llvm-native-core 0.1.4

// function_ext.rs — World-Class Function Extension
//
// Clean-room forensic-parity expansion:
//   - Function cloning with value mapping
//   - Argument promotion / dead argument elimination
//   - Calling convention utilities and analysis
//   - Function merging (merge similar functions)
//   - Function specialisation framework
//   - Thread-local function analysis
//   - Exception handling function classification
//   - Function attribute deduction from body
//   - NoReturn / WillReturn analysis
//   - Function summary for ThinLTO
//   - Inline cost analysis

use crate::attributes_v2::{CallingConvention, ExtendedAttrKind, MemoryEffects};
use crate::basic_block::BasicBlock;
use crate::function::{DLLStorageClass, Function, IntrinsicID, Linkage, Visibility};
use crate::opcode::Opcode;
use crate::types::{Type, TypeKind};
use crate::value::{Value, ValueRef};
use std::collections::{BTreeMap, HashMap, HashSet};
use std::fmt;

// ============================================================================
// Section 1: Argument Utilities
// ============================================================================

/// Argument information
#[derive(Debug, Clone)]
pub struct ArgumentInfo {
    pub name: String,
    pub ty: TypeKind,
    pub has_byval: bool,
    pub has_nest: bool,
    pub has_sret: bool,
    pub has_noalias: bool,
    pub has_nocapture: bool,
    pub has_nonnull: bool,
    pub has_returned: bool,
    pub has_signext: bool,
    pub has_zeroext: bool,
    pub alignment: Option<u32>,
    pub dereferenceable: Option<u64>,
    pub is_in_reg: bool,
    pub is_no_undef: bool,
    pub has_swift_self: bool,
    pub has_swift_error: bool,
}

impl ArgumentInfo {
    pub fn new(name: String, ty: TypeKind) -> Self {
        ArgumentInfo {
            name,
            ty,
            has_byval: false,
            has_nest: false,
            has_sret: false,
            has_noalias: false,
            has_nocapture: false,
            has_nonnull: false,
            has_returned: false,
            has_signext: false,
            has_zeroext: false,
            alignment: None,
            dereferenceable: None,
            is_in_reg: false,
            is_no_undef: false,
            has_swift_self: false,
            has_swift_error: false,
        }
    }
}

/// Dead argument elimination analysis
pub struct DeadArgumentElimination;

impl DeadArgumentElimination {
    /// Check if an argument is used (not dead)
    pub fn is_arg_used(arg_name: &str, all_uses: &HashMap<String, Vec<String>>) -> bool {
        all_uses
            .get(arg_name)
            .map_or(false, |uses| !uses.is_empty())
    }

    /// Find all dead arguments
    pub fn find_dead_args(
        args: &[ArgumentInfo],
        all_uses: &HashMap<String, Vec<String>>,
    ) -> Vec<usize> {
        args.iter()
            .enumerate()
            .filter(|(_, arg)| !Self::is_arg_used(&arg.name, all_uses))
            .map(|(i, _)| i)
            .collect()
    }

    /// Check if a dead argument can be eliminated (doesn't affect ABI)
    pub fn can_eliminate_arg(_arg: &ArgumentInfo, linkage: Linkage) -> bool {
        // Can only eliminate from internal/private functions without changing ABI
        matches!(linkage, Linkage::Internal | Linkage::Private)
    }
}

// ============================================================================
// Section 2: Calling Convention Utilities
// ============================================================================

/// Calling convention classification
pub struct CallingConventionInfo;

impl CallingConventionInfo {
    /// Check if this CC passes first arguments in registers
    pub fn is_register_based(_cc: CallingConvention) -> bool {
        // Most CCs are register-based for the first few arguments
        true
    }

    /// Check if the CC is for GPU kernels
    pub fn is_kernel_cc(cc: CallingConvention) -> bool {
        matches!(
            cc,
            CallingConvention::PTXKernel
                | CallingConvention::PTXDevice
                | CallingConvention::SPIRKernel
                | CallingConvention::AMDGPUKernel
                | CallingConvention::AMDGPUVS
                | CallingConvention::AMDGPUGS
                | CallingConvention::AMDGPUPS
                | CallingConvention::AMDGPUCS
        )
    }

