/* 
 * code generator for runtime LPC code
 */
#include "std.h"
#include "lpc_incl.h"
#include "icode.h"
#include "compiler.h"
#include "generate.h"

static void ins_real (double);
static void ins_short (short);
static void upd_short (int, int, const char *);
static void ins_byte (unsigned char);
static void upd_byte (int, unsigned char);
static void write_number (long);
static void ins_int (long);
#if SIZEOF_PTR == 8
static void ins_long (long);
#endif
void i_generate_node (parse_node_t *);
static void i_generate_if_branch (parse_node_t *, int);
static void i_generate_loop (int, parse_node_t *, parse_node_t *, 
                                  parse_node_t *);
static void i_update_branch_list (parse_node_t *, const char *);
static int try_to_push (int, int);

static int foreach_depth = 0;

static int current_num_values;

static unsigned int last_size_generated;
static unsigned int line_being_generated;

static int push_state;
static int push_start;

static parse_node_t *branch_list[3];
static int nforward_branches, nforward_branches_max;
static int *forward_branches = 0;

static void ins_real (double l)
{
    float f = (float)l;

    if (prog_code + 4 > prog_code_max) {
        mem_block_t *mbp = &mem_block[A_PROGRAM];

        UPDATE_PROGRAM_SIZE;
        realloc_mem_block(mbp);
        
        prog_code = mbp->block + mbp->current_size;
        prog_code_max = mbp->block + mbp->max_size;
    }
    STORE_FLOAT(prog_code, f);
}

/*
 * Store a 2 byte number. It is stored in such a way as to be sure
 * that correct byte order is used, regardless of machine architecture.
 * Also beware that some machines can't write a word to odd addresses.
 */
static void ins_short (short l)
{
    if (prog_code + 2 > prog_code_max) {
        mem_block_t *mbp = &mem_block[A_PROGRAM];
        UPDATE_PROGRAM_SIZE;
        realloc_mem_block(mbp);
        
        prog_code = mbp->block + mbp->current_size;
        prog_code_max = mbp->block + mbp->max_size;
    }
    STORE_SHORT(prog_code, l);
}

/*
 * Store a 4 byte number. It is stored in such a way as to be sure
 * that correct byte order is used, regardless of machine architecture.
 */
static void ins_int (long l)
{

    if (prog_code + SIZEOF_LONG > prog_code_max) {
        mem_block_t *mbp = &mem_block[A_PROGRAM];
        UPDATE_PROGRAM_SIZE;
        realloc_mem_block(mbp);
        
        prog_code = mbp->block + mbp->current_size;
        prog_code_max = mbp->block + mbp->max_size;
    }
    STORE_INT(prog_code, l);
}

/*
 * Store a 8 byte number. It is stored in such a way as to be sure
 * that correct byte order is used, regardless of machine architecture.
 */
#if SIZEOF_PTR == 8
static void ins_long (long l)
{
    if (prog_code + 8 > prog_code_max) {
        mem_block_t *mbp = &mem_block[A_PROGRAM];
        UPDATE_PROGRAM_SIZE;
        realloc_mem_block(mbp);
        
        prog_code = mbp->block + mbp->current_size;
        prog_code_max = mbp->block + mbp->max_size;
    }
    STORE_PTR(prog_code, l);
}
#endif

static void upd_short (int offset, int l, const char * where)
{
    unsigned short s;
    
    IF_DEBUG(UPDATE_PROGRAM_SIZE);
    DEBUG_CHECK2(offset > CURRENT_PROGRAM_SIZE,
                 "patch offset %x larger than current program size %x.\n",
                 offset, CURRENT_PROGRAM_SIZE);
    if (l > USHRT_MAX) {
        char buf[256];
        
        sprintf(buf, "branch limit exceeded in %s, near line %i",
                where, line_being_generated);
        yyerror(buf);
    }
    s = l;
    
    COPY_SHORT(mem_block[A_PROGRAM].block + offset, &s);
}

static void ins_rel_short (int l)
{
    if (l > USHRT_MAX) {
        char buf[256];
        
        sprintf(buf, "branch limit exceeded in switch table, near line %i",
                line_being_generated);
        yyerror(buf);
    }
    ins_short(l);
}

static void ins_byte (unsigned char b)
{
    if (prog_code == prog_code_max) {
        mem_block_t *mbp = &mem_block[A_PROGRAM];
        UPDATE_PROGRAM_SIZE;
        realloc_mem_block(mbp);
        
        prog_code = mbp->block + mbp->current_size;
        prog_code_max = mbp->block + mbp->max_size;
    }
    *prog_code++ = b;
}

static void upd_byte (int offset, unsigned char b)
{
    IF_DEBUG(UPDATE_PROGRAM_SIZE);
    DEBUG_CHECK2(offset > CURRENT_PROGRAM_SIZE,
                "patch offset %x larger than current program size %x.\n",
                offset, CURRENT_PROGRAM_SIZE);
    mem_block[A_PROGRAM].block[offset] = b;
}

static void end_pushes (void) {
    if (push_state) {
        if (push_state > 1)
            upd_byte(push_start, push_state);
        push_state = 0;
    }
}

