CSE: use commutativity to identify equivalent instructions

[smatch.git] / show-parse.c

/*
 * sparse/show-parse.c
 *
 * Copyright (C) 2003 Transmeta Corp.
 *               2003-2004 Linus Torvalds
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 *
 * Print out results of parsing for debugging and testing.
 */
#include <stdarg.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <ctype.h>
#include <unistd.h>
#include <fcntl.h>

#include "lib.h"
#include "allocate.h"
#include "token.h"
#include "parse.h"
#include "symbol.h"
#include "scope.h"
#include "expression.h"
#include "target.h"

static int show_symbol_expr(struct symbol *sym);
static int show_string_expr(struct expression *expr);

static void do_debug_symbol(struct symbol *sym, int indent)
{
        static const char indent_string[] = "                                  ";
        static const char *typestr[] = {
                [SYM_UNINITIALIZED] = "none",
                [SYM_PREPROCESSOR] = "cpp.",
                [SYM_BASETYPE] = "base",
                [SYM_NODE] = "node",
                [SYM_PTR] = "ptr.",
                [SYM_FN] = "fn..",
                [SYM_ARRAY] = "arry",
                [SYM_STRUCT] = "strt",
                [SYM_UNION] = "unin",
                [SYM_ENUM] = "enum",
                [SYM_TYPEDEF] = "tdef",
                [SYM_TYPEOF] = "tpof",
                [SYM_MEMBER] = "memb",
                [SYM_BITFIELD] = "bitf",
                [SYM_LABEL] = "labl",
                [SYM_RESTRICT] = "rstr",
                [SYM_FOULED] = "foul",
                [SYM_BAD] = "bad.",
        };
        struct context *context;
        int i;

        if (!sym)
                return;
        fprintf(stderr, "%.*s%s%3d:%lu %s %s (as: %d) %p (%s:%d:%d) %s\n",
                indent, indent_string, typestr[sym->type],
                sym->bit_size, sym->ctype.alignment,
                modifier_string(sym->ctype.modifiers), show_ident(sym->ident), sym->ctype.as,
                sym, stream_name(sym->pos.stream), sym->pos.line, sym->pos.pos,
                builtin_typename(sym) ?: "");
        i = 0;
        FOR_EACH_PTR(sym->ctype.contexts, context) {
                /* FIXME: should print context expression */
                fprintf(stderr, "< context%d: in=%d, out=%d\n",
                        i, context->in, context->out);
                fprintf(stderr, "  end context%d >\n", i);
                i++;
        } END_FOR_EACH_PTR(context);
        if (sym->type == SYM_FN) {
                struct symbol *arg;
                i = 0;
                FOR_EACH_PTR(sym->arguments, arg) {
                        fprintf(stderr, "< arg%d:\n", i);
                        do_debug_symbol(arg, 0);
                        fprintf(stderr, "  end arg%d >\n", i);
                        i++;
                } END_FOR_EACH_PTR(arg);
        }
        do_debug_symbol(sym->ctype.base_type, indent+2);
}

void debug_symbol(struct symbol *sym)
{
        do_debug_symbol(sym, 0);
}

/*
 * Symbol type printout. The type system is by far the most
 * complicated part of C - everything else is trivial.
 */
const char *modifier_string(unsigned long mod)
{
        static char buffer[100];
        int len = 0;
        int i;
        struct mod_name {
                unsigned long mod;
                const char *name;
        } *m;

        static struct mod_name mod_names[] = {
                {MOD_AUTO,              "auto"},
                {MOD_REGISTER,          "register"},
                {MOD_STATIC,            "static"},
                {MOD_EXTERN,            "extern"},
                {MOD_CONST,             "const"},
                {MOD_VOLATILE,          "volatile"},
                {MOD_SIGNED,            "[signed]"},
                {MOD_UNSIGNED,          "[unsigned]"},
                {MOD_CHAR,              "[char]"},
                {MOD_SHORT,             "[short]"},
                {MOD_LONG,              "[long]"},
                {MOD_LONGLONG,          "[long long]"},
                {MOD_LONGLONGLONG,      "[long long long]"},
                {MOD_TYPEDEF,           "[typedef]"},
                {MOD_TLS,               "[tls]"},
                {MOD_INLINE,            "inline"},
                {MOD_ADDRESSABLE,       "[addressable]"},
                {MOD_NOCAST,            "[nocast]"},
                {MOD_NODEREF,           "[noderef]"},
                {MOD_ACCESSED,          "[accessed]"},
                {MOD_TOPLEVEL,          "[toplevel]"},
                {MOD_ASSIGNED,          "[assigned]"},
                {MOD_TYPE,              "[type]"},
                {MOD_SAFE,              "[safe]"},
                {MOD_USERTYPE,          "[usertype]"},
                {MOD_NORETURN,          "[noreturn]"},
                {MOD_EXPLICITLY_SIGNED, "[explicitly-signed]"},
                {MOD_BITWISE,           "[bitwise]"},
                {MOD_PURE,              "[pure]"},
        };

