Simple devirtualization

src/ToolBox/superpmi/superpmi-shared/icorjitinfoimpl.h

@@ -125,6 +125,13 @@
             unsigned*                   offsetAfterIndirection  /* OUT */
             );
 
+    // Find the virtual method in implementingClass that overrides virtualMethod.
+    // Return null if devirtualization is not possible.
+    CORINFO_METHOD_HANDLE resolveVirtualMethod(
+        CORINFO_METHOD_HANDLE virtualMethod,
+        CORINFO_CLASS_HANDLE implementingClass
+        );
+
     // If a method's attributes have (getMethodAttribs) CORINFO_FLG_INTRINSIC set,
     // getIntrinsicID() returns the intrinsic ID.
     // *pMustExpand tells whether or not JIT must expand the intrinsic.

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

@@ -141,6 +141,7 @@ LWM(IsWriteBarrierHelperRequired, DWORDLONG, DWORD)
 LWM(MergeClasses, DLDL, DWORDLONG)
 LWM(PInvokeMarshalingRequired, Agnostic_PInvokeMarshalingRequired, DWORD)
 LWM(ResolveToken, Agnostic_CORINFO_RESOLVED_TOKENin, Agnostic_CORINFO_RESOLVED_TOKENout)
+LWM(ResolveVirtualMethod, DLDL, DWORDLONG)
 LWM(TryResolveToken, Agnostic_CORINFO_RESOLVED_TOKENin, Agnostic_CORINFO_RESOLVED_TOKENout)
 LWM(SatisfiesClassConstraints, DWORDLONG, DWORD)
 LWM(SatisfiesMethodConstraints, DLDL, DWORD)

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

@@ -3296,6 +3296,40 @@ void MethodContext::repGetMethodVTableOffset(CORINFO_METHOD_HANDLE method, unsig
     DEBUG_REP(dmpGetMethodVTableOffset((DWORDLONG)method, value));
 }
 
+void MethodContext::recResolveVirtualMethod(CORINFO_METHOD_HANDLE virtMethod, CORINFO_CLASS_HANDLE implClass, CORINFO_METHOD_HANDLE result)
+{
+    if (ResolveVirtualMethod == nullptr)
+    {
+        ResolveVirtualMethod = new LightWeightMap<DLDL, DWORDLONG>();
+    }
+
+    DLDL key;
+    key.A = (DWORDLONG)virtMethod;
+    key.B = (DWORDLONG)implClass;
+    ResolveVirtualMethod->Add(key, (DWORDLONG) result);
+    DEBUG_REC(dmpResolveVirtualMethod(key, result));
+}
+
+void MethodContext::dmpResolveVirtualMethod(DLDL key, DWORDLONG value)
+{
+    printf("ResolveVirtualMethod virtMethod-%016llX, implClass-%016llX, result-%016llX", key.A, key.B, value);
+}
+
+CORINFO_METHOD_HANDLE MethodContext::repResolveVirtualMethod(CORINFO_METHOD_HANDLE virtMethod, CORINFO_CLASS_HANDLE implClass)
+{
+    DLDL key;
+    key.A = (DWORDLONG)virtMethod;
+    key.B = (DWORDLONG)implClass;
+
+    AssertCodeMsg(ResolveVirtualMethod != nullptr, EXCEPTIONCODE_MC, "No ResolveVirtualMap map for %016llX-%016llX", key.A, key.B);
+    AssertCodeMsg(ResolveVirtualMethod->GetIndex(key) != -1, EXCEPTIONCODE_MC, "Didn't find %016llX-%016llx", key.A, key.B);
+    DWORDLONG result = ResolveVirtualMethod->Get(key);
+
+    DEBUG_REP(dmpResolveVirtualMethod(key, result));
+
+    return (CORINFO_METHOD_HANDLE)result;
+}
+
 void MethodContext::recGetTokenTypeAsHandle(CORINFO_RESOLVED_TOKEN * pResolvedToken, CORINFO_CLASS_HANDLE result)
 {
     if (GetTokenTypeAsHandle == nullptr)
@@ -6165,7 +6199,7 @@ mdMethodDef MethodContext::repGetMethodDefFromMethod(CORINFO_METHOD_HANDLE hMeth
 
     int index = GetMethodDefFromMethod->GetIndex((DWORDLONG)hMethod);
     if (index < 0)
-        return (mdMethodDef)0x06000001;    
+        return (mdMethodDef)0x06000001;
 
     return (mdMethodDef)GetMethodDefFromMethod->Get((DWORDLONG)hMethod);
 }

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

@@ -698,6 +698,10 @@ class MethodContext
     void dmpGetMethodVTableOffset(DWORDLONG key, DD value);
     void repGetMethodVTableOffset(CORINFO_METHOD_HANDLE method, unsigned *offsetOfIndirection, unsigned* offsetAfterIndirection);
 
