1 files changed, 34 insertions, 15 deletions

diff --git a/miscutils/bc.c b/miscutils/bc.c
index bdee14de4..7be2d0b9b 100644
--- a/miscutils/bc.c
+++ b/miscutils/bc.c
@@ -3437,11 +3437,11 @@ static BC_STATUS zdc_lex_token(BcLex *l)
 //                      break;
                 case '\n':
                         // '\n' is BC_LEX_NLINE, not BC_LEX_WHITESPACE
-                        // (and "case '\n'" is not just empty here)
+                        // (and "case '\n':" is not just empty here)
                         // only to allow interactive dc have a way to exit
                         // "parse" stage of "parse,execute" loop
-                        // on '\n', not on _next_ token (which would mean
-                        // command are not executed on pressing <enter>).
+                        // on <enter>, not on _next_ token (which would mean
+                        // commands are not executed on pressing <enter>).
                         // IOW: typing "1p<enter>" should print "1" _at once_,
                         // not after some more input.
                         l->t.t = BC_LEX_NLINE;
@@ -6673,6 +6673,9 @@ static BC_STATUS zbc_vm_process(const char *text)
         if (s) RETURN_STATUS(s);
 
         while (G.prs.l.t.t != BC_LEX_EOF) {
+                BcInstPtr *ip;
+                BcFunc *f;
+
                 dbg_lex("%s:%d G.prs.l.t.t:%d, parsing...", __func__, __LINE__, G.prs.l.t.t);
                 if (IS_BC) {
 // FIXME: "eating" of stmt delimiters is coded inconsistently
@@ -6695,6 +6698,15 @@ static BC_STATUS zbc_vm_process(const char *text)
                         bc_program_reset();
                         break;
                 }
+
+                ip = (void*)G.prog.exestack.v;
+#if SANITY_CHECKS
+                if (G.prog.exestack.len != 1) // should have only main's IP
+                        bb_error_msg_and_die("BUG:call stack");
+                if (ip->func != BC_PROG_MAIN)
+                        bb_error_msg_and_die("BUG:not MAIN");
+#endif
+                f = bc_program_func_BC_PROG_MAIN();
                 // bc discards strings, constants and code after each
                 // top-level statement in the "main program".
                 // This prevents "yes 1 | bc" from growing its memory
@@ -6706,22 +6718,10 @@ static BC_STATUS zbc_vm_process(const char *text)
                 // but bc stores function strings/constants in per-function
                 // storage.
                 if (IS_BC) {
-                        BcFunc *f;
-                        BcInstPtr *ip = (void*)G.prog.exestack.v;
-
 #if SANITY_CHECKS
                         if (G.prog.results.len != 0) // should be empty
                                 bb_error_msg_and_die("BUG:data stack");
-                        if (G.prog.exestack.len != 1) // should have only main's IP
-                                bb_error_msg_and_die("BUG:call stack");
-                        if (ip->func != BC_PROG_MAIN)
-                                bb_error_msg_and_die("BUG:not MAIN");
 #endif
-//bb_error_msg("ip->func:%d >idx:%d >len:%d", ip->func, ip->inst_idx, ip->len);
-                        f = bc_program_func_BC_PROG_MAIN();
-//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
-                        bc_vec_pop_all(&f->code);
-                        ip->inst_idx = 0;
                         IF_BC(bc_vec_pop_all(&f->strs);)
                         IF_BC(bc_vec_pop_all(&f->consts);)
                 } else {
@@ -6731,7 +6731,26 @@ static BC_STATUS zbc_vm_process(const char *text)
                                 s = zbc_lex_next(&G.prs.l);
                                 if (s) RETURN_STATUS(s);
                         }
+
+                        if (G.prog.results.len == 0
+                         && G.prog.vars.len == 0
+                        ) {
+                                // If stack is empty and no registers exist (TODO: or they are all empty),
+                                // we can get rid of accumulated strings and constants.
+                                // In this example dc process should not grow
+                                // its memory consumption with time:
+                                // yes 1pc | dc
+                                IF_DC(bc_vec_pop_all(&G.prog.strs);)
+                                IF_DC(bc_vec_pop_all(&G.prog.consts);)
+                        }
+                        // The code is discarded always (below), thus this example
+                        // should also not grow its memory consumption with time,
+                        // even though its data stack is not empty:
+                        // { echo 1; yes dk; } | dc
                 }
+                // We drop generated and executed code for both bc and dc:
+                bc_vec_pop_all(&f->code);
+                ip->inst_idx = 0;
         }
 
         dbg_lex_done("%s:%d done", __func__, __LINE__);