JIT: import static readonly fields holding frozen objects as const handles

src/coreclr/inc/corinfo.h

@@ -2486,6 +2486,10 @@ class ICorStaticInfo
             CORINFO_CLASS_HANDLE        cls
             ) = 0;
 
+    virtual CORINFO_CLASS_HANDLE getObjectType(
+            void*                       typeObj
+            ) = 0;
+
     virtual bool getReadyToRunHelper(
             CORINFO_RESOLVED_TOKEN *        pResolvedToken,
             CORINFO_LOOKUP_KIND *           pGenericLookupKind,
@@ -3150,6 +3154,17 @@ class ICorDynamicInfo : public ICorStaticInfo
                     void                  **ppIndirection = NULL
                     ) = 0;
 
+    // Returns true if the given field is "static readonly" and its value will never change
+    // also, returns its actual value via pValue argument. For now, it's either:
+    //  * integer/floating point primitive
+    //  * null
+    //  * frozen object
+    virtual bool getReadonlyStaticFieldValue(
+                    CORINFO_FIELD_HANDLE    field,
+                    uint8_t                *buffer,
+                    int                     bufferSize
+                    ) = 0;
+
     // If pIsSpeculative is NULL, return the class handle for the value of ref-class typed
     // static readonly fields, if there is a unique location for the static and the class
     // is already initialized.

src/coreclr/inc/icorjitinfoimpl_generated.h

@@ -288,6 +288,9 @@ CorInfoHelpFunc getUnBoxHelper(
 void* getRuntimeTypePointer(
           CORINFO_CLASS_HANDLE cls) override;
 
+CORINFO_CLASS_HANDLE getObjectType(
+          void* typeObj) override;
+
 bool getReadyToRunHelper(
           CORINFO_RESOLVED_TOKEN* pResolvedToken,
           CORINFO_LOOKUP_KIND* pGenericLookupKind,
@@ -605,6 +608,11 @@ void* getFieldAddress(
           CORINFO_FIELD_HANDLE field,
           void** ppIndirection) override;
 
+bool getReadonlyStaticFieldValue(
+          CORINFO_FIELD_HANDLE field,
+          uint8_t* buffer,
+          int bufferSize) override;
+
 CORINFO_CLASS_HANDLE getStaticFieldCurrentClass(
           CORINFO_FIELD_HANDLE field,
           bool* pIsSpeculative) override;

src/coreclr/inc/jiteeversionguid.h

@@ -43,11 +43,11 @@ typedef const GUID *LPCGUID;
 #define GUID_DEFINED
 #endif // !GUID_DEFINED
 
-constexpr GUID JITEEVersionIdentifier = { /* 11b4ea58-c400-4c3d-995e-4e2f0676f6e8 */
-    0x11b4ea58,
-    0xc400,
-    0x4c3d,
-    {0x99, 0x5e, 0x4e, 0x2f, 0x6, 0x76, 0xf6, 0xe8}
+constexpr GUID JITEEVersionIdentifier = { /* ebc78c0f-f765-41ea-9cf3-519e36dc6ce2 */
+    0xebc78c0f,
+    0xf765,
+    0x41ea,
+    {0x9c, 0xf3, 0x51, 0x9e, 0x36, 0xdc, 0x6c, 0xe2}
   };
 
 //////////////////////////////////////////////////////////////////////////////////////////////////////////

src/coreclr/jit/ICorJitInfo_API_names.h

@@ -72,6 +72,7 @@ DEF_CLR_API(getTypeForBox)
 DEF_CLR_API(getBoxHelper)
 DEF_CLR_API(getUnBoxHelper)
 DEF_CLR_API(getRuntimeTypePointer)
+DEF_CLR_API(getObjectType)
 DEF_CLR_API(getReadyToRunHelper)
 DEF_CLR_API(getReadyToRunDelegateCtorHelper)
 DEF_CLR_API(getHelperName)
@@ -152,6 +153,7 @@ DEF_CLR_API(canAccessFamily)
 DEF_CLR_API(isRIDClassDomainID)
 DEF_CLR_API(getClassDomainID)
 DEF_CLR_API(getFieldAddress)
+DEF_CLR_API(getReadonlyStaticFieldValue)
 DEF_CLR_API(getStaticFieldCurrentClass)
 DEF_CLR_API(getVarArgsHandle)
 DEF_CLR_API(canGetVarArgsHandle)

src/coreclr/jit/ICorJitInfo_API_wrapper.hpp

@@ -672,6 +672,15 @@ void* WrapICorJitInfo::getRuntimeTypePointer(
     return temp;
 }
 
