Remove lazy initialized string literals (#122076)

It seems it's not worth it to avoid allocations on the frozen heap - the
lazy string helper has a lock inside (Crst in GetStringLiteral) and it
badly impacts performance for `throw Exception(<string literal>)` code
(as was reported internally) especially under contention.

```cs
    static void Foo(bool cond)
    {
        throw new Exception("Hello");
    }
```
```diff
; Method Program:Foo(bool) (FullOpts)
       push     rbx
       sub      rsp, 32
       mov      rcx, 0x7FFBD79E2E10      ; System.Exception
       call     CORINFO_HELP_NEWSFAST
       mov      rbx, rax
-      mov      ecx, 1
-      mov      rdx, 0x7FFBD7FE0000
-      call     [CORINFO_HELP_STRCNS]
-      mov      rdx, rax
       mov      rcx, rbx
+      mov      rdx, 0x28922695108      ; 'Hello'
       call     [System.Exception:.ctor(System.String):this]
       mov      rcx, rbx
       call     CORINFO_HELP_THROW
       int3     
-; Total bytes of code: 65
+; Total bytes of code: 51
```

Author: EgorBo

docs/design/coreclr/botr/readytorun-format.md

@@ -872,7 +872,7 @@ enum ReadyToRunHelper
     READYTORUN_HELPER_MemCpy                    = 0x41,
 
     // Get string handle lazily
-    READYTORUN_HELPER_GetString                 = 0x50,
+    READYTORUN_HELPER_GetString                 = 0x50, // Unused since READYTORUN_MAJOR_VERSION 17.0
 
     // Used by /Tuning for Profile optimizations
     READYTORUN_HELPER_LogMethodEnter            = 0x51, // Unused since READYTORUN_MAJOR_VERSION 10.0

src/coreclr/System.Private.CoreLib/src/System/String.CoreCLR.cs

@@ -10,20 +10,6 @@ namespace System
 {
     public partial class String
     {
-        [LibraryImport(RuntimeHelpers.QCall, EntryPoint = "String_StrCns")]
-        private static unsafe partial string* StrCnsInternal(uint rid, IntPtr scopeHandle);
-
-        // implementation of CORINFO_HELP_STRCNS
-        [StackTraceHidden]
-        [DebuggerStepThrough]
-        [DebuggerHidden]
-        internal static unsafe string StrCns(uint rid, IntPtr scopeHandle)
-        {
-            string* ptr = StrCnsInternal(rid, scopeHandle);
-            Debug.Assert(ptr != null);
-            return *ptr;
-        }
-
         [MethodImpl(MethodImplOptions.InternalCall)]
         internal static extern unsafe string FastAllocateString(MethodTable *pMT, nint length);
 

src/coreclr/inc/corinfo.h

@@ -367,8 +367,6 @@ enum CorInfoHelpFunc
     CORINFO_HELP_NEWARR_1_VC,       // optimized 1-D value class arrays
     CORINFO_HELP_NEWARR_1_ALIGN8,   // like VC, but aligns the array start
 
-    CORINFO_HELP_STRCNS,            // create a new string literal
-
     /* Object model */
 
     CORINFO_HELP_INITCLASS,         // Initialize class if not already initialized
@@ -3237,12 +3235,6 @@ class ICorDynamicInfo : public ICorStaticInfo
             CORINFO_CONST_LOOKUP *  pResult
             ) = 0;
 
-    // get slow lazy string literal helper to use (CORINFO_HELP_STRCNS*).
-    // Returns CORINFO_HELP_UNDEF if lazy string literal helper cannot be used.
-    virtual CorInfoHelpFunc getLazyStringLiteralHelper(
-            CORINFO_MODULE_HANDLE   handle
-            ) = 0;
-
     virtual CORINFO_MODULE_HANDLE embedModuleHandle(
             CORINFO_MODULE_HANDLE   handle,
             void                  **ppIndirection = NULL

src/coreclr/inc/icorjitinfoimpl_generated.h

@@ -556,9 +556,6 @@ void getFunctionFixedEntryPoint(
           bool isUnsafeFunctionPointer,
           CORINFO_CONST_LOOKUP* pResult) override;
 
