>
> We can end up with an infinite recursion as gimple_register_type
> tries to register TYPE_MAIN_VARIANT first. This is because we
> are being called from the LTO type-fixup code which walks the
> type graph and adjusts types to their leaders. So we can
> be called for type SCCs that are only partially fixed up yet
> which means TYPE_MAIN_VARIANT might temporarily not honor
> the invariant that the main variant of a main variant is itself.
> Thus, simply avoid recursing more than once - we are sure that
> we will be reaching at most type duplicates in further recursion.
>
> Bootstrap & regtest pending on x86_64-unknown-linux-gnu.
With this funcion WPA stage passes with some improvements I repported to
mozilla metabug.
We now get ICE in ltrans:
#0 gimple_register_type (t=0x0) at ../../gcc/gimple.c:4616
#1 0x00000000005a0fc9 in gimple_register_canonical_type (t=0x7fffe851f498) at
../../gcc/gimple.c:4890
#2 0x000000000048f14d in lto_ft_type (t=0x7fffe851f498) at
../../gcc/lto/lto.c:401
#3 lto_fixup_types (t=0x7fffe851f498) at ../../gcc/lto/lto.c:581
#4 0x000000000048f4a0 in uniquify_nodes (node=Unhandled dwarf expression
opcode 0xf3
TYPE_MAIN_VARIANT is NULL.
(gdb) up
#1 0x00000000005a0fc9 in gimple_register_canonical_type (t=0x7fffe851f498) at
../../gcc/gimple.c:4890
4890 t = gimple_register_type (TYPE_MAIN_VARIANT (t));
(gdb) p debug_generic_stmt (t)
struct _ffi_type
$1 = void
(gdb) p debug_tree (t)
<record_type 0x7fffe851f498 _ffi_type BLK
size <integer_cst 0x7ffff7ecf680 type <integer_type 0x7ffff7eca0a8
bit_size_type> constant 192>
unit size <integer_cst 0x7ffff7ecf640 type <integer_type 0x7ffff7eca000>
constant 24>
align 64 symtab 0 alias set -1 structural equality
fields <field_decl 0x7fffe87684c0 size
type <integer_type 0x7ffff7eca690 long unsigned int public unsigned DI
size <integer_cst 0x7ffff7ecf1e0 constant 64>
unit size <integer_cst 0x7ffff7ecf200 constant 8>
align 64 symtab 0 alias set -1 canonical type 0x7ffff7eca690
precision 64 min <integer_cst 0x7ffff7ecf220 0> max <integer_cst 0x7ffff7ecf1c0
18446744073709551615>
pointer_to_this <pointer_type 0x7ffff5336150> reference_to_this
<reference_type 0x7ffff0aba000>>
used unsigned nonlocal DI file ctypes/libffi/include/ffi.h line 109 col
0 size <integer_cst 0x7ffff7ecf1e0 64> unit size <integer_cst 0x7ffff7ecf200 8>
align 64 offset_align 128
offset <integer_cst 0x7ffff7ebaf00 constant 0>
bit offset <integer_cst 0x7ffff7ecf420 constant 0> context <record_type
0x7fffe851f2a0 _ffi_type>
chain <field_decl 0x7fffe8768558 alignment type <integer_type
0x7ffff7eca3f0 short unsigned int>
used unsigned nonlocal HI file ctypes/libffi/include/ffi.h line 110
col 0
size <integer_cst 0x7ffff7ecf080 constant 16>
unit size <integer_cst 0x7ffff7ecf0a0 constant 2>
align 16 offset_align 128 offset <integer_cst 0x7ffff7ebaf00 0> bit
offset <integer_cst 0x7ffff7ecf1e0 64> context <record_type 0x7fffe851f2a0
_ffi_type> chain <field_decl 0x7fffe87685f0 type>>>
chain <type_decl 0x7fffe8966ac8 _ffi_type>>
$2 = void
Let me know if there is anything easy I could work out ;)
I think the bug may be in the recursion guard. When you have cycle of length
greater than 2 of MVs, you won't walk them all.
Honza