+CORINFO_CLASS_HANDLE WrapICorJitInfo::getObjectType(
+          void* typeObj)
+{
+    API_ENTER(getObjectType);
+    CORINFO_CLASS_HANDLE temp = wrapHnd->getObjectType(typeObj);
+    API_LEAVE(getObjectType);
+    return temp;
+}
+
 bool WrapICorJitInfo::getReadyToRunHelper(
           CORINFO_RESOLVED_TOKEN* pResolvedToken,
           CORINFO_LOOKUP_KIND* pGenericLookupKind,
@@ -1450,6 +1459,17 @@ void* WrapICorJitInfo::getFieldAddress(
     return temp;
 }
 
+bool WrapICorJitInfo::getReadonlyStaticFieldValue(
+          CORINFO_FIELD_HANDLE field,
+          uint8_t* buffer,
+          int bufferSize)
+{
+    API_ENTER(getReadonlyStaticFieldValue);
+    bool temp = wrapHnd->getReadonlyStaticFieldValue(field, buffer, bufferSize);
+    API_LEAVE(getReadonlyStaticFieldValue);
+    return temp;
+}
+
 CORINFO_CLASS_HANDLE WrapICorJitInfo::getStaticFieldCurrentClass(
           CORINFO_FIELD_HANDLE field,
           bool* pIsSpeculative)

src/coreclr/jit/compiler.h

@@ -3639,7 +3639,7 @@ class Compiler
 
     GenTree* impInitClass(CORINFO_RESOLVED_TOKEN* pResolvedToken);
 
-    GenTree* impImportStaticReadOnlyField(void* fldAddr, var_types lclTyp);
+    GenTree* impImportStaticReadOnlyField(uint8_t* buffer, int bufferSize, var_types valueType);
 
     GenTree* impImportStaticFieldAccess(CORINFO_RESOLVED_TOKEN* pResolvedToken,
                                         CORINFO_ACCESS_FLAGS    access,

src/coreclr/jit/gentree.cpp

@@ -17574,6 +17574,20 @@ CORINFO_CLASS_HANDLE Compiler::gtGetClassHandle(GenTree* tree, bool* pIsExact, b
             break;
         }
 
+        case GT_CNS_INT:
+        {
+            if (tree->IsIconHandle(GTF_ICON_OBJ_HDL))
+            {
+                objClass = info.compCompHnd->getObjectType((void*)tree->AsIntCon()->IconValue());
+                if (objClass != NO_CLASS_HANDLE)
+                {
+                    // if we managed to get a class handle it's definitely not null
+                    *pIsNonNull = true;
+                }
+            }
+            break;
+        }
+
         case GT_RET_EXPR:
         {
             // If we see a RET_EXPR, recurse through to examine the

src/coreclr/jit/importer.cpp

@@ -8116,133 +8116,92 @@ GenTree* Compiler::impInitClass(CORINFO_RESOLVED_TOKEN* pResolvedToken)
     return node;
 }
 
