/*
 * par2serial-cc: ir.h - Three-address code Intermediate Representation
 * Designed for optimization passes: parallel detection, vectorization, tiling
 */
#ifndef P2S_IR_H
#define P2S_IR_H

#include "ast.h"

/* ── IR Operation Codes ──────────────────────────────────── */
typedef enum {
    /* Arithmetic */
    IR_ADD, IR_SUB, IR_MUL, IR_DIV, IR_MOD,
    IR_NEG,
    IR_FADD, IR_FSUB, IR_FMUL, IR_FDIV, /* float variants */

    /* Bitwise */
    IR_AND, IR_OR, IR_XOR, IR_NOT,
    IR_SHL, IR_SHR,

    /* Comparison */
    IR_EQ, IR_NE, IR_LT, IR_GT, IR_LE, IR_GE,
    IR_FEQ, IR_FNE, IR_FLT, IR_FGT, IR_FLE, IR_FGE,

    /* Data movement */
    IR_LOAD,         /* dst = *src (memory load) */
    IR_STORE,        /* *dst = src (memory store) */
    IR_MOVE,         /* dst = src */
    IR_LOAD_IMM,     /* dst = immediate */
    IR_LOAD_FIMM,    /* dst = float immediate */
    IR_LOAD_ADDR,    /* dst = &var */
    IR_INDEX,        /* dst = base + idx * stride */

    /* Control flow */
    IR_LABEL,
    IR_JUMP,
    IR_BRANCH,       /* if cond goto label */
    IR_BRANCH_FALSE, /* if !cond goto label */
    IR_CALL,         /* dst = call func(args) */
    IR_RET,          /* return val */

    /* Type conversion */
    IR_INT_TO_FLOAT,
    IR_FLOAT_TO_INT,
    IR_WIDEN,        /* sign/zero extend */
    IR_NARROW,       /* truncate */

    /* Parallel constructs (high-level, lowered by optimization passes) */
    IR_PAR_FOR_BEGIN,    /* marks start of parallel for */
    IR_PAR_FOR_END,      /* marks end */
    IR_PAR_REDUCE_BEGIN, /* marks start of reduction */
    IR_PAR_REDUCE_END,
    IR_PAR_SCAN_BEGIN,
    IR_PAR_SCAN_END,
    IR_BARRIER,          /* synchronization barrier */
    IR_ATOMIC_ADD,       /* atomic add */

    /* SIMD operations (inserted by vectorization pass) */
    IR_SIMD_LOAD,        /* vdst = simd_load(addr) */
    IR_SIMD_STORE,       /* simd_store(addr, vsrc) */
    IR_SIMD_BROADCAST,   /* vdst = broadcast(scalar) */
    IR_SIMD_ADD,         /* vdst = vadd(va, vb) */
    IR_SIMD_SUB,
    IR_SIMD_MUL,
    IR_SIMD_FMA,         /* vdst = fma(va, vb, vc) */
    IR_SIMD_HADD,        /* horizontal add (reduction) */
    IR_SIMD_MIN,
    IR_SIMD_MAX,

    /* Memory operations */
    IR_PREFETCH,         /* prefetch hint */
    IR_ALLOCA,           /* stack allocation */

    /* Special */
    IR_NOP,
    IR_PHI,              /* SSA phi node */
    IR_COMMENT,          /* optimization annotation */

    IR_OP_COUNT
} IROp;

/* ── IR Value (virtual register or constant) ─────────────── */
typedef enum {
    VAL_REG,         /* virtual register %t0, %t1, ... */
    VAL_INT,         /* integer constant */
    VAL_FLOAT,       /* float constant */
    VAL_LABEL,       /* label reference */
    VAL_NAME,        /* named variable/function */
    VAL_NONE,        /* no value */
} IRValKind;

typedef struct {
    IRValKind kind;
    union {
        int         reg;       /* register number */
        int64_t     int_val;
        double      float_val;
        int         label_id;
        const char *name;
    };
    /* type info */
    TypeKind    type;         /* data type of this value */
    int         simd_width;   /* 0 = scalar, 4/8/16 = SIMD lanes */
} IRValue;

/* ── IR Instruction ──────────────────────────────────────── */
typedef struct IRInst {
    IROp         op;
    IRValue      dst;          /* destination */
    IRValue      src1;         /* first operand */
    IRValue      src2;         /* second operand */
    IRValue      src3;         /* third operand (FMA, etc) */
    SourceLoc    loc;          /* source location for diagnostics */

    /* Parallel metadata */
    struct {
        const char *iter_var;
        int         lo_reg;    /* register holding loop bound */
        int         hi_reg;
        int         step_reg;
        ReduceOp    reduce_op;
        int         accum_reg;
    } par;

    /* Annotations */
    const char  *comment;
    int          label_id;     /* for IR_LABEL */

    struct IRInst *next;
    struct IRInst *prev;
} IRInst;

VEC_TYPEDEF(IRInst*, IRInstVec);

/* ── IR Basic Block ──────────────────────────────────────── */
typedef struct IRBlock {
    int         id;
    const char *name;
    IRInstVec   insts;
    struct IRBlock *next;    /* linked list */

    /* CFG edges */
    struct IRBlock *succ[2]; /* successors (branch: [true, false]) */
    struct IRBlock **preds;
    int             pred_count;

    /* Loop info (filled by analysis) */
    bool is_loop_header;
    int  loop_depth;
    struct IRBlock *loop_latch;
} IRBlock;

VEC_TYPEDEF(IRBlock*, IRBlockVec);

/* ── IR Function ─────────────────────────────────────────── */
typedef struct IRFunc {
    const char *name;
    IRBlockVec  blocks;
    int         reg_count;     /* next register number */
    int         label_count;   /* next label number */
    int         param_count;
    TypeKind    return_type;
    struct IRFunc *next;
} IRFunc;

/* ── IR Module (compilation unit) ────────────────────────── */
typedef struct {
    Arena    *arena;
    IRFunc   *functions;       /* linked list */
    int       func_count;

    /* Global declarations (passed through) */
    NodeVec   preproc_lines;   /* #include, #define, etc */
    NodeVec   global_vars;     /* global variable declarations */
} IRModule;

/* ── IR Builder API ──────────────────────────────────────── */
IRModule *ir_module_create(Arena *arena);
IRFunc   *ir_func_create(IRModule *mod, const char *name);
IRBlock  *ir_block_create(IRFunc *func, const char *name);

/* Value constructors */
IRValue ir_reg(int reg, TypeKind type);
IRValue ir_int(int64_t val);
IRValue ir_float(double val);
IRValue ir_label(int id);
IRValue ir_name(const char *name);
IRValue ir_none(void);
IRValue ir_simd_reg(int reg, TypeKind type, int width);

/* Instruction emission */
int     ir_new_reg(IRFunc *func);
int     ir_new_label(IRFunc *func);
IRInst *ir_emit(Arena *arena, IRBlock *bb, IROp op,
                IRValue dst, IRValue src1, IRValue src2);
IRInst *ir_emit_comment(Arena *arena, IRBlock *bb, const char *comment);

/* AST → IR lowering */
IRModule *ir_build_from_ast(Arena *arena, ASTNode *program);

/* IR printing */
void ir_print_module(IRModule *mod);
void ir_print_value(IRValue v);
const char *ir_op_name(IROp op);

#endif /* P2S_IR_H */