//
// F_PUSH pushes multiple data items onto the stack.  This function
// sets up the multi push by reading the single push off the top of
// the stack and rewriting the mult-push into the stack.
//

static void initialize_push (void) {
    int what = mem_block[A_PROGRAM].block[push_start];
    int arg = 0;

    // This is only valid if it is not a one byte const target.
    if (what != F_CONST0 && what != F_CONST1) {
       arg = mem_block[A_PROGRAM].block[push_start + 1];
    }
    prog_code = mem_block[A_PROGRAM].block + push_start;
    ins_byte(F_PUSH);
    push_start++; /* now points to the zero here */
    ins_byte(0);

    switch (what) {
    case F_CONST0:
        ins_byte(PUSH_NUMBER | 0);
        break;
    case F_CONST1:
        ins_byte(PUSH_NUMBER | 1);
        break;
    case F_BYTE:
        ins_byte(PUSH_NUMBER | arg);
        break;
    case F_SHORT_STRING:
        ins_byte(PUSH_STRING | arg);
        break;
    case F_LOCAL:
        ins_byte(PUSH_LOCAL | arg);
        break;
    case F_GLOBAL:
        ins_byte(PUSH_GLOBAL | arg);
        break;
    }
}


/*
 * Generate the code to push a number on the stack.
 * This varies since there are several opcodes (for
 * optimizing speed and/or size).
 */
static void write_small_number (int val) {
    if (try_to_push(PUSH_NUMBER, val)) return;
    ins_byte(F_BYTE);
    ins_byte(val);
}

static void write_number (long val)
{
    if ((val & ~0xff) == 0)
        write_small_number(val);
    else {
        end_pushes();
        if (val < 0 && val > -256) {
            ins_byte(F_NBYTE);
            ins_byte(-val);
        } else if (val >= -32768 && val <= 32767) {
            ins_byte(F_SHORT_INT);
            ins_short(val);
        } else {
            ins_byte(F_NUMBER);
#if SIZEOF_LONG == 4
            ins_int(val);
#else
	    ins_long(val);
#endif
        }
    }
}

static void
generate_expr_list (parse_node_t * expr) {
    parse_node_t *pn;
    int n, flag;
    
    if (!expr) return;
    pn = expr;
    flag = n = 0;
    do {
        if (pn->type & 1) flag = 1;
        i_generate_node(pn->v.expr);
        n++;
    } while ((pn = pn->r.expr));
    
    if (flag) {
        pn = expr;
        do {
            n--;
            if (pn->type & 1) {
                end_pushes();
                ins_byte(F_EXPAND_VARARGS);
                ins_byte(n);
            }
        } while ((pn = pn->r.expr));
    }
}

static void
generate_lvalue_list (parse_node_t * expr) {
    while ((expr = expr->r.expr)) {
      i_generate_node(expr->l.expr);
      end_pushes();
      ins_byte(F_VOID_ASSIGN);
    }
}

INLINE_STATIC void
switch_to_line (unsigned int line) {
    unsigned int sz = CURRENT_PROGRAM_SIZE - last_size_generated;
    ADDRESS_TYPE s;
    unsigned char *p;

    if (sz) {
        s = line_being_generated;

        last_size_generated += sz;
        while (sz > 255) {
            p = (unsigned char *)allocate_in_mem_block(A_LINENUMBERS, sizeof(ADDRESS_TYPE) + 1);
            *p++ = 255;
#if !defined(USE_32BIT_ADDRESSES) 
            STORE_SHORT(p, s);
#else
            STORE4(p, s);
#endif
            sz -= 255;
        }
        p = (unsigned char *)allocate_in_mem_block(A_LINENUMBERS, sizeof(ADDRESS_TYPE) + 1);
        *p++ = sz;
#if !defined(USE_32BIT_ADDRESSES) 
        STORE_SHORT(p, s);
#else
        STORE4(p, s);
#endif
    }
    line_being_generated = line;
}

static int
try_to_push (int kind, int value) {
    if (push_state) {
        if (value <= PUSH_MASK) {
            if (push_state == 1)
                initialize_push();
            push_state++;
            ins_byte(kind | value);
            if (push_state == 255)
                end_pushes();
            return 1;
        } else end_pushes();
    } else if (value <= PUSH_MASK) {
        push_start = CURRENT_PROGRAM_SIZE;
        push_state = 1;
        switch (kind) {
        case PUSH_STRING: ins_byte(F_SHORT_STRING); break;
        case PUSH_LOCAL: ins_byte(F_LOCAL); break;
        case PUSH_GLOBAL: ins_byte(F_GLOBAL); break;
        case PUSH_NUMBER: 
            if (value == 0) {
                ins_byte(F_CONST0);
                return 1;
            } else if (value == 1) {
                ins_byte(F_CONST1);
                return 1;
            }
            ins_byte(F_BYTE);
        }
        ins_byte(value);
        return 1;
    }
    return 0;
}

void
i_generate_node (parse_node_t * expr) {
    if (!expr) return;
    
    if (expr->line && expr->line != line_being_generated)
        switch_to_line(expr->line);
    switch (expr->kind) {
    case NODE_FUNCTION:
      {
          unsigned short num;
          