-GenTree* Compiler::impImportStaticReadOnlyField(void* fldAddr, var_types lclTyp)
+GenTree* Compiler::impImportStaticReadOnlyField(uint8_t* buffer, int bufferSize, var_types valueType)
 {
-    GenTree* op1 = nullptr;
-
-#if defined(DEBUG)
-    // If we're replaying under SuperPMI, we're going to read the data stored by SuperPMI and use it
-    // for optimization. Unfortunately, SuperPMI doesn't implement a guarantee on the alignment of
-    // this data, so for some platforms which don't allow unaligned access (e.g., Linux arm32),
-    // this can fault. We should fix SuperPMI to guarantee alignment, but that is a big change.
-    // Instead, simply fix up the data here for future use.
-
-    // This variable should be the largest size element, with the largest alignment requirement,
-    // and the native C++ compiler should guarantee sufficient alignment.
-    double aligned_data   = 0.0;
-    void*  p_aligned_data = &aligned_data;
-    if (info.compMethodSuperPMIIndex != -1)
-    {
-        switch (lclTyp)
-        {
-            case TYP_BOOL:
-            case TYP_BYTE:
-            case TYP_UBYTE:
-                static_assert_no_msg(sizeof(unsigned __int8) == sizeof(bool));
-                static_assert_no_msg(sizeof(unsigned __int8) == sizeof(signed char));
-                static_assert_no_msg(sizeof(unsigned __int8) == sizeof(unsigned char));
-                // No alignment necessary for byte.
-                break;
-
-            case TYP_SHORT:
-            case TYP_USHORT:
-                static_assert_no_msg(sizeof(unsigned __int16) == sizeof(short));
-                static_assert_no_msg(sizeof(unsigned __int16) == sizeof(unsigned short));
-                if ((size_t)fldAddr % sizeof(unsigned __int16) != 0)
-                {
-                    *(unsigned __int16*)p_aligned_data = GET_UNALIGNED_16(fldAddr);
-                    fldAddr                            = p_aligned_data;
-                }
-                break;
-
-            case TYP_INT:
-            case TYP_UINT:
-            case TYP_FLOAT:
-                static_assert_no_msg(sizeof(unsigned __int32) == sizeof(int));
-                static_assert_no_msg(sizeof(unsigned __int32) == sizeof(unsigned int));
-                static_assert_no_msg(sizeof(unsigned __int32) == sizeof(float));
-                if ((size_t)fldAddr % sizeof(unsigned __int32) != 0)
-                {
-                    *(unsigned __int32*)p_aligned_data = GET_UNALIGNED_32(fldAddr);
-                    fldAddr                            = p_aligned_data;
-                }
-                break;
-
-            case TYP_LONG:
-            case TYP_ULONG:
-            case TYP_DOUBLE:
-                static_assert_no_msg(sizeof(unsigned __int64) == sizeof(__int64));
-                static_assert_no_msg(sizeof(unsigned __int64) == sizeof(double));
-                if ((size_t)fldAddr % sizeof(unsigned __int64) != 0)
-                {
-                    *(unsigned __int64*)p_aligned_data = GET_UNALIGNED_64(fldAddr);
-                    fldAddr                            = p_aligned_data;
-                }
-                break;
-
-            default:
-                assert(!"Unexpected lclTyp");
-                break;
-        }
-    }
-#endif // DEBUG
+    // We plan to support larger values (for structs), for now let's keep it 64 bit
+    assert(bufferSize == sizeof(INT64));
 
-    switch (lclTyp)
+    GenTree* tree = nullptr;
+    switch (valueType)
     {
-        int     ival;
-        __int64 lval;
-        double  dval;
+// Use memcpy to read from the buffer and create an Icon/Dcon tree
+#define CreateTreeFromBuffer(type, treeFactory)                                                                        \
+    type v##type;                                                                                                      \
+    memcpy(&v##type, buffer, sizeof(type));                                                                            \
+    tree = treeFactory(v##type);
 
         case TYP_BOOL:
-            ival = *((bool*)fldAddr);
-            goto IVAL_COMMON;
-
+        {
+            CreateTreeFromBuffer(bool, gtNewIconNode);
+            break;
+        }
         case TYP_BYTE:
-            ival = *((signed char*)fldAddr);
-            goto IVAL_COMMON;
-
+        {
+            CreateTreeFromBuffer(int8_t, gtNewIconNode);
+            break;
+        }
         case TYP_UBYTE:
-            ival = *((unsigned char*)fldAddr);
-            goto IVAL_COMMON;
-
+        {
+            CreateTreeFromBuffer(uint8_t, gtNewIconNode);
+            break;
+        }
         case TYP_SHORT:
-            ival = *((short*)fldAddr);
-            goto IVAL_COMMON;
-
+        {
+            CreateTreeFromBuffer(int16_t, gtNewIconNode);
+            break;
+        }
         case TYP_USHORT:
-            ival = *((unsigned short*)fldAddr);
-            goto IVAL_COMMON;
-
+        {
+            CreateTreeFromBuffer(uint16_t, gtNewIconNode);
+            break;
+        }
         case TYP_UINT:
         case TYP_INT:
-            ival = *((int*)fldAddr);
-        IVAL_COMMON:
-            op1 = gtNewIconNode(ival);
+        {
+            CreateTreeFromBuffer(int32_t, gtNewIconNode);
             break;
-
+        }
         case TYP_LONG:
         case TYP_ULONG:
-            lval = *((__int64*)fldAddr);
-            op1  = gtNewLconNode(lval);
+        {
+            CreateTreeFromBuffer(int64_t, gtNewLconNode);
             break;
-
+        }
         case TYP_FLOAT:
-            dval        = *((float*)fldAddr);
-            op1         = gtNewDconNode(dval);
-            op1->gtType = TYP_FLOAT;
+        {
+            CreateTreeFromBuffer(float, gtNewDconNode);
             break;
-
+        }
         case TYP_DOUBLE:
-            dval = *((double*)fldAddr);
-            op1  = gtNewDconNode(dval);
+        {
+            CreateTreeFromBuffer(double, gtNewDconNode);
             break;
+        }
+        case TYP_REF:
+        {
+            ssize_t ptr;
+            memcpy(&ptr, buffer, sizeof(ssize_t));
 
