hyperledger-solang_solang/src/codegen/cfg.rs

// SPDX-License-Identifier: Apache-2.0

use super::statements::{statement, LoopScopes};
use super::{
    constant_folding, dead_storage,
    expression::expression,
    reaching_definitions, strength_reduce,
    vartable::{Vars, Vartable},
    vector_to_slice, Options,
};
use crate::codegen::subexpression_elimination::common_sub_expression_elimination;
use crate::codegen::{undefined_variable, Expression, LLVMName};
use crate::sema::ast::{
    CallTy, Contract, FunctionAttributes, Namespace, Parameter, RetrieveType, Statement,
    StringLocation, StructType, Type,
};
use crate::sema::{contracts::collect_base_args, diagnostics::Diagnostics, Recurse};
use crate::{sema::ast, Target};
use indexmap::IndexMap;
use num_bigint::BigInt;
use num_traits::One;
use parse_display::Display;
use solang_parser::pt::CodeLocation;
use solang_parser::pt::Loc;
use solang_parser::pt::{self, FunctionTy};
use std::collections::{BTreeMap, BTreeSet, HashMap, HashSet};
use std::ops::AddAssign;
use std::str;
use std::sync::Arc;
use std::{fmt, fmt::Write};

// IndexMap <ArrayVariable res , res of temp variable>
pub type ArrayLengthVars = IndexMap<usize, usize>;

#[derive(Debug, Clone)]
#[allow(clippy::large_enum_variant)]
pub enum Instr {
    /// Set variable
    Set {
        loc: pt::Loc,
        res: usize,
        expr: Expression,
    },
    /// Call internal function, either static dispatch or dynamic dispatch
    Call {
        res: Vec<usize>,
        return_tys: Vec<Type>,
        call: InternalCallTy,
        args: Vec<Expression>,
    },
    /// Return
    Return { value: Vec<Expression> },
    /// Jump unconditionally
    Branch { block: usize },
    /// Jump conditionally
    BranchCond {
        cond: Expression,
        true_block: usize,
        false_block: usize,
    },
    /// Set array element in memory
    Store { dest: Expression, data: Expression },
    /// Abort execution
    AssertFailure { encoded_args: Option<Expression> },
    /// Print to log message
    Print { expr: Expression },
    /// Load storage (this is an instruction rather than an expression
    /// so that it can be moved around by the dead storage pass
    LoadStorage {
        res: usize,
        ty: Type,
        storage: Expression,
    },
    /// Clear storage at slot for ty (might span multiple slots)
    ClearStorage { ty: Type, storage: Expression },
    /// Set storage value at slot
    SetStorage {
        ty: Type,
        value: Expression,
        storage: Expression,
    },
    /// In storage slot, set the value at the offset
    SetStorageBytes {
        value: Expression,
        storage: Expression,
        offset: Expression,
    },
    /// Push an element onto an array in storage
    PushStorage {
        res: usize,
        ty: Type,
        value: Option<Expression>,
        storage: Expression,
    },
    /// Pop an element from an array in storage
    PopStorage {
        res: Option<usize>,
        ty: Type,
        storage: Expression,
    },
    /// Push element on memory array
    PushMemory {
        res: usize,
        ty: Type,
        array: usize,
        value: Box<Expression>,
    },
    /// Pop element from memory array. The push builtin returns a reference
    /// to the new element which is stored in res.
    PopMemory {
        res: usize,
        ty: Type,
        array: usize,
        loc: Loc,
    },
    /// Create contract and call constructor. If creating the contract fails,
    /// either store the result in success or abort success.
    Constructor {
        success: Option<usize>,
        res: usize,
        contract_no: usize,
        constructor_no: Option<usize>,
        encoded_args: Expression,
        value: Option<Expression>,
        gas: Expression,
        salt: Option<Expression>,
        address: Option<Expression>,
        seeds: Option<Expression>,
        accounts: Option<Expression>,
        loc: Loc,
    },
    /// Call external functions. If the call fails, set the success failure
    /// or abort if this is None
    ExternalCall {
        loc: Loc,
        success: Option<usize>,
        address: Option<Expression>,
        accounts: Option<Expression>,
        seeds: Option<Expression>,
        payload: Expression,
        value: Expression,
        gas: Expression,
        callty: CallTy,
        contract_function_no: Option<(usize, usize)>,
        flags: Option<Expression>,
    },
    /// Value transfer; either address.send() or address.transfer()
    ValueTransfer {
        success: Option<usize>,
        address: Expression,
        value: Expression,
    },
    /// Self destruct
    SelfDestruct { recipient: Expression },
    /// Emit event
    EmitEvent {
        event_no: usize,
        data: Expression,
        topics: Vec<Expression>,
    },
    /// Write Buffer
    WriteBuffer {
        buf: Expression,
        offset: Expression,
        value: Expression,
    },
    /// Copy bytes from source address to destination address
    MemCopy {
        source: Expression,
        destination: Expression,
        bytes: Expression,
    },
    Switch {
        cond: Expression,
        cases: Vec<(Expression, usize)>,
        default: usize,
    },
    /// Do nothing
    Nop,
    /// Return AbiEncoded data via an environment system call
    ReturnData {
        data: Expression,
        data_len: Expression,
    },
    /// Return a code at the end of a function
    ReturnCode { code: ReturnCode },
    /// For unimplemented code, e.g. unsupported yul builtins. This instruction should
    /// only occur for the evm target, for which no emit is implemented yet. Once evm emit
    /// is implemented and all yul builtins are supported, this instruction should
    /// be removed. We only have this so we can pass evm code through sema/codegen, which is used
    /// by the language server and the ethereum solidity tests.
    Unimplemented { reachable: bool },
    /// This instruction serves to track account accesses through 'tx.accounts.my_account'
    /// on Solana, and has no emit implementation. It is exchanged by the proper
    /// Expression::Subscript at solana_accounts/account_management.rs
    AccountAccess {
        loc: pt::Loc,
        var_no: usize,
        name: String,
    },
}

/// This struct defined the return codes that we send to the execution environment when we return
/// from a function.
#[derive(PartialEq, Eq, Hash, Clone, Debug, Display)]
#[display(style = "title case")]
pub enum ReturnCode {
    Success,
    FunctionSelectorInvalid,
    AbiEncodingInvalid,
    InvalidDataError,
    AccountDataTooSmall,
    InvalidProgramId,
}

impl Instr {
    pub fn recurse_expressions<T>(
        &self,
        cx: &mut T,
        f: fn(expr: &Expression, ctx: &mut T) -> bool,
    ) {
        match self {
            Instr::BranchCond { cond: expr, .. }
            | Instr::LoadStorage { storage: expr, .. }
            | Instr::ClearStorage { storage: expr, .. }
            | Instr::Print { expr }
            | Instr::AssertFailure {
                encoded_args: Some(expr),
            }
            | Instr::PopStorage { storage: expr, .. }
            | Instr::SelfDestruct { recipient: expr }
            | Instr::Set { expr, .. } => {
                expr.recurse(cx, f);
            }

            Instr::PushMemory { value: expr, .. } => {
                expr.recurse(cx, f);
            }

            Instr::SetStorage {
                value: item_1,
                storage: item_2,
                ..
            }
            | Instr::Store {
                dest: item_1,
                data: item_2,
            }
            | Instr::ReturnData {
                data: item_1,
                data_len: item_2,
            } => {
                item_1.recurse(cx, f);
                item_2.recurse(cx, f);
            }
            Instr::PushStorage { value, storage, .. } => {
                if let Some(value) = value {
                    value.recurse(cx, f);
                }
                storage.recurse(cx, f);
            }

            Instr::SetStorageBytes {
                value,
                storage,
                offset,
            } => {
                value.recurse(cx, f);
                storage.recurse(cx, f);
                offset.recurse(cx, f);
            }

