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-rw-r--r--bfs.h7
-rw-r--r--eval.c9
-rw-r--r--parse.c60
3 files changed, 42 insertions, 34 deletions
diff --git a/bfs.h b/bfs.h
index 16ce475..79a383a 100644
--- a/bfs.h
+++ b/bfs.h
@@ -206,8 +206,6 @@ struct expr {
bool always_true;
/** Whether this expression always evaluates to false. */
bool always_false;
- /** Whether this expression never returns. */
- bool never_returns;
/** Number of times this predicate was executed. */
size_t evaluations;
@@ -266,6 +264,11 @@ struct expr {
};
/**
+ * @return Whether expr is known to always quit.
+ */
+bool expr_never_returns(const struct expr *expr);
+
+/**
* Parse the command line.
*/
struct cmdline *parse_cmdline(int argc, char *argv[]);
diff --git a/eval.c b/eval.c
index 1d2da7c..e6664a6 100644
--- a/eval.c
+++ b/eval.c
@@ -911,9 +911,12 @@ static bool eval_expr(struct expr *expr, struct eval_state *state) {
++expr->successes;
}
- assert(!expr->always_true || ret);
- assert(!expr->always_false || !ret);
- assert(!expr->never_returns || *state->quit);
+ if (expr_never_returns(expr)) {
+ assert(*state->quit);
+ } else if (!*state->quit) {
+ assert(!expr->always_true || ret);
+ assert(!expr->always_false || !ret);
+ }
return ret;
}
diff --git a/parse.c b/parse.c
index 61c17a5..13c7be1 100644
--- a/parse.c
+++ b/parse.c
@@ -107,7 +107,6 @@ static struct expr *new_expr(eval_fn *eval, size_t argc, char **argv) {
expr->pure = false;
expr->always_true = false;
expr->always_false = false;
- expr->never_returns = false;
expr->evaluations = 0;
expr->successes = 0;
expr->elapsed.tv_sec = 0;
@@ -152,6 +151,21 @@ static struct expr *new_binary_expr(eval_fn *eval, struct expr *lhs, struct expr
}
/**
+ * Check if an expression never returns.
+ */
+bool expr_never_returns(const struct expr *expr) {
+ // Expressions that never return are vacuously both always true and always false
+ return expr->always_true && expr->always_false;
+}
+
+/**
+ * Set an expression to never return.
+ */
+static void expr_set_never_returns(struct expr *expr) {
+ expr->always_true = expr->always_false = true;
+}
+
+/**
* Dump the parsed expression tree, for debugging.
*/
static void dump_expr(CFILE *cfile, const struct expr *expr, bool verbose) {
@@ -973,7 +987,7 @@ static struct expr *parse_exit(struct parser_state *state, int arg1, int arg2) {
struct expr *expr = parse_action(state, eval_exit, argc);
if (expr) {
- expr->never_returns = true;
+ expr_set_never_returns(expr);
expr->idata = status;
}
return expr;
@@ -1729,7 +1743,7 @@ static struct expr *parse_prune(struct parser_state *state, int arg1, int arg2)
static struct expr *parse_quit(struct parser_state *state, int arg1, int arg2) {
struct expr *expr = parse_nullary_action(state, eval_quit);
if (expr) {
- expr->never_returns = true;
+ expr_set_never_returns(expr);
}
return expr;
}
@@ -2454,8 +2468,8 @@ static struct expr *new_not_expr(const struct parser_state *state, struct expr *
} else if (rhs == &expr_false) {
debug_opt(state, "-O1: constant propagation: (%s %e) <==> %e\n", argv[0], rhs, &expr_true);
return &expr_true;
- } else if (optlevel >= 2 && rhs->never_returns) {
- debug_opt(state, "-O2: reachability: (%s %e) <==> %e\n", argv[0], rhs, rhs);
+ } else if (expr_never_returns(rhs)) {
+ debug_opt(state, "-O1: reachability: (%s %e) <==> %e\n", argv[0], rhs, rhs);
return rhs;
} else if (rhs->eval == eval_not) {