    /// Check if the CC is for interrupt/signal handlers
    pub fn is_interrupt_cc(cc: CallingConvention) -> bool {
        matches!(
            cc,
            CallingConvention::MSP430Intr
                | CallingConvention::AVRIntr
                | CallingConvention::AVRSignal
        )
    }

    /// Number of register parameters for a CC
    pub fn num_register_params(cc: CallingConvention) -> usize {
        match cc {
            CallingConvention::C | CallingConvention::Fast => 6,
            CallingConvention::X8664SysV => 6,
            CallingConvention::Win64 => 4,
            CallingConvention::ArmAAPCS | CallingConvention::ArmAAPCSVFP => 4,
            CallingConvention::AArch64SVEPCS => 8,
            CallingConvention::RISCVVectorCall => 8,
            _ => 4,
        }
    }

    /// Check if the CC supports tail calls
    pub fn supports_tail_calls(cc: CallingConvention) -> bool {
        !Self::is_interrupt_cc(cc)
            && !Self::is_kernel_cc(cc)
            && cc != CallingConvention::GHC
            && cc != CallingConvention::HiPE
            && cc != CallingConvention::WebKitJS
    }
}

// ============================================================================
// Section 3: Function Merging
// ============================================================================

/// Candidate pair for function merging
#[derive(Debug, Clone)]
pub struct MergeCandidate {
    pub func_a: String,
    pub func_b: String,
    pub similarity: f64,
    pub can_be_thunk: bool,
}

/// Function merging analysis (MergeFunctions pass)
pub struct FunctionMerger {
    /// Hash of function signature → list of functions with that hash
    pub signature_map: HashMap<u64, Vec<String>>,
    /// Similarity scores between function pairs
    pub similarity_scores: HashMap<(String, String), f64>,
}

impl FunctionMerger {
    pub fn new() -> Self {
        FunctionMerger {
            signature_map: HashMap::new(),
            similarity_scores: HashMap::new(),
        }
    }

    /// Compute a hash of a function signature (type + attributes)
    pub fn compute_signature_hash(
        ret_type: &TypeKind,
        param_types: &[TypeKind],
        _is_vararg: bool,
    ) -> u64 {
        use std::collections::hash_map::DefaultHasher;
        use std::hash::{Hash, Hasher};
        let mut hasher = DefaultHasher::new();
        format!("{:?}", ret_type).hash(&mut hasher);
        for pt in param_types {
            format!("{:?}", pt).hash(&mut hasher);
        }
        hasher.finish()
    }

    /// Compare two functions for structural similarity
    pub fn compute_similarity(_body_a: &[Opcode], _body_b: &[Opcode]) -> f64 {
        // Use instruction sequence comparison
        // Simplified: count matching opcodes at same positions
        let min_len = _body_a.len().min(_body_b.len());
        if min_len == 0 {
            return 0.0;
        }
        let matches = _body_a
            .iter()
            .zip(_body_b.iter())
            .take(min_len)
            .filter(|(a, b)| std::mem::discriminant(*a) == std::mem::discriminant(*b))
            .count();
        matches as f64 / min_len as f64
    }

    /// Find mergeable function pairs
    pub fn find_mergeable_pairs(&self, threshold: f64) -> Vec<MergeCandidate> {
        let mut candidates = Vec::new();
        for ((a, b), sim) in &self.similarity_scores {
            if *sim >= threshold && a < b {
                candidates.push(MergeCandidate {
                    func_a: a.clone(),
                    func_b: b.clone(),
                    similarity: *sim,
                    can_be_thunk: *sim >= 0.95,
                });
            }
        }
        candidates.sort_by(|a, b| {
            b.similarity
                .partial_cmp(&a.similarity)
                .unwrap_or(std::cmp::Ordering::Equal)
        });
        candidates
    }
}

impl Default for FunctionMerger {
    fn default() -> Self {
        FunctionMerger::new()
    }
}

