diff options
| -rw-r--r-- | RELEASES.md | 52 | ||||
| -rw-r--r-- | eval.c | 4 | ||||
| -rw-r--r-- | parse.c | 20 |
3 files changed, 55 insertions, 21 deletions
diff --git a/RELEASES.md b/RELEASES.md index 2b55ff9..3d75210 100644 --- a/RELEASES.md +++ b/RELEASES.md @@ -9,21 +9,45 @@ 62/76 GNU find features supported. +- Rework optimization levels + - `-O1` (logical simplification): + - Constant propagation (`! -false <==> -true`, `! -true <==> -false`) + - Double negation (`! ! X <==> X`) + - Conjunction elimination: + - `-true -a X <==> X` + - `X -a -true <==> X` + - Disjunctive syllogism: + - `-false -o X <==> X` + - `X -o -false <==> X` + - Short-circuiting: + - `-false -a X <==> -false` + - `-true -o X <==> -true` + - De Morgan's laws (**new**): + - `( ! X -a ! Y ) <==> ! ( X -o Y )` + - `( ! X -o ! Y ) <==> ! ( X -a Y )` + - `! ( X -a ! Y ) <==> ( ! X -o Y )` + - `! ( X -o ! Y ) <==> ( ! X -a Y )` + - `! ( ! X -a Y ) <==> ( X -o ! Y )` + - `! ( ! X -o Y ) <==> ( X -a ! Y )` + - Unused result (**new**): `! X , Y <==> X , Y` + - `-O2` (purity): + - (These optimizations take the purity of predicates into account, allowing side-effect-free tests like `-name` or `-type` to be moved or removed) + - `PURE -a -false <==> -false` + - `PURE -o -true <==> -true` + - `PURE , X <==> X` + - Top-level unused result (**new**): `X (-a|-o|,) PURE <==> X` + - `-O3` (cost-based, **default**): + - Re-order tests to reduce the expected cost (TODO) + - `-O4` (aggressive): + - (These are very aggressive optimizations that may have surprising effects on warning/error messages and runtime, but still should not affect the resulting output) + - Change top-level expressions with no actions to `-false` (**new**): + - For example, `bfs -O4 -true -o -print` becomes `-false`, because `-print` is unreachable + - Skip the entire traversal if the top-level expression is `-false` + - `bfs -O4 -false` (or anything that optimizes to `-false`) will exit immediately + - This may cause messages about non-existent files, symbolic link cycles, etc. to be skipped + - `-Ofast`: + - Always the highest level, currently the same as `-O4` - Color files with multiple hard links correctly -- At `-O3`, replace command lines with no action with `-false` - - For example, `bfs -true -o -print` becomes `-false`, because `-print` is not reachable -- Move optimizations that rely on the purity of a predicate to `-O2` (the new default) -- Optimize using De Morgan's laws: - - `( ! X -a ! Y ) <==> ! ( X -o Y )` - - `( ! X -o ! Y ) <==> ! ( X -a Y )` - - `! ( X -a ! Y ) <==> ( ! X -o Y )` - - `! ( X -o ! Y ) <==> ( ! X -a Y )` - - `! ( ! X -a Y ) <==> ( X -o ! Y )` - - `! ( ! X -o Y ) <==> ( X -a ! Y )` -- At `-O2`, remove top-level pure expressions - - For example, `bfs -print , -false` becomes `-print`, because the top-level return value is ignored -- At `-O2`, remove negations from the left-hand side of the comma operator - - For example, `-not -print , -print` becomes `-print , -print`, because the return value of the LHS is ignored - Treat `-`, `)`, and `,` as paths when required to by POSIX - `)` and `,` are only supported before the expression begins - Implement `-D opt` @@ -917,9 +917,9 @@ int eval_cmdline(const struct cmdline *cmdline) { return 0; } - if (cmdline->optlevel >= 3 && cmdline->expr->eval == eval_false) { + if (cmdline->optlevel >= 4 && cmdline->expr->eval == eval_false) { if (cmdline->debug & DEBUG_OPT) { - fputs("-O3: skipping evaluation of top-level -false\n", stderr); + fputs("-O4: skipping evaluation of top-level -false\n", stderr); } return 0; } @@ -609,10 +609,20 @@ static struct expr *parse_debug(struct parser_state *state) { * Parse -On. */ static struct expr *parse_optlevel(struct parser_state *state) { - if (!parse_int(state, state->argv[0] + 2, &state->cmdline->optlevel, IF_INT)) { + int *optlevel = &state->cmdline->optlevel; + + if (strcmp(state->argv[0], "-Ofast") == 0) { + *optlevel = 4; + } else if (!parse_int(state, state->argv[0] + 2, optlevel, IF_INT)) { return NULL; } + if (*optlevel > 4) { + pretty_warning(state->cmdline->stderr_colors, + "warning: %s is the same as -O4.\n\n", + state->argv[0]); + } + return parse_nullary_flag(state); } @@ -1777,8 +1787,8 @@ static struct expr *optimize_whole_expr(const struct parser_state *state, struct } } - if (optlevel >= 3 && expr->pure && expr != &expr_false) { - debug_opt(state, "-O3: top-level purity: %e <==> %e\n", expr, &expr_false); + if (optlevel >= 4 && expr->pure && expr != &expr_false) { + debug_opt(state, "-O4: top-level purity: %e <==> %e\n", expr, &expr_false); free_expr(expr); expr = &expr_false; } @@ -1798,7 +1808,7 @@ static void dump_cmdline(const struct cmdline *cmdline) { fputs("-P ", stderr); } - if (cmdline->optlevel != 2) { + if (cmdline->optlevel != 3) { fprintf(stderr, "-O%d ", cmdline->optlevel); } @@ -1853,7 +1863,7 @@ struct cmdline *parse_cmdline(int argc, char *argv[]) { cmdline->mindepth = 0; cmdline->maxdepth = INT_MAX; cmdline->flags = BFTW_RECOVER; - cmdline->optlevel = 2; + cmdline->optlevel = 3; cmdline->debug = 0; cmdline->expr = &expr_true; cmdline->nopen_files = 0; |