/*
 * Copyright (C) 2003-2014, Parrot Foundation.
 */

/*

=head1 NAME

compilers/imcc/pcc.c

=head1 DESCRIPTION

Parrot calling convention implementation.

see: docs/pdds/pdd03_calling_conventions.pod

PCC Implementation by Leopold Toetsch

=head2 Functions

=over 4

=cut

*/

#include <stdlib.h>
#include <string.h>
#include "imc.h"
#include "parser.h"
#include "parrot/oplib/core_ops.h"

/* HEADERIZER HFILE: compilers/imcc/imc.h */

/* HEADERIZER BEGIN: static */
/* Don't modify between HEADERIZER BEGIN / HEADERIZER END.  Your changes will be lost. */

static void insert_tail_call(
    ARGMOD(imc_info_t * imcc),
    ARGIN(IMC_Unit *unit),
    ARGMOD(Instruction *ins),
    ARGMOD(SymReg *sub),
    ARGIN_NULLOK(SymReg *meth))
        __attribute__nonnull__(1)
        __attribute__nonnull__(2)
        __attribute__nonnull__(3)
        __attribute__nonnull__(4)
        FUNC_MODIFIES(* imcc)
        FUNC_MODIFIES(*ins)
        FUNC_MODIFIES(*sub);

PARROT_WARN_UNUSED_RESULT
PARROT_CAN_RETURN_NULL
static Instruction * insINS(
    ARGMOD(imc_info_t * imcc),
    ARGMOD(IMC_Unit *unit),
    ARGIN(Instruction *ins),
    ARGIN(const char *name),
    ARGIN(SymReg **regs),
    int n)
        __attribute__nonnull__(1)
        __attribute__nonnull__(2)
        __attribute__nonnull__(3)
        __attribute__nonnull__(4)
        __attribute__nonnull__(5)
        FUNC_MODIFIES(* imcc)
        FUNC_MODIFIES(*unit);

PARROT_CAN_RETURN_NULL
static Instruction* pcc_get_args(
    ARGMOD(imc_info_t * imcc),
    ARGMOD(IMC_Unit *unit),
    ARGIN(Instruction *ins),
    ARGIN(const char *op_name),
    int n,
    ARGIN_NULLOK(SymReg * const *args),
    ARGIN_NULLOK(const int *arg_flags))
        __attribute__nonnull__(1)
        __attribute__nonnull__(2)
        __attribute__nonnull__(3)
        __attribute__nonnull__(4)
        FUNC_MODIFIES(* imcc)
        FUNC_MODIFIES(*unit);

static void unshift_self(
    ARGMOD(imc_info_t * imcc),
    ARGIN(SymReg *sub),
    ARGIN(SymReg *obj))
        __attribute__nonnull__(1)
        __attribute__nonnull__(2)
        __attribute__nonnull__(3)
        FUNC_MODIFIES(* imcc);

#define ASSERT_ARGS_insert_tail_call __attribute__unused__ int _ASSERT_ARGS_CHECK = (\
       PARROT_ASSERT_ARG(imcc) \
    , PARROT_ASSERT_ARG(unit) \
    , PARROT_ASSERT_ARG(ins) \
    , PARROT_ASSERT_ARG(sub))
#define ASSERT_ARGS_insINS __attribute__unused__ int _ASSERT_ARGS_CHECK = (\
       PARROT_ASSERT_ARG(imcc) \
    , PARROT_ASSERT_ARG(unit) \
    , PARROT_ASSERT_ARG(ins) \
    , PARROT_ASSERT_ARG(name) \
    , PARROT_ASSERT_ARG(regs))
#define ASSERT_ARGS_pcc_get_args __attribute__unused__ int _ASSERT_ARGS_CHECK = (\
       PARROT_ASSERT_ARG(imcc) \
    , PARROT_ASSERT_ARG(unit) \
    , PARROT_ASSERT_ARG(ins) \
    , PARROT_ASSERT_ARG(op_name))
#define ASSERT_ARGS_unshift_self __attribute__unused__ int _ASSERT_ARGS_CHECK = (\
       PARROT_ASSERT_ARG(imcc) \
    , PARROT_ASSERT_ARG(sub) \
    , PARROT_ASSERT_ARG(obj))
/* Don't modify between HEADERIZER BEGIN / HEADERIZER END.  Your changes will be lost. */
/* HEADERIZER END: static */

/*

=item C<static Instruction * insINS(imc_info_t * imcc, IMC_Unit *unit,
Instruction *ins, const char *name, SymReg **regs, int n)>

Utility instruction routine. Creates and inserts an instruction
into the current block in one call.

