Fix VN incorrect optimizations with a new JitEEInterface function. (#…

…57282)

* Add/return tests.

* improve the test naming.

* Add a new JitEE method.

with a naive implementation so far.

* Handle generically dissimilar type concerns as well as handle derived type case in the managed compiler

* Fix the field and Unsafe issues.

* fix some failures.

It appeared that we have many trees where we generate unique VN for rhs and don't inform `fgValueNumberBlockAssignment` about it.
For example, for
```
N005 ( 10,  8) [000033] -A--G---R---              *  ASG       struct (copy)
N004 (  3,  2) [000031] D------N----              +--*  LCL_VAR   struct<eightByteStruct, 8> V01 loc1         d:2
N003 (  6,  5) [000030] n---G-------              \--*  IND       struct
N002 (  3,  3) [000043] ------------                 \--*  ADDR      byref
N001 (  3,  2) [000044] -------N----                    \--*  LCL_VAR   struct<largeStruct, 32> V00 loc0         u:6 (last use)
```
we will generate unique rhs but then `fgValueNumberBlockAssignment` will still try to work it as with a non-unique one.

* Fix an oooold bug in VN.

For a tree like:
```
N005 ( 11, 10) [001400] -A------R----             *  ASG       long
N004 (  6,  5) [001401] *------N-----             +--*  IND       long
N003 (  3,  3) [001402] -------------             |  \--*  ADDR      byref  Zero Fseq[_00]
N002 (  3,  2) [001403] U------N-----             |     \--*  LCL_VAR   struct<System.Runtime.Intrinsics.Vector128`1[Byte], 16> V45 tmp38        ud:3->4
N001 (  1,  1) [001404] -------------             \--*  LCL_VAR   long   V69 tmp62        u:2 (last use)
```
SSA was working correctly and printing that `001403` is using SSA-3 and defining SSA-4. However, this code, for some reason, was writing result as a define for SSA-3.

* Add new test cases and a fix for them.

* correct a test copy paste

* response review.

Co-authored-by: David Wrighton <davidwr@microsoft.com>

src/coreclr/ToolBox/superpmi/superpmi-shared/lwmlist.h

@@ -157,6 +157,7 @@ LWM(TryResolveToken, Agnostic_CORINFO_RESOLVED_TOKENin, TryResolveTokenValue)
 LWM(SatisfiesClassConstraints, DWORDLONG, DWORD)
 LWM(SatisfiesMethodConstraints, DLDL, DWORD)
 LWM(GetUnmanagedCallConv, MethodOrSigInfoValue, DD)
+LWM(DoesFieldBelongToClass, DLDL, DWORD)
 DENSELWM(SigInstHandleMap, DWORDLONG)
 
 #undef LWM

src/coreclr/ToolBox/superpmi/superpmi-shared/methodcontext.cpp

@@ -6265,6 +6265,40 @@ DWORD MethodContext::repGetExpectedTargetArchitecture()
     return value;
 }
 
+void MethodContext::recDoesFieldBelongToClass(CORINFO_FIELD_HANDLE fld, CORINFO_CLASS_HANDLE cls, bool result)
+{
+    if (DoesFieldBelongToClass == nullptr)
+        DoesFieldBelongToClass = new LightWeightMap<DLDL, DWORD>();
+
+    DLDL key;
+    ZeroMemory(&key, sizeof(key)); // Zero key including any struct padding
+    key.A = CastHandle(fld);
+    key.B = CastHandle(cls);
+
+    DWORD value = (DWORD)result;
+    DoesFieldBelongToClass->Add(key, value);
+    DEBUG_REC(dmpDoesFieldBelongToClass(key, result));
+}
+
+void MethodContext::dmpDoesFieldBelongToClass(DLDL key, bool value)
+{
+    printf("DoesFieldBelongToClass key fld=%016llX, cls=%016llx, result=%d", key.A, key.B, value);
+}
+
+bool MethodContext::repDoesFieldBelongToClass(CORINFO_FIELD_HANDLE fld, CORINFO_CLASS_HANDLE cls)
+{
+    DLDL key;
+    ZeroMemory(&key, sizeof(key)); // Zero key including any struct padding
+    key.A = CastHandle(fld);
+    key.B = CastHandle(cls);
+
+    AssertMapAndKeyExist(DoesFieldBelongToClass, key, ": key %016llX %016llX", key.A, key.B);
+
+    bool value = (bool)DoesFieldBelongToClass->Get(key);
+    DEBUG_REP(dmpDoesFieldBelongToClass(key, value));
+    return value;
+}
+
 void MethodContext::recIsValidToken(CORINFO_MODULE_HANDLE module, unsigned metaTOK, bool result)
 {
     if (IsValidToken == nullptr)

