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>

1 files changed, 26 insertions, 32 deletions

diff --git a/miscutils/bc.c b/miscutils/bc.c
index 441cb0467..abedbdf0b 100644
--- 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);