Properly type primary selectors in fgMemoryVNForLoopSideEffects (#6…

…0505)

* Proper types in fgMemoryVNForLoopSideEffects

To simplify our model for what types the memory maps should
have and, in the future, enable asserts acting on that.

* Switch to only typing statics

As these are the only maps that represent values
representable and useful in the Jit's type system.

src/coreclr/jit/compiler.h

@@ -7981,6 +7981,9 @@ class Compiler
 
     bool eeIsValueClass(CORINFO_CLASS_HANDLE clsHnd);
     bool eeIsJitIntrinsic(CORINFO_METHOD_HANDLE ftn);
+    bool eeIsFieldStatic(CORINFO_FIELD_HANDLE fldHnd);
+
+    var_types eeGetFieldType(CORINFO_FIELD_HANDLE fldHnd);
 
 #if defined(DEBUG) || defined(FEATURE_JIT_METHOD_PERF) || defined(FEATURE_SIMD) || defined(TRACK_LSRA_STATS)
 

src/coreclr/jit/ee_il_dll.hpp

@@ -61,6 +61,18 @@ bool Compiler::eeIsJitIntrinsic(CORINFO_METHOD_HANDLE ftn)
     return info.compCompHnd->isJitIntrinsic(ftn);
 }
 
+FORCEINLINE
+bool Compiler::eeIsFieldStatic(CORINFO_FIELD_HANDLE fldHnd)
+{
+    return info.compCompHnd->isFieldStatic(fldHnd);
+}
+
+FORCEINLINE
+var_types Compiler::eeGetFieldType(CORINFO_FIELD_HANDLE fldHnd)
+{
+    return JITtype2varType(info.compCompHnd->getFieldType(fldHnd));
+}
+
 FORCEINLINE
 void Compiler::eeGetSig(unsigned               sigTok,
                         CORINFO_MODULE_HANDLE  scope,

src/coreclr/jit/valuenum.cpp

@@ -6980,8 +6980,12 @@ ValueNum Compiler::fgMemoryVNForLoopSideEffects(MemoryKind  memoryKind,
                 }
 #endif // DEBUG
 
+                // Instance field maps get the placeholder TYP_REF - they do not represent "singular"
+                // values. Static field maps, on the other hand, do, and so must be given proper types.
+                var_types fldMapType = eeIsFieldStatic(fldHnd) ? eeGetFieldType(fldHnd) : TYP_REF;
+
                 newMemoryVN =
-                    vnStore->VNForMapStore(TYP_REF, newMemoryVN, fldHndVN, vnStore->VNForExpr(entryBlock, TYP_REF));
+                    vnStore->VNForMapStore(TYP_REF, newMemoryVN, fldHndVN, vnStore->VNForExpr(entryBlock, fldMapType));
             }
         }
         // Now do the array maps.