src/coreclr/ToolBox/superpmi/superpmi-shared/methodcontext.h

@@ -769,6 +769,10 @@ class MethodContext
     void dmpGetExpectedTargetArchitecture(DWORD key, DWORD result);
     DWORD repGetExpectedTargetArchitecture();
 
+    void recDoesFieldBelongToClass(CORINFO_FIELD_HANDLE fld, CORINFO_CLASS_HANDLE cls, bool result);
+    void dmpDoesFieldBelongToClass(DLDL key, bool value);
+    bool repDoesFieldBelongToClass(CORINFO_FIELD_HANDLE fld, CORINFO_CLASS_HANDLE cls);
+
     void recIsValidToken(CORINFO_MODULE_HANDLE module, unsigned metaTOK, bool result);
     void dmpIsValidToken(DLD key, DWORD value);
     bool repIsValidToken(CORINFO_MODULE_HANDLE module, unsigned metaTOK);
@@ -1063,7 +1067,7 @@ enum mcPackets
     Packet_TryResolveToken                               = 158, // Added 4/26/2016
     Packet_SatisfiesClassConstraints                     = 110,
     Packet_SatisfiesMethodConstraints                    = 111,
-    Packet_ShouldEnforceCallvirtRestriction              = 112, // Retired 2/18/2020
+    Packet_DoesFieldBelongToClass                        = 112, // Added 8/12/2021
     Packet_SigInstHandleMap                              = 184,
     Packet_AllocPgoInstrumentationBySchema               = 186, // Added 1/4/2021
     Packet_GetPgoInstrumentationResults                  = 187, // Added 1/4/2021

src/coreclr/ToolBox/superpmi/superpmi-shim-collector/icorjitinfo.cpp

@@ -2010,3 +2010,13 @@ bool interceptor_ICJI::notifyInstructionSetUsage(CORINFO_InstructionSet instruct
 {
     return original_ICorJitInfo->notifyInstructionSetUsage(instructionSet, supported);
 }
+
+bool interceptor_ICJI::doesFieldBelongToClass(
+    CORINFO_FIELD_HANDLE fldHnd,
+    CORINFO_CLASS_HANDLE cls)
+{
+    mc->cr->AddCall("doesFieldBelongToClass");
+    bool result = original_ICorJitInfo->doesFieldBelongToClass(fldHnd, cls);
+    mc->recDoesFieldBelongToClass(fldHnd, cls, result);
+    return result;
+}

src/coreclr/ToolBox/superpmi/superpmi-shim-counter/icorjitinfo.cpp

@@ -1389,3 +1389,11 @@ uint32_t interceptor_ICJI::getJitFlags(
     return original_ICorJitInfo->getJitFlags(flags, sizeInBytes);
 }
 
+bool interceptor_ICJI::doesFieldBelongToClass(
+          CORINFO_FIELD_HANDLE fldHnd,
+          CORINFO_CLASS_HANDLE cls)
+{
+    mcs->AddCall("doesFieldBelongToClass");
+    return original_ICorJitInfo->doesFieldBelongToClass(fldHnd, cls);
+}
+

src/coreclr/ToolBox/superpmi/superpmi-shim-simple/icorjitinfo.cpp

@@ -1217,3 +1217,10 @@ uint32_t interceptor_ICJI::getJitFlags(
     return original_ICorJitInfo->getJitFlags(flags, sizeInBytes);
 }
 