            Instr::Return { value: exprs } | Instr::Call { args: exprs, .. } => {
                for expr in exprs {
                    expr.recurse(cx, f);
                }
            }

            Instr::Constructor {
                encoded_args,
                value,
                gas,
                salt,
                address,
                accounts,
                ..
            } => {
                encoded_args.recurse(cx, f);
                if let Some(expr) = value {
                    expr.recurse(cx, f);
                }
                gas.recurse(cx, f);

                if let Some(expr) = salt {
                    expr.recurse(cx, f);
                }

                if let Some(expr) = address {
                    expr.recurse(cx, f);
                }

                if let Some(expr) = accounts {
                    expr.recurse(cx, f);
                }
            }

            Instr::ExternalCall {
                address,
                payload,
                value,
                gas,
                ..
            } => {
                if let Some(expr) = address {
                    expr.recurse(cx, f);
                }
                payload.recurse(cx, f);
                value.recurse(cx, f);
                gas.recurse(cx, f);
            }

            Instr::ValueTransfer { address, value, .. } => {
                address.recurse(cx, f);
                value.recurse(cx, f);
            }

            Instr::EmitEvent { data, topics, .. } => {
                data.recurse(cx, f);
                for expr in topics {
                    expr.recurse(cx, f);
                }
            }

            Instr::WriteBuffer { offset, value, .. } => {
                value.recurse(cx, f);
                offset.recurse(cx, f);
            }

            Instr::MemCopy {
                source: from,
                destination: to,
                bytes,
            } => {
                from.recurse(cx, f);
                to.recurse(cx, f);
                bytes.recurse(cx, f);
            }

            Instr::Switch { cond, cases, .. } => {
                cond.recurse(cx, f);
                for (case, _) in cases {
                    case.recurse(cx, f);
                }
            }

            Instr::AssertFailure { encoded_args: None }
            | Instr::Nop
            | Instr::ReturnCode { .. }
            | Instr::Branch { .. }
            | Instr::AccountAccess { .. }
            | Instr::PopMemory { .. }
            | Instr::Unimplemented { .. } => {}
        }
    }
}

#[derive(Clone, Debug)]
#[allow(clippy::large_enum_variant)]
pub enum InternalCallTy {
    Static { cfg_no: usize },
    Dynamic(Expression),
    Builtin { ast_func_no: usize },
}

#[derive(Clone, PartialEq, Eq)]
pub enum HashTy {
    Keccak256,
    Ripemd160,
    Sha256,
    Blake2_256,
    Blake2_128,
}

impl fmt::Display for HashTy {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        match self {
            HashTy::Keccak256 => write!(f, "keccak256"),
            HashTy::Ripemd160 => write!(f, "ripemd160"),
            HashTy::Sha256 => write!(f, "sha256"),
            HashTy::Blake2_128 => write!(f, "blake2_128"),
            HashTy::Blake2_256 => write!(f, "blake2_256"),
        }
    }
}

#[derive(Debug, Clone, Default)]
pub struct BasicBlock {
    pub phis: Option<BTreeSet<usize>>,
    pub name: String,
    pub instr: Vec<Instr>,
    pub defs: reaching_definitions::VarDefs,
    pub loop_reaching_variables: HashSet<usize>,
    pub transfers: Vec<Vec<reaching_definitions::Transfer>>,
}

#[derive(Debug, Clone)]
pub struct ControlFlowGraph {
    pub name: String,
    pub function_no: ASTFunction,
    pub params: Arc<Vec<Parameter>>,
    pub returns: Arc<Vec<Parameter>>,
    pub vars: Vars,
    pub blocks: Vec<BasicBlock>,
    pub nonpayable: bool,
    pub public: bool,
    pub ty: pt::FunctionTy,
    pub selector: Vec<u8>,
    current: usize,
    // A mapping between the res of an array and the res of the temp var holding its length.
    pub array_lengths_temps: ArrayLengthVars,
    /// Is this a modifier dispatch for which function number?
    pub modifier: Option<usize>,
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum ASTFunction {
    SolidityFunction(usize),
    YulFunction(usize),
    None,
}

impl BasicBlock {
    /// Fetch the blocks that can be executed after the block passed as argument
    pub fn successors(&self) -> Vec<usize> {
        let mut out = Vec::new();

        // out cfg has edge as the last instruction in a block
        for (i, instr) in self.instr.iter().rev().enumerate() {
            match instr {
                Instr::Branch { block } => {
                    assert_eq!(i, 0, "Branch is not last instruction in block");
                    out.push(*block);
                }
                Instr::BranchCond {
                    true_block,
                    false_block,
                    ..
                } => {
                    assert_eq!(i, 0, "BranchCond is not last instruction in block");
                    out.push(*true_block);
                    out.push(*false_block);
                }
                Instr::Switch { default, cases, .. } => {
                    assert_eq!(i, 0, "Switch is not last instruction in block");
                    out.push(*default);
                    for (_, goto) in cases {
                        out.push(*goto);
                    }
                }
                Instr::AssertFailure { .. }
                | Instr::SelfDestruct { .. }
                | Instr::ReturnCode { .. }
                | Instr::ReturnData { .. }
                | Instr::Return { .. }
                | Instr::Unimplemented { reachable: false } => {
                    assert_eq!(i, 0, "instruction should be last in block");
                }

                _ => {
                    assert_ne!(i, 0, "instruction should not be last in block");
                }
            }
        }

        out
    }
}

impl ControlFlowGraph {
    pub fn new(name: String, function_no: ASTFunction) -> Self {
        let mut cfg = ControlFlowGraph {
            name,
            function_no,
            params: Arc::new(Vec::new()),
            returns: Arc::new(Vec::new()),
            vars: IndexMap::new(),
            blocks: Vec::new(),
            nonpayable: false,
            public: false,
            ty: pt::FunctionTy::Function,
            selector: Vec::new(),
            current: 0,
            array_lengths_temps: IndexMap::new(),
            modifier: None,
        };

        cfg.new_basic_block("entry".to_string());

        cfg
    }

    /// Create an empty CFG which will be replaced later
    pub fn placeholder() -> Self {
        ControlFlowGraph {
            name: String::new(),
            function_no: ASTFunction::None,
            params: Arc::new(Vec::new()),
            returns: Arc::new(Vec::new()),
            vars: IndexMap::new(),
            blocks: Vec::new(),
            nonpayable: false,
            public: false,
            ty: pt::FunctionTy::Function,
            selector: Vec::new(),
            current: 0,
            array_lengths_temps: IndexMap::new(),
            modifier: None,
        }
    }

    /// Is this a placeholder
    pub fn is_placeholder(&self) -> bool {
        self.blocks.is_empty()
    }

    pub fn new_basic_block(&mut self, name: String) -> usize {
        let pos = self.blocks.len();

        self.blocks.push(BasicBlock {
            name,
            instr: Vec::new(),
            phis: None,
            transfers: Vec::new(),
            defs: IndexMap::new(),
            loop_reaching_variables: HashSet::new(),
        });

        pos
    }

    pub fn set_phis(&mut self, block: usize, phis: BTreeSet<usize>) {
        if !phis.is_empty() {
            self.blocks[block].phis = Some(phis);
        }
    }

    pub fn set_basic_block(&mut self, pos: usize) {
        self.current = pos;
    }

    /// Add an instruction to the CFG
    pub fn add(&mut self, vartab: &mut Vartable, ins: Instr) {
        if let Instr::Set { res, .. } = ins {
            vartab.set_dirty(res);
        }
        self.blocks[self.current].instr.push(ins);
    }

    /// Retrieve the basic block being processed
    pub fn current_block(&self) -> usize {
        self.current
    }