+    void recResolveVirtualMethod(CORINFO_METHOD_HANDLE virtMethod, CORINFO_CLASS_HANDLE implClass, CORINFO_METHOD_HANDLE result);
+    void dmpResolveVirtualMethod(DLDL key, DWORDLONG value);
+    CORINFO_METHOD_HANDLE repResolveVirtualMethod(CORINFO_METHOD_HANDLE virtMethod, CORINFO_CLASS_HANDLE implClass);
+
     void recGetTokenTypeAsHandle(CORINFO_RESOLVED_TOKEN * pResolvedToken, CORINFO_CLASS_HANDLE result);
     void dmpGetTokenTypeAsHandle(const Agnostic_CORINFO_RESOLVED_TOKEN& key, DWORDLONG value);
     CORINFO_CLASS_HANDLE repGetTokenTypeAsHandle(CORINFO_RESOLVED_TOKEN * pResolvedToken);
@@ -1016,7 +1020,7 @@ class MethodContext
 
 
 // ********************* Please keep this up-to-date to ease adding more ***************
-// Highest packet number: 159
+// Highest packet number: 160
 // *************************************************************************************
 enum mcPackets
 {
@@ -1151,6 +1155,7 @@ enum mcPackets
     Packet_MergeClasses = 107,
     Packet_PInvokeMarshalingRequired = 108,
     Packet_ResolveToken = 109,
+    Packet_ResolveVirtualMethod = 160, // Added 2/13/17
     Packet_TryResolveToken = 158, //Added 4/26/2016
     Packet_SatisfiesClassConstraints = 110,
     Packet_SatisfiesMethodConstraints = 111,

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

@@ -236,6 +236,19 @@ void interceptor_ICJI::getMethodVTableOffset (
     mc->recGetMethodVTableOffset(method, offsetOfIndirection, offsetAfterIndirection);
 }
 
+// Find the virtual method in implementingClass that overrides virtualMethod.
+// Return null if devirtualization is not possible.
+CORINFO_METHOD_HANDLE interceptor_ICJI::resolveVirtualMethod(
+    CORINFO_METHOD_HANDLE virtualMethod,
+    CORINFO_CLASS_HANDLE implementingClass
+    )
+{
+    mc->cr->AddCall("resolveVirtualMethod");
+    CORINFO_METHOD_HANDLE result = original_ICorJitInfo->resolveVirtualMethod(virtualMethod, implementingClass);
+    mc->recResolveVirtualMethod(virtualMethod, implementingClass, result);
+    return result;
+}
+
 // If a method's attributes have (getMethodAttribs) CORINFO_FLG_INTRINSIC set,
 // getIntrinsicID() returns the intrinsic ID.
 CorInfoIntrinsics interceptor_ICJI::getIntrinsicID(

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

@@ -165,6 +165,17 @@ void interceptor_ICJI::getMethodVTableOffset (
     original_ICorJitInfo->getMethodVTableOffset(method, offsetOfIndirection, offsetAfterIndirection);
 }
 
+// Find the virtual method in implementingClass that overrides virtualMethod.
+// Return null if devirtualization is not possible.
+CORINFO_METHOD_HANDLE interceptor_ICJI::resolveVirtualMethod(
+    CORINFO_METHOD_HANDLE virtualMethod,
+    CORINFO_CLASS_HANDLE implementingClass
+    )
+{
+    mcs->AddCall("resolveVirtualMethod");
+    return original_ICorJitInfo->resolveVirtualMethod(virtualMethod, implementingClass);
+}
+
 // If a method's attributes have (getMethodAttribs) CORINFO_FLG_INTRINSIC set,
 // getIntrinsicID() returns the intrinsic ID.
 CorInfoIntrinsics interceptor_ICJI::getIntrinsicID(

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

@@ -153,6 +153,16 @@ void interceptor_ICJI::getMethodVTableOffset (
     original_ICorJitInfo->getMethodVTableOffset(method, offsetOfIndirection, offsetAfterIndirection);
 }
 
