bc: fix infinite state growth for "yes 1 | bc" case
function old new delta zbc_vm_process 585 672 +87 bc_func_init 50 86 +36 zbc_program_num 990 1022 +32 bc_program_str 17 47 +30 bc_program_current_func - 22 +22 bc_parse_pushNUM 66 87 +21 bc_func_free 27 43 +16 zbc_num_binary 145 147 +2 bc_program_reset 64 61 -3 bc_parse_pushSTR 73 65 -8 ------------------------------------------------------------------------------ (add/remove: 1/0 grow/shrink: 7/2 up/down: 246/-11) Total: 235 bytes text data bss dec hex filename 981393 485 7296 989174 f17f6 busybox_old 981656 485 7296 989437 f18fd busybox_unstripped Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko
parent
447dc02c27
commit
5d57bc442d
141
miscutils/bc.c
141
miscutils/bc.c
@ -350,6 +350,8 @@ typedef struct BcFunc {
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BcVec code;
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IF_BC(BcVec labels;)
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IF_BC(BcVec autos;)
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IF_BC(BcVec strs;)
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IF_BC(BcVec consts;)
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IF_BC(size_t nparams;)
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} BcFunc;
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@ -694,8 +696,8 @@ typedef struct BcProgram {
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BcVec arrs;
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BcVec arr_map;
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BcVec strs;
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BcVec consts;
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IF_DC(BcVec strs;)
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IF_DC(BcVec consts;)
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const char *file;
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@ -1093,6 +1095,7 @@ static void bc_vec_pop_all(BcVec *v)
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bc_vec_npop(v, v->len);
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}
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//TODO: return index of pushed data - many callers can use that
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static void bc_vec_push(BcVec *v, const void *data)
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{
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if (v->len + 1 > v->cap) bc_vec_grow(v, 1);
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@ -1160,18 +1163,6 @@ static void *bc_vec_item(const BcVec *v, size_t idx)
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return v->v + v->size * idx;
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}
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static char** bc_program_str(size_t idx)
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{
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return bc_vec_item(&G.prog.strs, idx);
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}
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static BcFunc* bc_program_func(size_t idx)
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{
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return bc_vec_item(&G.prog.fns, idx);
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}
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// BC_PROG_MAIN is zeroth element, so:
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#define bc_program_func_BC_PROG_MAIN() ((BcFunc*)(G.prog.fns.v))
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static void *bc_vec_item_rev(const BcVec *v, size_t idx)
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{
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return v->v + v->size * (v->len - idx - 1);
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@ -1189,6 +1180,46 @@ static FAST_FUNC void bc_vec_free(void *vec)
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free(v->v);
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}
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static BcFunc* bc_program_func(size_t idx)
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{
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return bc_vec_item(&G.prog.fns, idx);
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}
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// BC_PROG_MAIN is zeroth element, so:
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#define bc_program_func_BC_PROG_MAIN() ((BcFunc*)(G.prog.fns.v))
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#if ENABLE_BC
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static BcFunc* bc_program_current_func(void)
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{
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BcInstPtr *ip = bc_vec_top(&G.prog.exestack);
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BcFunc *func = bc_program_func(ip->func);
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return func;
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}
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#endif
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static char** bc_program_str(size_t idx)
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{
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#if ENABLE_BC
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if (IS_BC) {
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BcFunc *func = bc_program_current_func();
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return bc_vec_item(&func->strs, idx);
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}
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#endif
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IF_DC(return bc_vec_item(&G.prog.strs, idx);)
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}
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static char** bc_program_const(size_t idx)
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{
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#if ENABLE_BC
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if (IS_BC) {
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BcFunc *func = bc_program_current_func();
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return bc_vec_item(&func->consts, idx);
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}
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#endif
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IF_DC(return bc_vec_item(&G.prog.consts, idx);)
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}
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static int bc_id_cmp(const void *e1, const void *e2)
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{
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return strcmp(((const BcId *) e1)->name, ((const BcId *) e2)->name);
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@ -2522,11 +2553,18 @@ static BC_STATUS zbc_func_insert(BcFunc *f, char *name, bool var)
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#define zbc_func_insert(...) (zbc_func_insert(__VA_ARGS__) COMMA_SUCCESS)
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#endif
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static FAST_FUNC void bc_string_free(void *string)
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{
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free(*(char**)string);
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}
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static void bc_func_init(BcFunc *f)
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{
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bc_char_vec_init(&f->code);
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IF_BC(bc_vec_init(&f->labels, sizeof(size_t), NULL);)
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IF_BC(bc_vec_init(&f->autos, sizeof(BcId), bc_id_free);)
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IF_BC(bc_vec_init(&f->strs, sizeof(char *), bc_string_free);)
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IF_BC(bc_vec_init(&f->consts, sizeof(char *), bc_string_free);)
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IF_BC(f->nparams = 0;)
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}
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@ -2536,6 +2574,8 @@ static FAST_FUNC void bc_func_free(void *func)
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bc_vec_free(&f->code);
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IF_BC(bc_vec_free(&f->labels);)
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IF_BC(bc_vec_free(&f->autos);)
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IF_BC(bc_vec_free(&f->strs);)
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IF_BC(bc_vec_free(&f->consts);)
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}
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static void bc_array_expand(BcVec *a, size_t len);
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@ -2585,11 +2625,6 @@ static void bc_array_copy(BcVec *d, const BcVec *s)
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}
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}
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static FAST_FUNC void bc_string_free(void *string)
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{
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free(*((char **) string));
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}
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#if ENABLE_DC