        for (i = 0; i < ARRAY_SIZE(mod_names); i++) {
                m = mod_names + i;
                if (mod & m->mod) {
                        char c;
                        const char *name = m->name;
                        while ((c = *name++) != '\0' && len + 2 < sizeof buffer)
                                buffer[len++] = c;
                        buffer[len++] = ' ';
                }
        }
        buffer[len] = 0;
        return buffer;
}

static void show_struct_member(struct symbol *sym)
{
        printf("\t%s:%d:%ld at offset %ld.%d", show_ident(sym->ident), sym->bit_size, sym->ctype.alignment, sym->offset, sym->bit_offset);
        printf("\n");
}

void show_symbol_list(struct symbol_list *list, const char *sep)
{
        struct symbol *sym;
        const char *prepend = "";

        FOR_EACH_PTR(list, sym) {
                puts(prepend);
                prepend = ", ";
                show_symbol(sym);
        } END_FOR_EACH_PTR(sym);
}

struct type_name {
        char *start;
        char *end;
};

static void FORMAT_ATTR(2) prepend(struct type_name *name, const char *fmt, ...)
{
        static char buffer[512];
        int n;

        va_list args;
        va_start(args, fmt);
        n = vsprintf(buffer, fmt, args);
        va_end(args);

        name->start -= n;
        memcpy(name->start, buffer, n);
}

static void FORMAT_ATTR(2) append(struct type_name *name, const char *fmt, ...)
{
        static char buffer[512];
        int n;

        va_list args;
        va_start(args, fmt);
        n = vsprintf(buffer, fmt, args);
        va_end(args);

        memcpy(name->end, buffer, n);
        name->end += n;
}

static struct ctype_name {
        struct symbol *sym;
        const char *name;
} typenames[] = {
        { & char_ctype,  "char" },
        { &schar_ctype,  "signed char" },
        { &uchar_ctype,  "unsigned char" },
        { & short_ctype, "short" },
        { &sshort_ctype, "signed short" },
        { &ushort_ctype, "unsigned short" },
        { & int_ctype,   "int" },
        { &sint_ctype,   "signed int" },
        { &uint_ctype,   "unsigned int" },
        { &slong_ctype,  "signed long" },
        { & long_ctype,  "long" },
        { &ulong_ctype,  "unsigned long" },
        { & llong_ctype, "long long" },
        { &sllong_ctype, "signed long long" },
        { &ullong_ctype, "unsigned long long" },
        { & lllong_ctype, "long long long" },
        { &slllong_ctype, "signed long long long" },
        { &ulllong_ctype, "unsigned long long long" },

        { &void_ctype,   "void" },
        { &bool_ctype,   "bool" },
        { &string_ctype, "string" },

        { &float_ctype,  "float" },
        { &double_ctype, "double" },
        { &ldouble_ctype,"long double" },
        { &incomplete_ctype, "incomplete type" },
        { &int_type, "abstract int" },
        { &fp_type, "abstract fp" },
        { &label_ctype, "label type" },
        { &bad_ctype, "bad type" },
};

const char *builtin_typename(struct symbol *sym)
{
        int i;

        for (i = 0; i < ARRAY_SIZE(typenames); i++)
                if (typenames[i].sym == sym)
                        return typenames[i].name;
        return NULL;
}

const char *builtin_ctypename(struct ctype *ctype)
{
        int i;

        for (i = 0; i < ARRAY_SIZE(typenames); i++)
                if (&typenames[i].sym->ctype == ctype)
                        return typenames[i].name;
        return NULL;
}