=cut

*/

PARROT_WARN_UNUSED_RESULT
PARROT_CAN_RETURN_NULL
static Instruction *
insINS(ARGMOD(imc_info_t * imcc), ARGMOD(IMC_Unit *unit), ARGIN(Instruction *ins),
        ARGIN(const char *name), ARGIN(SymReg **regs), int n)
{
    ASSERT_ARGS(insINS)
    /* INS can return NULL, but insert_ins() cannot take one */
    Instruction * const tmp = INS(imcc, unit, name, NULL, regs, n, 0, 0);
    if (tmp)
        insert_ins(unit, ins, tmp);
    return tmp;
}

/*

=item C<SymReg* get_pasm_reg(imc_info_t * imcc, const char *name)>

get or create the SymReg

=cut

*/

PARROT_WARN_UNUSED_RESULT
PARROT_CANNOT_RETURN_NULL
SymReg*
get_pasm_reg(ARGMOD(imc_info_t * imcc), ARGIN(const char *name))
{
    ASSERT_ARGS(get_pasm_reg)
    SymReg * const r = _get_sym(&imcc->cur_unit->hash, name);

    if (r)
        return r;

    return mk_pasm_reg(imcc, name);
}

/*

=item C<SymReg* get_const(imc_info_t * imcc, const char *name, int type)>

get or create a constant

=cut

*/

PARROT_WARN_UNUSED_RESULT
PARROT_CANNOT_RETURN_NULL
SymReg*
get_const(ARGMOD(imc_info_t * imcc), ARGIN(const char *name), int type)
{
    ASSERT_ARGS(get_const)
    SymReg * const r = _get_sym(&imcc->ghash, name);

    if (r && r->set == type)
        return r;

    return mk_const(imcc, name, type);
}

/*

=item C<static Instruction* pcc_get_args(imc_info_t * imcc, IMC_Unit *unit,
Instruction *ins, const char *op_name, int n, SymReg * const *args, const int
*arg_flags)>

set arguments or return values
get params or results
used by expand_pcc_sub_call and expand_pcc_sub

=cut

*/

PARROT_CAN_RETURN_NULL
static Instruction*
pcc_get_args(ARGMOD(imc_info_t * imcc), ARGMOD(IMC_Unit *unit),
        ARGIN(Instruction *ins), ARGIN(const char *op_name), int n,
        ARGIN_NULLOK(SymReg * const *args), ARGIN_NULLOK(const int *arg_flags))
{
    ASSERT_ARGS(pcc_get_args)
    /* Notes:
     * The created string is in the format "\"(0x0010,0x0220,0x0010)\"".
     * flags always has exactly 4 hex digits.
     * The hex number at the end of the list has no "," but we can safely
     * ignore this.
     */
    static const char pref[] = {'"', '('};
    static const char item[] = {'0', 'x', 'f', 'f', 'f', 'f', ','};
    /* The list suffix includes the '\0' terminator */
    static const char subf[] = {')', '"', '\0'};
    static const unsigned int lenpref = sizeof pref;
    static const unsigned int lenitem = sizeof item;
    static const unsigned int lensubf = sizeof subf;
    int i, flags;
    char s[16];

    /* Avoid allocations on frequent number of params.
     * Arbitrary value, some fine tuning may be good.
     */
    #define PCC_GET_ARGS_LIMIT 15
    SymReg *regcache[PCC_GET_ARGS_LIMIT + 1];
    char bufcache[sizeof (pref) + sizeof (item) * PCC_GET_ARGS_LIMIT + sizeof (subf)];

