Fix a bug that caused incorrect PIC code to be generated for exceptions.
The symptom was an assembler warning "GOT relocation burb: `___EXCEPTION_TABLE__' should be global" followed (sometimes) by a core dump. The fix makes the compiler generate the correct GOTOFF addressing for that symbol, rather than the GOT addressing it was emitting before. Warning: There is still at least one serious bug in the i386 exception code for PIC. The exception code that is generated clobbers the GOT register (%ebx) and then tries to use it later. That leads to core dumps at program execution time. I know where the problem is, but I do not have a fix for it at this time. Until it is fixed, exceptions will not work in PIC code. This is a general problem for all i386 platforms; it is not specific to FreeBSD.
This commit is contained in:
parent
8d1005c8c4
commit
87f11ab41b
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=18659
@ -1286,6 +1286,22 @@ do \
|
||||
} \
|
||||
while (0)
|
||||
|
||||
/* Define this macro if a SYMBOL_REF representing a non-global
|
||||
address must be marked specially. This is called for
|
||||
compiler-generated local symbols, such as "__EXCEPTION_TABLE__".
|
||||
|
||||
On i386, if using PIC, we use this to set the rtx's
|
||||
SYMBOL_REF_FLAG, so that we may access it directly as
|
||||
an offset from the GOT register. */
|
||||
|
||||
#define MARK_LOCAL_ADDRESS(X) \
|
||||
do \
|
||||
{ \
|
||||
if (flag_pic && GET_CODE (X) == SYMBOL_REF) \
|
||||
SYMBOL_REF_FLAG (X) = 1; \
|
||||
} \
|
||||
while (0)
|
||||
|
||||
/* Initialize data used by insn expanders. This is called from
|
||||
init_emit, once for each function, before code is generated.
|
||||
For 386, clear stack slot assignments remembered from previous
|
||||
|
@ -1614,9 +1614,15 @@ emit_exception_table ()
|
||||
void
|
||||
register_exception_table ()
|
||||
{
|
||||
rtx addr = gen_rtx (SYMBOL_REF, Pmode, "__EXCEPTION_TABLE__");
|
||||
|
||||
#ifdef MARK_LOCAL_ADDRESS
|
||||
MARK_LOCAL_ADDRESS(addr);
|
||||
#endif
|
||||
|
||||
emit_library_call (gen_rtx (SYMBOL_REF, Pmode, "__register_exceptions"), 0,
|
||||
VOIDmode, 1,
|
||||
gen_rtx (SYMBOL_REF, Pmode, "__EXCEPTION_TABLE__"),
|
||||
addr,
|
||||
Pmode);
|
||||
}
|
||||
|
||||
|
Loading…
Reference in New Issue
Block a user