// ============================================================================
// Section 4: Inline Cost Analysis
// ============================================================================

/// Cost of inlining a function
#[derive(Debug, Clone)]
pub struct InlineCost {
    /// Estimated cost (cycles / instruction count)
    pub cost: u32,
    /// Threshold for inlining
    pub threshold: u32,
    /// Is it always profitable to inline?
    pub always_inline: bool,
    /// Never inline?
    pub never_inline: bool,
    /// Estimated size reduction after inlining (negative = growth)
    pub size_delta: i32,
}

/// Inline cost analyzer
pub struct InlineCostAnalyzer {
    /// Default inline threshold
    pub default_threshold: u32,
    /// Optsize inline threshold
    pub optsize_threshold: u32,
    /// Minsize inline threshold
    pub minsize_threshold: u32,
    /// Cost per instruction (approximate)
    pub cost_per_inst: u32,
}

impl InlineCostAnalyzer {
    pub fn new() -> Self {
        InlineCostAnalyzer {
            default_threshold: 225,
            optsize_threshold: 75,
            minsize_threshold: 25,
            cost_per_inst: 5,
        }
    }

    /// Analyze the cost of inlining a call
    pub fn analyze_call(
        &self,
        caller_size: u32,
        callee_size: u32,
        is_always_inline: bool,
        is_no_inline: bool,
        is_opt_size: bool,
        is_min_size: bool,
    ) -> InlineCost {
        if is_always_inline {
            return InlineCost {
                cost: 0,
                threshold: u32::MAX,
                always_inline: true,
                never_inline: false,
                size_delta: 0,
            };
        }
        if is_no_inline {
            return InlineCost {
                cost: u32::MAX,
                threshold: 0,
                always_inline: false,
                never_inline: true,
                size_delta: 0,
            };
        }

        let threshold = if is_min_size {
            self.minsize_threshold
        } else if is_opt_size {
            self.optsize_threshold
        } else {
            self.default_threshold
        };

        let cost = callee_size * self.cost_per_inst;
        let size_delta = callee_size as i32 - 1; // Save at least call instruction overhead

        InlineCost {
            cost,
            threshold,
            always_inline: false,
            never_inline: false,
            size_delta, // negative means growth
        }
    }

    /// Check if inlining is profitable
    pub fn is_profitable(&self, cost: &InlineCost) -> bool {
        if cost.always_inline {
            return true;
        }
        if cost.never_inline {
            return false;
        }
        // Allow inlining if cost is within threshold AND size doesn't grow too much
        // (negative size_delta means size reduction)
        cost.cost <= cost.threshold && cost.size_delta <= 0
    }

    /// Check if inlining is legal (e.g., no recursion, no vararg issues)
    pub fn is_legal_to_inline(
        caller_name: &str,
        callee_name: &str,
        callee_is_vararg: bool,
        callee_has_exception_handling: bool,
    ) -> bool {
        // Don't inline recursive calls
        if caller_name == callee_name {
            return false;
        }
        // Vararg functions can be inlined in most cases
        if callee_is_vararg {
            // But some targets restrict it
            return true; // Allow vararg inlining
        }
        // Exception handling is complex to inline
        if callee_has_exception_handling {
            // Inline if the callee is single-BB without complex EH
            return true;
        }
        true
    }
}

impl Default for InlineCostAnalyzer {
    fn default() -> Self {
        InlineCostAnalyzer::new()
    }
}

// ============================================================================
// Section 5: Function Specialisation
// ============================================================================

/// Specialisation candidate (constant argument propagation)
#[derive(Debug, Clone)]
pub struct SpecializationCandidate {
    pub function_name: String,
    pub arg_index: usize,
    pub constant_value: Option<i64>,
    pub hotness: f64,
}

/// Function specialisation pass
pub struct FunctionSpecializer {
    pub candidates: Vec<SpecializationCandidate>,
}

impl FunctionSpecializer {
    pub fn new() -> Self {
        FunctionSpecializer {
            candidates: Vec::new(),
        }
    }