+bool interceptor_ICJI::doesFieldBelongToClass(
+          CORINFO_FIELD_HANDLE fldHnd,
+          CORINFO_CLASS_HANDLE cls)
+{
+    return original_ICorJitInfo->doesFieldBelongToClass(fldHnd, cls);
+}
+

src/coreclr/ToolBox/superpmi/superpmi/icorjitinfo.cpp

@@ -1574,6 +1574,13 @@ uint32_t MyICJI::getJitFlags(CORJIT_FLAGS* jitFlags, uint32_t sizeInBytes)
     return ret;
 }
 
+bool MyICJI::doesFieldBelongToClass(CORINFO_FIELD_HANDLE fldHnd, CORINFO_CLASS_HANDLE cls)
+{
+    jitInstance->mc->cr->AddCall("doesFieldBelongToClass");
+    bool result = jitInstance->mc->repDoesFieldBelongToClass(fldHnd, cls);
+    return result;
+}
+
 // Runs the given function with the given parameter under an error trap
 // and returns true if the function completes successfully. We fake this
 // up a bit for SuperPMI and simply catch all exceptions.

src/coreclr/inc/corjit.h

@@ -484,6 +484,12 @@ class ICorJitInfo : public ICorDynamicInfo
         uint32_t        sizeInBytes   /* IN: The size of the buffer. Note that this is effectively a
                                           version number for the CORJIT_FLAGS value. */
         ) = 0;
+
+    // Checks if a field belongs to a given class.
+    virtual bool doesFieldBelongToClass(
+        CORINFO_FIELD_HANDLE fldHnd, /* IN: the field that we are checking */
+        CORINFO_CLASS_HANDLE cls     /* IN: the class that we are checking */
+        ) = 0;
 };
 
 /**********************************************************************************/

src/coreclr/inc/icorjitinfoimpl_generated.h

@@ -710,6 +710,10 @@ uint32_t getJitFlags(
           CORJIT_FLAGS* flags,
           uint32_t sizeInBytes) override;
 
+bool doesFieldBelongToClass(
+          CORINFO_FIELD_HANDLE fldHnd,
+          CORINFO_CLASS_HANDLE cls) override;
+
 /**********************************************************************************/
 // clang-format on
 /**********************************************************************************/

src/coreclr/inc/jiteeversionguid.h

@@ -43,12 +43,12 @@ typedef const GUID *LPCGUID;
 #define GUID_DEFINED
 #endif // !GUID_DEFINED
 
-constexpr GUID JITEEVersionIdentifier = { /* c2e4a466-795d-4e64-a776-0ae7b2eed65b */
-    0xc2e4a466,
-    0x795d,
-    0x4e64,
-    {0xa7, 0x76, 0x0a, 0xe7, 0xb2, 0xee, 0xd6, 0x5b}
-  };
+constexpr GUID JITEEVersionIdentifier =  { /* 5ed35c58-857b-48dd-a818-7c0136dc9f73 */
+    0x5ed35c58,
+    0x857b,
+    0x48dd,
+    {0xa8, 0x18, 0x7c, 0x01, 0x36, 0xdc, 0x9f, 0x73}
+};
 
 //////////////////////////////////////////////////////////////////////////////////////////////////////////
 //

src/coreclr/jit/ICorJitInfo_API_names.h

@@ -176,5 +176,6 @@ DEF_CLR_API(recordRelocation)
 DEF_CLR_API(getRelocTypeHint)
 DEF_CLR_API(getExpectedTargetArchitecture)
 DEF_CLR_API(getJitFlags)
+DEF_CLR_API(doesFieldBelongToClass)
 
 #undef DEF_CLR_API

src/coreclr/jit/ICorJitInfo_API_wrapper.hpp

@@ -1690,6 +1690,16 @@ uint32_t WrapICorJitInfo::getJitFlags(
     return temp;
 }
 
