_FROM_VTABLE_ENTRY): Remove.
(SET_FNADDR_FROM_VTABLE_ENTRY): Likewise.
(lang_decl_flags): Add vcall_offset.
(THUNK_VCALL_OFFSET): Use it.
* decl.c (lang_mark_tree): Don't mark DECL_ACCESS for a thunk.
* method.c (make_thunk): Create the lang_decl here, not in
emit_thunk.
(emit_thunk): Make generic thunks into ordinary functions once
they have been fed to expand_body.
* semantics.c (expand_body): Set current_function_is_thunk here.
Index: cp-tree.h
===================================================================
RCS file: /cvs/gcc/egcs/gcc/cp/cp-tree.h,v
retrieving revision 1.450
diff -c -p -r1.450 cp-tree.h
*** cp-tree.h 2000/05/04 14:54:17 1.450
--- cp-tree.h 2000/05/05 03:05:44
*************** enum languages { lang_c, lang_cplusplus,
*** 1294,1306 ****
((CP_TYPE_QUALS (NODE) & (TYPE_QUAL_CONST | TYPE_QUAL_VOLATILE)) \
== TYPE_QUAL_CONST)
- #define DELTA_FROM_VTABLE_ENTRY(ENTRY) \
- (!flag_vtable_thunks ? \
- TREE_VALUE (CONSTRUCTOR_ELTS (ENTRY)) \
- : !DECL_THUNK_P (TREE_OPERAND ((ENTRY), 0)) \
- ? integer_zero_node \
- : build_int_2 (THUNK_DELTA (TREE_OPERAND ((ENTRY), 0)), 0))
-
/* Virtual function addresses can be gotten from a virtual function
table entry using this macro. */
#define FNADDR_FROM_VTABLE_ENTRY(ENTRY) \
--- 1294,1299 ----
*************** enum languages { lang_c, lang_cplusplus,
*** 1310,1317 ****
? (ENTRY) \
: DECL_INITIAL (TREE_OPERAND ((ENTRY), 0)))
- #define SET_FNADDR_FROM_VTABLE_ENTRY(ENTRY,VALUE) \
- (TREE_VALUE (TREE_CHAIN (TREE_CHAIN (CONSTRUCTOR_ELTS (ENTRY)))) = (VALUE))
#define FUNCTION_ARG_CHAIN(NODE) (TREE_CHAIN (TYPE_ARG_TYPES (TREE_TYPE (NODE))))
#define PROMOTES_TO_AGGR_TYPE(NODE,CODE) \
(((CODE) == TREE_CODE (NODE) \
--- 1303,1308 ----
*************** struct lang_decl_flags
*** 1900,1905 ****
--- 1891,1900 ----
/* In a namespace-scope FUNCTION_DECL, this is
GLOBAL_INIT_PRIORITY. */
int init_priority;
+
+ /* In a FUNCTION_DECL for which DECL_THUNK_P holds, this is
+ THUNK_VCALL_OFFSET. */
+ HOST_WIDE_INT vcall_offset;
} u2;
};
*************** extern int flag_new_for_scope;
*** 3039,3045 ****
vtable for the `this' pointer to find the vcall offset. (The vptr
is always located at offset zero from the f `this' pointer.) If
zero, then there is no vcall offset. */
! #define THUNK_VCALL_OFFSET(DECL) (DECL_CHECK (DECL)->decl.u2.i)
/* DECL_NEEDED_P holds of a declaration when we need to emit its
definition. This is true when the back-end tells us that
--- 3034,3041 ----
vtable for the `this' pointer to find the vcall offset. (The vptr
is always located at offset zero from the f `this' pointer.) If
zero, then there is no vcall offset. */
! #define THUNK_VCALL_OFFSET(DECL) \
! (DECL_LANG_SPECIFIC (DECL)->decl_flags.u2.vcall_offset)
/* DECL_NEEDED_P holds of a declaration when we need to emit its
definition. This is true when the back-end tells us that
Index: decl.c
===================================================================
RCS file: /cvs/gcc/egcs/gcc/cp/decl.c,v
retrieving revision 1.601
diff -c -p -r1.601 decl.c
*** decl.c 2000/05/03 22:25:20 1.601
--- decl.c 2000/05/05 03:05:53