          /* In the following we know that this function wins all the */
          /* rest  - Sym                                              */

          num = FUNCTION_TEMP(expr->v.number)->u.index;
          FUNC(num)->address = generate_function(FUNC(num),
                                  expr->r.expr, expr->l.number);
          break;
      }
    case NODE_TERNARY_OP:
        i_generate_node(expr->l.expr);
        expr = expr->r.expr;
    case NODE_BINARY_OP:
        i_generate_node(expr->l.expr);
        /* fall through */
    case NODE_UNARY_OP:
        i_generate_node(expr->r.expr);
        /* fall through */
    case NODE_OPCODE:
        end_pushes();
        ins_byte(expr->v.number);
        break;
    case NODE_TERNARY_OP_1:
        i_generate_node(expr->l.expr);
        expr = expr->r.expr;
        /* fall through */
    case NODE_BINARY_OP_1:
        i_generate_node(expr->l.expr);
        i_generate_node(expr->r.expr);
        end_pushes();
        ins_byte(expr->v.number);
        ins_byte(expr->type);
        break;
    case NODE_UNARY_OP_1:
        i_generate_node(expr->r.expr);
        /* fall through */
    case NODE_OPCODE_1:
        if (expr->v.number == F_LOCAL) {
            if (try_to_push(PUSH_LOCAL, expr->l.number)) break;
        } else if (expr->v.number == F_GLOBAL) {
            if (try_to_push(PUSH_GLOBAL, expr->l.number)) break;
        }
        end_pushes();
        ins_byte(expr->v.number);
        ins_byte(expr->l.number);
        break;
    case NODE_OPCODE_2:
        end_pushes();
        ins_byte(expr->v.number);
        ins_byte(expr->l.number);
        if (expr->v.number == F_LOOP_COND_NUMBER)
#if SIZEOF_LONG == 8
            ins_long(expr->r.number);
#else
	    ins_int(expr->r.number);
#endif
        else 
            ins_byte(expr->r.number);
        break;
    case NODE_RETURN:
        {
            int n;
            n = foreach_depth;
            end_pushes();
            while (n--)
                ins_byte(F_EXIT_FOREACH);

            if (expr->r.expr) {
                i_generate_node(expr->r.expr);
                end_pushes();
                ins_byte(F_RETURN);
            } else ins_byte(F_RETURN_ZERO);
            break;
        }
    case NODE_STRING:
        if (try_to_push(PUSH_STRING, expr->v.number)) break;
        if (expr->v.number <= 0xff) {
            ins_byte(F_SHORT_STRING);
            ins_byte(expr->v.number);
        } else {
            ins_byte(F_STRING);
            ins_short(expr->v.number);
        }
        break;
    case NODE_REAL:
        end_pushes();
        ins_byte(F_REAL);
        ins_real(expr->v.real);
        break;
    case NODE_NUMBER:
        write_number(expr->v.number);
        break;
    case NODE_LAND_LOR:
        i_generate_node(expr->l.expr);
        i_generate_forward_branch(expr->v.number);
        i_generate_node(expr->r.expr);
        if (expr->l.expr->kind == NODE_BRANCH_LINK)
            i_update_forward_branch_links(expr->v.number,expr->l.expr);
        else 
            i_update_forward_branch("&& or ||");
        break;
    case NODE_BRANCH_LINK:
        i_generate_node(expr->l.expr);
        end_pushes();
        ins_byte(0);
        expr->v.number = CURRENT_PROGRAM_SIZE;
        ins_short(0);
        i_generate_node(expr->r.expr);
        break;
    case NODE_CALL_2:
        generate_expr_list(expr->r.expr);
        end_pushes();
        ins_byte(expr->v.number);
        ins_byte(expr->l.number >> 16);
        ins_short(expr->l.number & 0xffff);
        ins_byte((expr->r.expr ? expr->r.expr->kind : 0));
        break;
    case NODE_CALL_1:
        generate_expr_list(expr->r.expr);
        end_pushes();
        if (expr->v.number == F_CALL_FUNCTION_BY_ADDRESS) {
            expr->l.number = comp_def_index_map[expr->l.number];
        }
        ins_byte(expr->v.number);
        ins_short(expr->l.number);
        ins_byte((expr->r.expr ? expr->r.expr->kind : 0));
        break;
    case NODE_CALL:
        generate_expr_list(expr->r.expr);
        end_pushes();
        ins_byte(expr->v.number);
        ins_short(expr->l.number);
        break;
    case NODE_TWO_VALUES:
        i_generate_node(expr->l.expr);
        i_generate_node(expr->r.expr);
        break;
    case NODE_CONTROL_JUMP:
        {
            int kind = expr->v.number;
            end_pushes();
            ins_byte(F_BRANCH);
            expr->v.expr = branch_list[kind];
            expr->l.number = CURRENT_PROGRAM_SIZE;
            ins_short(0);
            branch_list[kind] = expr;
            break;
        }
    case NODE_PARAMETER:
        {
            int which = expr->v.number + current_num_values;
            if (try_to_push(PUSH_LOCAL, which)) break;
            ins_byte(F_LOCAL);
            ins_byte(which);
            break;
        }
    case NODE_PARAMETER_LVALUE:
        end_pushes();
        ins_byte(F_LOCAL_LVALUE);
        ins_byte(expr->v.number + current_num_values);
        break;
    case NODE_IF:
        i_generate_if_branch(expr->v.expr, 0);
        i_generate_node(expr->l.expr);
        if (expr->r.expr) {
            i_generate_else();
            i_generate_node(expr->r.expr);
        }
        i_update_forward_branch("if");
        break;
    case NODE_LOOP:
        i_generate_loop(expr->type, expr->v.expr, expr->l.expr, expr->r.expr);
        break;
    case NODE_FOREACH:
        {
            int tmp = 0;

