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Managed StelemRef and LdelemaRef (#32722)
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* Managed `LdelemaRef` and `StelemRef`

* support ARM64 and OSX

* removed old JIT_Stelem_Ref implementation

* removed JIT_Ldelema_Ref

* Attributes for stack/debug hiding.

* PR feedback

* Avoid needing static initializer.

* couple small tweaks

* Avoid PreStub indirection in array element JIT helpers.

* Initialize `gcCoverLock` a bit earlier

* Added comment about revisiting after #5857 is fixed
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@VSadov
VSadov authored Mar 4, 2020
1 parent 4142643 commit 3fc245e
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Showing 24 changed files with 184 additions and 859 deletions.
107 changes: 101 additions & 6 deletions src/coreclr/src/System.Private.CoreLib/src/System/Runtime/CompilerServices/CastHelpers.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -168,6 +168,9 @@ private static CastResult TryGet(nuint source, nuint target)
[MethodImpl(MethodImplOptions.InternalCall)]
private static extern ref byte Unbox_Helper(void* toTypeHnd, object obj);

[MethodImpl(MethodImplOptions.InternalCall)]
private static extern void WriteBarrier(ref object? dst, object obj);

// IsInstanceOf test used for unusual cases (naked type parameters, variant generic types)
// Unlike the IsInstanceOfInterface and IsInstanceOfClass functions,
// this test must deal with all kinds of type tests
Expand Down Expand Up @@ -249,7 +252,7 @@ private static CastResult TryGet(nuint source, nuint target)
return obj;

slowPath:
return IsInstanceHelper(toTypeHnd, obj);
return IsInstance_Helper(toTypeHnd, obj);
}

[DebuggerHidden]
Expand Down Expand Up @@ -304,14 +307,14 @@ private static CastResult TryGet(nuint source, nuint target)
return obj;

slowPath:
return IsInstanceHelper(toTypeHnd, obj);
return IsInstance_Helper(toTypeHnd, obj);
}

[DebuggerHidden]
[StackTraceHidden]
[DebuggerStepThrough]
[MethodImpl(MethodImplOptions.NoInlining)]
private static object? IsInstanceHelper(void* toTypeHnd, object obj)
private static object? IsInstance_Helper(void* toTypeHnd, object obj)
{
CastResult result = TryGet((nuint)RuntimeHelpers.GetMethodTable(obj), (nuint)toTypeHnd);
if (result == CastResult.CanCast)
Expand Down Expand Up @@ -364,7 +367,7 @@ private static CastResult TryGet(nuint source, nuint target)
[StackTraceHidden]
[DebuggerStepThrough]
[MethodImpl(MethodImplOptions.NoInlining)]
private static object? ChkCastHelper(void* toTypeHnd, object obj)
private static object? ChkCast_Helper(void* toTypeHnd, object obj)
{
CastResult result = TryGet((nuint)RuntimeHelpers.GetMethodTable(obj), (nuint)toTypeHnd);
if (result == CastResult.CanCast)
Expand Down Expand Up @@ -416,7 +419,7 @@ private static CastResult TryGet(nuint source, nuint target)
return obj;

slowPath:
return ChkCastHelper(toTypeHnd, obj);
return ChkCast_Helper(toTypeHnd, obj);
}

[DebuggerHidden]
Expand Down Expand Up @@ -477,7 +480,7 @@ private static CastResult TryGet(nuint source, nuint target)
return obj;

slowPath:
return ChkCastHelper(toTypeHnd, obj);
return ChkCast_Helper(toTypeHnd, obj);
}

[DebuggerHidden]
Expand All @@ -491,5 +494,97 @@ private static ref byte Unbox(void* toTypeHnd, object obj)

return ref Unbox_Helper(toTypeHnd, obj);
}

internal struct ArrayElement
{
public object? Value;
}

[DebuggerHidden]
[StackTraceHidden]
[DebuggerStepThrough]
private static ref object? ThrowArrayMismatchException()
{
throw new ArrayTypeMismatchException();
}

[DebuggerHidden]
[StackTraceHidden]
[DebuggerStepThrough]
[MethodImpl(MethodImplOptions.AggressiveOptimization)]
private static ref object? LdelemaRef(Array array, int index, void* type)
{
// this will throw appropriate exceptions if array is null or access is out of range.
ref object? element = ref Unsafe.As<ArrayElement[]>(array)[index].Value;
void* elementType = RuntimeHelpers.GetMethodTable(array)->ElementType;

if (elementType == type)
return ref element;

return ref ThrowArrayMismatchException();
}

[DebuggerHidden]
[StackTraceHidden]
[DebuggerStepThrough]
[MethodImpl(MethodImplOptions.AggressiveOptimization)]
private static void StelemRef(Array array, int index, object? obj)
{
// this will throw appropriate exceptions if array is null or access is out of range.
ref object? element = ref Unsafe.As<ArrayElement[]>(array)[index].Value;
void* elementType = RuntimeHelpers.GetMethodTable(array)->ElementType;

if (obj == null)
goto assigningNull;

if (elementType != RuntimeHelpers.GetMethodTable(obj))
goto notExactMatch;

doWrite:
WriteBarrier(ref element, obj);
return;

assigningNull:
element = null;
return;

notExactMatch:
if (array.GetType() == typeof(object[]))
goto doWrite;

