1 /* Simple expression parser */
7 #include "util/debug.h"
14 %parse-param { double *final_val }
15 %parse-param { struct expr_parse_ctx *ctx }
16 %parse-param { bool compute_ids }
17 %parse-param {void *scanner}
18 %lex-param {void* scanner}
25 * When creating ids, holds the working set of event ids. NULL
26 * implies the set is empty.
30 * The metric value. When not creating ids this is the value
31 * read from a counter, a constant or some computed value. When
32 * creating ids the value is either a constant or BOTTOM. NAN is
33 * used as the special BOTTOM value, representing a "set of all
40 %token ID NUMBER MIN MAX IF ELSE LITERAL D_RATIO SOURCE_COUNT EXPR_ERROR
49 %type <num> NUMBER LITERAL
51 %destructor { free ($$); } <str>
52 %type <ids> expr if_expr
53 %destructor { ids__free($$.ids); } <ids>
56 static void expr_error(double *final_val __maybe_unused,
57 struct expr_parse_ctx *ctx __maybe_unused,
58 bool compute_ids __maybe_unused,
66 * During compute ids, the special "bottom" value uses NAN to represent the set
67 * of all values. NAN is selected as it isn't a useful constant value.
71 /* During computing ids, does val represent a constant (non-BOTTOM) value? */
72 static bool is_const(double val)
77 static struct ids union_expr(struct ids ids1, struct ids ids2)
81 .ids = ids__union(ids1.ids, ids2.ids),
86 static struct ids handle_id(struct expr_parse_ctx *ctx, char *id,
87 bool compute_ids, bool source_count)
93 * Compute the event's value from ID. If the ID isn't known then
94 * it isn't used to compute the formula so set to NAN.
96 struct expr_id_data *data;
99 if (expr__resolve_id(ctx, id, &data) == 0) {
100 result.val = source_count
101 ? expr_id_data__source_count(data)
102 : expr_id_data__value(data);
108 * Set the value to BOTTOM to show that any value is possible
109 * when the event is computed. Create a set of just the ID.
112 result.ids = ids__new();
113 if (!result.ids || ids__insert(result.ids, id)) {
114 pr_err("Error creating IDs for '%s'", id);
122 * If we're not computing ids or $1 and $3 are constants, compute the new
123 * constant value using OP. Its invariant that there are no ids. If computing
124 * ids for non-constants union the set of IDs that must be computed.
126 #define BINARY_LONG_OP(RESULT, OP, LHS, RHS) \
127 if (!compute_ids || (is_const(LHS.val) && is_const(RHS.val))) { \
128 assert(LHS.ids == NULL); \
129 assert(RHS.ids == NULL); \
130 RESULT.val = (long)LHS.val OP (long)RHS.val; \
133 RESULT = union_expr(LHS, RHS); \
136 #define BINARY_OP(RESULT, OP, LHS, RHS) \
137 if (!compute_ids || (is_const(LHS.val) && is_const(RHS.val))) { \
138 assert(LHS.ids == NULL); \
139 assert(RHS.ids == NULL); \
140 RESULT.val = LHS.val OP RHS.val; \
143 RESULT = union_expr(LHS, RHS); \
152 ctx->ids = ids__union($1.ids, ctx->ids);
159 if_expr: expr IF expr ELSE if_expr
161 if (fpclassify($3.val) == FP_ZERO) {
163 * The IF expression evaluated to 0 so treat as false, take the
164 * ELSE and discard everything else.
170 } else if (!compute_ids || is_const($3.val)) {
172 * If ids aren't computed then treat the expression as true. If
173 * ids are being computed and the IF expr is a non-zero
174 * constant, then also evaluate the true case.
180 } else if ($1.val == $5.val) {
182 * LHS == RHS, so both are an identical constant. No need to
183 * evaluate any events.
192 * Value is either the LHS or RHS and we need the IF expression
195 $$ = union_expr($1, union_expr($3, $5));
206 | ID { $$ = handle_id(ctx, $1, compute_ids, /*source_count=*/false); }
207 | SOURCE_COUNT '(' ID ')' { $$ = handle_id(ctx, $3, compute_ids, /*source_count=*/true); }
208 | expr '|' expr { BINARY_LONG_OP($$, |, $1, $3); }
209 | expr '&' expr { BINARY_LONG_OP($$, &, $1, $3); }
210 | expr '^' expr { BINARY_LONG_OP($$, ^, $1, $3); }
211 | expr '<' expr { BINARY_OP($$, <, $1, $3); }
212 | expr '>' expr { BINARY_OP($$, >, $1, $3); }
213 | expr '+' expr { BINARY_OP($$, +, $1, $3); }
214 | expr '-' expr { BINARY_OP($$, -, $1, $3); }
215 | expr '*' expr { BINARY_OP($$, *, $1, $3); }
218 if (fpclassify($3.val) == FP_ZERO) {
219 pr_debug("division by zero\n");
221 } else if (!compute_ids || (is_const($1.val) && is_const($3.val))) {
222 assert($1.ids == NULL);
223 assert($3.ids == NULL);
224 $$.val = $1.val / $3.val;
227 /* LHS and/or RHS need computing from event IDs so union. */
228 $$ = union_expr($1, $3);
233 if (fpclassify($3.val) == FP_ZERO) {
234 pr_debug("division by zero\n");
236 } else if (!compute_ids || (is_const($1.val) && is_const($3.val))) {
237 assert($1.ids == NULL);
238 assert($3.ids == NULL);
239 $$.val = (long)$1.val % (long)$3.val;
242 /* LHS and/or RHS need computing from event IDs so union. */
243 $$ = union_expr($1, $3);
246 | D_RATIO '(' expr ',' expr ')'
248 if (fpclassify($5.val) == FP_ZERO) {
250 * Division by constant zero always yields zero and no events
253 assert($5.ids == NULL);
257 } else if (!compute_ids || (is_const($3.val) && is_const($5.val))) {
258 assert($3.ids == NULL);
259 assert($5.ids == NULL);
260 $$.val = $3.val / $5.val;
263 /* LHS and/or RHS need computing from event IDs so union. */
264 $$ = union_expr($3, $5);
276 | MIN '(' expr ',' expr ')'
279 $$.val = $3.val < $5.val ? $3.val : $5.val;
282 $$ = union_expr($3, $5);
285 | MAX '(' expr ',' expr ')'
288 $$.val = $3.val > $5.val ? $3.val : $5.val;
291 $$ = union_expr($3, $5);