From 1b1aae4d607d0c5d0f6e8005d6280a282413dad8 Mon Sep 17 00:00:00 2001 From: Jon Turney Date: Sun, 24 Jul 2016 18:18:10 +0100 Subject: [PATCH 4/6] 7.8-symtab-cygwin See https://sourceware.org/ml/gdb-patches/2002-03/msg00557.html --- gdb/symtab.c | 37 +++++++++++++++++++++++++++++++++++++ 1 file changed, 37 insertions(+) diff --git a/gdb/symtab.c b/gdb/symtab.c index f2b1a14e006..fafe0b7dfc8 100644 --- a/gdb/symtab.c +++ b/gdb/symtab.c @@ -864,6 +864,10 @@ create_demangled_names_hash (struct objfile_per_bfd_storage *per_bfd) free_demangled_name_entry, xcalloc, xfree)); } +#ifdef __CYGWIN__ +#define LINKER_SYMBOLS_HAVE_WIN32_STDCALL_ARG_SIZES (1) +#endif + /* See symtab.h */ gdb::unique_xmalloc_ptr @@ -873,6 +877,39 @@ symbol_find_demangled_name (struct general_symbol_info *gsymbol, gdb::unique_xmalloc_ptr demangled; int i; + /* 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 = (char *)(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->m_language = language_auto; -- 2.40.0.windows.1