ec74a9c14
Denys Vlasenko
2018-12-22
Subject
bc: make long-running dc drop data it does not need (when it can)
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miscutils/bc.c+34 -15
| @@ -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__); | |