    /// Function to modify array length temp by inserting an add/sub instruction in the cfg right after a push/pop instruction.
    /// The operands of the add/sub instruction are the temp variable, and +/- 1.
    pub fn modify_temp_array_length(
        &mut self,
        loc: pt::Loc,
        minus: bool,      // If the function is called from pushMemory or popMemory
        array_pos: usize, // The res of array that push/pop is performed on
        vartab: &mut Vartable,
    ) {
        // If not empty
        if self.array_lengths_temps.contains_key(&array_pos) {
            let to_add = self.array_lengths_temps[&array_pos];
            let add_expr = if minus {
                Expression::Subtract {
                    loc,
                    ty: Type::Uint(32),
                    overflowing: true,
                    left: Box::new(Expression::Variable {
                        loc,
                        ty: Type::Uint(32),
                        var_no: to_add,
                    }),
                    right: Box::new(Expression::NumberLiteral {
                        loc,
                        ty: Type::Uint(32),
                        value: BigInt::one(),
                    }),
                }
            } else {
                Expression::Add {
                    loc,
                    ty: Type::Uint(32),
                    overflowing: true,
                    left: Box::new(Expression::Variable {
                        loc,
                        ty: Type::Uint(32),
                        var_no: to_add,
                    }),
                    right: Box::new(Expression::NumberLiteral {
                        loc,
                        ty: Type::Uint(32),
                        value: BigInt::one(),
                    }),
                }
            };

            // Add instruction to the cfg
            self.add(
                vartab,
                Instr::Set {
                    loc,
                    res: to_add,
                    expr: add_expr,
                },
            );
        }
    }

    pub fn expr_to_string(&self, contract: &Contract, ns: &Namespace, expr: &Expression) -> String {
        match expr {
            Expression::FunctionArg { arg_no, .. } => format!("(arg #{arg_no})"),
            Expression::BoolLiteral { value: false, .. } => "false".to_string(),
            Expression::BoolLiteral { value: true, .. } => "true".to_string(),
            Expression::BytesLiteral {
                ty: Type::String,
                value,
                ..
            } => {
                format!("{}", String::from_utf8_lossy(value))
            }
            Expression::BytesLiteral { value, .. } => format!("hex\"{}\"", hex::encode(value)),
            Expression::NumberLiteral {
                ty: ty @ Type::Address(_),
                value,
                ..
            } => {
                format!("{} {:#x}", ty.to_string(ns), value)
            }
            Expression::NumberLiteral { ty, value, .. } => {
                format!("{} {}", ty.to_string(ns), value)
            }
            Expression::RationalNumberLiteral { ty, rational, .. } => {
                format!("{} {}", ty.to_string(ns), rational)
            }
            Expression::StructLiteral { values, .. } => format!(
                "struct {{ {} }}",
                values
                    .iter()
                    .map(|e| self.expr_to_string(contract, ns, e))
                    .collect::<Vec<String>>()
                    .join(", ")
            ),
            Expression::ConstArrayLiteral {
                dimensions, values, ..
            } => format!(
                "constant {} [ {} ]",
                dimensions
                    .iter()
                    .map(|d| format!("[{d}]"))
                    .collect::<String>(),
                values
                    .iter()
                    .map(|e| self.expr_to_string(contract, ns, e))
                    .collect::<Vec<String>>()
                    .join(", ")
            ),
            Expression::ArrayLiteral {
                dimensions, values, ..
            } => format!(
                "{} [ {} ]",
                dimensions
                    .iter()
                    .map(|d| format!("[{d}]"))
                    .collect::<String>(),
                values
                    .iter()
                    .map(|e| self.expr_to_string(contract, ns, e))
                    .collect::<Vec<String>>()
                    .join(", ")
            ),
            Expression::Add {
                overflowing,
                left,
                right,
                ..
            } => format!(
                "({}{} + {})",
                if *overflowing { "overflowing " } else { "" },
                self.expr_to_string(contract, ns, left),
                self.expr_to_string(contract, ns, right)
            ),
            Expression::Subtract {
                overflowing,
                left,
                right,
                ..
            } => format!(
                "({}{} - {})",
                if *overflowing { "overflowing " } else { "" },
                self.expr_to_string(contract, ns, left),
                self.expr_to_string(contract, ns, right)
            ),
            Expression::BitwiseOr { left, right, .. } => format!(
                "({} | {})",
                self.expr_to_string(contract, ns, left),
                self.expr_to_string(contract, ns, right)
            ),
            Expression::BitwiseAnd { left, right, .. } => format!(
                "({} & {})",
                self.expr_to_string(contract, ns, left),
                self.expr_to_string(contract, ns, right)
            ),
            Expression::BitwiseXor { left, right, .. } => format!(
                "({} ^ {})",
                self.expr_to_string(contract, ns, left),
                self.expr_to_string(contract, ns, right)
            ),
            Expression::ShiftLeft { left, right, .. } => format!(
                "({} << {})",
                self.expr_to_string(contract, ns, left),
                self.expr_to_string(contract, ns, right)
            ),
            Expression::ShiftRight { left, right, .. } => format!(
                "({} >> {})",
                self.expr_to_string(contract, ns, left),
                self.expr_to_string(contract, ns, right)
            ),
            Expression::Multiply {
                overflowing,
                left,
                right,
                ..
            } => format!(
                "({}{} * {})",
                if *overflowing { "overflowing " } else { "" },
                self.expr_to_string(contract, ns, left),
                self.expr_to_string(contract, ns, right)
            ),
            Expression::SignedDivide { left, right, .. } => format!(
                "(signed divide {} / {})",
                self.expr_to_string(contract, ns, left),
                self.expr_to_string(contract, ns, right),
            ),
            Expression::UnsignedDivide { left, right, .. } => format!(
                "(unsigned divide {} / {})",
                self.expr_to_string(contract, ns, left),
                self.expr_to_string(contract, ns, right),
            ),
            Expression::SignedModulo { left, right, .. } => format!(
                "(signed modulo {} % {})",
                self.expr_to_string(contract, ns, left),
                self.expr_to_string(contract, ns, right)
            ),
            Expression::UnsignedModulo { left, right, .. } => format!(
                "(unsigned modulo {} % {})",
                self.expr_to_string(contract, ns, left),
                self.expr_to_string(contract, ns, right)
            ),
            Expression::Power {
                overflowing,
                base,
                exp,
                ..
            } => format!(
                "({}{} ** {})",
                if *overflowing { "overflowing " } else { "" },
                self.expr_to_string(contract, ns, base),
                self.expr_to_string(contract, ns, exp)
            ),
            Expression::Variable { var_no, .. } => {
                if let Some(var) = self.vars.get(var_no) {
                    format!("%{}", var.id.name)
                } else {
                    panic!("error: non-existing variable {var_no} in CFG");
                }
            }
            Expression::Load { expr, .. } => {
                format!("(load {})", self.expr_to_string(contract, ns, expr))
            }
            Expression::ZeroExt { ty, expr, .. } => format!(
                "(zext {} {})",
                ty.to_string(ns),
                self.expr_to_string(contract, ns, expr)
            ),
            Expression::SignExt { ty, expr, .. } => format!(
                "(sext {} {})",
                ty.to_string(ns),
                self.expr_to_string(contract, ns, expr)
            ),
            Expression::Trunc { ty, expr, .. } => format!(
                "(trunc {} {})",
                ty.to_string(ns),
                self.expr_to_string(contract, ns, expr)
            ),
            Expression::More {
                signed,
                left,
                right,
                ..
            } => format!(
                "({} more {} > {})",
                if *signed { "signed" } else { "unsigned" },
                self.expr_to_string(contract, ns, left),
                self.expr_to_string(contract, ns, right)
            ),
            Expression::Less {
                signed,
                left,
                right,
                ..
            } => format!(
                "({} less {} < {})",
                if *signed { "signed" } else { "unsigned" },
                self.expr_to_string(contract, ns, left),
                self.expr_to_string(contract, ns, right)
            ),
            Expression::MoreEqual {
                signed,
                left,
                right,
                ..
            } => format!(
                "({} {} >= {})",
                if *signed { "signed" } else { "unsigned" },
                self.expr_to_string(contract, ns, left),
                self.expr_to_string(contract, ns, right)
            ),
            Expression::LessEqual {
                signed,
                left,
                right,
                ..
            } => format!(
                "({} {} <= {})",
                if *signed { "signed" } else { "unsigned" },
                self.expr_to_string(contract, ns, left),
                self.expr_to_string(contract, ns, right)
            ),
            Expression::Equal { left, right, .. } => format!(
                "({} == {})",
                self.expr_to_string(contract, ns, left),
                self.expr_to_string(contract, ns, right)
            ),
            Expression::NotEqual { left, right, .. } => format!(
                "({} != {})",
                self.expr_to_string(contract, ns, left),
                self.expr_to_string(contract, ns, right)
            ),
            Expression::Subscript {
                array_ty: ty,
                expr,
                index,
                ..
            } => format!(
                "(subscript {} {}[{}])",
                ty.to_string(ns),
                self.expr_to_string(contract, ns, expr),
                self.expr_to_string(contract, ns, index)
            ),
            Expression::StorageArrayLength { array, elem_ty, .. } => format!(
                "(storage array length {}[{}])",
                self.expr_to_string(contract, ns, array),
                elem_ty.to_string(ns),
            ),
            Expression::StructMember { expr, member, .. } => format!(
                "(struct {} field {})",
                self.expr_to_string(contract, ns, expr),
                member
            ),
            Expression::Not { expr, .. } => {
                format!("!{}", self.expr_to_string(contract, ns, expr))
            }
            Expression::BitwiseNot { expr, .. } => {
                format!("~{}", self.expr_to_string(contract, ns, expr))
            }
            Expression::Negate { expr, .. } => {
                format!("-{}", self.expr_to_string(contract, ns, expr))
            }
            Expression::Poison => "☠".to_string(),
            Expression::AllocDynamicBytes {
                ty,
                size,
                initializer: None,
                ..
            } => {
                let ty = if let Type::Slice(ty) = ty {
                    format!("slice {}", ty.to_string(ns))
                } else {
                    ty.to_string(ns)
                };