-CorInfoHelpFunc getLazyStringLiteralHelper(
-          CORINFO_MODULE_HANDLE handle) override;
-
 CORINFO_MODULE_HANDLE embedModuleHandle(
           CORINFO_MODULE_HANDLE handle,
           void** ppIndirection) override;

src/coreclr/inc/jiteeversionguid.h

@@ -37,11 +37,11 @@
 
 #include <minipal/guid.h>
 
-constexpr GUID JITEEVersionIdentifier = { /* 567f89f4-2ddb-4d80-9107-0ce8c30a18ff */
-    0x567f89f4,
-    0x2ddb,
-    0x4d80,
-    {0x91, 0x07, 0x0c, 0xe8, 0xc3, 0x0a, 0x18, 0xff}
+constexpr GUID JITEEVersionIdentifier = { /* 4a42a64a-d034-44d4-8f0d-b7f67b3ea4dc */
+    0x4a42a64a,
+    0xd034,
+    0x44d4,
+    {0x8f, 0x0d, 0xb7, 0xf6, 0x7b, 0x3e, 0xa4, 0xdc}
   };
 
 #endif // JIT_EE_VERSIONING_GUID_H

src/coreclr/inc/jithelpers.h

@@ -112,8 +112,6 @@
     DYNAMICJITHELPER(CORINFO_HELP_NEWARR_1_VC,          RhpNewVariableSizeObject, METHOD__NIL)
     DYNAMICJITHELPER(CORINFO_HELP_NEWARR_1_ALIGN8,      RhpNewVariableSizeObject, METHOD__NIL)
 
-    DYNAMICJITHELPER(CORINFO_HELP_STRCNS,               NULL,       METHOD__STRING__STRCNS)
-
     // Object model
     DYNAMICJITHELPER(CORINFO_HELP_INITCLASS,           NULL, METHOD__INITHELPERS__INITCLASS)
     DYNAMICJITHELPER(CORINFO_HELP_INITINSTCLASS,       NULL, METHOD__INITHELPERS__INITINSTANTIATEDCLASS)

src/coreclr/inc/readytorun.h

@@ -360,7 +360,7 @@ enum ReadyToRunHelper
     READYTORUN_HELPER_ReversePInvokeExit        = 0x46,
 
     // Get string handle lazily
-    READYTORUN_HELPER_GetString                 = 0x50,
+    READYTORUN_HELPER_GetString                 = 0x50, // No longer supported as of READYTORUN_MAJOR_VERSION 17.0
 
     // Used by /Tuning for Profile optimizations
     READYTORUN_HELPER_LogMethodEnter            = 0x51, // No longer supported as of READYTORUN_MAJOR_VERSION 10.0

src/coreclr/jit/ICorJitInfo_names_generated.h

@@ -137,7 +137,6 @@ DEF_CLR_API(getAddrOfCaptureThreadGlobal)
 DEF_CLR_API(getHelperFtn)
 DEF_CLR_API(getFunctionEntryPoint)
 DEF_CLR_API(getFunctionFixedEntryPoint)
-DEF_CLR_API(getLazyStringLiteralHelper)
 DEF_CLR_API(embedModuleHandle)
 DEF_CLR_API(embedClassHandle)
 DEF_CLR_API(embedMethodHandle)

src/coreclr/jit/ICorJitInfo_wrapper_generated.hpp

@@ -1310,15 +1310,6 @@ void WrapICorJitInfo::getFunctionFixedEntryPoint(
     API_LEAVE(getFunctionFixedEntryPoint);
 }
 
-CorInfoHelpFunc WrapICorJitInfo::getLazyStringLiteralHelper(
-          CORINFO_MODULE_HANDLE handle)
-{
-    API_ENTER(getLazyStringLiteralHelper);
-    CorInfoHelpFunc temp = wrapHnd->getLazyStringLiteralHelper(handle);
-    API_LEAVE(getLazyStringLiteralHelper);
-    return temp;
-}
-
 CORINFO_MODULE_HANDLE WrapICorJitInfo::embedModuleHandle(
           CORINFO_MODULE_HANDLE handle,
           void** ppIndirection)

src/coreclr/jit/compiler.hpp

@@ -4057,7 +4057,7 @@ inline bool Compiler::IsSharedStaticHelper(GenTree* tree)
     bool result1 =
         // More helpers being added to IsSharedStaticHelper (that have similar behaviors but are not true
         // ShareStaticHelpers)
-        helper == CORINFO_HELP_STRCNS || helper == CORINFO_HELP_BOX ||
+        helper == CORINFO_HELP_BOX ||
 
         // helpers being added to IsSharedStaticHelper
         helper == CORINFO_HELP_GETSTATICFIELDADDR_TLS ||