Change RhNewString length argument to nint/intptr_t (#117552)

The RhNewString length argument is declared as int, but the asm
implementation was using the full 64 bits of the related argument
register. That doesn't match the calling convention where there is no
guarantee that the upper 32 bits are zeroed. That has caused problem in
the interpreter that always loads full registers from the interpreter
stack and so sometimes, the upper 32 bits were a garbage and the
function failed because the length was seemingly too large.

This change fixes it by changing signature of the RhNewString so that
the length is nint in managed code / intptr_t in native code.

Author: janvorli

src/coreclr/nativeaot/Runtime/portable.cpp

@@ -127,7 +127,7 @@ FCIMPL2(Array *, RhpNewArrayFast, MethodTable * pArrayEEType, int numElements)
 }
 FCIMPLEND
 
-FCIMPL2(String *, RhNewString, MethodTable * pArrayEEType, int numElements)
+FCIMPL2(String *, RhNewString, MethodTable * pArrayEEType, intptr_t numElements)
 {
     // TODO: Implement. We tail call to RhpNewArrayFast for now since there's a bunch of TODOs in the places
     // that matter anyway.

src/coreclr/nativeaot/System.Private.CoreLib/src/System/Runtime/RuntimeImports.cs

@@ -396,7 +396,7 @@ internal static IntPtr RhHandleAllocDependent(object primary, object secondary)
 
         [MethodImpl(MethodImplOptions.InternalCall)]
         [RuntimeImport(RuntimeLibrary, "RhNewString")]
-        internal static extern unsafe string RhNewString(MethodTable* pEEType, int length);
+        internal static extern unsafe string RhNewString(MethodTable* pEEType, nint length);
 
         [MethodImpl(MethodImplOptions.InternalCall)]
         [RuntimeImport(RuntimeLibrary, "RhUnbox")]

src/coreclr/nativeaot/System.Private.CoreLib/src/System/String.NativeAot.cs

@@ -18,7 +18,7 @@ public partial class String
         [Intrinsic]
         public static readonly string Empty = "";
 
-        internal static unsafe string FastAllocateString(int length)
+        internal static unsafe string FastAllocateString(nint length)
         {
             // We allocate one extra char as an interop convenience so that our strings are null-
             // terminated, however, we don't pass the extra +1 to the string allocation because the base

src/coreclr/nativeaot/Test.CoreLib/src/System/Runtime/RuntimeImports.cs

@@ -82,7 +82,7 @@ internal static IntPtr RhGetModuleSection(TypeManagerHandle module, ReadyToRunSe
 
         [MethodImpl(MethodImplOptions.InternalCall)]
         [RuntimeImport(RuntimeLibrary, "RhNewString")]
-        internal static extern unsafe string RhNewString(MethodTable* pEEType, int length);
+        internal static extern unsafe string RhNewString(MethodTable* pEEType, nint length);
 
         [DllImport(RuntimeLibrary)]
         internal static extern unsafe void RhAllocateNewArray(MethodTable* pArrayEEType, uint numElements, uint flags, void* pResult);

src/coreclr/runtime/amd64/AllocFast.S

@@ -173,7 +173,7 @@ NESTED_END RhpNewObject, _TEXT
 
 // Allocate a string.
 //  RDI == MethodTable
-//  ESI == character/element count
+//  RSI == character/element count
 LEAF_ENTRY RhNewString, _TEXT
 
         // we want to limit the element count to the non-negative 32-bit int range

src/coreclr/runtime/amd64/AllocFast.asm

@@ -128,7 +128,7 @@ ENDM ; NEW_ARRAY_FAST
 
 ;; Allocate a string.
 ;;  RCX == MethodTable
-;;  EDX == character/element count
+;;  RDX == character/element count
 LEAF_ENTRY RhNewString, _TEXT
 
         ; we want to limit the element count to the non-negative 32-bit int range

src/coreclr/vm/jitinterface.h

@@ -149,7 +149,7 @@ EXTERN_C FCDECL1(void*, JIT_GetDynamicNonGCStaticBaseNoCtor_Portable, DynamicSta
 EXTERN_C FCDECL1(Object*, RhpNewFast, CORINFO_CLASS_HANDLE typeHnd_);
 EXTERN_C FCDECL2(Object*, RhpNewArrayFast, CORINFO_CLASS_HANDLE typeHnd_, INT_PTR size);
 EXTERN_C FCDECL2(Object*, RhpNewPtrArrayFast, CORINFO_CLASS_HANDLE typeHnd_, INT_PTR size);
-EXTERN_C FCDECL2(Object*, RhNewString, CORINFO_CLASS_HANDLE typeHnd_, DWORD stringLength);
+EXTERN_C FCDECL2(Object*, RhNewString, CORINFO_CLASS_HANDLE typeHnd_, INT_PTR stringLength);
 
 #if defined(FEATURE_64BIT_ALIGNMENT)
 EXTERN_C FCDECL1(Object*, RhpNewFastAlign8, CORINFO_CLASS_HANDLE typeHnd_);
@@ -161,17 +161,14 @@ EXTERN_C FCDECL2(Object*, RhpNewArrayFastAlign8, CORINFO_CLASS_HANDLE typeHnd_,
 EXTERN_C FCDECL1(Object*, RhpNewFast_UP, CORINFO_CLASS_HANDLE typeHnd_);
 EXTERN_C FCDECL2(Object*, RhpNewArrayFast_UP, CORINFO_CLASS_HANDLE typeHnd_, INT_PTR size);
 EXTERN_C FCDECL2(Object*, RhpNewPtrArrayFast_UP, CORINFO_CLASS_HANDLE typeHnd_, INT_PTR size);
-EXTERN_C FCDECL2(Object*, RhNewString_UP, CORINFO_CLASS_HANDLE typeHnd_, DWORD stringLength);
+EXTERN_C FCDECL2(Object*, RhNewString_UP, CORINFO_CLASS_HANDLE typeHnd_, INT_PTR stringLength);
 #endif
 
 EXTERN_C FCDECL1(Object*, RhpNew, CORINFO_CLASS_HANDLE typeHnd_);
 EXTERN_C FCDECL2(Object*, RhpNewVariableSizeObject, CORINFO_CLASS_HANDLE typeHnd_, INT_PTR size);
 EXTERN_C FCDECL1(Object*, RhpNewMaybeFrozen, CORINFO_CLASS_HANDLE typeHnd_);
 EXTERN_C FCDECL2(Object*, RhpNewArrayMaybeFrozen, CORINFO_CLASS_HANDLE typeHnd_, INT_PTR size);
 
-EXTERN_C FCDECL1(Object*, AllocateStringFast, DWORD stringLength);
-EXTERN_C FCDECL1(Object*, AllocateStringSlow, DWORD stringLength);
-
 EXTERN_C FCDECL2(void, JITutil_MonReliableEnter, Object* obj, BYTE* pbLockTaken);
 EXTERN_C FCDECL3(void, JITutil_MonTryEnter, Object* obj, INT32 timeOut, BYTE* pbLockTaken);
 EXTERN_C FCDECL2(void, JITutil_MonReliableContention, AwareLock* awarelock, BYTE* pbLockTaken);