implement immutable variables codegen

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

crates/llvm-context/src/polkavm/context/function/runtime/entry.rs

@@ -31,6 +31,18 @@ impl Entry {
     where
         D: Dependency + Clone,
     {
+        context.declare_global(
+            revive_runtime_api::immutable_data::GLOBAL_IMMUTABLE_DATA_POINTER,
+            context.word_type().array_type(0),
+            AddressSpace::Stack,
+        );
+
+        context.declare_global(
+            revive_runtime_api::immutable_data::GLOBAL_IMMUTABLE_DATA_SIZE,
+            context.xlen_type(),
+            AddressSpace::Stack,
+        );
+
         let calldata_type = context.array_type(context.byte_type(), Self::MAX_CALLDATA_SIZE);
         context.set_global(
             crate::polkavm::GLOBAL_CALLDATA_POINTER,

crates/llvm-context/src/polkavm/context/global.rs

@@ -51,4 +51,31 @@ impl<'ctx> Global<'ctx> {
 
         global
     }
+
+    /// Construct an external global.
+    pub fn declare<D, T>(
+        context: &mut Context<'ctx, D>,
+        r#type: T,
+        address_space: AddressSpace,
+        name: &str,
+    ) -> Self
+    where
+        D: PolkaVMDependency + Clone,
+        T: BasicType<'ctx>,
+    {
+        let r#type = r#type.as_basic_type_enum();
+
+        let value = context
+            .module()
+            .add_global(r#type, Some(address_space.into()), name);
+        let global = Self { r#type, value };
+
+        global.value.set_linkage(inkwell::module::Linkage::External);
+        global
+            .value
+            .set_visibility(inkwell::GlobalVisibility::Default);
+        global.value.set_externally_initialized(true);
+
+        global
+    }
 }

crates/llvm-context/src/polkavm/context/mod.rs

@@ -162,6 +162,18 @@ where
         })
     }
 
+    fn link_immutable_data(&self, contract_path: &str) -> anyhow::Result<()> {
+        let size = self.solidity().immutables_size() as u32;
+        let exports = revive_runtime_api::immutable_data::module(self.llvm(), size);
+        self.module.link_in_module(exports).map_err(|error| {
+            anyhow::anyhow!(
+                "The contract `{}` immutable data module linking error: {}",
+                contract_path,
+                error
+            )
+        })
+    }
+
     /// Configure the PolkaVM minimum stack size.
     fn set_polkavm_stack_size(
         llvm: &'ctx inkwell::context::Context,
@@ -239,6 +251,7 @@ where
         let module_clone = self.module.clone();
 
         self.link_polkavm_exports(contract_path)?;
+        self.link_immutable_data(contract_path)?;
 
         let target_machine = TargetMachine::new(Target::PVM, self.optimizer.settings())?;
         target_machine.set_target_data(self.module());
@@ -381,6 +394,15 @@ where
         }
     }
 
+    /// Declare an external global.
+    pub fn declare_global<T>(&mut self, name: &str, r#type: T, address_space: AddressSpace)
+    where
+        T: BasicType<'ctx> + Clone + Copy,
+    {
+        let global = Global::declare(self, r#type, address_space, name);
+        self.globals.insert(name.to_owned(), global);
+    }
+
     /// Returns the LLVM intrinsics collection reference.
     pub fn intrinsics(&self) -> &Intrinsics<'ctx> {
         &self.intrinsics

crates/llvm-context/src/polkavm/context/solidity_data.rs

@@ -17,7 +17,7 @@ impl SolidityData {
         Self::default()
     }
 
-    /// Returns the current number of immutables values in the contract.
+    /// Returns the current size of immutable values in the contract.
     pub fn immutables_size(&self) -> usize {
         self.immutables.len() * revive_common::BYTE_LENGTH_WORD
     }