implement EXTCODESIZE

Signed-off-by: xermicus <cyrill@parity.io>

crates/llvm-context/src/polkavm/evm/ext_code.rs

@@ -1,17 +1,36 @@
 //! Translates the external code operations.
 
+use inkwell::values::BasicValue;
+
 use crate::polkavm::context::Context;
 use crate::polkavm::Dependency;
+use crate::polkavm_const::runtime_api;
 
 /// Translates the `extcodesize` instruction.
 pub fn size<'ctx, D>(
-    _context: &mut Context<'ctx, D>,
-    _address: inkwell::values::IntValue<'ctx>,
+    context: &mut Context<'ctx, D>,
+    address: inkwell::values::IntValue<'ctx>,
 ) -> anyhow::Result<inkwell::values::BasicValueEnum<'ctx>>
 where
     D: Dependency + Clone,
 {
-    todo!()
+    let address_pointer = context.build_alloca(context.word_type(), "value");
+    context.build_store(address_pointer, address)?;
+
+    let address_pointer_casted = context.builder().build_ptr_to_int(
+        address_pointer.value,
+        context.xlen_type(),
+        "address_pointer",
+    )?;
+    let value = context
+        .build_runtime_call(runtime_api::CODE_SIZE, &[address_pointer_casted.into()])
+        .unwrap_or_else(|| panic!("{} should return a value", runtime_api::CODE_SIZE))
+        .into_int_value();
+
+    Ok(context
+        .builder()
+        .build_int_z_extend(value, context.word_type(), "extcodesize")?
+        .as_basic_value_enum())
 }
 
 /// Translates the `extcodehash` instruction.