static void do_show_type(struct symbol *sym, struct type_name *name)
{
        const char *typename;
        unsigned long mod = 0;
        int as = 0;
        int was_ptr = 0;
        int restr = 0;
        int fouled = 0;

deeper:
        if (!sym || (sym->type != SYM_NODE && sym->type != SYM_ARRAY &&
                     sym->type != SYM_BITFIELD)) {
                const char *s;
                size_t len;

                if (as)
                        prepend(name, "<asn:%d>", as);

                s = modifier_string(mod);
                len = strlen(s);
                name->start -= len;    
                memcpy(name->start, s, len);  
                mod = 0;
                as = 0;
        }

        if (!sym)
                goto out;

        if ((typename = builtin_typename(sym))) {
                int len = strlen(typename);
                if (name->start != name->end)
                        *--name->start = ' ';
                name->start -= len;
                memcpy(name->start, typename, len);
                goto out;
        }

        /* Prepend */
        switch (sym->type) {
        case SYM_PTR:
                prepend(name, "*");
                mod = sym->ctype.modifiers;
                as = sym->ctype.as;
                was_ptr = 1;
                break;

        case SYM_FN:
                if (was_ptr) {
                        prepend(name, "( ");
                        append(name, " )");
                        was_ptr = 0;
                }
                append(name, "( ... )");
                break;

        case SYM_STRUCT:
                if (name->start != name->end)
                        *--name->start = ' ';
                prepend(name, "struct %s", show_ident(sym->ident));
                goto out;

        case SYM_UNION:
                if (name->start != name->end)
                        *--name->start = ' ';
                prepend(name, "union %s", show_ident(sym->ident));
                goto out;

        case SYM_ENUM:
                prepend(name, "enum %s ", show_ident(sym->ident));
                break;

        case SYM_NODE:
                append(name, "%s", show_ident(sym->ident));
                mod |= sym->ctype.modifiers;
                as |= sym->ctype.as;
                break;

        case SYM_BITFIELD:
                mod |= sym->ctype.modifiers;
                as |= sym->ctype.as;
                append(name, ":%d", sym->bit_size);
                break;

        case SYM_LABEL:
                append(name, "label(%s:%p)", show_ident(sym->ident), sym);
                return;

        case SYM_ARRAY:
                mod |= sym->ctype.modifiers;
                as |= sym->ctype.as;
                if (was_ptr) {
                        prepend(name, "( ");
                        append(name, " )");
                        was_ptr = 0;
                }
                append(name, "[%lld]", get_expression_value(sym->array_size));
                break;

        case SYM_RESTRICT:
                if (!sym->ident) {
                        restr = 1;
                        break;
                }
                if (name->start != name->end)
                        *--name->start = ' ';
                prepend(name, "restricted %s", show_ident(sym->ident));
                goto out;

        case SYM_FOULED:
                fouled = 1;
                break;

        default:
                if (name->start != name->end)
                        *--name->start = ' ';
                prepend(name, "unknown type %d", sym->type);
                goto out;
        }

        sym = sym->ctype.base_type;
        goto deeper;

out:
        if (restr)
                prepend(name, "restricted ");
        if (fouled)
                prepend(name, "fouled ");
}

void show_type(struct symbol *sym)
{
        char array[200];
        struct type_name name;

        name.start = name.end = array+100;
        do_show_type(sym, &name);
        *name.end = 0;
        printf("%s", name.start);
}

const char *show_typename(struct symbol *sym)
{
        static char array[200];
        struct type_name name;

        name.start = name.end = array+100;
        do_show_type(sym, &name);
        *name.end = 0;
        return name.start;
}

void show_symbol(struct symbol *sym)
{
        struct symbol *type;

        if (!sym)
                return;

        if (sym->ctype.alignment)
                printf(".align %ld\n", sym->ctype.alignment);

        show_type(sym);
        type = sym->ctype.base_type;
        if (!type) {
                printf("\n");
                return;
        }

