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Improve the performance of ConditionalWeakTable.TryGetValue #80059

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Original file line number Diff line number Diff line change
Expand Up @@ -114,6 +114,17 @@ public static unsafe void PrepareMethod(RuntimeMethodHandle method, RuntimeTypeH
[MethodImpl(MethodImplOptions.InternalCall)]
public static extern int GetHashCode(object? o);

/// <summary>
/// If a hash code has been assigned to the object, it is returned. Otherwise zero is
/// returned.
/// </summary>
/// <remarks>
/// The advantage of this over <see cref="GetHashCode" /> is that it avoids assigning a hash
/// code to the object if it does not already have one.
/// </remarks>
[MethodImpl(MethodImplOptions.InternalCall)]
internal static extern int TryGetHashCode(object o);

[MethodImpl(MethodImplOptions.InternalCall)]
public static extern new bool Equals(object? o1, object? o2);

Expand Down
41 changes: 41 additions & 0 deletions src/coreclr/classlibnative/bcltype/objectnative.cpp
Original file line number Diff line number Diff line change
Expand Up @@ -128,6 +128,47 @@ FCIMPL1(INT32, ObjectNative::GetHashCode, Object* obj) {
}
FCIMPLEND

FCIMPL1(INT32, ObjectNative::TryGetHashCode, Object* obj) {

CONTRACTL
{
FCALL_CHECK;
}
CONTRACTL_END;

VALIDATEOBJECT(obj);

if (obj == 0)
return 0;

OBJECTREF objRef(obj);

{
DWORD bits = objRef->GetHeader()->GetBits();

if (bits & BIT_SBLK_IS_HASH_OR_SYNCBLKINDEX)
{
if (bits & BIT_SBLK_IS_HASHCODE)
{
// Common case: the object already has a hash code
return bits & MASK_HASHCODE;
}
else
{
// We have a sync block index. There may be a hash code stored within the sync block.
SyncBlock *psb = objRef->PassiveGetSyncBlock();
if (psb != NULL)
{
return psb->GetHashCode();
}
}
}
}

return 0;
}
FCIMPLEND

//
// Compare by ref for normal classes, by value for value types.
//
Expand Down
1 change: 1 addition & 0 deletions src/coreclr/classlibnative/bcltype/objectnative.h
Original file line number Diff line number Diff line change
Expand Up @@ -30,6 +30,7 @@ class ObjectNative
// If the Class object doesn't exist then you must call the GetClass() method.
static FCDECL1(Object*, GetObjectValue, Object* vThisRef);
static FCDECL1(INT32, GetHashCode, Object* vThisRef);
static FCDECL1(INT32, TryGetHashCode, Object* vThisRef);
static FCDECL2(FC_BOOL_RET, Equals, Object *pThisRef, Object *pCompareRef);
static FCDECL1(Object*, AllocateUninitializedClone, Object* pObjUNSAFE);
static FCDECL1(Object*, GetClass, Object* pThis);
Expand Down
Original file line number Diff line number Diff line change
Expand Up @@ -104,6 +104,19 @@ public static unsafe int GetHashCode(object o)
return ObjectHeader.GetHashCode(o);
}

/// <summary>
/// If a hash code has been assigned to the object, it is returned. Otherwise zero is
/// returned.
/// </summary>
/// <remarks>
/// The advantage of this over <see cref="GetHashCode" /> is that it avoids assigning a hash
/// code to the object if it does not already have one.
/// </remarks>
internal static int TryGetHashCode(object o)
{
return ObjectHeader.TryGetHashCode(o);
}

[Obsolete("OffsetToStringData has been deprecated. Use string.GetPinnableReference() instead.")]
public static int OffsetToStringData
{
Expand Down
Original file line number Diff line number Diff line change
Expand Up @@ -85,6 +85,38 @@ public static unsafe int GetHashCode(object o)
}
}