StelemRef_Helper(ref element, elementType, obj);
}

[DebuggerHidden]
[StackTraceHidden]
[DebuggerStepThrough]
private static void StelemRef_Helper(ref object? element, void* elementType, object obj)
{
CastResult result = TryGet((nuint)RuntimeHelpers.GetMethodTable(obj), (nuint)elementType);
if (result == CastResult.CanCast)
{
WriteBarrier(ref element, obj);
return;
}

StelemRef_Helper_NoCacheLookup(ref element, elementType, obj);
}

[DebuggerHidden]
[StackTraceHidden]
[DebuggerStepThrough]
private static void StelemRef_Helper_NoCacheLookup(ref object? element, void* elementType, object obj)
{
Debug.Assert(obj != null);

obj = IsInstanceOfAny_NoCacheLookup(elementType, obj);
if (obj != null)
{
WriteBarrier(ref element, obj);
return;
}

throw new ArrayTypeMismatchException();
}
}
}
12 changes: 12 additions & 0 deletions .../src/System.Private.CoreLib/src/System/Runtime/CompilerServices/RuntimeHelpers.CoreCLR.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -304,6 +304,8 @@ internal unsafe struct MethodTable
public ushort InterfaceCount;
[FieldOffset(ParentMethodTableOffset)]
public MethodTable* ParentMethodTable;
[FieldOffset(ElementTypeOffset)]
public void* ElementType;
[FieldOffset(InterfaceMapOffset)]
public MethodTable** InterfaceMap;

Expand All @@ -322,6 +324,16 @@ internal unsafe struct MethodTable
#endif
;

#if TARGET_64BIT
private const int ElementTypeOffset = 0x30
#else
private const int ElementTypeOffset = 0x20
#endif
#if DEBUG
+ sizeof(nuint) // adjust for debug_m_szClassName
#endif
;

#if TARGET_64BIT
private const int InterfaceMapOffset = 0x38
#else
Expand Down
8 changes: 2 additions & 6 deletions src/coreclr/src/inc/jithelpers.h
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Original file line number Diff line number Diff line change
Expand Up @@ -107,12 +107,8 @@
JITHELPER(CORINFO_HELP_UNBOX_NULLABLE, JIT_Unbox_Nullable, CORINFO_HELP_SIG_4_STACK)

JITHELPER(CORINFO_HELP_GETREFANY, JIT_GetRefAny, CORINFO_HELP_SIG_8_STACK)
#if defined(TARGET_ARM)
DYNAMICJITHELPER(CORINFO_HELP_ARRADDR_ST, JIT_Stelem_Ref, CORINFO_HELP_SIG_4_STACK)
#else
JITHELPER(CORINFO_HELP_ARRADDR_ST, JIT_Stelem_Ref, CORINFO_HELP_SIG_4_STACK)
#endif // TARGET_ARM
JITHELPER(CORINFO_HELP_LDELEMA_REF, JIT_Ldelema_Ref, CORINFO_HELP_SIG_4_STACK)
DYNAMICJITHELPER(CORINFO_HELP_ARRADDR_ST, NULL, CORINFO_HELP_SIG_4_STACK)
DYNAMICJITHELPER(CORINFO_HELP_LDELEMA_REF, NULL, CORINFO_HELP_SIG_4_STACK)

// Exceptions
JITHELPER(CORINFO_HELP_THROW, IL_Throw, CORINFO_HELP_SIG_REG_ONLY)
Expand Down
123 changes: 0 additions & 123 deletions src/coreclr/src/vm/amd64/JitHelpers_Fast.asm
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Original file line number Diff line number Diff line change
Expand Up @@ -390,129 +390,6 @@ endif
LEAF_END_MARKED JIT_ByRefWriteBarrier, _TEXT


g_pObjectClass equ ?g_pObjectClass@@3PEAVMethodTable@@EA

EXTERN g_pObjectClass:qword
extern ArrayStoreCheck:proc
extern ObjIsInstanceOfCached:proc

; TODO: put definition for this in asmconstants.h
CanCast equ 1

;__declspec(naked) void F_CALL_CONV JIT_Stelem_Ref(PtrArray* array, unsigned idx, Object* val)
LEAF_ENTRY JIT_Stelem_Ref, _TEXT
; check for null PtrArray*
test rcx, rcx
je ThrowNullReferenceException

