I have only reproducer for this on redhat/gcc-4_4-branch, though I believe the
problem is just latent on vanilla 4.4 branch and likely on the trunk too,
therefore I want to discuss this here.
namespace std
{
template <class> struct char_traits;
}
typedef struct { union { char __wchb[4]; }; } mbstate_t;
namespace std
{
template <typename _StateT> struct fpos
{
long long _M_off;
_StateT _M_state;
fpos (long long):_M_off (), _M_state () { }
_StateT state () { return _M_state; }
};
typedef fpos <mbstate_t> streampos;
}
namespace std
{
template <> struct char_traits <char>
{
typedef streampos pos_type;
typedef long long off_type;
typedef mbstate_t state_type;
};
}
struct pthread_mutex_t;
namespace
{
enum _Ios_Openmode { _S_in = 3, _S_out };
enum _Ios_Seekdir { _S_beg };
struct ios_base
{
typedef _Ios_Openmode openmode;
static const openmode in = _S_in;
static const openmode out = _S_out;
typedef _Ios_Seekdir seekdir;
static const seekdir beg = _S_beg;
};
template < typename _CharT, typename > struct basic_streambuf
{
typedef _CharT char_type;
char_type * _M_in_beg;
char_type *eback () { return _M_in_beg; }
char_type *gptr () {}
};
}
namespace std
{
typedef struct pthread_mutex_t __c_lock;
template <typename> class __basic_file;
template <> struct __basic_file <char>
{
__basic_file (__c_lock * = 0);
bool is_open ();
};
template <typename _CharT, typename _Traits> struct basic_filebuf : public
basic_streambuf <_CharT, _Traits>
{
typedef _CharT char_type;
typedef _Traits traits_type;
typedef typename traits_type::pos_type pos_type;
typedef typename traits_type::off_type off_type;
typedef __basic_file < char >__file_type;
typedef typename traits_type::state_type __state_type;
__file_type _M_file;
char_type *_M_pback_cur_save;
bool _M_pback_init;
void _M_destroy_pback () throw ()
{
_M_pback_cur_save += this->gptr () != this->eback ();
_M_pback_init = false;
}
bool is_open () throw () { return _M_file.is_open (); }
pos_type seekpos (pos_type, ios_base::openmode = ios_base::in |
ios_base::out);
pos_type _M_seek (off_type, ios_base::seekdir, __state_type);
};
template <typename _CharT, typename _Traits>
typename basic_filebuf <_CharT, _Traits>::pos_type
basic_filebuf <_CharT, _Traits>::seekpos (pos_type __pos, ios_base::openmode)
{
pos_type __ret = (off_type ());
if (this->is_open ())
{
_M_destroy_pback ();
__ret = _M_seek (off_type (), ios_base::beg, __pos.state ());
}
return __ret;
}
template class basic_filebuf <char, char_traits <char> >;
}
ICEs on redhat/gcc-4_4-branch when compiled with -O3 -mavx -fPIC -m32
-mtune=core2 with:
snb.ii: In member function âtypename std::basic_filebuf<_CharT,
_Traits>::pos_type std::basic_filebuf<_CharT, _Traits>::seekpos(typename
_Traits::pos_type, <unnamed>::_Ios_Openmode) [with _CharT = char, _Traits =
std::char_traits<char>]â:
snb.ii:87: internal compiler error: in dwarf2out_frame_debug_expr, at
dwarf2out.c:2492
Vanilla 4.4 branch generates very similar rtl, the only change seems to be
slightly different sched2 decition.
It compiles seekpos into:
.cfi_startproc
.cfi_personality 0x9b,DW.ref.__gxx_personality_v0
.cfi_lsda 0x1b,.LLSDA9
# basic block 2
leal 4(%esp), %ecx
.cfi_def_cfa 1, 0
andl $-32, %esp
pushl -4(%ecx)
pushl %ebp
movl %esp, %ebp
.cfi_escape 0x10,0x5,0x1,0x55
subl $120, %esp
movl %ebx, 108(%esp)
movl %ecx, 104(%esp)
.cfi_escape 0xf,0x3,0x75,0x70,0x6
movl %esi, 112(%esp)
movl %edi, 116(%esp)
call .L17
.L17:
popl %ebx
addl $_GLOBAL_OFFSET_TABLE_+[.-.L17], %ebx
.cfi_escape 0x10,0x7,0x2,0x75,0x7c
.cfi_escape 0x10,0x6,0x2,0x75,0x78
.cfi_escape 0x10,0x3,0x2,0x75,0x74
movl (%ecx), %esi
movl %ecx, -60(%ebp)
but redhat/gcc-4_4-branch reorders the %ecx stores, so after sp = sp - 120
there is:
subl $120, %esp
movl %ecx, -60(%ebp)
movl %ebx, 108(%esp)
movl %esi, 112(%esp)
movl %ecx, 104(%esp)
movl %edi, 116(%esp)
([ebp-60] = ecx got moved earlier, and [sp+108] = ecx got moved later).
Given that both of these ecx stores are frame related, I don't see anything
wrong on that scheduling decision.
But when processing the frame related insns in dwarf2out, after sp = sp - 120
we have:
(gdb) p cfa
$1 = {offset = 0, base_offset = 0, reg = 2, indirect = 0, in_use = 0}
(gdb) p cfa_temp
$2 = {offset = 0, base_offset = 0, reg = 2, indirect = 0, in_use = 0}
(gdb) p cfa_store
$3 = {offset = 120, base_offset = 0, reg = 7, indirect = 0, in_use = 0}
and so ICE, because we don't know what offset to use:
2488 if (cfa_store.reg == (unsigned) regno)
2489 offset -= cfa_store.offset;
2490 else
2491 {
2492 gcc_assert (cfa_temp.reg == (unsigned) regno);
2493 offset -= cfa_temp.offset;
2494 }
The store using ebp comes from the code before IRA starting with
(set (reg:SI 71) (reg:SI %ecx)) and IRA spilling reg:SI 71 to the stack.
This insn has been created by ix86_get_drap_rtx ():
8098 drap_vreg = copy_to_reg (arg_ptr);
The second store of %ecx comes from prologue expansion.
--
Summary: ICE in dwarf2out_frame_debug_expr
Product: gcc
Version: 4.4.4
Status: UNCONFIRMED
Keywords: ice-on-valid-code
Severity: normal
Priority: P3
Component: debug
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: jakub at gcc dot gnu dot org
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43290