/// <summary>
/// If a hash code has been assigned to the object, it is returned. Otherwise zero is
/// returned.
/// </summary>
public static unsafe int TryGetHashCode(object o)
{
if (o == null)
return 0;

fixed (MethodTable** ppMethodTable = &o.GetMethodTableRef())
{
int* pHeader = GetHeaderPtr(ppMethodTable);
int bits = *pHeader;
int hashOrIndex = bits & MASK_HASHCODE_INDEX;
if ((bits & BIT_SBLK_IS_HASHCODE) != 0)
{
// Found the hash code in the header
Debug.Assert(hashOrIndex != 0);
return hashOrIndex;
}

if ((bits & BIT_SBLK_IS_HASH_OR_SYNCBLKINDEX) != 0)
{
// Look up the hash code in the SyncTable
return SyncTable.GetHashCode(hashOrIndex);
}

// The hash code has not yet been set.
return 0;
}
}

/// <summary>
/// Assigns a hash code to the object in a thread-safe way.
/// </summary>
Expand Down
1 change: 1 addition & 0 deletions src/coreclr/vm/ecalllist.h
Original file line number Diff line number Diff line change
Expand Up @@ -552,6 +552,7 @@ FCFuncStart(gRuntimeHelpers)
FCFuncElement("GetSpanDataFrom", ArrayNative::GetSpanDataFrom)
FCFuncElement("PrepareDelegate", ReflectionInvocation::PrepareDelegate)
FCFuncElement("GetHashCode", ObjectNative::GetHashCode)
FCFuncElement("TryGetHashCode", ObjectNative::TryGetHashCode)
FCFuncElement("Equals", ObjectNative::Equals)
FCFuncElement("AllocateUninitializedClone", ObjectNative::AllocateUninitializedClone)
FCFuncElement("EnsureSufficientExecutionStack", ReflectionInvocation::EnsureSufficientExecutionStack)
Expand Down
Original file line number Diff line number Diff line change
Expand Up @@ -48,7 +48,7 @@ public ConditionalWeakTable()
/// </param>
/// <returns>Returns "true" if key was found, "false" otherwise.</returns>
/// <remarks>
/// The key may get garbaged collected during the TryGetValue operation. If so, TryGetValue
/// The key may get garbage collected during the TryGetValue operation. If so, TryGetValue
/// may at its discretion, return "false" and set "value" to the default (as if the key was not present.)
/// </remarks>
public bool TryGetValue(TKey key, [MaybeNullWhen(false)] out TValue value)
Expand Down Expand Up @@ -538,7 +538,17 @@ internal int FindEntry(TKey key, out object? value)
{
Debug.Assert(key != null); // Key already validated as non-null.

int hashCode = RuntimeHelpers.GetHashCode(key) & int.MaxValue;
int hashCode = RuntimeHelpers.TryGetHashCode(key);

if (hashCode == 0)
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{
// No hash code has been assigned to the key, so therefore it has not been added
// to any ConditionalWeakTable.
value = null;
return -1;
}

hashCode &= int.MaxValue;
int bucket = hashCode & (_buckets.Length - 1);
for (int entriesIndex = Volatile.Read(ref _buckets[bucket]); entriesIndex != -1; entriesIndex = _entries[entriesIndex].Next)
{
Expand Down
Original file line number Diff line number Diff line change
Expand Up @@ -44,6 +44,22 @@ public static int GetHashCode(object? o)
return InternalGetHashCode(o);
}

[MethodImplAttribute(MethodImplOptions.InternalCall)]
private static extern int InternalTryGetHashCode(object? o);