    SymReg ** const regs  = n < PCC_GET_ARGS_LIMIT ? regcache
                            : mem_gc_allocate_n_zeroed_typed(imcc->interp, n + 1, SymReg *);

    unsigned int  bufpos  = 0;
    unsigned int  bufsize = lenpref + lenitem * n + lensubf;
    char         *buf     = n < PCC_GET_ARGS_LIMIT ? bufcache
                            : mem_gc_allocate_n_typed(imcc->interp, bufsize, char);

    memcpy(buf, pref, lenpref);
    bufpos += lenpref;
    for (i = 0; i < n; i++) {
        SymReg *arg = args[i];

        if (arg->type & VT_CONSTP) {
            arg = arg->reg;
            if (! arg)
                IMCC_fatal(imcc, 1, "wrong .const value");
        }

        regs[i + 1] = arg;
        flags       = 0;

        /* TODO: Should we be throwing normal Parrot exceptions here or
                 IMCC_fatal exceptions? */
        if (arg_flags[i] & VT_CALL_SIG) {
            if ((n > 1 || i != 0) && !(n == 2 && strcmp(args[0]->name, "self") == 0))
                Parrot_ex_throw_from_c_noargs(imcc->interp, EXCEPTION_INTERNAL_PANIC,
                    ":call_sig must be the first and only parameter besides self");
            if (arg_flags[i] & (VT_FLAT | VT_OPTIONAL | VT_OPT_FLAG | VT_NAMED))
                Parrot_ex_throw_from_c_noargs(imcc->interp, EXCEPTION_INTERNAL_PANIC,
                    ":call_sig cannot be combined with any other flags");
            if (arg->set != 'P')
                Parrot_ex_throw_from_c_noargs(imcc->interp, EXCEPTION_INTERNAL_PANIC,
                    ":call_sig must be a PMC");
            flags |= PARROT_ARG_CALL_SIG;
            flags |= PARROT_ARG_PMC;
        }
        else {
            if (arg_flags[i] & VT_FLAT)
                flags |= PARROT_ARG_FLATTEN;

            if (arg_flags[i] & VT_OPTIONAL)
                flags |= PARROT_ARG_OPTIONAL;
            else if (arg_flags[i] & VT_OPT_FLAG)
                flags |= PARROT_ARG_OPT_FLAG;

            if (arg_flags[i] & VT_NAMED)
                flags |= PARROT_ARG_NAME;

            /* add argument type bits */
            if (arg->type & VTCONST)
                flags |= PARROT_ARG_CONSTANT;

            /* TODO verify if const is allowed */
            switch (arg->set) {
              case 'I':
                break;
              case 'S':
                flags |= PARROT_ARG_STRING;
                break;
              case 'N':
                flags |= PARROT_ARG_FLOATVAL;
                break;
              case 'K':
              case 'P':
                flags |= PARROT_ARG_PMC;
                break;
              default :
                break;
            }
        }

        snprintf(s, sizeof (s), "0x%.4x,", flags);
        if (bufpos + lenitem >= bufsize)
            Parrot_ex_throw_from_c_noargs(imcc->interp, EXCEPTION_INTERNAL_PANIC,
                    "arg string is longer than allocated buffer");
        memcpy(buf + bufpos, s, lenitem);
        bufpos += lenitem;
    }

    /* Backtrack over the ending comma if this is a non-empty list. */
    if (bufpos != lenpref)
        bufpos--;
    memcpy(buf + bufpos, subf, lensubf);

    regs[0] = mk_const(imcc, buf, 'P');
    regs[0]->pmc_type = enum_class_FixedIntegerArray;
    ins     = insINS(imcc, unit, ins, op_name, regs, n + 1);

    if (n >= PCC_GET_ARGS_LIMIT) {
        mem_sys_free(regs);
        mem_sys_free(buf);
    }
    return ins;
    #undef PCC_GET_ARGS_LIMIT
}

