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-rw-r--r--RELEASES.md52
-rw-r--r--eval.c4
-rw-r--r--parse.c20
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`
diff --git a/eval.c b/eval.c
index c3e29d2..44b1fa4 100644
--- a/eval.c
+++ b/eval.c
@@ -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;
}
diff --git a/parse.c b/parse.c
index e9e1b52..c24592c 100644
--- a/parse.c
+++ b/parse.c
@@ -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;