/// <summary>
/// If a hash code has been assigned to the object, it is returned. Otherwise zero is
/// returned.
/// </summary>
/// <remarks>
/// The advantage of this over <see cref="GetHashCode" /> is that it avoids assigning a hash
/// code to the object if it does not already have one.
/// </remarks>
public static int TryGetHashCode(object? o)
{
return InternalTryGetHashCode(o);
}

public static new bool Equals(object? o1, object? o2)
{
if (o1 == o2)
Expand Down
3 changes: 2 additions & 1 deletion src/mono/mono/metadata/icall-def.h
Original file line number Diff line number Diff line change
Expand Up @@ -427,7 +427,8 @@ HANDLES(RUNH_1, "GetObjectValue", ves_icall_System_Runtime_CompilerServices_Runt
HANDLES(RUNH_6, "GetSpanDataFrom", ves_icall_System_Runtime_CompilerServices_RuntimeHelpers_GetSpanDataFrom, gpointer, 3, (MonoClassField_ptr, MonoType_ptr, gpointer))
HANDLES(RUNH_2, "GetUninitializedObjectInternal", ves_icall_System_Runtime_CompilerServices_RuntimeHelpers_GetUninitializedObjectInternal, MonoObject, 1, (MonoType_ptr))
HANDLES(RUNH_3, "InitializeArray", ves_icall_System_Runtime_CompilerServices_RuntimeHelpers_InitializeArray, void, 2, (MonoArray, MonoClassField_ptr))
HANDLES(RUNH_7, "InternalGetHashCode", mono_object_hash_icall, int, 1, (MonoObject))
HANDLES(RUNH_7, "InternalGetHashCode", ves_icall_System_Runtime_CompilerServices_RuntimeHelpers_InternalGetHashCode, int, 1, (MonoObject))
HANDLES(RUNH_8, "InternalTryGetHashCode", ves_icall_System_Runtime_CompilerServices_RuntimeHelpers_InternalTryGetHashCode, int, 1, (MonoObject))
HANDLES(RUNH_3a, "PrepareMethod", ves_icall_System_Runtime_CompilerServices_RuntimeHelpers_PrepareMethod, void, 3, (MonoMethod_ptr, gpointer, int))
HANDLES(RUNH_4, "RunClassConstructor", ves_icall_System_Runtime_CompilerServices_RuntimeHelpers_RunClassConstructor, void, 1, (MonoType_ptr))
HANDLES(RUNH_5, "RunModuleConstructor", ves_icall_System_Runtime_CompilerServices_RuntimeHelpers_RunModuleConstructor, void, 1, (MonoImage_ptr))
Expand Down
12 changes: 12 additions & 0 deletions src/mono/mono/metadata/icall.c
Original file line number Diff line number Diff line change
Expand Up @@ -1072,6 +1072,18 @@ ves_icall_System_Runtime_CompilerServices_RuntimeHelpers_InitializeArray (MonoAr
#endif
}

int
ves_icall_System_Runtime_CompilerServices_RuntimeHelpers_InternalGetHashCode (MonoObjectHandle obj, MonoError* error)
{
return mono_object_hash_internal (MONO_HANDLE_RAW (obj));
}

int
ves_icall_System_Runtime_CompilerServices_RuntimeHelpers_InternalTryGetHashCode (MonoObjectHandle obj, MonoError* error)
{
return mono_object_try_get_hash_internal (MONO_HANDLE_RAW (obj));
}

MonoObjectHandle
ves_icall_System_Runtime_CompilerServices_RuntimeHelpers_GetObjectValue (MonoObjectHandle obj, MonoError *error)
{
Expand Down
54 changes: 46 additions & 8 deletions src/mono/mono/metadata/monitor.c
Original file line number Diff line number Diff line change
Expand Up @@ -515,6 +515,12 @@ mono_monitor_inflate (MonoObject *obj)

