implement immutable variables codegen (#70)

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

@@ -91,7 +91,8 @@ impl<'ctx> Function<'ctx> {
             || (name.starts_with("__")
                 && name != self::runtime::FUNCTION_ENTRY
                 && name != self::runtime::FUNCTION_DEPLOY_CODE
-                && name != self::runtime::FUNCTION_RUNTIME_CODE)
+                && name != self::runtime::FUNCTION_RUNTIME_CODE
+                && name != self::runtime::FUNCTION_LOAD_IMMUTABLE_DATA)
     }
 
     /// Checks whether the function is related to the near call ABI.

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/function/runtime/immutable_data_load.rs

@@ -0,0 +1,116 @@
+//! The immutable data runtime function.
+
+use crate::polkavm::context::address_space::AddressSpace;
+use crate::polkavm::context::function::runtime;
+use crate::polkavm::context::pointer::Pointer;
+use crate::polkavm::context::Context;
+use crate::polkavm::WriteLLVM;
+use crate::polkavm::{runtime_api, Dependency};
+
+/// A function for requesting the immutable data from the runtime.
+/// This is a special function that is only used by the front-end generated code.
+///
+/// The runtime API is called lazily and subsequent calls are no-ops.
+///
+/// The bytes written is asserted to match the expected length.
+/// This should never fail; the length is known.
+/// However, this is a one time assertion, hence worth it.
+#[derive(Debug)]
+pub struct ImmutableDataLoad;
+
+impl<D> WriteLLVM<D> for ImmutableDataLoad
+where
+    D: Dependency + Clone,
+{
+    fn declare(&mut self, context: &mut Context<D>) -> anyhow::Result<()> {
+        context.add_function(
+            runtime::FUNCTION_LOAD_IMMUTABLE_DATA,
+            context.void_type().fn_type(Default::default(), false),
+            0,
+            Some(inkwell::module::Linkage::Private),
+        )?;
+
+        Ok(())
+    }
+
+    fn into_llvm(self, context: &mut Context<D>) -> anyhow::Result<()> {
+        context.set_current_function(runtime::FUNCTION_LOAD_IMMUTABLE_DATA)?;
+        context.set_basic_block(context.current_function().borrow().entry_block());
+
+        let immutable_data_size_pointer = context
+            .get_global(revive_runtime_api::immutable_data::GLOBAL_IMMUTABLE_DATA_SIZE)?
+            .value
+            .as_pointer_value();
+        let immutable_data_size = context.build_load(
+            Pointer::new(
+                context.xlen_type(),
+                AddressSpace::Stack,
+                immutable_data_size_pointer,
+            ),
+            "immutable_data_size_load",
+        )?;
+
+        let load_immutable_data_block = context.append_basic_block("load_immutables_block");
+        let return_block = context.current_function().borrow().return_block();
+        let immutable_data_size_is_zero = context.builder().build_int_compare(
+            inkwell::IntPredicate::EQ,
+            context.xlen_type().const_zero(),
+            immutable_data_size.into_int_value(),
+            "immutable_data_size_is_zero",
+        )?;
+        context.build_conditional_branch(
+            immutable_data_size_is_zero,
+            return_block,
+            load_immutable_data_block,
+        )?;
+
+        context.set_basic_block(load_immutable_data_block);
+        let output_pointer = context
+            .get_global(revive_runtime_api::immutable_data::GLOBAL_IMMUTABLE_DATA_POINTER)?
+            .value
+            .as_pointer_value();
+        context.build_runtime_call(
+            runtime_api::imports::GET_IMMUTABLE_DATA,
+            &[
+                context
+                    .builder()
+                    .build_ptr_to_int(output_pointer, context.xlen_type(), "ptr_to_xlen")?
+                    .into(),
+                context
+                    .builder()
+                    .build_ptr_to_int(
+                        immutable_data_size_pointer,
+                        context.xlen_type(),
+                        "ptr_to_xlen",
+                    )?
+                    .into(),
+            ],
+        );
+        let bytes_written = context.builder().build_load(
+            context.xlen_type(),
+            immutable_data_size_pointer,
+            "bytes_written",
+        )?;
+        context.builder().build_store(
+            immutable_data_size_pointer,
+            context.xlen_type().const_zero(),
+        )?;
+        let overflow_block = context.append_basic_block("immutable_data_overflow");
+        let is_overflow = context.builder().build_int_compare(
+            inkwell::IntPredicate::UGT,
+            immutable_data_size.into_int_value(),
+            bytes_written.into_int_value(),
+            "is_overflow",
+        )?;
+        context.build_conditional_branch(is_overflow, overflow_block, return_block)?;
+
+        context.set_basic_block(overflow_block);
+        context.build_call(context.intrinsics().trap, &[], "invalid_trap");
+        context.build_unreachable();
+
+        context.set_basic_block(return_block);
+        context.build_return(None);
+
+        Ok(())
+    }
+}

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

@@ -2,6 +2,7 @@
 
 pub mod deploy_code;
 pub mod entry;
+pub mod immutable_data_load;
 pub mod runtime_code;
 
 /// The main entry function name.
@@ -12,3 +13,6 @@ pub const FUNCTION_DEPLOY_CODE: &str = "__deploy";
 
 /// The runtime code function name.
 pub const FUNCTION_RUNTIME_CODE: &str = "__runtime";
+
+/// The immutable data load function name.
+pub const FUNCTION_LOAD_IMMUTABLE_DATA: &str = "__immutable_data_load";

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
     }