diff options
Diffstat (limited to 'gcc/cp/cp-tree.def')
| -rw-r--r-- | gcc/cp/cp-tree.def | 22 |
1 files changed, 16 insertions, 6 deletions
diff --git a/gcc/cp/cp-tree.def b/gcc/cp/cp-tree.def index 70a41b5..a57742c 100644 --- a/gcc/cp/cp-tree.def +++ b/gcc/cp/cp-tree.def @@ -1,7 +1,7 @@ /* This file contains the definitions and documentation for the additional tree codes used in the GNU C++ compiler (see tree.def for the standard codes). - Copyright (C) 1987,88,90,93,97-8,1999 Free Software Foundation, Inc. + Copyright (C) 1987,88,90,93,97-8,1999, 2000 Free Software Foundation, Inc. Hacked by Michael Tiemann (tiemann@cygnus.com) This file is part of GNU CC. @@ -159,12 +159,22 @@ DEFTREECODE (TYPEOF_TYPE, "typeof_type", 't', 0) /* A thunk is a stub function. - Thunks are used to implement multiple inheritance: - At run-time, such a thunk subtracts THUNK_DELTA (an int, not a tree) - from the this pointer, and then jumps to DECL_INITIAL - (which is an ADDR_EXPR whose operand is a FUNCTION_DECL). + A THUNK_DECL is an alternate entry point for an ordinary + FUNCTION_DECL. It's job is to adjust the `this' poitner before + transferring control to the FUNCTION_DECL. - Other kinds of thunks may be defined later. */ + A thunk may perform either, or both, of the following operations: + + o Adjust the `this' pointer by a constant offset. + o Adjust the `this' pointer by looking up a vcall-offset + in the vtable. + + If both operations are performed, then the constant adjument to + `this' is performed first. + + The constant adjustment is given by THUNK_DELTA. If the + vcall-offset is required, the index into the vtable is given by + THUNK_VCALL_OFFSET. */ DEFTREECODE (THUNK_DECL, "thunk_decl", 'd', 0) /* A using declaration. DECL_INITIAL contains the specified scope. |