-        default:
-            assert(!"Unexpected lclTyp");
+            if (ptr == 0)
+            {
+                tree = gtNewNull();
+            }
+            else
+            {
+                setMethodHasFrozenObjects();
+                tree         = gtNewIconEmbHndNode((void*)ptr, nullptr, GTF_ICON_OBJ_HDL, nullptr);
+                tree->gtType = TYP_REF;
+                INDEBUG(tree->AsIntCon()->gtTargetHandle = (size_t)ptr);
+            }
             break;
+        }
+        default:
+            return nullptr;
     }
 
-    return op1;
+    assert(tree != nullptr);
+    tree->gtType = genActualType(valueType);
+    return tree;
 }
 
 GenTree* Compiler::impImportStaticFieldAccess(CORINFO_RESOLVED_TOKEN* pResolvedToken,
@@ -15322,34 +15281,20 @@ void Compiler::impImportBlockCode(BasicBlock* block)
                     case CORINFO_FIELD_STATIC_ADDRESS:
                         // Replace static read-only fields with constant if possible
                         if ((aflags & CORINFO_ACCESS_GET) && (fieldInfo.fieldFlags & CORINFO_FLG_FIELD_FINAL) &&
-                            !(fieldInfo.fieldFlags & CORINFO_FLG_FIELD_STATIC_IN_HEAP) &&
-                            (varTypeIsIntegral(lclTyp) || varTypeIsFloating(lclTyp)))
+                            !(fieldInfo.fieldFlags & CORINFO_FLG_FIELD_STATIC_IN_HEAP))
                         {
-                            CorInfoInitClassResult initClassResult =
-                                info.compCompHnd->initClass(resolvedToken.hField, info.compMethodHnd,
-                                                            impTokenLookupContextHandle);
-
-                            if (initClassResult & CORINFO_INITCLASS_INITIALIZED)
+                            const int bufferSize         = sizeof(uint64_t);
+                            uint8_t   buffer[bufferSize] = {0};
+                            if (info.compCompHnd->getReadonlyStaticFieldValue(resolvedToken.hField, buffer, bufferSize))
                             {
-                                void** pFldAddr = nullptr;
-                                void*  fldAddr =
-                                    info.compCompHnd->getFieldAddress(resolvedToken.hField, (void**)&pFldAddr);
-
-                                // We should always be able to access this static's address directly
-                                //
-                                assert(pFldAddr == nullptr);
-
-                                op1 = impImportStaticReadOnlyField(fldAddr, lclTyp);
-
-                                // Widen small types since we're propagating the value
-                                // instead of producing an indir.
-                                //
-                                op1->gtType = genActualType(lclTyp);
-
-                                goto FIELD_DONE;
+                                GenTree* cnsValue = impImportStaticReadOnlyField(buffer, bufferSize, lclTyp);
+                                if (cnsValue != nullptr)
+                                {
+                                    op1 = cnsValue;
+                                    goto FIELD_DONE;
+                                }
                             }
                         }
-
                         FALLTHROUGH;
 
                     case CORINFO_FIELD_STATIC_RVA_ADDRESS: