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Re: RFA: strip stdcall suffixes under cygwin
- From: Christopher Faylor <cgf at redhat dot com>
- To: Jim Blandy <jimb at redhat dot com>
- Cc: gdb-patches at sources dot redhat dot com
- Date: Wed, 27 Mar 2002 18:48:50 -0500
- Subject: Re: RFA: strip stdcall suffixes under cygwin
- References: <20020327233525.1164E5EA11@zwingli.cygnus.com>
On Wed, Mar 27, 2002 at 06:35:25PM -0500, Jim Blandy wrote:
>Chris, I think I need your approval for this.
Approved.
Thanks,
cgf
>2002-03-27 Jim Blandy <jimb@redhat.com>
>
> * config/i386/tm-cygwin.h: #define
> LINKER_SYMBOLS_HAVE_WIN32_STDCALL_ARG_SIZES.
> * symtab.c (LINKER_SYMBOLS_HAVE_WIN32_STDCALL_ARG_SIZES): Provide
> default #definition here, if tm-*.h file doesn't have one.
> (symbol_init_mangled_name): If the above is #defined, strip off
> the stdcall arg size, if present, from linker symbol names before
> trying to demangle them.
>
>Index: gdb/symtab.c
>===================================================================
>RCS file: /cvs/src/src/gdb/symtab.c,v
>retrieving revision 1.59
>diff -c -r1.59 symtab.c
>*** gdb/symtab.c 2002/03/27 23:10:23 1.59
>--- gdb/symtab.c 2002/03/27 23:19:07
>***************
>*** 353,358 ****
>--- 353,362 ----
>
> /* Initialize a symbol's mangled name. */
>
>+ #ifndef LINKER_SYMBOLS_HAVE_WIN32_STDCALL_ARG_SIZES
>+ #define LINKER_SYMBOLS_HAVE_WIN32_STDCALL_ARG_SIZES (0)
>+ #endif
>+
> /* Try to initialize the demangled name for a symbol, based on the
> language of that symbol. If the language is set to language_auto,
> it will attempt to find any demangling algorithm that works and
>***************
>*** 369,381 ****
> char *mangled = gsymbol->name;
> char *demangled = NULL;
>
> if (gsymbol->language == language_unknown)
> gsymbol->language = language_auto;
> if (gsymbol->language == language_cplus
> || gsymbol->language == language_auto)
> {
> demangled =
>! cplus_demangle (gsymbol->name, DMGL_PARAMS | DMGL_ANSI);
> if (demangled != NULL)
> {
> gsymbol->language = language_cplus;
>--- 373,418 ----
> char *mangled = gsymbol->name;
> char *demangled = NULL;
>
>+ /* On Windows, some functions use the `stdcall' calling convention,
>+ in which the callee is expected to pop the arguments off the
>+ stack. Normally, the caller takes care of this, because only the
>+ caller knows how many arguments it really passed. To avoid
>+ confusion, the linker symbols for `stdcall' functions have names
>+ with a suffix "@N" attached to them, where "N" is the number of
>+ bytes they'll pop. That way, if a caller thinks some `stdcall'
>+ function `foo' expects M argument bytes, but the definition of
>+ `foo' expects N argument bytes, N != M, then the call will be a
>+ reference to `foo@M', but the definition will have a linker
>+ symbol `foo@N', and you'll get a link-time `symbol not found'
>+ error, instead of a crash at run-time.
>+
>+ (Note how this fails to address calls through function pointers,
>+ since the byte count isn't part of the function pointer's type.
>+ Go, Microsoft!)
>+
>+ Whatever. But our demangler doesn't like that '@N' suffix, so we
>+ need to strip it off. */
>+ if (LINKER_SYMBOLS_HAVE_WIN32_STDCALL_ARG_SIZES)
>+ {
>+ char *arg_byte_suffix = strchr (mangled, '@');
>+ if (arg_byte_suffix)
>+ {
>+ int prefix_len = arg_byte_suffix - mangled;
>+ char *mangled_sans_suffix = alloca (prefix_len + 1);
>+ memcpy (mangled_sans_suffix, mangled, prefix_len);
>+ mangled_sans_suffix[prefix_len] = '\0';
>+
>+ mangled = mangled_sans_suffix;
>+ }
>+ }
>+
> if (gsymbol->language == language_unknown)
> gsymbol->language = language_auto;
> if (gsymbol->language == language_cplus
> || gsymbol->language == language_auto)
> {
> demangled =
>! cplus_demangle (mangled, DMGL_PARAMS | DMGL_ANSI);
> if (demangled != NULL)
> {
> gsymbol->language = language_cplus;
>***************
>*** 391,397 ****
> if (gsymbol->language == language_java)
> {
> demangled =
>! cplus_demangle (gsymbol->name,
> DMGL_PARAMS | DMGL_ANSI | DMGL_JAVA);
> if (demangled != NULL)
> {
>--- 428,434 ----
> if (gsymbol->language == language_java)
> {
> demangled =
>! cplus_demangle (mangled,
> DMGL_PARAMS | DMGL_ANSI | DMGL_JAVA);
> if (demangled != NULL)
> {
>Index: gdb/symtab.h
>===================================================================
>RCS file: /cvs/src/src/gdb/symtab.h,v
>retrieving revision 1.29
>diff -c -r1.29 symtab.h
>*** gdb/symtab.h 2002/03/27 23:10:24 1.29
>--- gdb/symtab.h 2002/03/27 23:19:08
>***************
>*** 159,170 ****
> } \
> } while (0)
>
> #define SYMBOL_INIT_DEMANGLED_NAME(symbol,obstack) \
> (symbol_init_demangled_name (&symbol->ginfo, (obstack)))
> extern void symbol_init_demangled_name (struct general_symbol_info *symbol,
> struct obstack *obstack);
>
>-
> /* Macro that returns the demangled name for a symbol based on the language
> for that symbol. If no demangled name exists, returns NULL. */
>
>--- 159,171 ----
> } \
> } while (0)
>
>+
> #define SYMBOL_INIT_DEMANGLED_NAME(symbol,obstack) \
> (symbol_init_demangled_name (&symbol->ginfo, (obstack)))
> extern void symbol_init_demangled_name (struct general_symbol_info *symbol,
> struct obstack *obstack);
>+
>
> /* Macro that returns the demangled name for a symbol based on the language
> for that symbol. If no demangled name exists, returns NULL. */
>
>Index: gdb/config/i386/tm-cygwin.h
>===================================================================
>RCS file: /cvs/src/src/gdb/config/i386/tm-cygwin.h,v
>retrieving revision 1.11
>diff -c -r1.11 tm-cygwin.h
>*** gdb/config/i386/tm-cygwin.h 2001/11/27 05:15:58 1.11
>--- gdb/config/i386/tm-cygwin.h 2002/03/27 23:19:12
>***************
>*** 47,49 ****
>--- 47,51 ----
> char *child_solib_loaded_library_pathname(int);
> void child_clear_solibs (void);
> void dll_symbol_command (char *, int);
>+
>+ #define LINKER_SYMBOLS_HAVE_WIN32_STDCALL_ARG_SIZES (1)