                format!(
                    "(alloc {} len {})",
                    ty,
                    self.expr_to_string(contract, ns, size)
                )
            }
            Expression::AllocDynamicBytes {
                ty,
                size,
                initializer: Some(init),
                ..
            } => {
                let ty = if let Type::Slice(ty) = ty {
                    format!("slice {}", ty.to_string(ns))
                } else {
                    ty.to_string(ns)
                };

                format!(
                    "(alloc {} {} {})",
                    ty,
                    self.expr_to_string(contract, ns, size),
                    match str::from_utf8(init) {
                        Ok(s) => format!("\"{}\"", s.escape_debug()),
                        Err(_) => format!("hex\"{}\"", hex::encode(init)),
                    }
                )
            }
            Expression::StringCompare { left, right, .. } => format!(
                "(strcmp ({}) ({}))",
                self.location_to_string(contract, ns, left),
                self.location_to_string(contract, ns, right)
            ),
            Expression::StringConcat { left, right, .. } => format!(
                "(concat ({}) ({}))",
                self.location_to_string(contract, ns, left),
                self.location_to_string(contract, ns, right)
            ),
            Expression::Keccak256 { exprs, .. } => format!(
                "(keccak256 {})",
                exprs
                    .iter()
                    .map(|e| self.expr_to_string(contract, ns, e))
                    .collect::<Vec<String>>()
                    .join(", ")
            ),
            Expression::InternalFunctionCfg { cfg_no, .. } => {
                format!("function {}", contract.cfg[*cfg_no].name)
            }
            Expression::ReturnData { .. } => "(external call return data)".to_string(),
            Expression::Cast { ty, expr, .. } => format!(
                "{}({})",
                ty.to_string(ns),
                self.expr_to_string(contract, ns, expr)
            ),
            Expression::BytesCast { ty, from, expr, .. } => format!(
                "{} from:{} ({})",
                ty.to_string(ns),
                from.to_string(ns),
                self.expr_to_string(contract, ns, expr)
            ),
            Expression::Builtin {
                kind: builtin,
                args,
                ..
            } => format!(
                "(builtin {:?} ({}))",
                builtin,
                args.iter()
                    .map(|a| self.expr_to_string(contract, ns, a))
                    .collect::<Vec<String>>()
                    .join(", ")
            ),
            Expression::FormatString { args: fields, .. } => format!(
                "(format string {})",
                fields
                    .iter()
                    .map(|(spec, a)| format!("({} {})", spec, self.expr_to_string(contract, ns, a)))
                    .collect::<Vec<String>>()
                    .join(", ")
            ),
            Expression::Undefined { .. } => "undef".to_string(),
            Expression::AdvancePointer {
                pointer,
                bytes_offset,
            } => {
                format!(
                    "(advance ptr: {}, by: {})",
                    self.expr_to_string(contract, ns, pointer),
                    self.expr_to_string(contract, ns, bytes_offset)
                )
            }
            Expression::GetRef { expr, .. } => {
                format!("(deref {}", self.expr_to_string(contract, ns, expr))
            }
            _ => panic!("{expr:?}"),
        }
    }

    fn location_to_string(
        &self,
        contract: &Contract,
        ns: &Namespace,
        l: &StringLocation<Expression>,
    ) -> String {
        match l {
            StringLocation::RunTime(e) => self.expr_to_string(contract, ns, e),
            StringLocation::CompileTime(literal) => match str::from_utf8(literal) {
                Ok(s) => format!("\"{}\"", s.to_owned()),
                Err(_) => format!("hex\"{}\"", hex::encode(literal)),
            },
        }
    }

    pub fn instr_to_string(&self, contract: &Contract, ns: &Namespace, instr: &Instr) -> String {
        match instr {
            Instr::Return { value } => format!(
                "return {}",
                value
                    .iter()
                    .map(|expr| self.expr_to_string(contract, ns, expr))
                    .collect::<Vec<String>>()
                    .join(", ")
            ),
            Instr::Set { res, expr, .. } => format!(
                "ty:{} %{} = {}",
                self.vars[res].ty.to_string(ns),
                self.vars[res].id.name,
                self.expr_to_string(contract, ns, expr)
            ),
            Instr::Branch { block } => format!("branch block{block}"),
            Instr::BranchCond {
                cond,
                true_block,
                false_block,
            } => format!(
                "branchcond {}, block{}, block{}",
                self.expr_to_string(contract, ns, cond),
                true_block,
                false_block,
            ),
            Instr::LoadStorage { ty, res, storage } => format!(
                "%{} = load storage slot({}) ty:{}",
                self.vars[res].id.name,
                self.expr_to_string(contract, ns, storage),
                ty.to_string(ns),
            ),
            Instr::ClearStorage { ty, storage } => format!(
                "clear storage slot({}) ty:{}",
                self.expr_to_string(contract, ns, storage),
                ty.to_string(ns),
            ),
            Instr::SetStorage { ty, value, storage } => format!(
                "store storage slot({}) ty:{} = {}",
                self.expr_to_string(contract, ns, storage),
                ty.to_string(ns),
                self.expr_to_string(contract, ns, value),
            ),
            Instr::SetStorageBytes {
                value,
                storage,
                offset,
            } => format!(
                "set storage slot({}) offset:{} = {}",
                self.expr_to_string(contract, ns, storage),
                self.expr_to_string(contract, ns, offset),
                self.expr_to_string(contract, ns, value),
            ),
            Instr::PushStorage {
                res,
                ty,
                storage,
                value,
            } => {
                format!(
                    "%{} = push storage ty:{} slot:{} = {}",
                    self.vars[res].id.name,
                    ty.to_string(ns),
                    self.expr_to_string(contract, ns, storage),
                    if let Some(value) = value {
                        self.expr_to_string(contract, ns, value)
                    } else {
                        String::from("empty")
                    }
                )
            }
            Instr::PopStorage {
                res: Some(res),
                ty,
                storage,
            } => {
                format!(
                    "%{} = pop storage ty:{} slot({})",
                    self.vars[res].id.name,
                    ty.to_string(ns),
                    self.expr_to_string(contract, ns, storage),
                )
            }
            Instr::PopStorage {
                res: None,
                ty,
                storage,
            } => {
                format!(
                    "pop storage ty:{} slot({})",
                    ty.to_string(ns),
                    self.expr_to_string(contract, ns, storage),
                )
            }
            Instr::PushMemory {
                res,
                ty,
                array,
                value,
            } => format!(
                "%{}, %{} = push array ty:{} value:{}",
                self.vars[res].id.name,
                self.vars[array].id.name,
                ty.to_string(ns),
                self.expr_to_string(contract, ns, value),
            ),
            Instr::PopMemory { res, ty, array, loc:_ } => format!(
                "%{}, %{} = pop array ty:{}",
                self.vars[res].id.name,
                self.vars[array].id.name,
                ty.to_string(ns),
            ),
            Instr::AssertFailure { encoded_args: None } => "assert-failure".to_string(),
            Instr::AssertFailure { encoded_args: Some(expr) } => {
                format!("assert-failure: buffer: {}",
                        self.expr_to_string(contract, ns, expr),
                )
            }
            Instr::Call {
                res,
                call: InternalCallTy::Builtin { ast_func_no },
                args,
                ..
            } => format!(
                "{} = call builtin {} {}",
                res.iter()
                    .map(|local| format!("%{}", self.vars[local].id.name))
                    .collect::<Vec<String>>()
                    .join(", "),
                ns.functions[*ast_func_no].name,
                args.iter()
                    .map(|expr| self.expr_to_string(contract, ns, expr))
                    .collect::<Vec<String>>()
                    .join(", ")
            ),
            Instr::Call {
                res,
                call: InternalCallTy::Static { cfg_no },
                args,
                ..
            } => format!(
                "{} = call {} {}",
                res.iter()
                    .map(|local| format!("%{}", self.vars[local].id.name))
                    .collect::<Vec<String>>()
                    .join(", "),
                contract.cfg[*cfg_no].name,
                args.iter()
                    .map(|expr| self.expr_to_string(contract, ns, expr))
                    .collect::<Vec<String>>()
                    .join(", ")
            ),
            Instr::Call {
                res,
                call: InternalCallTy::Dynamic(cfg),
                args,
                ..
            } => format!(
                "{} = call {} {}",
                res.iter()
                    .map(|local| format!("%{}", self.vars[local].id.name))
                    .collect::<Vec<String>>()
                    .join(", "),
                self.expr_to_string(contract, ns, cfg),
                args.iter()
                    .map(|expr| self.expr_to_string(contract, ns, expr))
                    .collect::<Vec<String>>()
                    .join(", ")
            ),
            Instr::ExternalCall {
                success,
                address,
                payload,
                value,
                accounts,
                seeds,
                gas,
                callty,
                contract_function_no,
                flags, ..
            } => {
                format!(
                    "{} = external call::{} address:{} payload:{} value:{} gas:{} accounts:{} seeds:{} contract|function:{} flags:{}",
                    match success {
                        Some(i) => format!("%{}", self.vars[i].id.name),
                        None => "_".to_string(),
                    },
                    callty,
                    if let Some(address) = address {
                        self.expr_to_string(contract, ns, address)
                    } else {
                        String::new()
                    },
                    self.expr_to_string(contract, ns, payload),
                    self.expr_to_string(contract, ns, value),
                    self.expr_to_string(contract, ns, gas),
                    if let Some(accounts) = accounts {
                        self.expr_to_string(contract, ns, accounts)
                    } else {
                        String::new()
                    },
                    if let Some(seeds) = seeds {
                        self.expr_to_string(contract, ns, seeds)
                    } else {
                        String::new()
                    },
                    if let Some((contract_no, function_no)) = contract_function_no {
                        format!("({contract_no}, {function_no})")
                    } else {
                        "_".to_string()
                    },
                    flags.as_ref().map(|e| self.expr_to_string(contract, ns, e)).unwrap_or_default()
                )
            }
            Instr::ValueTransfer {
                success,
                address,
                value,
            } => {
                format!(
                    "{} = value transfer address:{} value:{}",
                    match success {
                        Some(i) => format!("%{}", self.vars[i].id.name),
                        None => "_".to_string(),
                    },
                    self.expr_to_string(contract, ns, address),
                    self.expr_to_string(contract, ns, value),
                )
            }
            Instr::Store { dest, data } => format!(
                "store {}, {}",
                self.expr_to_string(contract, ns, dest),
                self.expr_to_string(contract, ns, data),
            ),
            Instr::Print { expr } => format!("print {}", self.expr_to_string(contract, ns, expr)),
            Instr::Constructor {
                success,
                res,
                contract_no,
                encoded_args,
                gas,
                salt,
                value,
                address,seeds,
                accounts,
                constructor_no,
                loc:_
            } => format!(
                "%{}, {} = constructor(no: {}) salt:{} value:{} gas:{} address:{} seeds:{} {} encoded buffer: {} accounts: {}",
                self.vars[res].id.name,
                match success {
                    Some(i) => format!("%{}", self.vars[i].id.name),
                    None => "_".to_string(),
                },
                if let Some(no) = constructor_no {
                    format!("{}", no)
                } else {
                    String::new()
                },
                match salt {
                    Some(salt) => self.expr_to_string(contract, ns, salt),
                    None => "".to_string(),
                },
                match value {
                    Some(value) => self.expr_to_string(contract, ns, value),
                    None => "".to_string(),
                },
                self.expr_to_string(contract, ns, gas),
                match address {
                    Some(address) => self.expr_to_string(contract, ns, address),
                    None => "".to_string(),
                },
                if let Some(seeds) = seeds {
                    self.expr_to_string(contract, ns, seeds)
                } else {
                    String::new()
                },
                ns.contracts[*contract_no].name,
                self.expr_to_string(contract, ns, encoded_args),
                if let Some(accounts) = accounts {
                    self.expr_to_string(contract, ns, accounts)
                } else {
                    String::new()
                }
            ),
            Instr::SelfDestruct { recipient } => format!(
                "selfdestruct {}",
                self.expr_to_string(contract, ns, recipient)
            ),
            Instr::WriteBuffer { buf, offset, value } => format!(
                "writebuffer buffer:{} offset:{} value:{}",
                self.expr_to_string(contract, ns, buf),
                self.expr_to_string(contract, ns, offset),
                self.expr_to_string(contract, ns, value)
            ),
            Instr::EmitEvent {
                data,
                topics,
                event_no,
                ..
            } => format!(
                "emit event {} topics {} data {} ",
                ns.events[*event_no].symbol_name(ns),
                topics
                    .iter()
                    .map(|expr| self.expr_to_string(contract, ns, expr))
                    .collect::<Vec<String>>()
                    .join(", "),
                self.expr_to_string(contract, ns, data)
            ),
            Instr::Nop => String::from("nop"),
            Instr::MemCopy {
                source: from,
                destination: to,
                bytes,
            } => {
                format!(
                    "memcpy src: {}, dest: {}, bytes_len: {}",
                    self.expr_to_string(contract, ns, from),
                    self.expr_to_string(contract, ns, to),
                    self.expr_to_string(contract, ns, bytes)
                )
            }
            Instr::Switch {
                cond,
                cases,
                default,
            } => {
                let mut description =
                    format!("switch {}:", self.expr_to_string(contract, ns, cond),);
                for item in cases {
                    description.push_str(
                        format!(
                            "\n\t\tcase {}: goto block #{}",
                            self.expr_to_string(contract, ns, &item.0),
                            item.1
                        )
                        .as_str(),
                    );
                }
                description.push_str(format!("\n\t\tdefault: goto block #{default}").as_str());
                description
            }