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static void dc_result_copy(BcResult *d, BcResult *src)
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{
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@ -3501,8 +3536,8 @@ static BC_STATUS bc_parse_pushSTR(BcParse *p)
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char *str = xstrdup(p->l.t.v.v);
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bc_parse_push(p, BC_INST_STR);
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bc_parse_pushIndex(p, G.prog.strs.len);
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bc_vec_push(&G.prog.strs, &str);
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bc_parse_pushIndex(p, p->func->strs.len);
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bc_vec_push(&p->func->strs, &str);
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RETURN_STATUS(zbc_lex_next(&p->l));
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}
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@ -3512,10 +3547,16 @@ static BC_STATUS bc_parse_pushSTR(BcParse *p)
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static void bc_parse_pushNUM(BcParse *p)
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{
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char *num = xstrdup(p->l.t.v.v);
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#if ENABLE_BC && ENABLE_DC
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size_t idx = IS_BC ? p->func->consts.len : G.prog.consts.len;
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bc_vec_push(IS_BC ? &p->func->consts : &G.prog.consts, &num);
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#elif ENABLE_BC
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size_t idx = p->func->consts.len;
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bc_vec_push(&p->func->consts, &num);
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#else // DC
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size_t idx = G.prog.consts.len;
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bc_vec_push(&G.prog.consts, &num);
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#endif
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bc_parse_push(p, BC_INST_NUM);
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bc_parse_pushIndex(p, idx);
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}
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@ -3556,7 +3597,7 @@ static void bc_program_reset(void)
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bc_vec_npop(&G.prog.exestack, G.prog.exestack.len - 1);
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bc_vec_pop_all(&G.prog.results);
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f = bc_program_func(0);
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f = bc_program_func_BC_PROG_MAIN();
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ip = bc_vec_top(&G.prog.exestack);
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ip->idx = f->code.len;
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}
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@ -5027,9 +5068,12 @@ static BC_STATUS zbc_program_num(BcResult *r, BcNum **num, bool hex)
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break;
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case BC_RESULT_CONSTANT: {
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BcStatus s;
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char *str = *(char**)bc_vec_item(&G.prog.consts, r->d.id.idx);
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char *str;
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unsigned base_t;
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size_t len = strlen(str);
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size_t len;
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str = *bc_program_const(r->d.id.idx);
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len = strlen(str);
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bc_num_init(&r->d.n, len);
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@ -6667,6 +6711,43 @@ static BC_STATUS zbc_vm_process(const char *text)
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bc_program_reset();
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break;
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}
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// bc discards strings, constants and code after each
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// top-level statement in the "main program".
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// This prevents "yes 1 | bc" from growing its memory
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// without bound. This can be done because data stack
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// is empty and thus can't hold any references to
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// strings or constants, there is no generated code
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// which can hold references (after we discard one
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// we just executed). Code of functions can have references,
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// but bc stores function strings/constants in per-function
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// storage.
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if (IS_BC) {
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BcFunc *f;
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BcInstPtr *ip;
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//FIXME: this does not clear up the stack
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//for(i=1; i<3; i++) {
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// i
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// if(i==2) continue
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// 77
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//}
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// if (G.prog.results.len != 0)
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// bb_error_msg_and_die("data stack not empty: %d slots", G.prog.results.len);
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if (G.prog.exestack.len != 1) // should be empty
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bb_error_msg_and_die("BUG:call stack");
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ip = (void*)G.prog.exestack.v;
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if (ip->func != BC_PROG_MAIN)
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bb_error_msg_and_die("BUG:not MAIN");
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//bb_error_msg("ip->func:%d >idx:%d >len:%d", ip->func, ip->idx, ip->len);
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f = bc_program_func_BC_PROG_MAIN();
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//bb_error_msg("MAIN->code.len:%d >strs.len:%d >consts.len:%d", f->code.len, f->strs.len, f->consts.len); // labels, autos, nparams
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bc_vec_pop_all(&f->code);
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ip->idx = 0;
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IF_BC(bc_vec_pop_all(&f->strs);)
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IF_BC(bc_vec_pop_all(&f->consts);)
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}
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}
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dbg_lex_done("%s:%d done", __func__, __LINE__);
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@ -6999,8 +7080,8 @@ static void bc_program_free(void)
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bc_vec_free(&G.prog.var_map);
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bc_vec_free(&G.prog.arrs);
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bc_vec_free(&G.prog.arr_map);
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bc_vec_free(&G.prog.strs);
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bc_vec_free(&G.prog.consts);
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IF_DC(bc_vec_free(&G.prog.strs);)
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IF_DC(bc_vec_free(&G.prog.consts);)
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bc_vec_free(&G.prog.results);
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bc_vec_free(&G.prog.exestack);
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IF_BC(bc_num_free(&G.prog.last);)
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@ -7057,8 +7138,8 @@ static void bc_program_init(void)
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bc_vec_init(&G.prog.arrs, sizeof(BcVec), bc_vec_free);
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bc_vec_init(&G.prog.arr_map, sizeof(BcId), bc_id_free);
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bc_vec_init(&G.prog.strs, sizeof(char *), bc_string_free);
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bc_vec_init(&G.prog.consts, sizeof(char *), bc_string_free);
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IF_DC(bc_vec_init(&G.prog.strs, sizeof(char *), bc_string_free);)
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IF_DC(bc_vec_init(&G.prog.consts, sizeof(char *), bc_string_free);)
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bc_vec_init(&G.prog.results, sizeof(BcResult), bc_result_free);
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bc_vec_init(&G.prog.exestack, sizeof(BcInstPtr), NULL);
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bc_vec_push(&G.prog.exestack, &ip);
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