*************** lang_mark_tree (t)
*** 14731,14737 ****
if (ld)
{
ggc_mark (ld);
! if (!DECL_GLOBAL_CTOR_P (t) && !DECL_GLOBAL_DTOR_P (t))
ggc_mark_tree (ld->decl_flags.u2.access);
ggc_mark_tree (ld->decl_flags.context);
if (TREE_CODE (t) != NAMESPACE_DECL)
--- 14731,14739 ----
if (ld)
{
ggc_mark (ld);
! if (!DECL_GLOBAL_CTOR_P (t)
! && !DECL_GLOBAL_DTOR_P (t)
! && !DECL_THUNK_P (t))
ggc_mark_tree (ld->decl_flags.u2.access);
ggc_mark_tree (ld->decl_flags.context);
if (TREE_CODE (t) != NAMESPACE_DECL)
Index: method.c
===================================================================
RCS file: /cvs/gcc/egcs/gcc/cp/method.c,v
retrieving revision 1.153
diff -c -p -r1.153 method.c
*** method.c 2000/05/03 22:25:20 1.153
--- method.c 2000/05/05 03:05:57
*************** make_thunk (function, delta, vcall_index
*** 2055,2060 ****
--- 2055,2063 ----
if (thunk == NULL_TREE)
{
thunk = build_decl (FUNCTION_DECL, thunk_id, TREE_TYPE (func_decl));
+ DECL_LANG_SPECIFIC (thunk) = DECL_LANG_SPECIFIC (func_decl);
+ copy_lang_decl (func_decl);
+ DECL_CONTEXT (thunk) = DECL_CONTEXT (func_decl);
TREE_READONLY (thunk) = TREE_READONLY (func_decl);
TREE_THIS_VOLATILE (thunk) = TREE_THIS_VOLATILE (func_decl);
comdat_linkage (thunk);
*************** make_thunk (function, delta, vcall_index
*** 2063,2074 ****
THUNK_DELTA (thunk) = delta;
THUNK_VCALL_OFFSET (thunk)
= vcall_index * int_size_in_bytes (vtable_entry_type);
DECL_EXTERNAL (thunk) = 1;
DECL_ARTIFICIAL (thunk) = 1;
- DECL_CONTEXT (thunk) = DECL_CONTEXT (func_decl);
/* Even if this thunk is a member of a local class, we don't
need a static chain. */
DECL_NO_STATIC_CHAIN (thunk) = 1;
/* So that finish_file can write out any thunks that need to be: */
pushdecl_top_level (thunk);
}
--- 2066,2087 ----
THUNK_DELTA (thunk) = delta;
THUNK_VCALL_OFFSET (thunk)
= vcall_index * int_size_in_bytes (vtable_entry_type);
+ /* 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 FUNC_DECL is. */
+ DECL_PENDING_INLINE_P (thunk) = 0;
+ /* Nor has it been deferred. */
+ DECL_DEFERRED_FN (thunk) = 0;
/* So that finish_file can write out any thunks that need to be: */
pushdecl_top_level (thunk);
}
*************** void
*** 2081,2095 ****
emit_thunk (thunk_fndecl)
tree thunk_fndecl;
{
! tree fnaddr = DECL_INITIAL (thunk_fndecl);
! tree function = TREE_OPERAND (fnaddr, 0);
! int delta = THUNK_DELTA (thunk_fndecl);
! int vcall_offset = THUNK_VCALL_OFFSET (thunk_fndecl);
if (TREE_ASM_WRITTEN (thunk_fndecl))
return;
! TREE_ASM_WRITTEN (thunk_fndecl) = 1;
TREE_ADDRESSABLE (function) = 1;
mark_used (function);
--- 2094,2118 ----
emit_thunk (thunk_fndecl)
tree thunk_fndecl;
{
! tree fnaddr;
! tree function;
! int delta;
! int vcall_offset;
if (TREE_ASM_WRITTEN (thunk_fndecl))
return;
! if (TREE_CODE (DECL_INITIAL (thunk_fndecl)) != ADDR_EXPR)
! /* We already turned this thunk into an ordinary function.
! There's no need to process this thunk again. (We can't just
! clear DECL_THUNK_P because that will confuse
! FNADDR_FROM_VTABLE_ENTRY and friends.) */
! return;
!