            i_generate_node(expr->v.expr);
            end_pushes();
            ins_byte(F_FOREACH);
            if (expr->l.expr->v.number == F_GLOBAL_LVALUE) 
                tmp |= FOREACH_RIGHT_GLOBAL;
            else if (expr->l.expr->v.number == F_REF_LVALUE)
                tmp |= FOREACH_REF;
            if (expr->r.expr) {
                if (tmp & FOREACH_RIGHT_GLOBAL)
                    tmp = (tmp & ~FOREACH_RIGHT_GLOBAL) | FOREACH_LEFT_GLOBAL;

                tmp |= FOREACH_MAPPING;
                if (expr->r.expr->v.number == F_GLOBAL_LVALUE) 
                    tmp |= FOREACH_RIGHT_GLOBAL;
                else if (expr->r.expr->v.number == F_REF_LVALUE)
                    tmp |= FOREACH_REF;
            }
            ins_byte(tmp);
            ins_byte(expr->l.expr->l.number);
            if (expr->r.expr)
                ins_byte(expr->r.expr->l.number);
        }
        break;
    case NODE_CASE_NUMBER:
    case NODE_CASE_STRING:
        if (expr->v.expr) {
            parse_node_t *other = expr->v.expr;
            expr->v.number = 1;
            other->l.expr = expr->l.expr;
            other->v.number = CURRENT_PROGRAM_SIZE;
            expr->l.expr = other;
        } else {
            expr->v.number = CURRENT_PROGRAM_SIZE;
        }
        end_pushes();
        break;
    case NODE_DEFAULT:
        expr->v.number = CURRENT_PROGRAM_SIZE;
        end_pushes();
        break;
    case NODE_SWITCH_STRINGS:
    case NODE_SWITCH_NUMBERS:
    case NODE_SWITCH_DIRECT:
    case NODE_SWITCH_RANGES:
        {
            long addr, last_break;
            parse_node_t *sub = expr->l.expr;
            parse_node_t *save_switch_breaks = branch_list[CJ_BREAK_SWITCH];
            
            i_generate_node(sub);
            branch_list[CJ_BREAK_SWITCH] = 0;
            end_pushes();
            ins_byte(F_SWITCH);
            addr = CURRENT_PROGRAM_SIZE;
            /* all these are addresses in here are relative to addr now,
             * which is also the value of pc in f_switch().  Note that
             * addr is one less than it was in older drivers.
             */
            ins_byte(0xff); /* kind of table */
            ins_short(0); /* address of table */
            ins_short(0); /* end of table */
            ins_short(0); /* default address */
            i_generate_node(expr->r.expr);
            if (expr->v.expr && expr->v.expr->kind == NODE_DEFAULT) {
                upd_short(addr + 5, expr->v.expr->v.number - addr,
                          "switch");
                expr->v.expr = expr->v.expr->l.expr;
            } else {
                upd_short(addr + 5, CURRENT_PROGRAM_SIZE - addr, "switch");
            }
            /* just in case the last case doesn't have a break */
            end_pushes();
            ins_byte(F_BRANCH);
            last_break = CURRENT_PROGRAM_SIZE;
            ins_short(0);
            /* build table */
            upd_short(addr + 1, CURRENT_PROGRAM_SIZE - addr, "switch");
#ifdef BINARIES
            if (pragmas & PRAGMA_SAVE_BINARY) {
                if (expr->kind == NODE_SWITCH_STRINGS) {
                    short sw;
                    sw = addr - 1;
                    add_to_mem_block(A_PATCH, (char *)&sw, sizeof sw);
                }
            }
#endif
            if (expr->kind == NODE_SWITCH_DIRECT) {
                parse_node_t *pn = expr->v.expr;
                while (pn) {
                    ins_rel_short(pn->v.number - addr);
                    pn = pn->l.expr;
                }
                ins_int(expr->v.expr->r.number);
                mem_block[A_PROGRAM].block[addr] = (char)0xfe;
            } else {
                int table_size = 0;
                int power_of_two = 1;
                int i = 0;
                parse_node_t *pn = expr->v.expr;
                
