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WIP managed write barrier for Boehm. #1456

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68 changes: 67 additions & 1 deletion mono/metadata/boehm-gc.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1174,15 +1174,81 @@ mono_gc_get_write_barrier (void)
if (*write_barrier_method_addr)
return *write_barrier_method_addr;

/* GC_dirty(ptr) -> GC_dirty_inner ->
*
* word index = PHT_HASH(p); -> # define PHT_HASH(addr) ((((word)(addr)) >> LOG_HBLKSIZE) & (PHT_ENTRIES - 1))
* async_set_pht_entry_from_index(GC_dirty_pages, index); # define async_set_pht_entry_from_index(db, index) \ set_pht_entry_from_index_concurrent(db, index)
*
* # define set_pht_entry_from_index_concurrent(bl, index) \
AO_or((volatile AO_t *)&(bl)[divWORDSZ(index)], \
(AO_t)((word)1 << modWORDSZ(index)))
/

/* Create the IL version of mono_gc_barrier_generic_store () */
sig = mono_metadata_signature_alloc(mono_defaults.corlib, 1);
sig->ret = mono_get_void_type();
sig->params[0] = mono_get_int_type();

/*MonoClass* interlocked = mono_class_from_name (mono_defaults.corlib, "System.Threading", "Interlocked");
void* iter = NULL;
MonoMethod* method_iter = NULL;
MonoMethod* interlocked_or = NULL;
while (method_iter = mono_class_get_methods (interlocked, &iter))
{
if (strcmp(method_iter->name, "Or"))
continue;
if (method_iter->signature->param_count != 2)
continue;
if (method_iter->signature->params[0]->type != MONO_TYPE_U8 || method_iter->signature->params[1]->type != MONO_TYPE_U8)
continue;
interlocked_or = method_iter;
}

g_assert (interlocked_or);*/

mb = mono_mb_new (mono_defaults.object_class, "wbarrier_conc", MONO_WRAPPER_WRITE_BARRIER);
int index = mono_mb_add_local (mb, m_class_get_byval_arg (mono_defaults.uint_class));
int div_wordszs = mono_mb_add_local (mb, m_class_get_byval_arg (mono_defaults.uint_class));
int mod_wordszs = mono_mb_add_local (mb, m_class_get_byval_arg (mono_defaults.uint_class));
int page_ptr = mono_mb_add_local (mb, m_class_get_byval_arg (mono_defaults.uint_class));

mono_mb_emit_ldarg (mb, 0);
mono_mb_emit_icall (mb, mono_gc_wbarrier_generic_nostore_internal);
mono_mb_emit_icon (mb, LOG_HBLKSIZE);
mono_mb_emit_byte (mb, MONO_CEE_SHR_UN);
mono_mb_emit_icon (mb, PHT_ENTRIES - 1);
mono_mb_emit_byte (mb, MONO_CEE_AND);
mono_mb_emit_stloc (mb, index);

mono_mb_emit_ldloc (mb, index);
mono_mb_emit_icon (mb, LOGWL);
mono_mb_emit_byte (mb, MONO_CEE_SHR_UN);
mono_mb_emit_stloc (mb, div_wordszs);

mono_mb_emit_icon8 (mb, (gint64)GC_dirty_pages_addr());
mono_mb_emit_ldloc (mb, div_wordszs);
mono_mb_emit_icon (mb, 8);
mono_mb_emit_byte (mb, MONO_CEE_MUL);
mono_mb_emit_byte (mb, MONO_CEE_ADD);
mono_mb_emit_stloc (mb, page_ptr);

mono_mb_emit_icon (mb, 1);
mono_mb_emit_byte (mb, MONO_CEE_CONV_I);
mono_mb_emit_ldloc (mb, index);
mono_mb_emit_icon (mb, 0x3f);
mono_mb_emit_byte (mb, MONO_CEE_AND);
mono_mb_emit_byte (mb, MONO_CEE_SHL);
mono_mb_emit_stloc (mb, mod_wordszs);

mono_mb_emit_ldloc (mb, page_ptr);

mono_mb_emit_ldloc (mb, mod_wordszs);
mono_mb_emit_ldloc (mb, page_ptr);
mono_mb_emit_byte (mb, MONO_CEE_LDIND_I);
/* FIXME: this needs to be atomic */
mono_mb_emit_byte (mb, MONO_CEE_OR);

mono_mb_emit_byte (mb, MONO_CEE_STIND_I);

mono_mb_emit_byte (mb, MONO_CEE_RET);

res = mono_mb_create_method (mb, sig, 16);
Expand Down