[EVM] ConstantUnfolding: add fallback to size optimization mode when module bytecode exceeds the 24KB limit

Key changes introduced:

 - Transitioned from a MachineFunction pass to a Module-level pass
 - Implemented module-wide code size estimation
   (not 100% exact but sufficiently accurate for our purpose)
 - Applied transformations by iterating over functions within the module.
   For each function:
   - Handled both loop and non-loop basic blocks using the default heuristic
     (i.e., based on the presence of the OptSize attribute)
   - If the module size exceeds the defined limit, switched to a fallback mode
     that treats all functions as if they have OptSize flag.
 - Repeatedly traversed all functions, targeting only basic blocks at a specific
   loop nesting depth (starting from depth 0 for non-loop blocks), and
   re-evaluated module size. The process stops once the size drops below the
   limit, or reaching the loop depth limit.

This enables a balanced distribution of runtime gas regressions across functions
within the module, resulting from aggressive constant unfolding.

Author: PavelKopyl

llvm/lib/Target/EVM/EVM.h

@@ -42,13 +42,8 @@ namespace EVMCOST {
 unsigned constexpr SWAP = 3;
 unsigned constexpr DUP = 3;
 unsigned constexpr POP = 2;
-unsigned constexpr PUSH0 = 2;
 unsigned constexpr PUSH = 3;
 unsigned constexpr MLOAD = 3;
-unsigned constexpr SHIFT = 3;
-unsigned constexpr ADD = 3;
-unsigned constexpr SUB = 3;
-unsigned constexpr NOT = 3;
 } // namespace EVMCOST
 
 // LLVM IR passes.
@@ -75,7 +70,7 @@ FunctionPass *createEVMBPStackification();
 FunctionPass *createEVMLowerJumpUnless();
 ModulePass *createEVMFinalizeStackFrames();
 ModulePass *createEVMMarkRecursiveFunctionsPass();
-FunctionPass *createEVMConstantUnfolding();
+ModulePass *createEVMConstantUnfolding();
 
 // PassRegistry initialization declarations.
 void initializeEVMCodegenPreparePass(PassRegistry &);