add Compiler::truncateThenExtend

include/avian/codegen/compiler.h

@@ -107,6 +107,11 @@ class Compiler {
   virtual void checkBounds(Operand* object, unsigned lengthOffset,
                            Operand* index, intptr_t handler) = 0;
 
+  virtual Operand* truncateThenExtend(ir::SignExtendMode signExtend,
+                                      ir::Type extendType,
+                                      ir::Type truncateType,
+                                      Operand* src) = 0;
+
   virtual void store(ir::Type srcType,
                      Operand* src,
                      Operand* dst) = 0;

src/codegen/compiler.cpp

@@ -2609,6 +2609,22 @@ class MyCompiler: public Compiler {
                       static_cast<Value*>(index), handler);
   }
 
+  virtual Operand* truncateThenExtend(ir::SignExtendMode signExtend,
+                                      ir::Type extendType,
+                                      ir::Type truncateType,
+                                      Operand* src)
+  {
+    Value* dst = value(&c, extendType);
+    appendMove(&c,
+               signExtend == ir::SignExtend ? lir::Move : lir::MoveZ,
+               TargetBytesPerWord,
+               truncateType.size(),
+               static_cast<Value*>(src),
+               extendType.size(),
+               dst);
+    return dst;
+  }
+
   virtual void store(ir::Type srcType,
                      Operand* src,
                      Operand* dst)

src/compile.cpp

@@ -4831,8 +4831,8 @@ compile(MyThread* t, Frame* initialFrame, unsigned initialIp,
     } break;
 
     case i2l:
-      frame->pushLong(c->load(
+      frame->pushLong(c->truncateThenExtend(
-          ir::SignExtend, types.address, types.i4, frame->popInt(), types.i8));
+          ir::SignExtend, types.i8, types.i4, frame->popInt()));
       break;
 
     case i2s: {