JIT: Don't allocate string literals inside potential BBJ_THROW candidates (#50112)

Author: EgorBo

src/coreclr/jit/morph.cpp

@@ -9590,7 +9590,19 @@ GenTree* Compiler::fgMorphConst(GenTree* tree)
     // guarantee slow performance for that block. Instead cache the return value
     // of CORINFO_HELP_STRCNS and go to cache first giving reasonable perf.
 
+    bool useLazyStrCns = false;
     if (compCurBB->bbJumpKind == BBJ_THROW)
+    {
+        useLazyStrCns = true;
+    }
+    else if (fgGlobalMorph && compCurStmt->GetRootNode()->IsCall())
+    {
+        // Quick check: if the root node of the current statement happens to be a noreturn call.
+        GenTreeCall* call = compCurStmt->GetRootNode()->AsCall();
+        useLazyStrCns     = call->IsNoReturn() || fgIsThrow(call);
+    }
+
+    if (useLazyStrCns)
     {
         CorInfoHelpFunc helper = info.compCompHnd->getLazyStringLiteralHelper(tree->AsStrCon()->gtScpHnd);
         if (helper != CORINFO_HELP_UNDEF)