/*

=item C<static void unshift_self(imc_info_t * imcc, SymReg *sub, SymReg *obj)>

prepend the object to args or self to params

=cut

*/

static void
unshift_self(ARGMOD(imc_info_t * imcc), ARGIN(SymReg *sub), ARGIN(SymReg *obj))
{
    ASSERT_ARGS(unshift_self)
    struct pcc_sub_t * const pcc_sub = sub->pcc_sub;
    const int                n       = pcc_sub->nargs;
    int                      i;

    pcc_sub->args      = mem_gc_realloc_n_typed(imcc->interp, pcc_sub->args,
                                n + 1, SymReg *);
    pcc_sub->arg_flags = mem_gc_realloc_n_typed(imcc->interp, pcc_sub->arg_flags,
                                n + 1, int);

    for (i = n; i; --i) {
        pcc_sub->args[i]      = pcc_sub->args[i - 1];
        pcc_sub->arg_flags[i] = pcc_sub->arg_flags[i - 1];
    }

    pcc_sub->args[0]      = obj;
    pcc_sub->arg_flags[0] = 0;
    pcc_sub->nargs++;
}

/*

=item C<void expand_pcc_sub(imc_info_t * imcc, IMC_Unit *unit, Instruction
*ins)>

Expand a PCC (Parrot Calling Convention) subroutine
by generating the appropriate prologue and epilogue
for parameter passing/returning.

=cut

*/

void
expand_pcc_sub(ARGMOD(imc_info_t * imcc), ARGMOD(IMC_Unit *unit), ARGIN(Instruction *ins))
{
    ASSERT_ARGS(expand_pcc_sub)
    int          nargs;
    SymReg      *sub = ins->symregs[0];
    SymReg      *regs[2];

    /* if this sub is a method, unshift 'self' as first param */
    if ((unit->type & IMC_HAS_SELF)
    ||  (sub->pcc_sub->pragma & (P_METHOD | P_VTABLE))) {
        SymReg *self = get_sym(imcc, "self");
        if (!self) {
            self       = mk_symreg(imcc, "self", 'P');
            self->type = VTIDENTIFIER;
        }

        if (sub->pcc_sub->nargs == 0 || STRNEQ(sub->pcc_sub->args[0]->name, "self"))
            unshift_self(imcc, sub, self);
    }

    /* Don't generate any parameter checking code if there
     * are no named arguments.  */
    nargs = sub->pcc_sub->nargs;

    if (nargs)
        ins = pcc_get_args(imcc, unit, ins, "get_params", nargs,
                sub->pcc_sub->args, sub->pcc_sub->arg_flags);

    /* check if there is a return */
    if (unit->last_ins->type          & (ITPCCSUB)
    &&  unit->last_ins->symreg_count == 1) {
        sub = unit->last_ins->symregs[0];

        if (sub->pcc_sub
        && !sub->pcc_sub->object
        /* s. src/inter_call.c:119 */
        && sub->pcc_sub->tailcall) {
            IMCC_debug(imcc, DEBUG_IMC, "sub tailcall - %s\n", unit->last_ins->opname);
            return;
        }
    }

    if (unit->last_ins->type != (ITPCCSUB|ITLABEL)
            && STRNEQ(unit->last_ins->opname, "ret")
            && STRNEQ(unit->last_ins->opname, "exit")
            && STRNEQ(unit->last_ins->opname, "end")
            && STRNEQ(unit->last_ins->opname, "branch")
               /* was adding rets multiple times... */
            && STRNEQ(unit->last_ins->opname, "returncc")) {
        Instruction *tmp;

        /* check to make sure the sub is ok before we try to use it */
        if (!sub)
            Parrot_ex_throw_from_c_noargs(imcc->interp, EXCEPTION_UNEXPECTED_NULL,
                    "NULL sub detected");

        if (!sub->pcc_sub)
            Parrot_ex_throw_from_c_noargs(imcc->interp, EXCEPTION_UNEXPECTED_NULL,
                "NULL sub->pcc_sub detected");

        {
            (void)pcc_get_args(imcc, unit, unit->last_ins,
                    "set_returns", 0, NULL, NULL);
            tmp = INS(imcc, unit, "returncc", NULL, regs, 0, 0, 0);
        }