        /*
         * Show actual implementation information
         */
        switch (type->type) {
                struct symbol *member;

        case SYM_STRUCT:
        case SYM_UNION:
                printf(" {\n");
                FOR_EACH_PTR(type->symbol_list, member) {
                        show_struct_member(member);
                } END_FOR_EACH_PTR(member);
                printf("}\n");
                break;

        case SYM_FN: {
                struct statement *stmt = type->stmt;
                printf("\n");
                if (stmt) {
                        int val;
                        val = show_statement(stmt);
                        if (val)
                                printf("\tmov.%d\t\tretval,%d\n", stmt->ret->bit_size, val);
                        printf("\tret\n");
                }
                break;
        }

        default:
                printf("\n");
                break;
        }

        if (sym->initializer) {
                printf(" = \n");
                show_expression(sym->initializer);
        }
}

static int show_symbol_init(struct symbol *sym);

static int new_pseudo(void)
{
        static int nr = 0;
        return ++nr;
}

static int new_label(void)
{
        static int label = 0;
        return ++label;
}

static void show_switch_statement(struct statement *stmt)
{
        int val = show_expression(stmt->switch_expression);
        struct symbol *sym;
        printf("\tswitch v%d\n", val);

        /*
         * Debugging only: Check that the case list is correct
         * by printing it out.
         *
         * This is where a _real_ back-end would go through the
         * cases to decide whether to use a lookup table or a
         * series of comparisons etc
         */
        printf("# case table:\n");
        FOR_EACH_PTR(stmt->switch_case->symbol_list, sym) {
                struct statement *case_stmt = sym->stmt;
                struct expression *expr = case_stmt->case_expression;
                struct expression *to = case_stmt->case_to;

                if (!expr) {
                        printf("    default");
                } else {
                        if (expr->type == EXPR_VALUE) {
                                printf("    case %lld", expr->value);
                                if (to) {
                                        if (to->type == EXPR_VALUE) {
                                                printf(" .. %lld", to->value);
                                        } else {
                                                printf(" .. what?");
                                        }
                                }
                        } else
                                printf("    what?");
                }
                printf(": .L%p\n", sym);
        } END_FOR_EACH_PTR(sym);
        printf("# end case table\n");

        show_statement(stmt->switch_statement);

        if (stmt->switch_break->used)
                printf(".L%p:\n", stmt->switch_break);
}

static void show_symbol_decl(struct symbol_list *syms)
{
        struct symbol *sym;
        FOR_EACH_PTR(syms, sym) {
                show_symbol_init(sym);
        } END_FOR_EACH_PTR(sym);
}

static int show_return_stmt(struct statement *stmt);

/*
 * Print out a statement
 */
int show_statement(struct statement *stmt)
{
        if (!stmt)
                return 0;
        switch (stmt->type) {
        case STMT_DECLARATION:
                show_symbol_decl(stmt->declaration);
                return 0;
        case STMT_RETURN:
                return show_return_stmt(stmt);
        case STMT_COMPOUND: {
                struct statement *s;
                int last = 0;

                if (stmt->inline_fn) {
                        show_statement(stmt->args);
                        printf("\tbegin_inline \t%s\n", show_ident(stmt->inline_fn->ident));
                }
                FOR_EACH_PTR(stmt->stmts, s) {
                        last = show_statement(s);
                } END_FOR_EACH_PTR(s);
                if (stmt->ret) {
                        int addr, bits;
                        printf(".L%p:\n", stmt->ret);
                        addr = show_symbol_expr(stmt->ret);
                        bits = stmt->ret->bit_size;
                        last = new_pseudo();
                        printf("\tld.%d\t\tv%d,[v%d]\n", bits, last, addr);
                }
                if (stmt->inline_fn)
                        printf("\tend_inlined\t%s\n", show_ident(stmt->inline_fn->ident));
                return last;
        }

        case STMT_EXPRESSION:
                return show_expression(stmt->expression);
        case STMT_IF: {
                int val, target;
                struct expression *cond = stmt->if_conditional;

/* This is only valid if nobody can jump into the "dead" statement */
#if 0
                if (cond->type == EXPR_VALUE) {
                        struct statement *s = stmt->if_true;
                        if (!cond->value)
                                s = stmt->if_false;
                        show_statement(s);
                        break;
                }
#endif
                val = show_expression(cond);
                target = new_label();
                printf("\tje\t\tv%d,.L%d\n", val, target);
                show_statement(stmt->if_true);
                if (stmt->if_false) {
                        int last = new_label();
                        printf("\tjmp\t\t.L%d\n", last);
                        printf(".L%d:\n", target);
                        target = last;
                        show_statement(stmt->if_false);
                }
                printf(".L%d:\n", target);
                break;
        }
        case STMT_SWITCH:
                show_switch_statement(stmt);
                break;