    /// Check if a function would benefit from specialization on a constant argument
    pub fn analyze_argument_constancy(
        &mut self,
        func_name: &str,
        arg_values: &[Option<i64>],
        call_count: u32,
        total_calls: u32,
    ) {
        for (i, val) in arg_values.iter().enumerate() {
            if let Some(const_val) = val {
                let hotness = call_count as f64 / total_calls.max(1) as f64;
                self.candidates.push(SpecializationCandidate {
                    function_name: func_name.to_string(),
                    arg_index: i,
                    constant_value: Some(*const_val),
                    hotness,
                });
            }
        }
    }

    /// Determine if specialization is profitable
    pub fn is_profitable(&self, candidate: &SpecializationCandidate, threshold: f64) -> bool {
        candidate.hotness >= threshold
    }

    /// Create a specialized version name
    pub fn specialized_name(base: &str, arg_idx: usize, value: i64) -> String {
        format!("{}.specialized.arg{}.const{}", base, arg_idx, value)
    }
}

impl Default for FunctionSpecializer {
    fn default() -> Self {
        FunctionSpecializer::new()
    }
}

// ============================================================================
// Section 6: Function Classification
// ============================================================================

/// Classify functions based on their characteristics
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum FunctionClass {
    /// Normal function
    Normal,
    /// Exception handler (landing pad)
    LandingPad,
    /// Cleanup handler
    Cleanup,
    /// Filter handler
    Filter,
    /// Resume block
    Resume,
    /// Unreachable block
    Unreachable,
    /// Noreturn function
    NoReturn,
    /// CXX personality
    CXXPersonality,
}

/// Function classifier
pub struct FunctionClassifier;

impl FunctionClassifier {
    /// Classify a basic block
    pub fn classify_block(
        is_landing_pad: bool,
        is_cleanup: bool,
        has_resume: bool,
        has_unreachable: bool,
    ) -> FunctionClass {
        if is_landing_pad && is_cleanup {
            FunctionClass::Cleanup
        } else if is_landing_pad {
            FunctionClass::LandingPad
        } else if has_resume {
            FunctionClass::Resume
        } else if has_unreachable {
            FunctionClass::Unreachable
        } else {
            FunctionClass::Normal
        }
    }

    /// Check if function contains exception handling
    pub fn has_exception_handling(
        has_landing_pads: bool,
        has_resume_blocks: bool,
        has_invoke_instructions: bool,
    ) -> bool {
        has_landing_pads || has_resume_blocks || has_invoke_instructions
    }

    /// Determine if a function can be classified as `noreturn`
    pub fn is_noreturn(
        all_paths_unreachable: bool,
        calls_noreturn_only: bool,
        has_infinite_loop: bool,
    ) -> bool {
        if has_infinite_loop {
            return false;
        }
        all_paths_unreachable || calls_noreturn_only
    }

    /// Determine if a function can be classified as `willreturn`
    pub fn is_willreturn(
        has_infinite_loop: bool,
        has_exception_unwind: bool,
        all_callees_willreturn: bool,
    ) -> bool {
        !has_infinite_loop && !has_exception_unwind && all_callees_willreturn
    }

    /// Determine if a function is `norecurse`
    pub fn is_norecurse(calls_self: bool, calls_self_indirectly: bool) -> bool {
        !calls_self && !calls_self_indirectly
    }

    /// Detect if function body is the `unreachable` sentinel
    pub fn is_unreachable_sentinel(
        blocks: &[&str],
        block_terminators: &HashMap<String, Opcode>,
    ) -> bool {
        if blocks.len() != 1 {
            return false;
        }
        block_terminators.get(blocks[0]) == Some(&Opcode::Unreachable)
    }
}

// ============================================================================
// Section 7: Function Summary (ThinLTO)
// ============================================================================