+// Find the virtual method in implementingClass that overrides virtualMethod.
+// Return null if devirtualization is not possible.
+CORINFO_METHOD_HANDLE interceptor_ICJI::resolveVirtualMethod(
+    CORINFO_METHOD_HANDLE virtualMethod,
+    CORINFO_CLASS_HANDLE implementingClass
+    )
+{
+    return original_ICorJitInfo->resolveVirtualMethod(virtualMethod, implementingClass);
+}
+
 // If a method's attributes have (getMethodAttribs) CORINFO_FLG_INTRINSIC set,
 // getIntrinsicID() returns the intrinsic ID.
 CorInfoIntrinsics interceptor_ICJI::getIntrinsicID(

src/ToolBox/superpmi/superpmi/icorjitinfo.cpp

@@ -185,6 +185,18 @@ void MyICJI::getMethodVTableOffset (
     jitInstance->mc->repGetMethodVTableOffset(method, offsetOfIndirection, offsetAfterIndirection);
 }
 
+// Find the virtual method in implementingClass that overrides virtualMethod.
+// Return null if devirtualization is not possible.
+CORINFO_METHOD_HANDLE MyICJI::resolveVirtualMethod(
+    CORINFO_METHOD_HANDLE virtualMethod,
+    CORINFO_CLASS_HANDLE implementingClass
+    )
+{
+    jitInstance->mc->cr->AddCall("resolveVirtualMethod");
+    CORINFO_METHOD_HANDLE result = jitInstance->mc->repResolveVirtualMethod(virtualMethod, implementingClass);
+    return result;
+}
+
 // If a method's attributes have (getMethodAttribs) CORINFO_FLG_INTRINSIC set,
 // getIntrinsicID() returns the intrinsic ID.
 CorInfoIntrinsics MyICJI::getIntrinsicID(

src/inc/corinfo.h

@@ -231,12 +231,12 @@ TODO: Talk about initializing strutures before use
 #if COR_JIT_EE_VERSION > 460
 
 // Update this one
-SELECTANY const GUID JITEEVersionIdentifier = { /* 4bd06266-8ef7-4172-bec6-d3149fde7859 */
-    0x4bd06266,
-    0x8ef7,
-    0x4172,
-    {0xbe, 0xc6, 0xd3, 0x14, 0x9f, 0xde, 0x78, 0x59}
-};
+SELECTANY const GUID JITEEVersionIdentifier = { /* cda334f7-0020-4622-a4a5-8b8ac71ee5cf */
+    0xcda334f7,
+    0x0020,
+    0x4622,
+    {0xa4, 0xa5, 0x8b, 0x8a, 0xc7, 0x1e, 0xe5, 0xcf}
+  };
 
 #else
 
@@ -2116,6 +2116,15 @@ class ICorStaticInfo
             unsigned*                   offsetAfterIndirection  /* OUT */
             ) = 0;
 
+#if COR_JIT_EE_VERSION > 460
+    // Find the virtual method in implementingClass that overrides virtualMethod.
+    // Return null if devirtualization is not possible.
+    virtual CORINFO_METHOD_HANDLE resolveVirtualMethod(
+        CORINFO_METHOD_HANDLE virtualMethod,        /* IN */
+        CORINFO_CLASS_HANDLE implementingClass      /* IN */
+        ) = 0;
+#endif
+
     // If a method's attributes have (getMethodAttribs) CORINFO_FLG_INTRINSIC set,
     // getIntrinsicID() returns the intrinsic ID.
     // *pMustExpand tells whether or not JIT must expand the intrinsic.

src/jit/compiler.h

@@ -322,6 +322,8 @@ class LclVarDsc
 #endif                                       // FEATURE_SIMD
     unsigned char lvRegStruct : 1;           // This is a reg-sized non-field-addressed struct.
 
+    unsigned char lvClassIsExact : 1; // lvClassHandle is the exact type
+
     union {
         unsigned lvFieldLclStart; // The index of the local var representing the first field in the promoted struct
                                   // local.
@@ -704,6 +706,8 @@ class LclVarDsc
 
     typeInfo lvVerTypeInfo; // type info needed for verification
 
+    CORINFO_CLASS_HANDLE lvClassHnd; // class handle for the local, or null if not known
+
     BYTE* lvGcLayout; // GC layout info for structs
 
 #if ASSERTION_PROP
@@ -2875,6 +2879,11 @@ class Compiler
                             CORINFO_CALL_INFO* callInfo,
                             IL_OFFSET          rawILOffset);
 
