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https://github.com/mirror/tinycc.git
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switch: collect case ranges first, then generate code
Collect cases first, then emit lookup code. Elliminates jumps to implement pass-through and jumps to link cases.
This commit is contained in:
Pavlas, Zdenek
parent
d5a1e32ac3
commit
fc0fc6aba3
114
tccgen.c
114
tccgen.c
@ -72,6 +72,13 @@ ST_DATA const char *funcname;
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ST_DATA CType char_pointer_type, func_old_type, int_type, size_type;
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ST_DATA struct switch_t {
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struct case_t {
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int v1, v2, sym;
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} **p; int n; /* list of case ranges */
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int def_sym; /* default symbol */
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} *cur_switch; /* current switch */
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/* ------------------------------------------------------------------------- */
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static void gen_cast(CType *type);
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static inline CType *pointed_type(CType *type);
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@ -80,7 +87,7 @@ static int parse_btype(CType *type, AttributeDef *ad);
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static void type_decl(CType *type, AttributeDef *ad, int *v, int td);
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static void parse_expr_type(CType *type);
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static void decl_initializer(CType *type, Section *sec, unsigned long c, int first, int size_only);
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static void block(int *bsym, int *csym, int *case_sym, int *def_sym, int case_reg, int is_expr);
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static void block(int *bsym, int *csym, int is_expr);
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static void decl_initializer_alloc(CType *type, AttributeDef *ad, int r, int has_init, int v, int scope);
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static int decl0(int l, int is_for_loop_init);
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static void expr_eq(void);
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@ -3859,7 +3866,7 @@ ST_FUNC void unary(void)
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save_regs(0);
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/* statement expression : we do not accept break/continue
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inside as GCC does */
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block(NULL, NULL, NULL, NULL, 0, 1);
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block(NULL, NULL, 1);
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skip(')');
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} else {
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gexpr();
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@ -4876,8 +4883,10 @@ static void label_or_decl(int l)
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decl(l);
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}
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static void block(int *bsym, int *csym, int *case_sym, int *def_sym,
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int case_reg, int is_expr)
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static int case_cmp(const void *a, const void *b)
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{ return (*(struct case_t**) a)->v1 - (*(struct case_t**) b)->v1; }
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static void block(int *bsym, int *csym, int is_expr)
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{
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int a, b, c, d;
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Sym *s;
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@ -4903,13 +4912,13 @@ static void block(int *bsym, int *csym, int *case_sym, int *def_sym,
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gexpr();
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skip(')');
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a = gvtst(1, 0);
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block(bsym, csym, case_sym, def_sym, case_reg, 0);
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block(bsym, csym, 0);
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c = tok;
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if (c == TOK_ELSE) {
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next();
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d = gjmp(0);
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gsym(a);
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block(bsym, csym, case_sym, def_sym, case_reg, 0);
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block(bsym, csym, 0);
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gsym(d); /* patch else jmp */
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} else
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gsym(a);
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@ -4923,7 +4932,7 @@ static void block(int *bsym, int *csym, int *case_sym, int *def_sym,
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a = gvtst(1, 0);
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b = 0;
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++local_scope;
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block(&a, &b, case_sym, def_sym, case_reg, 0);
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block(&a, &b, 0);
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--local_scope;
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if(!nocode_wanted)
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gjmp_addr(d);
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@ -4960,7 +4969,7 @@ static void block(int *bsym, int *csym, int *case_sym, int *def_sym,
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if (tok != '}') {
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if (is_expr)
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vpop();
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block(bsym, csym, case_sym, def_sym, case_reg, is_expr);
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block(bsym, csym, is_expr);
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}
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}
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/* pop locally defined labels */
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@ -5115,7 +5124,7 @@ static void block(int *bsym, int *csym, int *case_sym, int *def_sym,
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gsym(e);
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}
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skip(')');
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block(&a, &b, case_sym, def_sym, case_reg, 0);
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block(&a, &b, 0);
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if(!nocode_wanted)
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gjmp_addr(c);
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gsym(a);
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@ -5130,7 +5139,7 @@ static void block(int *bsym, int *csym, int *case_sym, int *def_sym,
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b = 0;
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d = ind;
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vla_sp_restore();
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block(&a, &b, case_sym, def_sym, case_reg, 0);
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block(&a, &b, 0);
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skip(TOK_WHILE);
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skip('(');
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gsym(b);
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@ -5142,58 +5151,65 @@ static void block(int *bsym, int *csym, int *case_sym, int *def_sym,
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skip(';');
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} else
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if (tok == TOK_SWITCH) {
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struct switch_t *saved, sw;
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next();
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skip('(');
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gexpr();
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/* XXX: other types than integer */
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case_reg = gv(RC_INT);