        case STMT_CASE:
                printf(".L%p:\n", stmt->case_label);
                show_statement(stmt->case_statement);
                break;

        case STMT_ITERATOR: {
                struct statement  *pre_statement = stmt->iterator_pre_statement;
                struct expression *pre_condition = stmt->iterator_pre_condition;
                struct statement  *statement = stmt->iterator_statement;
                struct statement  *post_statement = stmt->iterator_post_statement;
                struct expression *post_condition = stmt->iterator_post_condition;
                int val, loop_top = 0, loop_bottom = 0;

                show_symbol_decl(stmt->iterator_syms);
                show_statement(pre_statement);
                if (pre_condition) {
                        if (pre_condition->type == EXPR_VALUE) {
                                if (!pre_condition->value) {
                                        loop_bottom = new_label();   
                                        printf("\tjmp\t\t.L%d\n", loop_bottom);
                                }
                        } else {
                                loop_bottom = new_label();
                                val = show_expression(pre_condition);
                                printf("\tje\t\tv%d, .L%d\n", val, loop_bottom);
                        }
                }
                if (!post_condition || post_condition->type != EXPR_VALUE || post_condition->value) {
                        loop_top = new_label();
                        printf(".L%d:\n", loop_top);
                }
                show_statement(statement);
                if (stmt->iterator_continue->used)
                        printf(".L%p:\n", stmt->iterator_continue);
                show_statement(post_statement);
                if (!post_condition) {
                        printf("\tjmp\t\t.L%d\n", loop_top);
                } else if (post_condition->type == EXPR_VALUE) {
                        if (post_condition->value)
                                printf("\tjmp\t\t.L%d\n", loop_top);
                } else {
                        val = show_expression(post_condition);
                        printf("\tjne\t\tv%d, .L%d\n", val, loop_top);
                }
                if (stmt->iterator_break->used)
                        printf(".L%p:\n", stmt->iterator_break);
                if (loop_bottom)
                        printf(".L%d:\n", loop_bottom);
                break;
        }
        case STMT_NONE:
                break;
        
        case STMT_LABEL:
                printf(".L%p:\n", stmt->label_identifier);
                show_statement(stmt->label_statement);
                break;

        case STMT_GOTO:
                if (stmt->goto_expression) {
                        int val = show_expression(stmt->goto_expression);
                        printf("\tgoto\t\t*v%d\n", val);
                } else {
                        printf("\tgoto\t\t.L%p\n", stmt->goto_label);
                }
                break;
        case STMT_ASM:
                printf("\tasm( .... )\n");
                break;
        case STMT_CONTEXT: {
                int val = show_expression(stmt->expression);
                printf("\tcontext( %d )\n", val);
                break;
        }
        case STMT_RANGE: {
                int val = show_expression(stmt->range_expression);
                int low = show_expression(stmt->range_low);
                int high = show_expression(stmt->range_high);
                printf("\trange( %d %d-%d)\n", val, low, high); 
                break;
        }       
        }
        return 0;
}

static int show_call_expression(struct expression *expr)
{
        struct symbol *direct;
        struct expression *arg, *fn;
        int fncall, retval;
        int framesize;

        if (!expr->ctype) {
                warning(expr->pos, "\tcall with no type!");
                return 0;
        }

        framesize = 0;
        FOR_EACH_PTR_REVERSE(expr->args, arg) {
                int new = show_expression(arg);
                int size = arg->ctype->bit_size;
                printf("\tpush.%d\t\tv%d\n", size, new);
                framesize += bits_to_bytes(size);
        } END_FOR_EACH_PTR_REVERSE(arg);

        fn = expr->fn;