                while (pn) {
                    if (expr->kind == NODE_SWITCH_STRINGS) {
                        if (pn->r.number) {
                            INS_POINTER((POINTER_INT)
                                        PROG_STRING(pn->r.number));
                        } else 
                            INS_POINTER((POINTER_INT)0);
                    } else
                        INS_POINTER((POINTER_INT)pn->r.expr);
                    if (pn->v.number == 1)
                        ins_short(1);
                    else
                        ins_rel_short(pn->v.number - addr);
                    pn = pn->l.expr;
                    table_size += 1;
                }
                while ((power_of_two<<1) <= table_size) {
                    power_of_two <<= 1;
                    i++;
                }
                if (expr->kind != NODE_SWITCH_STRINGS)
                    mem_block[A_PROGRAM].block[addr] = (char)(0xf0+i);
                else
                    mem_block[A_PROGRAM].block[addr] = (char)(i*0x10+0x0f);
            }
            i_update_branch_list(branch_list[CJ_BREAK_SWITCH], "switch break");
            branch_list[CJ_BREAK_SWITCH] = save_switch_breaks;
            upd_short(last_break, CURRENT_PROGRAM_SIZE - last_break, "switch break");
            upd_short(addr+3, CURRENT_PROGRAM_SIZE - addr, "switch");
            break;
        }
    case NODE_CATCH:
        {
            int addr;

            end_pushes();
            ins_byte(F_CATCH);
            addr = CURRENT_PROGRAM_SIZE;
            ins_short(0);
            i_generate_node(expr->r.expr);
            ins_byte(F_END_CATCH);
            upd_short(addr, CURRENT_PROGRAM_SIZE - addr, "catch");
            break;
        }
    case NODE_TIME_EXPRESSION:
        {
            end_pushes();
            ins_byte(F_TIME_EXPRESSION);
            i_generate_node(expr->r.expr);
            ins_byte(F_END_TIME_EXPRESSION);
            break;
        }
    case NODE_LVALUE_EFUN:
        i_generate_node(expr->l.expr);
        generate_lvalue_list(expr->r.expr);
        break;
    case NODE_FUNCTION_CONSTRUCTOR:
        if (expr->r.expr) {
            generate_expr_list(expr->r.expr);
            end_pushes();
            ins_byte(F_AGGREGATE);
            ins_short(expr->r.expr->kind);
        } else {
            end_pushes();
            ins_byte(F_CONST0);
        }
        end_pushes();

        ins_byte(F_FUNCTION_CONSTRUCTOR);
        ins_byte(expr->v.number & 0xff);

        switch (expr->v.number & 0xff) {
        case FP_SIMUL:
            ins_short(expr->v.number >> 8);
            break;
        case FP_LOCAL:
            ins_short(comp_def_index_map[expr->v.number >> 8]);
            break;
        case FP_EFUN:
            ins_short(predefs[expr->v.number >> 8].token);
            break;
        case FP_FUNCTIONAL:
        case FP_FUNCTIONAL | FP_NOT_BINDABLE:
            {
                int addr, save_current_num_values = current_num_values;
                ins_byte(expr->v.number >> 8);
                addr = CURRENT_PROGRAM_SIZE;
                ins_short(0);
                current_num_values = expr->r.expr ? expr->r.expr->kind : 0;
                i_generate_node(expr->l.expr);
                current_num_values = save_current_num_values;
                end_pushes();
                ins_byte(F_RETURN);
                upd_short(addr, CURRENT_PROGRAM_SIZE - addr - 2,
                          "function pointer");
                break;
            }
        }
        break;
    case NODE_ANON_FUNC:
        {
            int addr;
            int save_fd = foreach_depth;