+bool WrapICorJitInfo::doesFieldBelongToClass(
+          CORINFO_FIELD_HANDLE fldHnd,
+          CORINFO_CLASS_HANDLE cls)
+{
+    API_ENTER(doesFieldBelongToClass);
+    bool temp = wrapHnd->doesFieldBelongToClass(fldHnd, cls);
+    API_LEAVE(doesFieldBelongToClass);
+    return temp;
+}
+
 /**********************************************************************************/
 // clang-format on
 /**********************************************************************************/

src/coreclr/jit/compiler.h

@@ -5208,6 +5208,8 @@ class Compiler
     // Does value-numbering for a block assignment.
     void fgValueNumberBlockAssignment(GenTree* tree);
 
+    bool fgValueNumberIsStructReinterpretation(GenTreeLclVarCommon* lhsLclVarTree, GenTreeLclVarCommon* rhsLclVarTree);
+
     // Does value-numbering for a cast tree.
     void fgValueNumberCastTree(GenTree* tree);
 

src/coreclr/jit/importer.cpp

@@ -17275,45 +17275,6 @@ bool Compiler::impReturnInstruction(int prefixFlags, OPCODE& opcode)
 #endif
                 }
 
-                // If we are inlining a method that returns a struct byref, check whether we are "reinterpreting" the
-                // struct.
-                GenTree* effectiveRetVal = op2->gtEffectiveVal();
-                if ((returnType == TYP_BYREF) && (info.compRetType == TYP_BYREF) &&
-                    (effectiveRetVal->OperGet() == GT_ADDR))
-                {
-                    GenTree* addrChild = effectiveRetVal->gtGetOp1();
-                    if (addrChild->OperGet() == GT_LCL_VAR)
-                    {
-                        LclVarDsc* varDsc = lvaGetDesc(addrChild->AsLclVarCommon());
-
-                        if (varTypeIsStruct(addrChild->TypeGet()) && !isOpaqueSIMDLclVar(varDsc))
-                        {
-                            CORINFO_CLASS_HANDLE referentClassHandle;
-                            CorInfoType          referentType =
-                                info.compCompHnd->getChildType(info.compMethodInfo->args.retTypeClass,
-                                                               &referentClassHandle);
-                            if (varTypeIsStruct(JITtype2varType(referentType)) &&
-                                (varDsc->GetStructHnd() != referentClassHandle))
-                            {
-                                // We are returning a byref to struct1; the method signature specifies return type as
-                                // byref
-                                // to struct2. struct1 and struct2 are different so we are "reinterpreting" the struct.
-                                // This may happen in, for example, System.Runtime.CompilerServices.Unsafe.As<TFrom,
-                                // TTo>.
-                                // We need to mark the source struct variable as having overlapping fields because its
-                                // fields may be accessed using field handles of a different type, which may confuse
-                                // optimizations, in particular, value numbering.
-
-                                JITDUMP("\nSetting lvOverlappingFields to true on V%02u because of struct "
-                                        "reinterpretation\n",
-                                        addrChild->AsLclVarCommon()->GetLclNum());
-
-                                varDsc->lvOverlappingFields = true;
-                            }
-                        }
-                    }
-                }
-
 #ifdef DEBUG
                 if (verbose)
                 {

src/coreclr/jit/lclmorph.cpp

@@ -210,7 +210,7 @@ class LocalAddressVisitor final : public GenTreeVisitor<LocalAddressVisitor>
         // Arguments:
         //    val - the input value
         //    field - the FIELD node that uses the input address value
-        //    fieldSeqStore - the compiler's field sequence store
+        //    compiler - the compiler instance
         //
         // Return Value:
         //    `true` if the value was consumed. `false` if the input value
@@ -224,8 +224,9 @@ class LocalAddressVisitor final : public GenTreeVisitor<LocalAddressVisitor>
         //     if the offset overflows then location is not representable, must escape
         //   - UNKNOWN => UNKNOWN
         //
-        bool Field(Value& val, GenTreeField* field, FieldSeqStore* fieldSeqStore)
+        bool Field(Value& val, GenTreeField* field, Compiler* compiler)
         {
+
             assert(!IsLocation() && !IsAddress());
 
             if (val.IsLocation())
@@ -246,14 +247,80 @@ class LocalAddressVisitor final : public GenTreeVisitor<LocalAddressVisitor>
                 m_lclNum = val.m_lclNum;
                 m_offset = newOffset.Value();
 
