add another msize test case

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

crates/integration/contracts/MSize.sol

@@ -6,4 +6,11 @@ contract MSize {
             size := msize()
         }
     }
+
+    function mStore100() public pure returns (uint size) {
+        assembly {
+            mstore(100, msize())
+            size := msize()
+        }
+    }
 }

crates/integration/src/lib.rs

@@ -163,7 +163,7 @@ mod tests {
     }
 
     #[test]
-    fn msize() {
+    fn msize_plain() {
         sol!(
             #[derive(Debug, PartialEq, Eq)]
             contract MSize {
@@ -175,9 +175,9 @@ mod tests {
             include_str!("../contracts/MSize.sol"),
             false,
         );
+        let (instance, export) = mock_runtime::prepare(&code, None);
 
         let input = MSize::mSizeCall::new(()).abi_encode();
-        let (instance, export) = mock_runtime::prepare(&code, None);
         let state = crate::mock_runtime::call(State::new(input), &instance, export);
 
         assert_eq!(state.output.flags, 0);
@@ -187,4 +187,32 @@ mod tests {
         let received = U256::from_be_bytes::<32>(state.output.data.try_into().unwrap());
         assert_eq!(received, expected);
     }
+
+    #[test]
+    fn msize_non_word_sized_access() {
+        sol!(
+            #[derive(Debug, PartialEq, Eq)]
+            contract MSize {
+                function mStore100() public pure returns (uint);
+            }
+        );
+        let code = crate::compile_blob_with_options(
+            "MSize",
+            include_str!("../contracts/MSize.sol"),
+            false,
+        );
+        let (instance, export) = mock_runtime::prepare(&code, None);
+
+        let input = MSize::mStore100Call::new(()).abi_encode();
+        let state = crate::mock_runtime::call(State::new(input), &instance, export);
+
+        assert_eq!(state.output.flags, 0);
+
+        // https://docs.zksync.io/build/developer-reference/differences-with-ethereum.html#mstore-mload
+        // "Unlike EVM, where the memory growth is in words, on zkEVM the memory growth is counted in bytes."
+        // "For example, if you write mstore(100, 0) the msize on zkEVM will be 132, but on the EVM it will be 160."
+        let expected = U256::try_from(132).unwrap();
+        let received = U256::from_be_bytes::<32>(state.output.data.try_into().unwrap());
+        assert_eq!(received, expected);
+    }
 }

crates/llvm-context/src/eravm/evm/context.rs

@@ -201,5 +201,8 @@ where
             .build_ptr_to_int(heap_start, context.xlen_type(), "heap_start")?,
         "heap_size",
     )?;
-    Ok(heap_size.as_basic_value_enum())
+    Ok(context
+        .builder()
+        .build_int_z_extend(heap_size, context.field_type(), "heap_size_extended")?
+        .as_basic_value_enum())
 }

crates/llvm-context/src/eravm/evm/return_data.rs

@@ -89,5 +89,5 @@ where
         "return_data_copy_memcpy_from_return_data",
     )?;
 
-    Ok(())
+    todo!("Build heap GEP to allocate if necessary")
 }