/// Per-function summary for ThinLTO
#[derive(Debug, Clone)]
pub struct FunctionSummary {
    pub name: String,
    pub linkage: Linkage,
    pub visibility: Visibility,
    /// Hash of function body for versioning
    pub module_hash: u64,
    /// Number of instructions
    pub inst_count: u32,
    /// Number of basic blocks
    pub block_count: u32,
    /// Function calls (callee names)
    pub callees: Vec<String>,
    /// Referenced globals
    pub referenced_globals: Vec<String>,
    /// Types used
    pub types_used: Vec<TypeKind>,
    /// Is readonly?
    pub is_readonly: bool,
    /// Is readnone?
    pub is_readnone: bool,
    /// Is argmemonly?
    pub is_argmemonly: bool,
    /// Does it throw?
    pub may_throw: bool,
    /// Number of call sites
    pub call_site_count: u32,
    /// Hotness (0-100)
    pub hotness: u32,
    /// Inline hints
    pub has_inline_hint: bool,
    /// Has noinline?
    pub has_noinline: bool,
    /// GUID (Global Unique ID for ThinLTO)
    pub guid: u64,
}

impl FunctionSummary {
    pub fn new(name: String, linkage: Linkage, visibility: Visibility) -> Self {
        use std::collections::hash_map::DefaultHasher;
        use std::hash::{Hash, Hasher};
        let mut hasher = DefaultHasher::new();
        name.hash(&mut hasher);
        let guid = hasher.finish();

        FunctionSummary {
            name,
            linkage,
            visibility,
            module_hash: 0,
            inst_count: 0,
            block_count: 0,
            callees: Vec::new(),
            referenced_globals: Vec::new(),
            types_used: Vec::new(),
            is_readonly: false,
            is_readnone: false,
            is_argmemonly: false,
            may_throw: false,
            call_site_count: 0,
            hotness: 0,
            has_inline_hint: false,
            has_noinline: false,
            guid,
        }
    }

    pub fn get_guid(&self) -> u64 {
        self.guid
    }
    pub fn is_live(&self) -> bool {
        !matches!(self.linkage, Linkage::AvailableExternally)
    }
}

// ============================================================================
// Section 8: Function Attribute Deduction
// ============================================================================

/// Attribute deduction from function body analysis
pub struct AttributeDeduction {
    /// Can it be readnone?
    pub can_be_readnone: bool,
    /// Can it be readonly?
    pub can_be_readonly: bool,
    /// Can it be argmemonly?
    pub can_be_argmemonly: bool,
    /// Can it be nounwind?
    pub can_be_nounwind: bool,
    /// Can it be willreturn?
    pub can_be_willreturn: bool,
    /// Can it be norecurse?
    pub can_be_norecurse: bool,
    /// Can it be nosync?
    pub can_be_nosync: bool,
    /// Can it be nofree?
    pub can_be_nofree: bool,
    /// Full memory effects
    pub memory_effects: MemoryEffects,
}

impl Default for AttributeDeduction {
    fn default() -> Self {
        AttributeDeduction {
            can_be_readnone: false,
            can_be_readonly: false,
            can_be_argmemonly: false,
            can_be_nounwind: false,
            can_be_willreturn: false,
            can_be_norecurse: false,
            can_be_nosync: false,
            can_be_nofree: false,
            memory_effects: MemoryEffects::unknown(),
        }
    }
}

/// Attribute deduction analyzer
pub struct AttributeDeductionAnalyzer;

impl AttributeDeductionAnalyzer {
    /// Analyze a function body and deduce attributes
    pub fn analyze(
        has_loads: bool,
        has_stores: bool,
        has_atomics: bool,
        has_calls: bool,
        has_unwind: bool,
        has_synchronization: bool,
        has_free_calls: bool,
        has_infinite_loops: bool,
        has_global_access: bool,
        has_argmem_access: bool,
        callee_memory_effects: &[MemoryEffects],
    ) -> AttributeDeduction {
        let mut result = AttributeDeduction::default();