        IMCC_debug(imcc, DEBUG_IMC, "add sub ret - %d %s\n", tmp, unit->last_ins->opname);
        insert_ins(unit, unit->last_ins, tmp);
    }
    /* end is currently forbidden inside methods. it will be translated to a returncc */
    else if (STREQ(unit->last_ins->opname, "end") && sub && sub->pcc_sub) {
        Instruction *tmp;
        IMCC_debug(imcc, DEBUG_IMC, "sub ret via end => returncc\n");
        tmp = INS(imcc, unit, "returncc", NULL, regs, 0, 0, 0);
        subst_ins(unit, unit->last_ins, tmp, 1);
    }
}

/*

=item C<void expand_pcc_sub_ret(imc_info_t * imcc, IMC_Unit *unit, Instruction
*ins)>

Expand a PCC sub return directive into its PASM instructions

=cut

*/

void
expand_pcc_sub_ret(ARGMOD(imc_info_t * imcc), ARGMOD(IMC_Unit *unit),
        ARGIN(Instruction *ins))
{
    ASSERT_ARGS(expand_pcc_sub_ret)
    const int is_yield = ins->type & ITPCCYIELD;
    SymReg * const sub = ins->symregs[0];
    const int n        = sub->pcc_sub->nret;

    /* TODO implement return conventions */
    ins = pcc_get_args(imcc, unit, ins, "set_returns", n,
                       sub->pcc_sub->ret, sub->pcc_sub->ret_flags);

    /* we have a pcc_begin_yield */
    if (is_yield) {
        SymReg *regs[2];
        ins        = insINS(imcc, unit, ins, "yield", regs, 0);
        ins->type |= ITPCCYIELD;
    }
    else {
        SymReg *regs[2];
        /* insert return invoke */
        ins        = insINS(imcc, unit, ins, "returncc", regs, 0);
        ins->type |= ITPCCRET;
    }
}

typedef struct move_info_t {
    IMC_Unit    *unit;
    NOTNULL(Instruction *ins);
    int          n;
    SymReg      **dest;
    SymReg      **src;
} move_info_t;

/*

=item C<static void insert_tail_call(imc_info_t * imcc, IMC_Unit *unit,
Instruction *ins, SymReg *sub, SymReg *meth)>

Creates and inserts an appropriate tailcall instruction for either a sub call
or a method call.

=cut

*/

static void
insert_tail_call(ARGMOD(imc_info_t * imcc), ARGIN(IMC_Unit *unit),
        ARGMOD(Instruction *ins), ARGMOD(SymReg *sub), ARGIN_NULLOK(SymReg *meth))
{
    ASSERT_ARGS(insert_tail_call)
    SymReg *regs[3];

    if (meth) {
        regs[0] = sub->pcc_sub->object;
        regs[1] = meth;
        ins     = insINS(imcc, unit, ins, "tailcallmethod", regs, 2);
    }
    else {
        regs[0] = sub->pcc_sub->sub;
        ins     = insINS(imcc, unit, ins, "tailcall", regs, 1);
    }

    /* don't leak this sub SymReg; it gets detached here */
    if (regs[0]->pcc_sub)
        free_pcc_sub(regs[0]->pcc_sub);

    /* this register is always the symbol "self", global to this IMC_Unit */
    regs[0]->pcc_sub  = sub->pcc_sub;

    sub->pcc_sub      = NULL;
    ins->type        |= ITPCCSUB;
}

/*

=item C<void expand_pcc_sub_call(imc_info_t * imcc, IMC_Unit *unit, Instruction
*ins)>

Expand a PCC subroutine call (IMC) into its PASM instructions
This is the nuts and bolts of pdd03 routine call style

=cut

*/

void
expand_pcc_sub_call(ARGMOD(imc_info_t * imcc), ARGMOD(IMC_Unit *unit),
        ARGMOD(Instruction *ins))
{
    ASSERT_ARGS(expand_pcc_sub_call)
    SymReg *arg, *reg, *regs[3];
    int          n;
    int          tail_call;
    int          meth_call = 0;
    SymReg      *meth      = NULL;
    Instruction *get_name;

    SymReg * const sub = ins->symregs[0];

    PARROT_ASSERT(sub);
    PARROT_ASSERT(sub->pcc_sub);

    if (ins->type & ITRESULT) {
        const int nret = sub->pcc_sub->nret;
        ins         = pcc_get_args(imcc, unit, ins, "get_results", nret,
                        sub->pcc_sub->ret, sub->pcc_sub->ret_flags);
        return;
    }

    tail_call = sub->pcc_sub->tailcall;

    if (sub->pcc_sub->object)
        meth_call = 1;