            Instr::ReturnData { data, data_len } => {
                format!(
                    "return data {}, data length: {}",
                    self.expr_to_string(contract, ns, data),
                    self.expr_to_string(contract, ns, data_len)
                )
            }

            Instr::ReturnCode { code } => {
                format!("return code: {code}")
            }

            Instr::Unimplemented { .. } => {
                "unimplemented".into()
            }

            Instr::AccountAccess { .. } => {
                unreachable!("Instr::AccountAccess shall never be in the final CFG")
            }
        }
    }

    pub fn basic_block_to_string(&self, contract: &Contract, ns: &Namespace, pos: usize) -> String {
        let mut s = format!("block{}: # {}\n", pos, self.blocks[pos].name);

        if let Some(ref phis) = self.blocks[pos].phis {
            writeln!(
                s,
                "\t# phis: {}",
                phis.iter()
                    .map(|p| -> &str { &self.vars[p].id.name })
                    .collect::<Vec<&str>>()
                    .join(",")
            )
            .unwrap();
        }

        let defs = &self.blocks[pos].defs;

        if !defs.is_empty() {
            writeln!(
                s,
                "\t# reaching:{}",
                defs.iter()
                    .map(|(var_no, defs)| format!(
                        " {}:[{}]",
                        &self.vars[var_no].id.name,
                        defs.keys()
                            .map(|d| format!("{}:{}", d.block_no, d.instr_no))
                            .collect::<Vec<String>>()
                            .join(", ")
                    ))
                    .collect::<Vec<String>>()
                    .join(", ")
            )
            .unwrap();
        }

        for ins in &self.blocks[pos].instr {
            writeln!(s, "\t{}", self.instr_to_string(contract, ns, ins)).unwrap();
        }

        s
    }

    pub fn to_string(&self, contract: &Contract, ns: &Namespace) -> String {
        let mut s = String::from("");

        for i in 0..self.blocks.len() {
            s.push_str(&self.basic_block_to_string(contract, ns, i));
        }

        s
    }
}

/// Checks whether there is a virtual fallback or receive function
fn is_there_virtual_function(
    ns: &Namespace,
    contract_no: usize,
    function_no: Option<usize>,
) -> bool {
    let default_constructor = &ns.default_constructor(contract_no);

    let func = match function_no {
        Some(function_no) => &ns.functions[function_no],
        None => default_constructor,
    };

    // if the function is a fallback or receive, then don't bother with the overriden functions; they cannot be used
    if func.ty == pt::FunctionTy::Receive {
        // if there is a virtual receive function, and it's not this one, ignore it
        if let Some(receive) = ns.contracts[contract_no].virtual_functions.get("@receive") {
            if Some(*receive) != function_no {
                return true;
            }
        }
    }

    if func.ty == pt::FunctionTy::Fallback {
        // if there is a virtual fallback function, and it's not this one, ignore it
        if let Some(fallback) = ns.contracts[contract_no].virtual_functions.get("@fallback") {
            if Some(*fallback) != function_no {
                return true;
            }
        }
    }

    if func.ty == pt::FunctionTy::Modifier || !func.has_body {
        return true;
    }

    false
}

/// Generate the CFG for a function. If function_no is None, generate the implicit default
/// constructor
pub fn generate_cfg(
    contract_no: usize,
    function_no: Option<usize>,
    cfg_no: usize,
    all_cfgs: &mut Vec<ControlFlowGraph>,
    ns: &mut Namespace,
    opt: &Options,
) {
    if is_there_virtual_function(ns, contract_no, function_no) {
        return;
    }

    let mut cfg = function_cfg(contract_no, function_no, ns, opt);
    let ast_fn = function_no
        .map(ASTFunction::SolidityFunction)
        .unwrap_or(ASTFunction::None);
    optimize_and_check_cfg(&mut cfg, ns, ast_fn, opt);

    if let Some(func_no) = function_no {
        let func = &ns.functions[func_no];
        // if the function has any modifiers, generate the modifier chain
        if !func.modifiers.is_empty() {
            // only function can have modifiers
            assert_eq!(func.ty, pt::FunctionTy::Function);
            let public = cfg.public;
            let nonpayable = cfg.nonpayable;

            cfg.public = false;

            for chain_no in (0..func.modifiers.len()).rev() {
                let modifier_cfg_no = all_cfgs.len();

                all_cfgs.push(cfg);

                cfg = generate_modifier_dispatch(
                    contract_no,
                    func_no,
                    modifier_cfg_no,
                    chain_no,
                    ns,
                    opt,
                );
                optimize_and_check_cfg(&mut cfg, ns, ast_fn, opt);
            }

            cfg.public = public;
            cfg.nonpayable = nonpayable;
            cfg.selector = ns.functions[func_no].selector(ns, &contract_no);
            cfg.modifier = Some(func_no);
        }
    }

    all_cfgs[cfg_no] = cfg;
}

/// resolve modifier call
fn resolve_modifier_call<'a>(
    call: &'a ast::Expression,
    contract: &Contract,
) -> (usize, &'a Vec<ast::Expression>) {
    if let ast::Expression::InternalFunctionCall { function, args, .. } = call {
        if let ast::Expression::InternalFunction {
            function_no,
            signature,
            ..
        } = function.as_ref()
        {
            // is it a virtual function call
            let function_no = if let Some(signature) = signature {
                contract.virtual_functions[signature]
            } else {
                *function_no
            };

            return (function_no, args);
        }
    }

    panic!("modifier should resolve to internal call");
}

/// Detect undefined variables and run codegen optimizer passess
pub fn optimize_and_check_cfg(
    cfg: &mut ControlFlowGraph,
    ns: &mut Namespace,
    func_no: ASTFunction,
    opt: &Options,
) {
    reaching_definitions::find(cfg);
    if func_no != ASTFunction::None {
        // If there are undefined variables, we raise an error and don't run optimizations
        if undefined_variable::find_undefined_variables(cfg, ns, func_no) {
            return;
        }
    }

    // constant folding generates diagnostics, so always run it. This means that the diagnostics
    // do not depend which passes are enabled. If the constant_folding is not enabled, run it
    // dry mode.
    constant_folding::constant_folding(cfg, !opt.constant_folding, ns);
    if opt.vector_to_slice {
        vector_to_slice::vector_to_slice(cfg, ns);
    }
    if opt.strength_reduce {
        strength_reduce::strength_reduce(cfg, ns);
    }
    if opt.dead_storage {
        dead_storage::dead_storage(cfg, ns);
    }

    // If the function is a default constructor, there is nothing to optimize.
    if opt.common_subexpression_elimination && func_no != ASTFunction::None {
        common_sub_expression_elimination(cfg, ns);
    }
}

/// Generate the CFG for a function. If function_no is None, generate the implicit default
/// constructor
fn function_cfg(
    contract_no: usize,
    function_no: Option<usize>,
    ns: &mut Namespace,
    opt: &Options,
) -> ControlFlowGraph {
    let mut vartab = match function_no {
        Some(function_no) => {
            Vartable::from_symbol_table(&ns.functions[function_no].symtable, ns.next_id)
        }
        None => Vartable::new(ns.next_id),
    };

    let mut loops = LoopScopes::new();
    let default_constructor = &ns.default_constructor(contract_no);

    let func = match function_no {
        Some(function_no) => &ns.functions[function_no],
        None => default_constructor,
    };