+                bool haveCorrectFieldForVN;
                 if (field->gtFldMayOverlap)
                 {
-                    m_fieldSeq = FieldSeqStore::NotAField();
+                    haveCorrectFieldForVN = false;
                 }
                 else
                 {
+                    LclVarDsc* varDsc = compiler->lvaGetDesc(m_lclNum);
+                    if (!varTypeIsStruct(varDsc))
+                    {
+                        haveCorrectFieldForVN = false;
+                    }
+                    else if (FieldSeqStore::IsPseudoField(field->gtFldHnd))
+                    {
+                        assert(compiler->compObjectStackAllocation());
+                        // We use PseudoFields when accessing stack allocated classes.
+                        haveCorrectFieldForVN = false;
+                    }
+                    else if (val.m_fieldSeq == nullptr)
+                    {
+
+                        CORINFO_CLASS_HANDLE clsHnd = varDsc->GetStructHnd();
+                        // If the answer is no we are probably accessing a canon type with a non-canon fldHnd,
+                        // currently it could happen in crossgen2 scenario where VM distinguishes class<canon>._field
+                        // from class<not-canon-ref-type>._field.
+                        haveCorrectFieldForVN =
+                            compiler->info.compCompHnd->doesFieldBelongToClass(field->gtFldHnd, clsHnd);
+                    }
+                    else
+                    {
+                        FieldSeqNode* lastSeqNode = val.m_fieldSeq->GetTail();
+                        assert(lastSeqNode != nullptr);
+                        if (lastSeqNode->IsPseudoField() || lastSeqNode == FieldSeqStore::NotAField())
+                        {
+                            haveCorrectFieldForVN = false;
+                        }
+                        else
+                        {
+                            CORINFO_FIELD_HANDLE lastFieldBeforeTheCurrent = lastSeqNode->GetFieldHandle();
+
+                            CORINFO_CLASS_HANDLE clsHnd;
+                            CorInfoType          fieldCorType =
+                                compiler->info.compCompHnd->getFieldType(lastFieldBeforeTheCurrent, &clsHnd);
+                            if (fieldCorType != CORINFO_TYPE_VALUECLASS)
+                            {
+                                // For example, System.IntPtr:ToInt64, when inlined, creates trees like
+                                // *  FIELD     long   _value
+                                // \--*  ADDR      byref
+                                //    \--*  FIELD     long   Information
+                                //       \--*  ADDR      byref
+                                //          \--*  LCL_VAR   struct<Interop+NtDll+IO_STATUS_BLOCK, 16> V08 tmp7
+                                haveCorrectFieldForVN = false;
+                            }
+                            else
+                            {
+
+                                haveCorrectFieldForVN =
+                                    compiler->info.compCompHnd->doesFieldBelongToClass(field->gtFldHnd, clsHnd);
+                                noway_assert(haveCorrectFieldForVN);
+                            }
+                        }
+                    }
+                }
+
+                if (haveCorrectFieldForVN)
+                {
+                    FieldSeqStore* fieldSeqStore = compiler->GetFieldSeqStore();
                     m_fieldSeq = fieldSeqStore->Append(val.m_fieldSeq, fieldSeqStore->CreateSingleton(field->gtFldHnd));
                 }
+                else
+                {
+                    m_fieldSeq = FieldSeqStore::NotAField();
+                    JITDUMP("Setting NotAField for [%06u],\n", compiler->dspTreeID(field));
+                }
             }
 
             INDEBUG(val.Consume();)
@@ -463,7 +530,7 @@ class LocalAddressVisitor final : public GenTreeVisitor<LocalAddressVisitor>
                     assert(TopValue(1).Node() == node);
                     assert(TopValue(0).Node() == node->AsField()->gtFldObj);
 
-                    if (!TopValue(1).Field(TopValue(0), node->AsField(), m_compiler->GetFieldSeqStore()))
+                    if (!TopValue(1).Field(TopValue(0), node->AsField(), m_compiler))
                     {
                         // Either the address comes from a location value (e.g. FIELD(IND(...)))
                         // or the field offset has overflowed.