#define MONO_OBJECT_ALIGNMENT_SHIFT 3

/*
* Wang's address-based hash function:
* http://www.concentric.net/~Ttwang/tech/addrhash.htm
*/
#define HASH_OBJECT(obj) (GPOINTER_TO_UINT (obj) >> MONO_OBJECT_ALIGNMENT_SHIFT) * 2654435761u

int
mono_object_hash_internal (MonoObject* obj)
{
Expand Down Expand Up @@ -542,11 +548,14 @@ mono_object_hash_internal (MonoObject* obj)
* another thread computes the hash at the same time, because it'll end up
* with the same value.
*/
hash = (GPOINTER_TO_UINT (obj) >> MONO_OBJECT_ALIGNMENT_SHIFT) * 2654435761u;
hash = HASH_OBJECT(obj);
#if SIZEOF_VOID_P == 4
/* clear the top bits as they can be discarded */
hash &= ~(LOCK_WORD_STATUS_MASK << (32 - LOCK_WORD_STATUS_BITS));
#endif
if (hash == 0) {
hash = 1;
}
if (lock_word_is_free (lw)) {
LockWord old_lw;
lw = lock_word_new_thin_hash (hash);
Expand Down Expand Up @@ -581,19 +590,48 @@ mono_object_hash_internal (MonoObject* obj)

#else

/*
* Wang's address-based hash function:
* http://www.concentric.net/~Ttwang/tech/addrhash.htm
*/
return (GPOINTER_TO_UINT (obj) >> MONO_OBJECT_ALIGNMENT_SHIFT) * 2654435761u;
unsigned int hash = HASH_OBJECT(obj);
if (hash == 0) {
hash = 1;
}
return hash;

#endif

}

int
mono_object_hash_icall (MonoObjectHandle obj, MonoError* error)
mono_object_try_get_hash_internal (MonoObject* obj)
{
return mono_object_hash_internal (MONO_HANDLE_RAW (obj));
#ifdef HAVE_MOVING_COLLECTOR

LockWord lw;
if (!obj)
return 0;
lw.sync = obj->synchronisation;

LOCK_DEBUG (g_message("%s: (%d) Get hash for object %p; LW = %p", __func__, mono_thread_info_get_small_id (), obj, obj->synchronisation));

if (lock_word_has_hash (lw)) {
if (lock_word_is_inflated (lw)) {
return lock_word_get_inflated_lock (lw)->hash_code;
} else {
return lock_word_get_hash (lw);
}
}

return 0;

#else

unsigned int hash = HASH_OBJECT(obj);
if (hash == 0) {
hash = 1;
}
return hash;

#endif

}

/*
Expand Down
3 changes: 3 additions & 0 deletions src/mono/mono/metadata/object-internals.h
Original file line number Diff line number Diff line change
Expand Up @@ -1997,6 +1997,9 @@ mono_string_hash_internal (MonoString *s);
MONO_COMPONENT_API int
mono_object_hash_internal (MonoObject* obj);

int
mono_object_try_get_hash_internal (MonoObject* obj);

ICALL_EXPORT
void
mono_value_copy_internal (void* dest, const void* src, MonoClass *klass);
Expand Down
5 changes: 5 additions & 0 deletions src/mono/mono/mini/interp/interp.c
Original file line number Diff line number Diff line change
Expand Up @@ -7510,6 +7510,11 @@ MINT_IN_CASE(MINT_BRTRUE_I8_SP) ZEROP_SP(gint64, !=); MINT_IN_BREAK;
ip += 3;
MINT_IN_BREAK;
}
MINT_IN_CASE(MINT_INTRINS_TRY_GET_HASHCODE) {
LOCAL_VAR (ip [1], gint32) = mono_object_try_get_hash_internal (LOCAL_VAR (ip [2], MonoObject*));
ip += 3;
MINT_IN_BREAK;
}
MINT_IN_CASE(MINT_INTRINS_GET_TYPE) {
MonoObject *o = LOCAL_VAR (ip [2], MonoObject*);
NULL_CHECK (o);
Expand Down
1 change: 1 addition & 0 deletions src/mono/mono/mini/interp/mintops.def
Original file line number Diff line number Diff line change
Expand Up @@ -794,6 +794,7 @@ OPDEF(MINT_TIER_PATCHPOINT, "tier_patchpoint", 2, 0, 0, MintOpShortInt)