    /*
     * See if we need to create a temporary sub object for the short
     * function call syntax _f()
     */
    get_name = NULL;

    if (ins->type & ITCALL) {
        SymReg * const the_sub = sub->pcc_sub->sub;
        /* If this condition is true the generator must haven't be called,
         * but check it as a last resort.
         * See also TT #737 */
        if (the_sub == NULL)
            IMCC_fatal(imcc, 1, "expand_pcc_sub_call: no such sub");

        if (!meth_call && (the_sub->type & VTADDRESS)) {
            /* sub->pcc_sub->sub is an actual subroutine name, not a variable */
            reg = mk_temp_reg(imcc, 'P');
            add_pcc_sub(sub, reg);

            /* insert set_p_pc with the sub as constant */
            the_sub->set    = 'p';
            the_sub->usage |= U_FIXUP;
            the_sub->type  &= ~VTADDRESS;
            the_sub->type  |= VTCONST;   /* preserve VT_ENCODED */
            regs[0]         = reg;
            regs[1]         = the_sub;

            /*
             * set_p_pc gets replaced in imcc/pbc.c, if the
             * function can't be located in the current namespace
             */
            get_name   = INS(imcc, unit, "set_p_pc", "", regs, 2, 0, 0);
            ins->type &= ~ITCALL;
        }
    }

    if (sub->pcc_sub->object)
        unshift_self(imcc, sub, sub->pcc_sub->object);

    /* insert arguments */
    n   = sub->pcc_sub->nargs;
    ins = pcc_get_args(imcc, unit, ins, "set_args", n,
            sub->pcc_sub->args, sub->pcc_sub->arg_flags);

    /*
     * insert get_name after args have been setup, so that
     * a possible MMD call can inspect the passed arguments
     */
    if (get_name) {
        insert_ins(unit, ins, get_name);
        ins = get_name;
    }

    arg = sub->pcc_sub->sub;
    if (arg == NULL)
        Parrot_ex_throw_from_c_noargs(imcc->interp, EXCEPTION_UNEXPECTED_NULL,
            "Subroutine is not defined");

    if (meth_call) {
        meth = arg;

        if (arg->set != 'P') {
            if (!(arg->type == VTIDENTIFIER
            ||    arg->type == VTPASM
            ||    arg->type == VTREG)) {
                if (arg->type & VT_ENCODED) {
                    meth = mk_const(imcc, arg->name, 'U');
                }
                else {
                    meth = mk_const(imcc, arg->name, 'S');
                }
            }
        }
    }

    /* if we have a tail call then insert a tailcall opcode */
    if (tail_call) {
        insert_tail_call(imcc, unit, ins, sub, meth);
        return;
    }

    /* insert the call */
    if (meth_call) {
        regs[0] = sub->pcc_sub->object;
        regs[1] = meth;
        arg     = sub->pcc_sub->cc;

        if (arg) {
            regs[2] = arg;
            ins     = insINS(imcc, unit, ins, "callmethod" , regs, 3);
        }
        else {
            ins = insINS(imcc, unit, ins, "callmethodcc" , regs, 2);
        }
    }
    else {
        regs[0] = sub->pcc_sub->sub;
        arg     = sub->pcc_sub->cc;

        if (arg) {
            regs[1] = arg;
            ins     = insINS(imcc, unit, ins, "invoke" , regs, 2);
        }
        else {
            ins = insINS(imcc, unit, ins, "invokecc" , regs, 1);
        }
    }

    ins->type |= ITPCCSUB;

    /* handle return results */
    n   = sub->pcc_sub->nret;
    ins = pcc_get_args(imcc, unit, ins, "get_results", n,
            sub->pcc_sub->ret, sub->pcc_sub->ret_flags);
}

/*

=back

=cut

*/

/*
 * Local variables:
 *   c-file-style: "parrot"
 * End:
 * vim: expandtab shiftwidth=4 cinoptions='\:2=2' :
 */