debug_opt(state, "-O1: double negation: (%s %e) <==> %e\n", argv[0], rhs, rhs->rhs);
@@ -2493,7 +2507,6 @@ static struct expr *new_not_expr(const struct parser_state *state, struct expr *
expr->pure = rhs->pure;
expr->always_true = rhs->always_false;
expr->always_false = rhs->always_true;
- expr->never_returns = rhs->never_returns;
}
return expr;
}
@@ -2572,10 +2585,6 @@ static struct expr *new_and_expr(const struct parser_state *state, struct expr *
debug_opt(state, "-O2: purity: (%s %e %e) <==> %e\n", argv[0], lhs, rhs, rhs);
free_expr(lhs);
return rhs;
- } else if (optlevel >= 2 && lhs->never_returns) {
- debug_opt(state, "-O2: reachability: (%s %e %e) <==> %e\n", argv[0], lhs, rhs, lhs);
- free_expr(rhs);
- return lhs;
} else if (lhs->eval == eval_not && rhs->eval == eval_not) {
char **not_arg = lhs->argv;
debug_opt(state, "-O1: De Morgan's laws: (%s %e %e) <==> (%s (%s %e %e))\n",
@@ -2599,7 +2608,6 @@ static struct expr *new_and_expr(const struct parser_state *state, struct expr *
expr->pure = lhs->pure && rhs->pure;
expr->always_true = lhs->always_true && rhs->always_true;
expr->always_false = lhs->always_false || rhs->always_false;
- expr->never_returns = lhs->never_returns || (lhs->always_true && rhs->never_returns);
}
return expr;
}
@@ -2668,10 +2676,6 @@ static struct expr *new_or_expr(const struct parser_state *state, struct expr *l
debug_opt(state, "-O2: purity: (%s %e %e) <==> %e\n", argv[0], lhs, rhs, rhs);
free_expr(lhs);
return rhs;
- } else if (optlevel >= 2 && lhs->never_returns) {
- debug_opt(state, "-O2: reachability: (%s %e %e) <==> %e\n", argv[0], lhs, rhs, lhs);
- free_expr(rhs);
- return lhs;
} else if (lhs->eval == eval_not && rhs->eval == eval_not) {
char **not_arg = lhs->argv;
debug_opt(state, "-O1: De Morgan's laws: (%s %e %e) <==> (%s (%s %e %e))\n",
@@ -2695,7 +2699,6 @@ static struct expr *new_or_expr(const struct parser_state *state, struct expr *l
expr->pure = lhs->pure && rhs->pure;
expr->always_true = lhs->always_true || rhs->always_true;
expr->always_false = lhs->always_false && rhs->always_false;
- expr->never_returns = lhs->never_returns || (lhs->always_false && rhs->never_returns);
}
return expr;
}
@@ -2751,25 +2754,24 @@ static struct expr *new_comma_expr(const struct parser_state *state, struct expr
lhs = extract_child_expr(lhs, &lhs->rhs);
}
- if (optlevel >= 2) {
- if (lhs->pure) {
- debug_opt(state, "-O2: purity: (%s %e %e) <==> %e\n", argv[0], lhs, rhs, rhs);
- free_expr(lhs);
- return rhs;
- } else if (lhs->never_returns) {
- debug_opt(state, "-O2: reachability: (%s %e %e) <==> %e\n", argv[0], lhs, rhs, lhs);
- free_expr(rhs);
- return lhs;
- }
+ if (expr_never_returns(lhs)) {
+ debug_opt(state, "-O1: reachability: (%s %e %e) <==> %e\n", argv[0], lhs, rhs, lhs);
+ free_expr(rhs);
+ return lhs;
+ }
+
+ if (optlevel >= 2 && lhs->pure) {
+ debug_opt(state, "-O2: purity: (%s %e %e) <==> %e\n", argv[0], lhs, rhs, rhs);
+ free_expr(lhs);
+ return rhs;
}
}
struct expr *expr = new_binary_expr(eval_comma, lhs, rhs, argv);
if (expr) {
expr->pure = lhs->pure && rhs->pure;
- expr->always_true = rhs->always_true;
- expr->always_false = rhs->always_false;
- expr->never_returns = lhs->never_returns || rhs->never_returns;
+ expr->always_true = expr_never_returns(lhs) || rhs->always_true;
+ expr->always_false = expr_never_returns(lhs) || rhs->always_false;
}
return expr;
}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-01 00:10:07 +0000