            foreach_depth = 0;
            end_pushes();
            ins_byte(F_FUNCTION_CONSTRUCTOR);
            if (expr->v.number & 0x10000)
                ins_byte(FP_ANONYMOUS | FP_NOT_BINDABLE);
            else
                ins_byte(FP_ANONYMOUS);
            ins_byte(expr->v.number & 0xff);
            ins_byte(expr->l.number);
            addr = CURRENT_PROGRAM_SIZE;
            ins_short(0);
            i_generate_node(expr->r.expr);
            upd_short(addr, CURRENT_PROGRAM_SIZE - addr - 2,
                      "function pointer");
            foreach_depth = save_fd;
            break;
        }
    case NODE_EFUN:
        {
            int novalue_used = expr->v.number & NOVALUE_USED_FLAG;
            int f = expr->v.number & ~NOVALUE_USED_FLAG;
            
            generate_expr_list(expr->r.expr);
            end_pushes();
            if (f < ONEARG_MAX) {
                ins_byte(f);
            } else {
                /* max_arg == -1 must use F_EFUNV so that varargs expansion works*/
                if (expr->l.number < 4 && instrs[f].max_arg != -1)
                    ins_byte(F_EFUN0 + expr->l.number);
                else {
                    ins_byte(F_EFUNV);
                    ins_byte(expr->l.number);
                }
                ins_byte(f - ONEARG_MAX);
            }
            if (novalue_used) {
                /* the value of a void efun was used.  Put in a zero. */
                ins_byte(F_CONST0);
            }
            break;
	}
        default:
            fatal("Unknown node %i in i_generate_node.\n", expr->kind);
    }
}

static void i_generate_loop (int test_first, parse_node_t * block,
                               parse_node_t * inc, parse_node_t * test) {
    parse_node_t *save_breaks = branch_list[CJ_BREAK];
    parse_node_t *save_continues = branch_list[CJ_CONTINUE];
    int forever = node_always_true(test);
    int pos;
    
    if (test_first == 2) foreach_depth++;
    branch_list[CJ_BREAK] = branch_list[CJ_CONTINUE] = 0;
    end_pushes();
    if (!forever && test_first)
        i_generate_forward_branch(F_BRANCH);
    pos = CURRENT_PROGRAM_SIZE;
    i_generate_node(block);
    i_update_branch_list(branch_list[CJ_CONTINUE], "continue");
    if (inc) i_generate_node(inc);
    if (!forever && test_first) i_update_forward_branch("loop");
    if (test && (test->v.number == F_LOOP_COND_LOCAL ||
        test->v.number == F_LOOP_COND_NUMBER ||
        test->v.number == F_NEXT_FOREACH)) {
        i_generate_node(test);
        ins_short(CURRENT_PROGRAM_SIZE - pos);
    } else i_branch_backwards(generate_conditional_branch(test), pos);
    i_update_branch_list(branch_list[CJ_BREAK], "break");
    branch_list[CJ_BREAK] = save_breaks;
    branch_list[CJ_CONTINUE] = save_continues;
    if (test_first == 2) foreach_depth--;
}

static void
i_generate_if_branch (parse_node_t * node, int invert) {
    int generate_both = 0;
    int branch = (invert ? F_BRANCH_WHEN_NON_ZERO : F_BRANCH_WHEN_ZERO);
    
    switch (node->kind) {
    case NODE_UNARY_OP:
        if (node->v.number == F_NOT) {
            i_generate_if_branch(node->r.expr, !invert);
            return;
        }
        break;
    case NODE_BINARY_OP:
        switch (node->v.number) {
        case F_EQ:
            generate_both = 1;
            branch = (invert ? F_BRANCH_EQ : F_BRANCH_NE);
            break;
        case F_GE:
            if (invert) {
                generate_both = 1;
                branch = F_BRANCH_GE;
            }
            break;
        case F_LE:
            if (invert) {
                generate_both = 1;
                branch = F_BRANCH_LE;
            }
            break;
        case F_LT:
            if (!invert) {
                generate_both = 1;
                branch = F_BRANCH_GE;
            }
            break;
         case F_GT:
            if (!invert) {
                generate_both = 1;
                branch = F_BRANCH_LE;
            }
            break;
         case F_NE:
            generate_both = 1;
            branch = (invert ? F_BRANCH_NE : F_BRANCH_EQ);
            break;
        }
    }
    if (generate_both) {
        i_generate_node(node->l.expr);
        i_generate_node(node->r.expr);
    } else {
        i_generate_node(node);
    }
    i_generate_forward_branch(branch);
}

void
i_generate_inherited_init_call (int index, short f) {
    end_pushes();
    ins_byte(F_CALL_INHERITED);
    ins_byte(index);
    ins_short(f);
    ins_byte(0);
    ins_byte(F_POP_VALUE);
}

void i_generate_forward_branch (char b) {
    end_pushes();
    ins_byte(b);
    if (nforward_branches == nforward_branches_max) {
        nforward_branches_max += 10;
        forward_branches = RESIZE(forward_branches, nforward_branches_max, int,
                                  TAG_COMPILER, "forward_branches");
    }

