[v2,7/7] x86: GOT is an ELF-only entity
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Commit Message
Make md_undefined_symbol() conditional upon dealing with ELF, much like
other architectures (e.g. Arm32 and Arm64) have it. This avoids errors
in gas and even assertions in libbfd when "accidentally" e.g. a COFF-
targeting source file uses "_GLOBAL_OFFSET_TABLE_" for whatever reason.
While there also convert the final return statement to properly use
NULL.
NB: In principle 64-bit Mach-O knows GOT, too. Yet only an i?86-macho
assembler can be built right now, as per configure.tgt. Pretty clearly
adjustments to gotrel[] would also be necessary before these targets
could actually work reasonably cleanly.
---
Afaict the as_bad() in the function can't ever trigger: With one
exception, md_undefined_symbol() is called only after symbol_find() has
already returned NULL. The one exception is symbol_make(), which in turn
has no use where "_GLOBAL_OFFSET_TABLE_" would come into play as a name.
The check here in particular does _not_ guard against a new symbol of
that name being defined (leading to interesting anomalies when in fact
it is). What's the deal? Would lex_got() perhaps better call
md_undefined_symbol() instead of symbol_find_or_make()? Or mimic its
behavior by combining symbol_find() and symbol_new()?
Quite likely the variable GOT_symbol should become ELF-only altogether.
---
v2: New.
@@ -18034,6 +18034,7 @@ i386_target_format (void)
#endif /* ELF / PE / MACH_O */
+#ifdef OBJ_ELF
symbolS *
md_undefined_symbol (char *name)
{
@@ -18051,8 +18052,9 @@ md_undefined_symbol (char *name)
};
return GOT_symbol;
}
- return 0;
+ return NULL;
}
+#endif
#ifdef OBJ_AOUT
/* Round up a section size to the appropriate boundary. */
@@ -144,6 +144,7 @@ int i386_validate_fix (struct fix *);
extern int tc_i386_fix_adjustable (struct fix *);
#else
#define tc_fix_adjustable(X) ((void)(X), 1)
+#define md_undefined_symbol(N) ((void)(N), NULL)
#endif
/* Values passed to md_apply_fix don't include the symbol value. */