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c = gv(RC_INT);
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vpop();
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skip(')');
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a = 0;
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b = gjmp(0); /* jump to first case */
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c = 0;
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block(&a, csym, &b, &c, case_reg, 0);
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/* if no default, jmp after switch */
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if (c == 0)
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c = ind;
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/* default label */
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gsym_addr(b, c);
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sw.p = NULL; sw.n = 0; sw.def_sym = 0;
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saved = cur_switch;
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cur_switch = &sw; block(&a, csym, 0);
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cur_switch = saved;
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a = gjmp(a); /* add implicit break */
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gsym(b);
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qsort(sw.p, sw.n, sizeof(void*), case_cmp);
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for (b = 0; b < sw.n; b++) {
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int v = sw.p[b]->v1;
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if (b && v <= d)
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tcc_error("duplicate case value");
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d = sw.p[b]->v2;
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vseti(c, 0);
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vpushi(v);
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if (v == d) {
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gen_op(TOK_EQ);
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gsym_addr(gtst(0, 0), sw.p[b]->sym);
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} else {
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int e;
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gen_op(TOK_GE);
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e = gtst(1, 0);
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vseti(c, 0);
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vpushi(d);
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gen_op(TOK_LE);
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gsym_addr(gtst(0, 0), sw.p[b]->sym);
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gsym(e);
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}
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}
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if (sw.def_sym)
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gjmp_addr(sw.def_sym);
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/* break label */
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gsym(a);
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} else
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if (tok == TOK_CASE) {
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int v1, v2;
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if (!case_sym)
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struct case_t *cr = tcc_malloc(sizeof(struct case_t));
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if (!cur_switch)
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expect("switch");
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next();
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v1 = expr_const();
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v2 = v1;
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cr->v1 = cr->v2 = expr_const();
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if (gnu_ext && tok == TOK_DOTS) {
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next();
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v2 = expr_const();
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if (v2 < v1)
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cr->v2 = expr_const();
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if (cr->v2 < cr->v1)
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tcc_warning("empty case range");
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}
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/* since a case is like a label, we must skip it with a jmp */
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b = gjmp(0);
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gsym(*case_sym);
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vseti(case_reg, 0);
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vdup();
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vpushi(v1);
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if (v1 == v2) {
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gen_op(TOK_EQ);
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*case_sym = gtst(1, 0);
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} else {
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gen_op(TOK_GE);
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*case_sym = gtst(1, 0);
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vseti(case_reg, 0);
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vpushi(v2);
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gen_op(TOK_LE);
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*case_sym = gtst(1, *case_sym);
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}
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case_reg = gv(RC_INT);
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vpop();
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gsym(b);
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cr->sym = ind;
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dynarray_add((void***) &cur_switch->p, &cur_switch->n, cr);
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skip(':');
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is_expr = 0;
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goto block_after_label;
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@ -5201,11 +5217,11 @@ static void block(int *bsym, int *csym, int *case_sym, int *def_sym,
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if (tok == TOK_DEFAULT) {
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next();
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skip(':');
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if (!def_sym)
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if (!cur_switch)
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expect("switch");
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if (*def_sym)
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if (cur_switch->def_sym)
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tcc_error("too many 'default'");
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*def_sym = ind;
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cur_switch->def_sym = ind;
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is_expr = 0;
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goto block_after_label;
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} else
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@ -5261,7 +5277,7 @@ static void block(int *bsym, int *csym, int *case_sym, int *def_sym,
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} else {
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if (is_expr)
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vpop();
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block(bsym, csym, case_sym, def_sym, case_reg, is_expr);
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block(bsym, csym, is_expr);
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}
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} else {
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/* expression case */
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@ -6177,7 +6193,7 @@ static void gen_function(Sym *sym)
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}
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#endif
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rsym = 0;
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block(NULL, NULL, NULL, NULL, 0, 0);
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block(NULL, NULL, 0);
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gsym(rsym);
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gfunc_epilog();
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cur_text_section->data_offset = ind;
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