    forward_branches[nforward_branches++] = CURRENT_PROGRAM_SIZE;
    ins_short(0);
}

void
i_update_forward_branch (const char * what) {
    end_pushes();
    nforward_branches--;
    upd_short(forward_branches[nforward_branches],
              CURRENT_PROGRAM_SIZE - forward_branches[nforward_branches],
              what);
}

void i_update_forward_branch_links (char kind, parse_node_t * link_start) {
    int i;

    end_pushes();
    nforward_branches--;
    upd_short(forward_branches[nforward_branches], 
              CURRENT_PROGRAM_SIZE - forward_branches[nforward_branches],
              "&& or ||");
    do {
        i = link_start->v.number;
        upd_byte(i-1, kind);
        upd_short(i, CURRENT_PROGRAM_SIZE - i, "&& or ||");
        link_start = link_start->l.expr;
    } while (link_start->kind == NODE_BRANCH_LINK);
}

void
i_branch_backwards (char b, int addr) {
    end_pushes();
    if (b) {
        if (b != F_WHILE_DEC)
            ins_byte(b);
        ins_short(CURRENT_PROGRAM_SIZE - addr);
    } 
}

static void
i_update_branch_list (parse_node_t * bl, const char * what) {
    int current_size;
    
    end_pushes();
    current_size = CURRENT_PROGRAM_SIZE;

    while (bl) {
        upd_short(bl->l.number, current_size - bl->l.number, what);
        bl = bl->v.expr;
    }
}

void
i_generate_else() {
    int old;
    
    old = forward_branches[nforward_branches - 1];

    /* set up a new branch to after the end of the if */
    end_pushes();
    ins_byte(F_BRANCH);
    forward_branches[nforward_branches-1] = CURRENT_PROGRAM_SIZE;
    ins_short(0);

    /* update the old branch to point to this point */
    upd_short(old, CURRENT_PROGRAM_SIZE - old, "if");
}

void
i_initialize_parser() {
    foreach_depth = 0;

    if (!forward_branches) {
        forward_branches = CALLOCATE(10, int, TAG_COMPILER, "forward_branches");
        nforward_branches_max = 10;
    }
    nforward_branches = 0;
    
    branch_list[CJ_BREAK] = 0;
    branch_list[CJ_BREAK_SWITCH] = 0;
    branch_list[CJ_CONTINUE] = 0;

    prog_code = mem_block[A_PROGRAM].block;
    prog_code_max = mem_block[A_PROGRAM].block + mem_block[A_PROGRAM].max_size;

    line_being_generated = 0;
    last_size_generated = 0;
}

void
i_uninitialize_parser() {
#ifdef DEBUGMALLOC_EXTENSIONS
    /*
     * The intention is to keep the allocated space for forward branches
     * hanging around between compiles so we don't have to keep allocating it.
     * The problem is that with DEBUGMALLOC_EXENTIONS compiled in, it'll be
     * reported as a memory leak, so clean it up here.  Yes, it's a performance
     * hit, but we're trying to debug not run a race, so deal with it.
     * -- Marius, 11-Aug-2000
     */
    if (forward_branches) {
        FREE(forward_branches);
        forward_branches = 0;
    }
#endif
}

void
i_generate_final_program (int x) {
    if (!x) {
        UPDATE_PROGRAM_SIZE;
/* This needs work
 * if (pragmas & PRAGMA_OPTIMIZE)
 *     optimize_icode(0, 0, 0);
 */
        save_file_info(current_file_id, current_line - current_line_saved);
        switch_to_line(-1); /* generate line numbers for the end */
    }
}