    // symbol name
    let contract_name = match func.contract_no {
        Some(base_contract_no) => format!(
            "{}::{}",
            ns.contracts[contract_no].name, ns.contracts[base_contract_no].name
        ),
        None => ns.contracts[contract_no].name.to_string(),
    };

    let name = match func.ty {
        pt::FunctionTy::Function => {
            format!("{}::function::{}", contract_name, func.llvm_symbol(ns))
        }
        // There can be multiple constructors on Polkadot, give them an unique name
        pt::FunctionTy::Constructor => {
            format!(
                "{}::constructor::{}",
                contract_name,
                hex::encode(func.selector(ns, &contract_no))
            )
        }
        _ => format!("{}::{}", contract_name, func.ty),
    };

    let mut cfg = ControlFlowGraph::new(
        name,
        if let Some(num) = function_no {
            ASTFunction::SolidityFunction(num)
        } else {
            ASTFunction::None
        },
    );

    cfg.params = func.params.clone();
    cfg.returns = func.returns.clone();
    cfg.selector = func.selector(ns, &contract_no);

    cfg.public = ns.function_externally_callable(contract_no, function_no);
    cfg.ty = func.ty;
    cfg.nonpayable = !func.is_payable();

    // populate the argument variables
    populate_arguments(func, &mut cfg, &mut vartab);

    // Hold your breath, this is the trickest part of the codegen ahead.
    // For each contract, the top-level constructor calls the base constructors. The base
    // constructors do not call their base constructors; everything is called from the top
    // level constructor. This is done because the arguments to base constructor are only
    // known the top level constructor, since the arguments can be specified elsewhere
    // on a constructor for a superior class
    if func.ty == pt::FunctionTy::Constructor && func.contract_no == Some(contract_no) {
        let mut all_base_args = BTreeMap::new();
        let mut diagnostics = Diagnostics::default();

        // Find all the resolved arguments for base contracts. These can be attached
        // to the contract, or the constructor. Contracts can have multiple constructors
        // so this needs to follow the correct constructors all the way
        collect_base_args(
            contract_no,
            function_no,
            &mut all_base_args,
            &mut diagnostics,
            ns,
        );

        // We shouldn't have problems. sema should have checked this
        assert!(diagnostics.is_empty());

        let order = ns.contract_bases(contract_no);
        let mut gen_base_args: HashMap<usize, (usize, Vec<Expression>)> = HashMap::new();

        for base_no in order.iter().rev() {
            if *base_no == contract_no {
                // we can't evaluate arguments to ourselves.
                continue;
            }

            if let Some(base_args) = all_base_args.get(base_no) {
                // There might be some temporary variables needed from the symbol table where
                // the constructor arguments were defined
                if let Some(defined_constructor_no) = base_args.defined_constructor_no {
                    let func = &ns.functions[defined_constructor_no];
                    vartab.add_symbol_table(&func.symtable);
                }

                // So we are evaluating the base arguments, from superior to inferior. The results
                // must be stored somewhere, for two reasons:
                // - The results must be stored by-value, so that variable value don't change
                //   by later base arguments (e.g. x++)
                // - The results are also arguments to the next constructor arguments, so they
                //   might be used again. Therefore we store the result in the vartable entry
                //   for the argument; this means values are passed automatically to the next
                //   constructor. We do need the symbol table for the called constructor, therefore
                //   we have the following two lines which look a bit odd at first
                let func = &ns.functions[base_args.calling_constructor_no];
                vartab.add_symbol_table(&func.symtable);

                let args: Vec<Expression> = base_args
                    .args
                    .iter()
                    .enumerate()
                    .map(|(i, a)| {
                        let expr =
                            expression(a, &mut cfg, contract_no, Some(func), ns, &mut vartab, opt);

                        if let Some(id) = &func.symtable.arguments[i] {
                            let ty = expr.ty();
                            let loc = expr.loc();

                            cfg.add(
                                &mut vartab,
                                Instr::Set {
                                    loc: func.params[i].loc,
                                    res: *id,
                                    expr,
                                },
                            );
                            Expression::Variable {
                                loc,
                                ty,
                                var_no: *id,
                            }
                        } else {
                            Expression::Poison
                        }
                    })
                    .collect();

                gen_base_args.insert(*base_no, (base_args.calling_constructor_no, args));
            }
        }

        for base_no in order.iter() {
            if *base_no == contract_no {
                // we can't evaluate arguments to ourselves.
                continue;
            }

            if let Some((constructor_no, args)) = gen_base_args.remove(base_no) {
                let cfg_no = ns.contracts[contract_no].all_functions[&constructor_no];

                cfg.add(
                    &mut vartab,
                    Instr::Call {
                        res: Vec::new(),
                        return_tys: Vec::new(),
                        call: InternalCallTy::Static { cfg_no },
                        args,
                    },
                );
            } else if let Some(constructor_no) = ns.contracts[*base_no].no_args_constructor(ns) {
                let cfg_no = ns.contracts[contract_no].all_functions[&constructor_no];

                cfg.add(
                    &mut vartab,
                    Instr::Call {
                        res: Vec::new(),
                        return_tys: Vec::new(),
                        call: InternalCallTy::Static { cfg_no },
                        args: Vec::new(),
                    },
                );
            }
        }
    }

    // named returns should be populated
    populate_named_returns(func, ns, &mut cfg, &mut vartab);

    for stmt in &func.body {
        statement(
            stmt,
            func,
            &mut cfg,
            contract_no,
            ns,
            &mut vartab,
            &mut loops,
            None,
            None,
            opt,
        );
    }

    if func.body.last().map(Statement::reachable).unwrap_or(true) {
        let loc = match func.body.last() {
            Some(ins) => ins.loc(),
            None => pt::Loc::Codegen,
        };
        // add implicit return
        cfg.add(
            &mut vartab,
            Instr::Return {
                value: func
                    .symtable
                    .returns
                    .iter()
                    .map(|pos| Expression::Variable {
                        loc,
                        ty: func.symtable.vars[pos].ty.clone(),
                        var_no: *pos,
                    })
                    .collect::<Vec<_>>(),
            },
        );
    }

    vartab.finalize(ns, &mut cfg);

    // walk cfg to check for use for before initialize
    cfg
}

/// Populate the arguments of a function
pub(crate) fn populate_arguments<T: FunctionAttributes>(
    func: &T,
    cfg: &mut ControlFlowGraph,
    vartab: &mut Vartable,
) {
    for (i, arg) in func.get_symbol_table().arguments.iter().enumerate() {
        if let Some(pos) = arg {
            let var = &func.get_symbol_table().vars[pos];
            cfg.add(
                vartab,
                Instr::Set {
                    loc: func.get_parameters()[i].loc,
                    res: *pos,
                    expr: Expression::FunctionArg {
                        loc: var.id.loc,
                        ty: var.ty.clone(),
                        arg_no: i,
                    },
                },
            );
        }
    }
}

/// Populate returns of functions that have named returns
pub(crate) fn populate_named_returns<T: FunctionAttributes>(
    func: &T,
    ns: &Namespace,
    cfg: &mut ControlFlowGraph,
    vartab: &mut Vartable,
) {
    for (i, pos) in func.get_symbol_table().returns.iter().enumerate() {
        if let Some(name) = &func.get_returns()[i].id {
            if let Some(expr) = func.get_returns()[i].ty.default(ns) {
                cfg.add(
                    vartab,
                    Instr::Set {
                        loc: name.loc,
                        res: *pos,
                        expr,
                    },
                );
            }
        }
    }
}