; we only want the lower 32-bits of edx, it might be dirty
or edx, edx

; check that index is in bounds
cmp edx, dword ptr [rcx + OFFSETOF__PtrArray__m_NumComponents] ; 8h -> array size offset
jae ThrowIndexOutOfRangeException

; r10 = Array MT
mov r10, [rcx]

; if we're assigning a null object* then we don't need a write barrier
test r8, r8
jz AssigningNull

mov r9, [r10 + OFFSETOF__MethodTable__m_ElementType] ; 10h -> typehandle offset

; check for exact match
cmp r9, [r8]
jne NotExactMatch

DoWrite:
lea rcx, [rcx + 8*rdx + OFFSETOF__PtrArray__m_Array]
mov rdx, r8

; JIT_WriteBarrier(Object** dst, Object* src)
jmp JIT_WriteBarrier

AssigningNull:
; write barrier is not needed for assignment of NULL references
mov [rcx + 8*rdx + OFFSETOF__PtrArray__m_Array], r8
ret

NotExactMatch:
cmp r9, [g_pObjectClass]
je DoWrite

jmp JIT_Stelem_Ref__ObjIsInstanceOfCached_Helper

ThrowNullReferenceException:
mov rcx, CORINFO_NullReferenceException_ASM
jmp JIT_InternalThrow

ThrowIndexOutOfRangeException:
mov rcx, CORINFO_IndexOutOfRangeException_ASM
jmp JIT_InternalThrow
LEAF_END JIT_Stelem_Ref, _TEXT

NESTED_ENTRY JIT_Stelem_Ref__ObjIsInstanceOfCached_Helper, _TEXT
alloc_stack MIN_SIZE
save_reg_postrsp rcx, MIN_SIZE + 8h
save_reg_postrsp rdx, MIN_SIZE + 10h
save_reg_postrsp r8, MIN_SIZE + 18h
END_PROLOGUE

; need to get TypeHandle before setting rcx to be the Obj* because that trashes the PtrArray*
mov rdx, r9
mov rcx, r8

; TypeHandle::CastResult ObjIsInstanceOfCached(Object *pElement, TypeHandle toTypeHnd)
call ObjIsInstanceOfCached

mov rcx, [rsp + MIN_SIZE + 8h]
mov rdx, [rsp + MIN_SIZE + 10h]
mov r8, [rsp + MIN_SIZE + 18h]

cmp eax, CanCast
jne NeedCheck

lea rcx, [rcx + 8*rdx + OFFSETOF__PtrArray__m_Array]
mov rdx, r8
add rsp, MIN_SIZE

; JIT_WriteBarrier(Object** dst, Object* src)
jmp JIT_WriteBarrier

NeedCheck:
add rsp, MIN_SIZE
jmp JIT_Stelem_Ref__ArrayStoreCheck_Helper
NESTED_END JIT_Stelem_Ref__ObjIsInstanceOfCached_Helper, _TEXT

; Need to save r8 to provide a stack address for the Object*
NESTED_ENTRY JIT_Stelem_Ref__ArrayStoreCheck_Helper, _TEXT
alloc_stack MIN_SIZE
save_reg_postrsp rcx, MIN_SIZE + 8h
save_reg_postrsp rdx, MIN_SIZE + 10h
save_reg_postrsp r8, MIN_SIZE + 18h
END_PROLOGUE

lea rcx, [rsp + MIN_SIZE + 18h]
lea rdx, [rsp + MIN_SIZE + 8h]

; HCIMPL2(FC_INNER_RET, ArrayStoreCheck, Object** pElement, PtrArray** pArray)
call ArrayStoreCheck

mov rcx, [rsp + MIN_SIZE + 8h]
mov rdx, [rsp + MIN_SIZE + 10h]
mov r8, [rsp + MIN_SIZE + 18h]

lea rcx, [rcx + 8*rdx + OFFSETOF__PtrArray__m_Array]
mov rdx, r8
add rsp, MIN_SIZE

; JIT_WriteBarrier(Object** dst, Object* src)
jmp JIT_WriteBarrier

NESTED_END JIT_Stelem_Ref__ArrayStoreCheck_Helper, _TEXT


extern JIT_FailFast:proc
extern s_gsCookie:qword

Expand Down
1 change: 0 additions & 1 deletion src/coreclr/src/vm/amd64/cgencpu.h
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Original file line number Diff line number Diff line change
Expand Up @@ -528,7 +528,6 @@ inline BOOL ClrFlushInstructionCache(LPCVOID pCodeAddr, size_t sizeOfCode)
#define JIT_GetSharedGCStaticBaseNoCtor JIT_GetSharedGCStaticBaseNoCtor_SingleAppDomain
#define JIT_GetSharedNonGCStaticBaseNoCtor JIT_GetSharedNonGCStaticBaseNoCtor_SingleAppDomain

#define JIT_Stelem_Ref JIT_Stelem_Ref

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// Call counting
Expand Down
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