/* Currently, this procedure handles:
 * - jump threading
 */
void
optimize_icode (char * start, char * pc, char * end) {
    int instr;
    if (start == 0) {
        /* we don't optimize the initializer block right now b/c all the
         * stuff we do (jump threading, etc) can't occur there.
         */
        start = mem_block[A_PROGRAM].block;
        pc = start;
        end = pc + mem_block[A_PROGRAM].current_size;
        if (*pc == 0) {
            /* no initializer jump */
            pc += 3;
        }
    }
    while (pc < end) {
        switch (instr = EXTRACT_UCHAR(pc++)) {
#if SIZEOF_LONG == 4
        case F_NUMBER:
#endif
        case F_REAL:
        case F_CALL_INHERITED:
            pc += 4;
            break;
#if SIZEOF_LONG == 8
	case F_NUMBER:
	    pc += 8;
	    break;
#endif
        case F_SIMUL_EFUN:
        case F_CALL_FUNCTION_BY_ADDRESS:
            pc += 3;
            break;
        case F_BRANCH:
        case F_BRANCH_WHEN_ZERO:
        case F_BRANCH_WHEN_NON_ZERO:
        case F_BBRANCH:
        case F_BBRANCH_WHEN_ZERO:
        case F_BBRANCH_WHEN_NON_ZERO:
            {
                char *tmp;
                short sarg;
                /* thread jumps */
                COPY_SHORT(&sarg, pc);
                if (instr > F_BRANCH)
                    tmp = pc - sarg;
                else 
                    tmp = pc + sarg;
                sarg = 0;
                while (1) {
                    if (EXTRACT_UCHAR(tmp) == F_BRANCH) {
                        COPY_SHORT(&sarg, tmp + 1);
                        tmp += sarg + 1;
                    } else if (EXTRACT_UCHAR(tmp) == F_BBRANCH) {
                        COPY_SHORT(&sarg, tmp + 1);
                        tmp -= sarg - 1;
                    } else break;
                }
                if (!sarg) {
                    pc += 2;
                    break;
                }
                /* be careful; in the process of threading a forward jump
                 * may have changed to a reverse one or vice versa
                 */
                if (tmp > pc) {
                    if (instr > F_BRANCH) {
                        pc[-1] -= 3;   /* change to forward branch */
                    }
                    sarg = tmp - pc;
                } else {
                    if (instr <= F_BRANCH) {
                        pc[-1] += 3;   /* change to backwards branch */
                    }
                    sarg = pc - tmp;
                }
                STORE_SHORT(pc, sarg);
                break;
            }
#ifdef F_LOR
        case F_LOR:
        case F_LAND:
            {
                char *tmp;
                short sarg;
                /* thread jumps */
                COPY_SHORT(&sarg, pc);
                tmp = pc + sarg;
                sarg = 0;
                while (1) {
                    if (EXTRACT_UCHAR(tmp) == F_BRANCH) {
                        COPY_SHORT(&sarg, tmp + 1);
                        tmp += sarg + 1;
                    } else if (EXTRACT_UCHAR(tmp) == F_BBRANCH) {
                        COPY_SHORT(&sarg, tmp + 1);
                        tmp -= sarg - 1;
                    } else break;
                }
                if (!sarg) {
                    pc += 2;
                    break;
                }
                /* be careful; in the process of threading a forward jump
                 * may have changed to a reverse one or vice versa
                 */
                if (tmp > pc) {
                    sarg = tmp - pc;
                } else {
#ifdef DEBUG
                    fprintf(stderr,"Optimization failed; can't || or && backwards.\n");
#endif
                    pc += 2;
                    break;
                }
                STORE_SHORT(pc, sarg);
                break;
            }
#endif
        case F_CATCH:
        case F_AGGREGATE:
        case F_AGGREGATE_ASSOC:
        case F_STRING:
#ifdef F_JUMP_WHEN_ZERO
        case F_JUMP_WHEN_ZERO:
        case F_JUMP_WHEN_NON_ZERO:
#endif
#ifdef F_JUMP
        case F_JUMP:
#endif
            pc += 2;
            break;
        case F_GLOBAL_LVALUE:
        case F_GLOBAL:
        case F_SHORT_STRING:
        case F_LOOP_INCR:
        case F_WHILE_DEC:
        case F_LOCAL:
        case F_LOCAL_LVALUE:
        case F_REF:
        case F_REF_LVALUE:
        case F_SSCANF:
        case F_PARSE_COMMAND:
        case F_BYTE:
        case F_NBYTE:
            pc++;
            break;
        case F_FUNCTION_CONSTRUCTOR:
            switch (EXTRACT_UCHAR(pc++)) {
            case FP_SIMUL:
            case FP_LOCAL:
                pc += 2;
                break;
            case FP_FUNCTIONAL:
            case FP_FUNCTIONAL | FP_NOT_BINDABLE:
                pc += 3;
                break;
            case FP_ANONYMOUS:
            case FP_ANONYMOUS | FP_NOT_BINDABLE:
                pc += 4;
                break;
            case FP_EFUN:
                pc += 2;
                break;
            }
            break;
        case F_SWITCH:
            {
                unsigned short stable, etable;
                pc++; /* table type */
                LOAD_SHORT(stable, pc);
                LOAD_SHORT(etable, pc);
                pc += 2; /* def */
                DEBUG_CHECK(stable < pc - start || etable < pc - start 
                            || etable < stable,
                            "Error in switch table found while optimizing\n");
                /* recursively optimize the inside of the switch */
                optimize_icode(start, pc, start + stable);
                pc = start + etable;
                break;
            }
        case F_EFUN0:
        case F_EFUN1:
        case F_EFUN2:
        case F_EFUN3:
        case F_EFUNV:
            instr = EXTRACT_UCHAR(pc++) + ONEARG_MAX;
        default:
            if ((instr >= BASE) && 
                (instrs[instr].min_arg != instrs[instr].max_arg))
                pc++;
        }
    }
}