+    void impDevirtualizeCall(GenTreeCall*            call,
+                             GenTreePtr              obj,
+                             CORINFO_CALL_INFO*      callInfo,
+                             CORINFO_CONTEXT_HANDLE* exactContextHnd);
+
     bool impMethodInfo_hasRetBuffArg(CORINFO_METHOD_INFO* methInfo);
 
     GenTreePtr impFixupCallStructReturn(GenTreePtr call, CORINFO_CLASS_HANDLE retClsHnd);

src/jit/flowgraph.cpp

@@ -21148,6 +21148,7 @@ void Compiler::fgInline()
             }
 
             // See if we need to replace the return value place holder.
+            // Also, see if this update enables further devirtualization.
             fgWalkTreePre(&stmt->gtStmtExpr, fgUpdateInlineReturnExpressionPlaceHolder, (void*)this);
 
             // See if stmt is of the form GT_COMMA(call, nop)
@@ -21419,11 +21420,46 @@ void Compiler::fgAttachStructInlineeToAsg(GenTreePtr tree, GenTreePtr child, COR
 
 #endif // FEATURE_MULTIREG_RET
 
-/*****************************************************************************
- * Callback to replace the inline return expression place holder (GT_RET_EXPR)
- */
+//------------------------------------------------------------------------
+// fgUpdateInlineReturnExpressionPlaceHolder: callback to replace the
+// inline return expression placeholder.
+//
+// Arguments:
+//    pTree -- pointer to tree to examine for updates
+//    data  -- context data for the tree walk
+//
+// Returns:
+//    fgWalkResult indicating the walk should continue; that
+//    is we wish to fully explore the tree.
+//
+// Notes:
+//    Looks for GT_RET_EXPR nodes that arose from tree splitting done
+//    during importation for inline candidates, and replaces them.
+//
+//    For successful inlines, substitutes the return value expression
+//    from the inline body for the GT_RET_EXPR.
+//
+//    For failed inlines, rejoins the original call into the tree from
+//    whence it was split during importation.
+//
+//    The code doesn't actually know if the corresponding inline
+//    succeeded or not; it relies on the fact that gtInlineCandidate
+//    initially points back at the call and is modified in place to
+//    the inlinee return expression if the inline is successful (see
+//    tail end of fgInsertInlineeBlocks for the update of iciCall).
+//
+//    If the parent of the GT_RET_EXPR is a virtual call,
+//    devirtualization is attempted. This should only succeed in the
+//    successful inline case, when the inlinee's return value
+//    expression provides a better type than the return type of the
+//    method. Note for failed inlines, the devirtualizer can only go
+//    by the return type, and any devirtualization that type enabled
+//    would have already happened during importation.
+//
+//    If the return type is a struct type and we're on a platform
+//    where structs can be returned in multiple registers, ensure the
+//    call has a suitable parent.
 
-/* static */
 Compiler::fgWalkResult Compiler::fgUpdateInlineReturnExpressionPlaceHolder(GenTreePtr* pTree, fgWalkData* data)
 {
     GenTreePtr           tree      = *pTree;
@@ -21469,6 +21505,41 @@ Compiler::fgWalkResult Compiler::fgUpdateInlineReturnExpressionPlaceHolder(GenTr
             }
 #endif // DEBUG
         } while (tree->gtOper == GT_RET_EXPR);
+
+        // Now see if this return value expression feeds the 'this'
+        // object at a virtual call site.
+        //
+        // Note for void returns where the inline failed, the
+        // GT_RET_EXPR may be top-level.
+        //
+        // May miss cases where there are intermediaries between call
+        // and this, eg commas.
+        GenTreePtr parentTree = data->parent;
+
+        if ((parentTree != nullptr) && (parentTree->gtOper == GT_CALL))
+        {
+            GenTreeCall* call          = parentTree->AsCall();
+            bool         tryLateDevirt = call->IsVirtual() && (call->gtCallObjp == tree);
+
+#ifdef DEBUG
+            tryLateDevirt = tryLateDevirt && (JitConfig.JitEnableLateDevirtualization() == 1);
+#endif // DEBUG
+
+            if (tryLateDevirt)
+            {
+#ifdef DEBUG
+                if (comp->verbose)
+                {
+                    printf("**** Late devirt opportunity\n");
+                    comp->gtDispTree(call);
+                }
+#endif // DEBUG
+
+                CORINFO_CALL_INFO x = {};
+                x.hMethod           = call->gtCallMethHnd;
+                comp->impDevirtualizeCall(call, tree, &x, nullptr);
+            }
+        }
     }
 
 #if FEATURE_MULTIREG_RET