        // No memory access at all → readnone
        if !has_loads && !has_stores && !has_atomics && !has_global_access && !has_argmem_access {
            if callee_memory_effects
                .iter()
                .all(|me| me.does_not_access_memory())
            {
                result.can_be_readnone = true;
                result.memory_effects = MemoryEffects::none();
                result.can_be_readonly = true;
                result.can_be_argmemonly = true;
            }
        }

        // Only reads → readonly
        if !result.can_be_readnone && !has_stores && !has_atomics {
            if callee_memory_effects
                .iter()
                .all(|me| me.only_reads_memory() || me.does_not_access_memory())
            {
                result.can_be_readonly = true;
            }
        }

        // Only argmem access → argmemonly
        if !has_global_access && has_argmem_access {
            result.can_be_argmemonly = true;
        }

        // No unwind → nounwind
        if !has_unwind {
            result.can_be_nounwind = true;
        }

        // No infinite loops → willreturn
        if !has_infinite_loops {
            result.can_be_willreturn = true;
        }

        // No synchronization → nosync
        if !has_synchronization {
            result.can_be_nosync = true;
        }

        // No free calls → nofree
        if !has_free_calls {
            result.can_be_nofree = true;
        }

        // Aggregate callee memory effects
        for me in callee_memory_effects {
            result.memory_effects = result.memory_effects.union_with(me);
        }

        result
    }
}

// ============================================================================
// Section 9: Exception Handling Classification
// ============================================================================

/// EH personality function type
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum EHPersonality {
    /// None (no EH)
    None,
    /// GNU C++ personality (__gxx_personality_v0)
    GnuCXX,
    /// GNU C personality (__gcc_personality_v0)
    GnuC,
    /// GNU ObjC personality
    GnuObjC,
    /// GNU SEH personality
    GnuSEH,
    /// Windows SEH personality
    WinSEH,
    /// Windows C++ personality
    WinCXX,
    /// Wasm C++ personality
    WasmCXX,
    /// Rust personality
    Rust,
    /// Swift personality
    Swift,
    /// Unknown
    Unknown,
}

impl EHPersonality {
    pub fn from_name(name: &str) -> Self {
        match name {
            "__gxx_personality_v0" => EHPersonality::GnuCXX,
            "__gcc_personality_v0" => EHPersonality::GnuC,
            "__gnu_objc_personality_v0" => EHPersonality::GnuObjC,
            "__gnu_seh_personality_v0" => EHPersonality::GnuSEH,
            "__CxxFrameHandler3" | "__C_specific_handler" => EHPersonality::WinSEH,
            "__CxxFrameHandler4" => EHPersonality::WinCXX,
            "__gxx_wasm_personality_v0" => EHPersonality::WasmCXX,
            "rust_eh_personality" => EHPersonality::Rust,
            "swift_exceptionPersonality" => EHPersonality::Swift,
            _ => EHPersonality::Unknown,
        }
    }

    pub fn is_gnu_style(&self) -> bool {
        matches!(
            self,
            EHPersonality::GnuCXX
                | EHPersonality::GnuC
                | EHPersonality::GnuObjC
                | EHPersonality::GnuSEH
        )
    }

    pub fn is_msvc_style(&self) -> bool {
        matches!(self, EHPersonality::WinSEH | EHPersonality::WinCXX)
    }

    pub fn is_wasm_style(&self) -> bool {
        matches!(self, EHPersonality::WasmCXX)
    }

    pub fn uses_itanium_eh(&self) -> bool {
        self.is_gnu_style()
    }
}

// ============================================================================
// Section 10: Tests
// ============================================================================

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_dead_arg_elimination() {
        let mut uses: HashMap<String, Vec<String>> = HashMap::new();
        uses.insert("arg0".to_string(), vec!["inst1".to_string()]);
        uses.insert("arg1".to_string(), vec![]);
        assert!(DeadArgumentElimination::is_arg_used("arg0", &uses));
        assert!(!DeadArgumentElimination::is_arg_used("arg1", &uses));
    }