OPDEF(MINT_INTRINS_ENUM_HASFLAG, "intrins_enum_hasflag", 5, 1, 2, MintOpClassToken)
OPDEF(MINT_INTRINS_GET_HASHCODE, "intrins_get_hashcode", 3, 1, 1, MintOpNoArgs)
OPDEF(MINT_INTRINS_TRY_GET_HASHCODE, "intrins_try_get_hashcode", 3, 1, 1, MintOpNoArgs)
OPDEF(MINT_INTRINS_GET_TYPE, "intrins_get_type", 3, 1, 1, MintOpNoArgs)
OPDEF(MINT_INTRINS_SPAN_CTOR, "intrins_span_ctor", 4, 1, 2, MintOpNoArgs)
OPDEF(MINT_INTRINS_UNSAFE_BYTE_OFFSET, "intrins_unsafe_byte_offset", 4, 1, 2, MintOpNoArgs)
Expand Down
8 changes: 5 additions & 3 deletions src/mono/mono/mini/interp/transform.c
Original file line number Diff line number Diff line change
Expand Up @@ -2368,6 +2368,10 @@ interp_handle_intrinsics (TransformData *td, MonoMethod *target_method, MonoClas
interp_ins_set_dreg (td->last_ins, td->sp [-1].local);
td->ip += 5;
return TRUE;
} else if (!strcmp (tm, "InternalGetHashCode")) {
*op = MINT_INTRINS_GET_HASHCODE;
} else if (!strcmp (tm, "InternalTryGetHashCode")) {
*op = MINT_INTRINS_TRY_GET_HASHCODE;
} else if (!strcmp (tm, "GetRawData")) {
interp_add_ins (td, MINT_LDFLDA_UNSAFE);
td->last_ins->data [0] = (gint16) MONO_ABI_SIZEOF (MonoObject);
Expand Down Expand Up @@ -2426,9 +2430,7 @@ interp_handle_intrinsics (TransformData *td, MonoMethod *target_method, MonoClas
td->sp [-1].klass == mono_defaults.runtimetype_class && td->sp [-2].klass == mono_defaults.runtimetype_class) {
*op = MINT_CNE_P;
} else if (in_corlib && target_method->klass == mono_defaults.object_class) {
if (!strcmp (tm, "InternalGetHashCode")) {
*op = MINT_INTRINS_GET_HASHCODE;
} else if (!strcmp (tm, "GetType")) {
if (!strcmp (tm, "GetType")) {
if (constrained_class && m_class_is_valuetype (constrained_class) && !mono_class_is_nullable (constrained_class)) {
// If constrained_class is valuetype we already know its type.
// Resolve GetType to a constant so we can fold type comparisons
Expand Down
9 changes: 0 additions & 9 deletions src/mono/mono/mini/intrinsics.c
Original file line number Diff line number Diff line change
Expand Up @@ -877,15 +877,6 @@ mini_emit_inst_for_method (MonoCompile *cfg, MonoMethod *cmethod, MonoMethodSign
mini_type_to_eval_stack_type (cfg, fsig->ret, ins);
ins->klass = mono_defaults.runtimetype_class;
*ins_type_initialized = TRUE;
return ins;
} else if (!cfg->backend->emulate_mul_div && strcmp (cmethod->name, "InternalGetHashCode") == 0 && fsig->param_count == 1 && !mono_gc_is_moving ()) {
int dreg = alloc_ireg (cfg);
int t1 = alloc_ireg (cfg);

MONO_EMIT_NEW_BIALU_IMM (cfg, OP_SHR_IMM, t1, args [0]->dreg, 3);
EMIT_NEW_BIALU_IMM (cfg, ins, OP_MUL_IMM, dreg, t1, 2654435761u);
ins->type = STACK_I4;

return ins;
} else if (strcmp (cmethod->name, ".ctor") == 0 && fsig->param_count == 0) {
MONO_INST_NEW (cfg, ins, OP_NOP);
Expand Down
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