bc: optimize bc_vec_push() usage

function                                             old     new   delta
bc_parse_pushNUM                                      87      80      -7
zbc_parse_stmt_possibly_auto                        1697    1689      -8
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 0/2 up/down: 0/-15)             Total: -15 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

diff --git a/miscutils/bc.c b/miscutils/bc.c
index 441cb04676ed235e5f669836c70101d8fda1d6cf..abedbdf0b4d3a888620f714b3c6bddd54a9a9675 100644 (file)
--- a/miscutils/bc.c
+++ b/miscutils/bc.c
@@ -1097,24 +1097,25 @@ static void bc_vec_pop_all(BcVec *v)
        bc_vec_npop(v, v->len);
 }
 
-//TODO: return index of pushed data - many callers can use that
-static void bc_vec_push(BcVec *v, const void *data)
+static size_t bc_vec_push(BcVec *v, const void *data)
 {
-       if (v->len + 1 > v->cap) bc_vec_grow(v, 1);
-       memmove(v->v + (v->size * v->len), data, v->size);
-       v->len += 1;
+       size_t len = v->len;
+       if (len >= v->cap) bc_vec_grow(v, 1);
+       memmove(v->v + (v->size * len), data, v->size);
+       v->len++;
+       return len;
 }
 
-static void bc_vec_pushByte(BcVec *v, char data)
+static size_t bc_vec_pushByte(BcVec *v, char data)
 {
-       bc_vec_push(v, &data);
+       return bc_vec_push(v, &data);
 }
 
-static void bc_vec_pushZeroByte(BcVec *v)
+static size_t bc_vec_pushZeroByte(BcVec *v)
 {
-       //bc_vec_pushByte(v, '\0');
+       //return bc_vec_pushByte(v, '\0');
        // better:
-       bc_vec_push(v, &const_int_0);
+       return bc_vec_push(v, &const_int_0);
 }
 
 static void bc_vec_pushAt(BcVec *v, const void *data, size_t idx)
@@ -3548,14 +3549,11 @@ static void bc_parse_pushNUM(BcParse *p)
 {
        char *num = xstrdup(p->l.t.v.v);
 #if ENABLE_BC && ENABLE_DC
-       size_t idx = IS_BC ? p->func->consts.len : G.prog.consts.len;
-       bc_vec_push(IS_BC ? &p->func->consts : &G.prog.consts, &num);
+       size_t idx = bc_vec_push(IS_BC ? &p->func->consts : &G.prog.consts, &num);
 #elif ENABLE_BC
-       size_t idx = p->func->consts.len;
-       bc_vec_push(&p->func->consts, &num);
+       size_t idx = bc_vec_push(&p->func->consts, &num);
 #else // DC
-       size_t idx = G.prog.consts.len;
-       bc_vec_push(&G.prog.consts, &num);
+       size_t idx = bc_vec_push(&G.prog.consts, &num);
 #endif
        bc_parse_push(p, BC_INST_NUM);
        bc_parse_pushIndex(p, idx);
@@ -3652,7 +3650,7 @@ static void bc_program_add_fn(void)
        //size_t idx;
        BcFunc f;
        bc_func_init(&f);
-       //idx = G.prog.fns.len;
+       //idx =
        bc_vec_push(&G.prog.fns, &f);
        //return idx;
 }
@@ -4135,12 +4133,13 @@ static BC_STATUS zbc_parse_if(BcParse *p)
        if (s) RETURN_STATUS(s);
        s = zbc_parse_expr(p, BC_PARSE_REL);
        if (s) RETURN_STATUS(s);
-
        if (p->l.t.t != BC_LEX_RPAREN) RETURN_STATUS(bc_error_bad_token());
 
-       ip_idx = p->func->labels.len;
+       // Encode "if zero, jump to ..."
+       // Pushed value (destination of the jump) is uninitialized,
+       // will be rewritten to be address of "end of if()" or of "else".
+       ip_idx = bc_vec_push(&p->func->labels, &ip_idx);
        bc_parse_pushJUMP_ZERO(p, ip_idx);
-       bc_vec_push(&p->func->labels, &ip_idx);
 
        s = zbc_parse_stmt_allow_NLINE_before(p, STRING_if);
        if (s) RETURN_STATUS(s);
@@ -4149,15 +4148,14 @@ static BC_STATUS zbc_parse_if(BcParse *p)
        if (p->l.t.t == BC_LEX_KEY_ELSE) {
                size_t ip2_idx;
 
-               ip2_idx = p->func->labels.len;
-
-               dbg_lex("%s:%d after if() body: BC_INST_JUMP to %zd", __func__, __LINE__, ip2_idx);
+               // Encode "after then_stmt, jump to end of if()"
+               ip2_idx = bc_vec_push(&p->func->labels, &ip2_idx);
+               dbg_lex("%s:%d after if() then_stmt: BC_INST_JUMP to %zd", __func__, __LINE__, ip2_idx);
                bc_parse_pushJUMP(p, ip2_idx);
 
                dbg_lex("%s:%d rewriting 'if_zero' label to jump to 'else'-> %zd", __func__, __LINE__, p->func->code.len);
                rewrite_label_to_current(p, ip_idx);
 
-               bc_vec_push(&p->func->labels, &ip2_idx);
                ip_idx = ip2_idx;
 
                s = zbc_parse_stmt_allow_NLINE_before(p, STRING_else);
@@ -4184,10 +4182,8 @@ static BC_STATUS zbc_parse_while(BcParse *p)
        s = zbc_lex_next(&p->l);
        if (s) RETURN_STATUS(s);
 
-       cond_idx = p->func->labels.len;
+       cond_idx = bc_vec_push(&p->func->labels, &p->func->code.len);
        ip_idx = cond_idx + 1;
-
-       bc_vec_push(&p->func->labels, &p->func->code.len);
        bc_vec_push(&p->conds, &cond_idx);
 
        bc_vec_push(&p->exits, &ip_idx);
@@ -4240,13 +4236,11 @@ static BC_STATUS zbc_parse_for(BcParse *p)
        s = zbc_lex_next(&p->l);
        if (s) RETURN_STATUS(s);
 
-       cond_idx = p->func->labels.len;
+       cond_idx = bc_vec_push(&p->func->labels, &p->func->code.len);
        update_idx = cond_idx + 1;
        body_idx = update_idx + 1;
        exit_idx = body_idx + 1;
 
-       bc_vec_push(&p->func->labels, &p->func->code.len);
-
        if (p->l.t.t != BC_LEX_SCOLON)
                s = zbc_parse_expr(p, BC_PARSE_REL);
        else {
@@ -4272,14 +4266,14 @@ static BC_STATUS zbc_parse_for(BcParse *p)
 
        if (p->l.t.t != BC_LEX_RPAREN) {
                s = zbc_parse_expr(p, 0);
-               bc_parse_push(p, BC_INST_POP);
                if (s) RETURN_STATUS(s);
+               if (p->l.t.t != BC_LEX_RPAREN) RETURN_STATUS(bc_error_bad_token());
+               bc_parse_push(p, BC_INST_POP);
        } else {
                s = bc_POSIX_does_not_allow_empty_X_expression_in_for("update");
                IF_ERROR_RETURN_POSSIBLE(if (s) RETURN_STATUS(s);)
        }
 
-       if (p->l.t.t != BC_LEX_RPAREN) RETURN_STATUS(bc_error_bad_token());
        bc_parse_pushJUMP(p, cond_idx);
        bc_vec_push(&p->func->labels, &p->func->code.len);