        /* Remove dereference, if any */
        direct = NULL;
        if (fn->type == EXPR_PREOP) {
                if (fn->unop->type == EXPR_SYMBOL) {
                        struct symbol *sym = fn->unop->symbol;
                        if (sym->ctype.base_type->type == SYM_FN)
                                direct = sym;
                }
        }
        if (direct) {
                printf("\tcall\t\t%s\n", show_ident(direct->ident));
        } else {
                fncall = show_expression(fn);
                printf("\tcall\t\t*v%d\n", fncall);
        }
        if (framesize)
                printf("\tadd.%d\t\tvSP,vSP,$%d\n", bits_in_pointer, framesize);

        retval = new_pseudo();
        printf("\tmov.%d\t\tv%d,retval\n", expr->ctype->bit_size, retval);
        return retval;
}

static int show_comma(struct expression *expr)
{
        show_expression(expr->left);
        return show_expression(expr->right);
}

static int show_binop(struct expression *expr)
{
        int left = show_expression(expr->left);
        int right = show_expression(expr->right);
        int new = new_pseudo();
        const char *opname;
        static const char *name[] = {
                ['+'] = "add", ['-'] = "sub",
                ['*'] = "mul", ['/'] = "div",
                ['%'] = "mod", ['&'] = "and",
                ['|'] = "lor", ['^'] = "xor"
        };
        unsigned int op = expr->op;

        opname = show_special(op);
        if (op < ARRAY_SIZE(name))
                opname = name[op];
        printf("\t%s.%d\t\tv%d,v%d,v%d\n", opname,
                expr->ctype->bit_size,
                new, left, right);
        return new;
}

static int show_slice(struct expression *expr)
{
        int target = show_expression(expr->base);
        int new = new_pseudo();
        printf("\tslice.%d\t\tv%d,v%d,%d\n", expr->r_nrbits, target, new, expr->r_bitpos);
        return new;
}

static int show_regular_preop(struct expression *expr)
{
        int target = show_expression(expr->unop);
        int new = new_pseudo();
        static const char *name[] = {
                ['!'] = "nonzero", ['-'] = "neg",
                ['~'] = "not",
        };
        unsigned int op = expr->op;
        const char *opname;

        opname = show_special(op);
        if (op < ARRAY_SIZE(name))
                opname = name[op];
        printf("\t%s.%d\t\tv%d,v%d\n", opname, expr->ctype->bit_size, new, target);
        return new;
}

/*
 * FIXME! Not all accesses are memory loads. We should
 * check what kind of symbol is behind the dereference.
 */
static int show_address_gen(struct expression *expr)
{
        return show_expression(expr->unop);
}

static int show_load_gen(int bits, struct expression *expr, int addr)
{
        int new = new_pseudo();

        printf("\tld.%d\t\tv%d,[v%d]\n", bits, new, addr);
        return new;
}

static void show_store_gen(int bits, int value, struct expression *expr, int addr)
{
        /* FIXME!!! Bitfield store! */
        printf("\tst.%d\t\tv%d,[v%d]\n", bits, value, addr);
}

static int show_assignment(struct expression *expr)
{
        struct expression *target = expr->left;
        int val, addr, bits;

        if (!expr->ctype)
                return 0;

        bits = expr->ctype->bit_size;
        val = show_expression(expr->right);
        addr = show_address_gen(target);
        show_store_gen(bits, val, target, addr);
        return val;
}

static int show_return_stmt(struct statement *stmt)
{
        struct expression *expr = stmt->ret_value;
        struct symbol *target = stmt->ret_target;

        if (expr && expr->ctype) {
                int val = show_expression(expr);
                int bits = expr->ctype->bit_size;
                int addr = show_symbol_expr(target);
                show_store_gen(bits, val, NULL, addr);
        }
        printf("\tret\t\t(%p)\n", target);
        return 0;
}

static int show_initialization(struct symbol *sym, struct expression *expr)
{
        int val, addr, bits;

        if (!expr->ctype)
                return 0;

        bits = expr->ctype->bit_size;
        val = show_expression(expr);
        addr = show_symbol_expr(sym);
        // FIXME! The "target" expression is for bitfield store information.
        // Leave it NULL, which works fine.
        show_store_gen(bits, val, NULL, addr);
        return 0;
}

static int show_access(struct expression *expr)
{
        int addr = show_address_gen(expr);
        return show_load_gen(expr->ctype->bit_size, expr, addr);
}

static int show_inc_dec(struct expression *expr, int postop)
{
        int addr = show_address_gen(expr->unop);
        int retval, new;
        const char *opname = expr->op == SPECIAL_INCREMENT ? "add" : "sub";
        int bits = expr->ctype->bit_size;

