Implement delegate_call (#80)

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

@@ -13,7 +13,7 @@ const REENTRANT_CALL_FLAG: u32 = 0b0000_1000;
 #[allow(clippy::too_many_arguments)]
 pub fn call<'ctx, D>(
     context: &mut Context<'ctx, D>,
-    _gas: inkwell::values::IntValue<'ctx>,
+    gas: inkwell::values::IntValue<'ctx>,
     address: inkwell::values::IntValue<'ctx>,
     value: Option<inkwell::values::IntValue<'ctx>>,
     input_offset: inkwell::values::IntValue<'ctx>,
@@ -40,7 +40,7 @@ where
     // TODO: What to supply here? Is there a weight to gas?
     let _gas = context
         .builder()
-        .build_int_truncate(_gas, context.integer_type(64), "gas")?;
+        .build_int_truncate(gas, context.integer_type(64), "gas")?;
 
     let input_pointer = context.build_heap_gep(input_offset, input_length)?;
     let output_pointer = context.build_heap_gep(output_offset, output_length)?;
@@ -102,20 +102,80 @@ where
 
 #[allow(clippy::too_many_arguments)]
 pub fn delegate_call<'ctx, D>(
-    _context: &mut Context<'ctx, D>,
-    _gas: inkwell::values::IntValue<'ctx>,
-    _address: inkwell::values::IntValue<'ctx>,
-    _value: Option<inkwell::values::IntValue<'ctx>>,
-    _input_offset: inkwell::values::IntValue<'ctx>,
-    _input_length: inkwell::values::IntValue<'ctx>,
-    _output_offset: inkwell::values::IntValue<'ctx>,
-    _output_length: inkwell::values::IntValue<'ctx>,
+    context: &mut Context<'ctx, D>,
+    gas: inkwell::values::IntValue<'ctx>,
+    address: inkwell::values::IntValue<'ctx>,
+    input_offset: inkwell::values::IntValue<'ctx>,
+    input_length: inkwell::values::IntValue<'ctx>,
+    output_offset: inkwell::values::IntValue<'ctx>,
+    output_length: inkwell::values::IntValue<'ctx>,
     _constants: Vec<Option<num::BigUint>>,
 ) -> anyhow::Result<inkwell::values::BasicValueEnum<'ctx>>
 where
     D: Dependency + Clone,
 {
-    todo!()
+    let address_pointer = context.build_address_argument_store(address)?;
+
+    let input_offset = context.safe_truncate_int_to_xlen(input_offset)?;
+    let input_length = context.safe_truncate_int_to_xlen(input_length)?;
+    let output_offset = context.safe_truncate_int_to_xlen(output_offset)?;
+    let output_length = context.safe_truncate_int_to_xlen(output_length)?;
+
+    // TODO: What to supply here? Is there a weight to gas?
+    let _gas = context
+        .builder()
+        .build_int_truncate(gas, context.integer_type(64), "gas")?;
+
+    let input_pointer = context.build_heap_gep(input_offset, input_length)?;
+    let output_pointer = context.build_heap_gep(output_offset, output_length)?;
+
+    let output_length_pointer = context.build_alloca_at_entry(context.xlen_type(), "output_length");
+    context.build_store(output_length_pointer, output_length)?;
+
+    let flags = context.xlen_type().const_int(0u64, false);
+
+    let argument_type = revive_runtime_api::calling_convention::delegate_call(context.llvm());
+    let argument_pointer = context.build_alloca_at_entry(argument_type, "delegate_call_arguments");
+    let arguments = &[
+        flags.as_basic_value_enum(),
+        address_pointer.value.as_basic_value_enum(),
+        context.integer_const(64, 0).as_basic_value_enum(),
+        context.integer_const(64, 0).as_basic_value_enum(),
+        context.sentinel_pointer().value.as_basic_value_enum(),
+        input_pointer.value.as_basic_value_enum(),
+        input_length.as_basic_value_enum(),
+        output_pointer.value.as_basic_value_enum(),
+        output_length_pointer.value.as_basic_value_enum(),
+    ];
+    revive_runtime_api::calling_convention::spill(
+        context.builder(),
+        argument_pointer.value,
+        argument_type,
+        arguments,
+    )?;
+
+    let name = revive_runtime_api::polkavm_imports::DELEGATE_CALL;
+    let argument_pointer = context.builder().build_ptr_to_int(
+        argument_pointer.value,
+        context.xlen_type(),
+        "delegate_call_argument_pointer",
+    )?;
+    let success = context
+        .build_runtime_call(name, &[argument_pointer.into()])
+        .unwrap_or_else(|| panic!("{name} should return a value"))
+        .into_int_value();
+
+    let is_success = context.builder().build_int_compare(
+        inkwell::IntPredicate::EQ,
+        success,
+        context.xlen_type().const_zero(),
+        "is_success",
+    )?;
+
+    Ok(context
+        .builder()
+        .build_int_z_extend(is_success, context.word_type(), "success")?
+        .as_basic_value_enum())
 }
 
 /// Translates the Yul `linkersymbol` instruction.