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Re: [rfc] Teach i386 prologue reader about _alloca and __main
Daniel Jacobowitz wrote:
On Sat, Oct 13, 2007 at 08:54:45PM +0100, Pedro Alves wrote:
* gdbarch.sh (gdbarch_skip___main_call): New.
* gdbarch.h, gdbarch.c: Regenerate.
I don't have time or experience to look at this thoroughly right now,
but I did notice this: you can just put this in i386's gdbarch_tdep.
The __main call is not i386 specific. Eg. arm-wince has the same problem.
More precisely, it matches the targets where this is true in gcc/function.c.
void
expand_main_function (void)
{
#if (defined(INVOKE__main) \
|| (!defined(HAS_INIT_SECTION) \
&& !defined(INIT_SECTION_ASM_OP) \
&& !defined(INIT_ARRAY_SECTION_ASM_OP)))
emit_library_call (init_one_libfunc (NAME__MAIN), LCT_NORMAL, VOIDmode, 0);
#endif
}
I've also experimented with calling skip__main_call from
find_function_start_sal, but later moved it into i386-tdep.c.
That's still an open issue for me.
--- symtab.c 2007-10-13 20:08:38.000000000 +0100
+++ symtab.c.skip_main 2007-10-13 20:08:32.000000000 +0100
@@ -2493,6 +2493,16 @@ find_function_start_sal (struct symbol *
/* Recalculate the line number (might not be N+1). */
sal = find_pc_sect_line (pc, SYMBOL_BFD_SECTION (sym), 0);
}
+
+ /* Skip __main call in targets without .init section and/or that
+ emit a call to __main in main as the first thing after the
+ prologue, before user code. */
+ if (funfirstline
+ && gdbarch_skip___main_call_p (current_gdbarch)
+ && SYMBOL_LINKAGE_NAME (sym)
+ && strcmp (SYMBOL_LINKAGE_NAME (sym), "main") == 0)
+ pc = gdbarch_skip___main_call (current_gdbarch, pc);
+
sal.pc = pc;
return sal;
I'll experiment a bit more with it.
I'm mostly asking for advice on:
- Is the gdb-only solution preferable? That is, the line info
currently marks the prologue ending *before* the __main call.
Last year's version changed that, this one doesn't. Does anyone
see any problem with that?
Cheers,
Pedro Alves