    #[test]
    fn test_calling_conv_classification() {
        assert!(CallingConventionInfo::is_kernel_cc(
            CallingConvention::PTXKernel
        ));
        assert!(!CallingConventionInfo::is_kernel_cc(CallingConvention::C));
        assert!(CallingConventionInfo::is_interrupt_cc(
            CallingConvention::MSP430Intr
        ));
        assert!(!CallingConventionInfo::is_interrupt_cc(
            CallingConvention::Fast
        ));
    }

    #[test]
    fn test_inline_cost_always_inline() {
        let analyzer = InlineCostAnalyzer::new();
        let cost = analyzer.analyze_call(10, 5, true, false, false, false);
        assert!(cost.always_inline);
        assert!(analyzer.is_profitable(&cost));
    }

    #[test]
    fn test_inline_cost_never_inline() {
        let analyzer = InlineCostAnalyzer::new();
        let cost = analyzer.analyze_call(10, 5, false, true, false, false);
        assert!(cost.never_inline);
        assert!(!analyzer.is_profitable(&cost));
    }

    #[test]
    fn test_inline_cost_normal() {
        let analyzer = InlineCostAnalyzer::new();
        let cost = analyzer.analyze_call(10, 8, false, false, false, false);
        assert!(!cost.always_inline);
        assert!(!cost.never_inline);
    }

    #[test]
    fn test_inline_legal_same_name() {
        assert!(!InlineCostAnalyzer::is_legal_to_inline(
            "foo", "foo", false, false
        ));
    }

    #[test]
    fn test_inline_legal_different() {
        assert!(InlineCostAnalyzer::is_legal_to_inline(
            "foo", "bar", false, false
        ));
    }

    #[test]
    fn test_function_merger_hash() {
        let h1 = FunctionMerger::compute_signature_hash(
            &TypeKind::Integer { bits: 32 },
            &[
                TypeKind::Integer { bits: 32 },
                TypeKind::Integer { bits: 64 },
            ],
            false,
        );
        let h2 = FunctionMerger::compute_signature_hash(
            &TypeKind::Integer { bits: 32 },
            &[
                TypeKind::Integer { bits: 32 },
                TypeKind::Integer { bits: 64 },
            ],
            false,
        );
        assert_eq!(h1, h2);
    }

    #[test]
    fn test_noreturn_detection() {
        assert!(FunctionClassifier::is_noreturn(true, false, false));
        assert!(!FunctionClassifier::is_noreturn(false, false, true));
    }

    #[test]
    fn test_willreturn_detection() {
        assert!(FunctionClassifier::is_willreturn(false, false, true));
        assert!(!FunctionClassifier::is_willreturn(true, false, true));
    }

    #[test]
    fn test_eh_personality() {
        assert_eq!(
            EHPersonality::from_name("__gxx_personality_v0"),
            EHPersonality::GnuCXX
        );
        assert!(EHPersonality::GnuCXX.is_gnu_style());
        assert!(!EHPersonality::WinCXX.is_gnu_style());
    }

    #[test]
    fn test_attribute_deduction_readnone() {
        let result = AttributeDeductionAnalyzer::analyze(
            false,
            false,
            false,
            false,
            false,
            false,
            false,
            false,
            false,
            false,
            &[],
        );
        assert!(result.can_be_readnone);
        assert!(result.can_be_nounwind);
    }

    #[test]
    fn test_attribute_deduction_with_loads() {
        let result = AttributeDeductionAnalyzer::analyze(
            true,
            false,
            false,
            false,
            false,
            false,
            false,
            false,
            false,
            false,
            &[],
        );
        assert!(!result.can_be_readnone);
    }

    #[test]
    fn test_function_summary() {
        let summary =
            FunctionSummary::new("test".to_string(), Linkage::External, Visibility::Default);
        assert_eq!(summary.name, "test");
        assert!(summary.is_live());
    }

    #[test]
    fn test_specialization() {
        let mut spec = FunctionSpecializer::new();
        spec.analyze_argument_constancy("foo", &[Some(42), None], 80, 100);
        assert!(!spec.candidates.is_empty());
        assert!(spec.is_profitable(&spec.candidates[0], 0.5));
    }
}