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authorDenys Vlasenko2018-12-22 19:23:46 +0100
committerDenys Vlasenko2018-12-22 19:23:46 +0100
commitec74a9c14572f17ad4a5ff94813a743bc6e6222d (patch)
tree413b40630f7a5be6ff0941851cfd95e85a5ff344
parent5cf0b2d46617cdc52009da526c127ead57ab554f (diff)
downloadbusybox-ec74a9c14572f17ad4a5ff94813a743bc6e6222d.zip
busybox-ec74a9c14572f17ad4a5ff94813a743bc6e6222d.tar.gz
bc: make long-running dc drop data it does not need (when it can)
function old new delta zbc_vm_process 765 824 +59 Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
-rw-r--r--miscutils/bc.c49
1 files changed, 34 insertions, 15 deletions
diff --git a/miscutils/bc.c b/miscutils/bc.c
index bdee14d..7be2d0b 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__);