        retval = show_load_gen(bits, expr->unop, addr);
        new = retval;
        if (postop)
                new = new_pseudo();
        printf("\t%s.%d\t\tv%d,v%d,$1\n", opname, bits, new, retval);
        show_store_gen(bits, new, expr->unop, addr);
        return retval;
}       

static int show_preop(struct expression *expr)
{
        /*
         * '*' is an lvalue access, and is fundamentally different
         * from an arithmetic operation. Maybe it should have an
         * expression type of its own..
         */
        if (expr->op == '*')
                return show_access(expr);
        if (expr->op == SPECIAL_INCREMENT || expr->op == SPECIAL_DECREMENT)
                return show_inc_dec(expr, 0);
        return show_regular_preop(expr);
}

static int show_postop(struct expression *expr)
{
        return show_inc_dec(expr, 1);
}       

static int show_symbol_expr(struct symbol *sym)
{
        int new = new_pseudo();

        if (sym->initializer && sym->initializer->type == EXPR_STRING)
                return show_string_expr(sym->initializer);

        if (sym->ctype.modifiers & (MOD_TOPLEVEL | MOD_EXTERN | MOD_STATIC)) {
                printf("\tmovi.%d\t\tv%d,$%s\n", bits_in_pointer, new, show_ident(sym->ident));
                return new;
        }
        if (sym->ctype.modifiers & MOD_ADDRESSABLE) {
                printf("\taddi.%d\t\tv%d,vFP,$%lld\n", bits_in_pointer, new, sym->value);
                return new;
        }
        printf("\taddi.%d\t\tv%d,vFP,$offsetof(%s:%p)\n", bits_in_pointer, new, show_ident(sym->ident), sym);
        return new;
}

static int show_symbol_init(struct symbol *sym)
{
        struct expression *expr = sym->initializer;

        if (expr) {
                int val, addr, bits;

                bits = expr->ctype->bit_size;
                val = show_expression(expr);
                addr = show_symbol_expr(sym);
                show_store_gen(bits, val, NULL, addr);
        }
        return 0;
}

static int type_is_signed(struct symbol *sym)
{
        if (sym->type == SYM_NODE)
                sym = sym->ctype.base_type;
        if (sym->type == SYM_PTR)
                return 0;
        return !(sym->ctype.modifiers & MOD_UNSIGNED);
}

static int show_cast_expr(struct expression *expr)
{
        struct symbol *old_type, *new_type;
        int op = show_expression(expr->cast_expression);
        int oldbits, newbits;
        int new, is_signed;

        old_type = expr->cast_expression->ctype;
        new_type = expr->cast_type;
        
        oldbits = old_type->bit_size;
        newbits = new_type->bit_size;
        if (oldbits >= newbits)
                return op;
        new = new_pseudo();
        is_signed = type_is_signed(old_type);
        if (is_signed) {
                printf("\tsext%d.%d\tv%d,v%d\n", oldbits, newbits, new, op);
        } else {
                printf("\tandl.%d\t\tv%d,v%d,$%lu\n", newbits, new, op, (1UL << oldbits)-1);
        }
        return new;
}

static int show_value(struct expression *expr)
{
        int new = new_pseudo();
        unsigned long long value = expr->value;

        printf("\tmovi.%d\t\tv%d,$%llu\n", expr->ctype->bit_size, new, value);
        return new;
}

static int show_fvalue(struct expression *expr)
{
        int new = new_pseudo();
        long double value = expr->fvalue;

        printf("\tmovf.%d\t\tv%d,$%Lf\n", expr->ctype->bit_size, new, value);
        return new;
}

static int show_string_expr(struct expression *expr)
{
        int new = new_pseudo();

        printf("\tmovi.%d\t\tv%d,&%s\n", bits_in_pointer, new, show_string(expr->string));
        return new;
}

static int show_label_expr(struct expression *expr)
{
        int new = new_pseudo();
        printf("\tmovi.%d\t\tv%d,.L%p\n",bits_in_pointer, new, expr->label_symbol);
        return new;
}

static int show_conditional_expr(struct expression *expr)
{
        int cond = show_expression(expr->conditional);
        int true = show_expression(expr->cond_true);
        int false = show_expression(expr->cond_false);
        int new = new_pseudo();

        printf("[v%d]\tcmov.%d\t\tv%d,v%d,v%d\n", cond, expr->ctype->bit_size, new, true, false);
        return new;
}

static int show_statement_expr(struct expression *expr)
{
        return show_statement(expr->statement);
}

static int show_position_expr(struct expression *expr, struct symbol *base)
{
        int new = show_expression(expr->init_expr);
        struct symbol *ctype = expr->init_expr->ctype;
        int bit_offset;

        bit_offset = ctype ? ctype->bit_offset : -1;

        printf("\tinsert v%d at [%d:%d] of %s\n", new,
                expr->init_offset, bit_offset,
                show_ident(base->ident));
        return 0;
}

static int show_initializer_expr(struct expression *expr, struct symbol *ctype)
{
        struct expression *entry;