! fnaddr = DECL_INITIAL (thunk_fndecl);
! function = TREE_OPERAND (fnaddr, 0);
! delta = THUNK_DELTA (thunk_fndecl);
! vcall_offset = THUNK_VCALL_OFFSET (thunk_fndecl);
TREE_ADDRESSABLE (function) = 1;
mark_used (function);
*************** emit_thunk (thunk_fndecl)
*** 2097,2104 ****
if (current_function_decl)
abort ();
#ifdef ASM_OUTPUT_MI_THUNK
! if (!flag_syntax_only && vcall_offset == 0)
{
const char *fnname;
current_function_decl = thunk_fndecl;
--- 2120,2133 ----
if (current_function_decl)
abort ();
+ if (flag_syntax_only)
+ {
+ TREE_ASM_WRITTEN (thunk_fndecl) = 1;
+ return;
+ }
+
#ifdef ASM_OUTPUT_MI_THUNK
! if (vcall_offset == 0)
{
const char *fnname;
current_function_decl = thunk_fndecl;
*************** emit_thunk (thunk_fndecl)
*** 2115,2120 ****
--- 2144,2150 ----
assemble_end_function (thunk_fndecl, fnname);
current_function_decl = 0;
cfun = 0;
+ TREE_ASM_WRITTEN (thunk_fndecl) = 1;
}
else
#endif /* ASM_OUTPUT_MI_THUNK */
*************** emit_thunk (thunk_fndecl)
*** 2141,2161 ****
a = nreverse (t);
DECL_ARGUMENTS (thunk_fndecl) = a;
DECL_RESULT (thunk_fndecl) = NULL_TREE;
- DECL_LANG_SPECIFIC (thunk_fndecl) = DECL_LANG_SPECIFIC (function);
- copy_lang_decl (thunk_fndecl);
- DECL_INTERFACE_KNOWN (thunk_fndecl) = 1;
- DECL_NOT_REALLY_EXTERN (thunk_fndecl) = 1;
- DECL_SAVED_FUNCTION_DATA (thunk_fndecl) = NULL;
- /* The thunk itself is not a constructor or destructor, even if
- the thing it is thunking to is. */
- DECL_DESTRUCTOR_P (thunk_fndecl) = 0;
- DECL_CONSTRUCTOR_P (thunk_fndecl) = 0;
-
push_to_top_level ();
start_function (NULL_TREE, thunk_fndecl, NULL_TREE, SF_PRE_PARSED);
store_parm_decls ();
- current_function_is_thunk = 1;
/* Adjust the this pointer by the constant. */
t = ssize_int (delta);
--- 2171,2180 ----
*************** emit_thunk (thunk_fndecl)
*** 2199,2217 ****
finish_expr_stmt (t);
/* The back-end expects DECL_INITIAL to contain a BLOCK, so we
! clear this here. */
! DECL_INITIAL (thunk_fndecl) = NULL_TREE;
DECL_INITIAL (thunk_fndecl) = make_node (BLOCK);
BLOCK_VARS (DECL_INITIAL (thunk_fndecl))
= DECL_ARGUMENTS (thunk_fndecl);
expand_body (finish_function (0));
- /* Restore the DECL_INITIAL for the THUNK_DECL. */
- DECL_INITIAL (thunk_fndecl) = fnaddr;
pop_from_top_level ();
-
- /* Don't let the backend defer this function. */
- if (DECL_DEFER_OUTPUT (thunk_fndecl))
- output_inline_function (thunk_fndecl);
}
}
--- 2218,2229 ----
finish_expr_stmt (t);
/* The back-end expects DECL_INITIAL to contain a BLOCK, so we
! create one. */
DECL_INITIAL (thunk_fndecl) = make_node (BLOCK);
BLOCK_VARS (DECL_INITIAL (thunk_fndecl))
= DECL_ARGUMENTS (thunk_fndecl);
expand_body (finish_function (0));
pop_from_top_level ();
}
}
Index: semantics.c
===================================================================
RCS file: /cvs/gcc/egcs/gcc/cp/semantics.c,v
retrieving revision 1.138
diff -c -p -r1.138 semantics.c
*** semantics.c 2000/04/11 20:16:36 1.138
--- semantics.c 2000/05/05 03:06:01
*************** expand_body (fn)
*** 2775,2780 ****
--- 2775,2781 ----
start_function (NULL_TREE, fn, NULL_TREE, SF_PRE_PARSED | SF_EXPAND);
store_parm_decls ();
+ current_function_is_thunk = DECL_THUNK_P (fn);
/* We don't need to redeclare __FUNCTION__, __PRETTY_FUNCTION__, or
any of the other magic variables we set up when starting a