/// Generate the CFG for a modifier on a function
fn generate_modifier_dispatch(
    contract_no: usize,
    func_no: usize,
    cfg_no: usize,
    chain_no: usize,
    ns: &mut Namespace,
    opt: &Options,
) -> ControlFlowGraph {
    let (modifier_no, args) = resolve_modifier_call(
        &ns.functions[func_no].modifiers[chain_no],
        &ns.contracts[contract_no],
    );
    let func = &ns.functions[func_no];
    let modifier = &ns.functions[modifier_no];
    let name = format!(
        "{}::{}::{}::modifier{}::{}",
        &ns.contracts[contract_no].name,
        &ns.contracts[func.contract_no.unwrap()].name,
        func.llvm_symbol(ns),
        chain_no,
        modifier.llvm_symbol(ns)
    );
    let mut cfg = ControlFlowGraph::new(name, ASTFunction::None);

    cfg.params = func.params.clone();
    cfg.returns = func.returns.clone();

    let mut vartab = Vartable::from_symbol_table(&func.symtable, ns.next_id);

    vartab.add_symbol_table(&modifier.symtable);
    let mut loops = LoopScopes::new();

    // a modifier takes the same arguments as the function it is applied to. This way we can pass
    // the arguments to the function
    for (i, arg) in func.symtable.arguments.iter().enumerate() {
        if let Some(pos) = arg {
            let var = &func.symtable.vars[pos];
            cfg.add(
                &mut vartab,
                Instr::Set {
                    loc: var.id.loc,
                    res: *pos,
                    expr: Expression::FunctionArg {
                        loc: var.id.loc,
                        ty: var.ty.clone(),
                        arg_no: i,
                    },
                },
            );
        }
    }

    // now set the modifier args
    for (i, arg) in modifier.symtable.arguments.iter().enumerate() {
        if let Some(pos) = arg {
            let expr = expression(
                &args[i],
                &mut cfg,
                contract_no,
                Some(func),
                ns,
                &mut vartab,
                opt,
            );
            cfg.add(
                &mut vartab,
                Instr::Set {
                    loc: expr.loc(),
                    res: *pos,
                    expr,
                },
            );
        }
    }

    // modifiers do not have return values in their syntax, but the return values from the function
    // need to be passed on. So, we need to create some var
    let mut value = Vec::new();
    let mut return_tys = Vec::new();

    for (i, arg) in func.returns.iter().enumerate() {
        value.push(Expression::Variable {
            loc: arg.loc,
            ty: arg.ty.clone(),
            var_no: func.symtable.returns[i],
        });
        return_tys.push(arg.ty.clone());
    }

    let return_instr = Instr::Return { value };

    // create the instruction for the place holder
    let placeholder = Instr::Call {
        res: func.symtable.returns.clone(),
        call: InternalCallTy::Static { cfg_no },
        return_tys,
        args: func
            .params
            .iter()
            .enumerate()
            .map(|(i, p)| Expression::FunctionArg {
                loc: p.loc,
                ty: p.ty.clone(),
                arg_no: i,
            })
            .collect(),
    };

    for stmt in &modifier.body {
        statement(
            stmt,
            modifier,
            &mut cfg,
            contract_no,
            ns,
            &mut vartab,
            &mut loops,
            Some(&placeholder),
            Some(&return_instr),
            opt,
        );
    }

    if modifier
        .body
        .last()
        .map(Statement::reachable)
        .unwrap_or(true)
    {
        let loc = match func.body.last() {
            Some(ins) => ins.loc(),
            None => pt::Loc::Codegen,
        };
        // add implicit return
        cfg.add(
            &mut vartab,
            Instr::Return {
                value: func
                    .symtable
                    .returns
                    .iter()
                    .map(|pos| Expression::Variable {
                        loc,
                        ty: func.symtable.vars[pos].ty.clone(),
                        var_no: *pos,
                    })
                    .collect::<Vec<_>>(),
            },
        );
    }

    vartab.finalize(ns, &mut cfg);

    cfg
}

impl Contract {
    /// Print the entire contract; storage initializers, constructors and functions and their CFGs
    pub fn print_cfg(&self, ns: &Namespace) -> String {
        let mut out = format!("#\n# Contract: {}\n#\n\n", self.name);

        for cfg in &self.cfg {
            if !cfg.is_placeholder() {
                writeln!(
                    out,
                    "\n# {} {} public:{} selector:{} nonpayable:{}",
                    cfg.ty,
                    cfg.name,
                    cfg.public,
                    hex::encode(&cfg.selector),
                    cfg.nonpayable,
                )
                .unwrap();

                writeln!(
                    out,
                    "# params: {}",
                    cfg.params
                        .iter()
                        .map(|p| {
                            if p.id.is_some() {
                                format!("{} {}", p.ty.to_string(ns), p.name_as_str())
                            } else {
                                p.ty.to_string(ns)
                            }
                        })
                        .collect::<Vec<String>>()
                        .join(",")
                )
                .unwrap();

                writeln!(
                    out,
                    "# returns: {}",
                    cfg.returns
                        .iter()
                        .map(|p| {
                            if p.id.is_some() {
                                format!("{} {}", p.ty.to_string(ns), p.name_as_str())
                            } else {
                                p.ty.to_string(ns)
                            }
                        })
                        .collect::<Vec<String>>()
                        .join(",")
                )
                .unwrap();

                out += &cfg.to_string(self, ns);
            }
        }

        out
    }

    /// Get the storage slot for a variable, possibly from base contract
    pub fn get_storage_slot(
        &self,
        loc: pt::Loc,
        var_contract_no: usize,
        var_no: usize,
        ns: &Namespace,
        ty: Option<Type>,
    ) -> Expression {
        if let Some(layout) = self
            .layout
            .iter()
            .find(|l| l.contract_no == var_contract_no && l.var_no == var_no)
        {
            Expression::NumberLiteral {
                loc,
                ty: ty.unwrap_or_else(|| ns.storage_type()),
                value: layout.slot.clone(),
            }
        } else {
            panic!("get_storage_slot called on non-storage variable");
        }
    }
}

impl Namespace {
    /// Determine whether a function should be included in the dispatcher and metadata,
    /// taking inheritance into account.
    ///
    /// `function_no` is optional because default constructors require creating a CFG
    /// without any corresponding function definition.
    pub fn function_externally_callable(
        &self,
        contract_no: usize,
        function_no: Option<usize>,
    ) -> bool {
        let default_constructor = &self.default_constructor(contract_no);
        let func = function_no
            .map(|n| &self.functions[n])
            .unwrap_or(default_constructor);

        // If a function is virtual, and it is overriden, do not make it public;
        // Otherwise the runtime function dispatch will have two identical functions to dispatch to.
        if func.is_virtual
            && self.contracts[contract_no]
                .virtual_functions
                .get(&func.signature)
                != function_no.as_ref()
        {
            return false;
        }

        if let Some(base_contract_no) = func.contract_no {
            return !(self.contracts[base_contract_no].is_library()
                || func.is_constructor() && contract_no != base_contract_no)
                && func.is_public()
                && func.ty != FunctionTy::Modifier;
        }

        false
    }

    /// Type storage
    pub fn storage_type(&self) -> Type {
        if self.target == Target::Solana {
            Type::Uint(32)
        } else {
            Type::Uint(256)
        }
    }

    /// Return the value type
    pub fn value_type(&self) -> Type {
        Type::Uint(8 * self.value_length as u16)
    }

    /// Checks if struct contains only primitive types and returns its memory non-padded size
    pub fn calculate_struct_non_padded_size(&self, struct_type: &StructType) -> Option<BigInt> {
        let mut size = BigInt::from(0u8);
        for field in &struct_type.definition(self).fields {
            let ty = field.ty.clone().unwrap_user_type(self);
            if !ty.is_primitive() {
                // If a struct contains a non-primitive type, we cannot calculate its
                // size during compile time
                if let Type::Struct(struct_ty) = &field.ty {
                    if let Some(struct_size) = self.calculate_struct_non_padded_size(struct_ty) {
                        size.add_assign(struct_size);
                        continue;
                    }
                }
                return None;
            } else {
                size.add_assign(ty.memory_size_of(self));
            }
        }

        Some(size)
    }
}