        FOR_EACH_PTR(expr->expr_list, entry) {

again:
                // Nested initializers have their positions already
                // recursively calculated - just output them too
                if (entry->type == EXPR_INITIALIZER) {
                        show_initializer_expr(entry, ctype);
                        continue;
                }

                // Initializer indexes and identifiers should
                // have been evaluated to EXPR_POS
                if (entry->type == EXPR_IDENTIFIER) {
                        printf(" AT '%s':\n", show_ident(entry->expr_ident));
                        entry = entry->ident_expression;
                        goto again;
                }
                        
                if (entry->type == EXPR_INDEX) {
                        printf(" AT '%d..%d:\n", entry->idx_from, entry->idx_to);
                        entry = entry->idx_expression;
                        goto again;
                }
                if (entry->type == EXPR_POS) {
                        show_position_expr(entry, ctype);
                        continue;
                }
                show_initialization(ctype, entry);
        } END_FOR_EACH_PTR(entry);
        return 0;
}

int show_symbol_expr_init(struct symbol *sym)
{
        struct expression *expr = sym->initializer;

        if (expr)
                show_expression(expr);
        return show_symbol_expr(sym);
}

/*
 * Print out an expression. Return the pseudo that contains the
 * variable.
 */
int show_expression(struct expression *expr)
{
        if (!expr)
                return 0;

        if (!expr->ctype) {
                struct position *pos = &expr->pos;
                printf("\tno type at %s:%d:%d\n",
                        stream_name(pos->stream),
                        pos->line, pos->pos);
                return 0;
        }
                
        switch (expr->type) {
        case EXPR_CALL:
                return show_call_expression(expr);
                
        case EXPR_ASSIGNMENT:
                return show_assignment(expr);

        case EXPR_COMMA:
                return show_comma(expr);
        case EXPR_BINOP:
        case EXPR_COMPARE:
        case EXPR_LOGICAL:
                return show_binop(expr);
        case EXPR_PREOP:
                return show_preop(expr);
        case EXPR_POSTOP:
                return show_postop(expr);
        case EXPR_SYMBOL:
                return show_symbol_expr(expr->symbol);
        case EXPR_DEREF:
        case EXPR_SIZEOF:
        case EXPR_PTRSIZEOF:
        case EXPR_ALIGNOF:
        case EXPR_OFFSETOF:
                warning(expr->pos, "invalid expression after evaluation");
                return 0;
        case EXPR_CAST:
        case EXPR_FORCE_CAST:
        case EXPR_IMPLIED_CAST:
                return show_cast_expr(expr);
        case EXPR_VALUE:
                return show_value(expr);
        case EXPR_FVALUE:
                return show_fvalue(expr);
        case EXPR_STRING:
                return show_string_expr(expr);
        case EXPR_INITIALIZER:
                return show_initializer_expr(expr, expr->ctype);
        case EXPR_SELECT:
        case EXPR_CONDITIONAL:
                return show_conditional_expr(expr);
        case EXPR_STATEMENT:
                return show_statement_expr(expr);
        case EXPR_LABEL:
                return show_label_expr(expr);
        case EXPR_SLICE:
                return show_slice(expr);

        // None of these should exist as direct expressions: they are only
        // valid as sub-expressions of initializers.
        case EXPR_POS:
                warning(expr->pos, "unable to show plain initializer position expression");
                return 0;
        case EXPR_IDENTIFIER:
                warning(expr->pos, "unable to show identifier expression");
                return 0;
        case EXPR_INDEX:
                warning(expr->pos, "unable to show index expression");
                return 0;
        case EXPR_TYPE:
                warning(expr->pos, "unable to show type expression");
                return 0;
        }
        return 0;
}