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1/* Simple expression parser */2%{3#ifndef NDEBUG4#define YYDEBUG 15#endif6#include <assert.h>7#include <math.h>8#include <stdlib.h>9#include "util/debug.h"10#define IN_EXPR_Y 111#include "expr.h"12#include "expr-bison.h"13int expr_lex(YYSTYPE * yylval_param , void *yyscanner);14%}15 16%define api.pure full17 18%parse-param { double *final_val }19%parse-param { struct expr_parse_ctx *ctx }20%parse-param { bool compute_ids }21%parse-param {void *scanner}22%lex-param {void* scanner}23 24%union {25 double num;26 char *str;27 struct ids {28 /*29 * When creating ids, holds the working set of event ids. NULL30 * implies the set is empty.31 */32 struct hashmap *ids;33 /*34 * The metric value. When not creating ids this is the value35 * read from a counter, a constant or some computed value. When36 * creating ids the value is either a constant or BOTTOM. NAN is37 * used as the special BOTTOM value, representing a "set of all38 * values" case.39 */40 double val;41 } ids;42}43 44%token ID NUMBER MIN MAX IF ELSE LITERAL D_RATIO SOURCE_COUNT HAS_EVENT STRCMP_CPUID_STR EXPR_ERROR45%left MIN MAX IF46%left '|'47%left '^'48%left '&'49%left '<' '>'50%left '-' '+'51%left '*' '/' '%'52%left NEG NOT53%type <num> NUMBER LITERAL54%type <str> ID55%destructor { free ($$); } <str>56%type <ids> expr if_expr57%destructor { ids__free($$.ids); } <ids>58 59%{60static void expr_error(double *final_val __maybe_unused,61 struct expr_parse_ctx *ctx __maybe_unused,62 bool compute_ids __maybe_unused,63 void *scanner __maybe_unused,64 const char *s)65{66 pr_debug("%s\n", s);67}68 69/*70 * During compute ids, the special "bottom" value uses NAN to represent the set71 * of all values. NAN is selected as it isn't a useful constant value.72 */73#define BOTTOM NAN74 75/* During computing ids, does val represent a constant (non-BOTTOM) value? */76static bool is_const(double val)77{78 return isfinite(val);79}80 81static struct ids union_expr(struct ids ids1, struct ids ids2)82{83 struct ids result = {84 .val = BOTTOM,85 .ids = ids__union(ids1.ids, ids2.ids),86 };87 return result;88}89 90static struct ids handle_id(struct expr_parse_ctx *ctx, char *id,91 bool compute_ids, bool source_count)92{93 struct ids result;94 95 if (!compute_ids) {96 /*97 * Compute the event's value from ID. If the ID isn't known then98 * it isn't used to compute the formula so set to NAN.99 */100 struct expr_id_data *data;101 102 result.val = NAN;103 if (expr__resolve_id(ctx, id, &data) == 0) {104 result.val = source_count105 ? expr_id_data__source_count(data)106 : expr_id_data__value(data);107 }108 result.ids = NULL;109 free(id);110 } else {111 /*112 * Set the value to BOTTOM to show that any value is possible113 * when the event is computed. Create a set of just the ID.114 */115 result.val = BOTTOM;116 result.ids = ids__new();117 if (!result.ids || ids__insert(result.ids, id)) {118 pr_err("Error creating IDs for '%s'", id);119 free(id);120 }121 }122 return result;123}124 125/*126 * If we're not computing ids or $1 and $3 are constants, compute the new127 * constant value using OP. Its invariant that there are no ids. If computing128 * ids for non-constants union the set of IDs that must be computed.129 */130#define BINARY_OP(RESULT, OP, LHS, RHS) \131 if (!compute_ids || (is_const(LHS.val) && is_const(RHS.val))) { \132 assert(LHS.ids == NULL); \133 assert(RHS.ids == NULL); \134 if (isnan(LHS.val) || isnan(RHS.val)) { \135 RESULT.val = NAN; \136 } else { \137 RESULT.val = LHS.val OP RHS.val; \138 } \139 RESULT.ids = NULL; \140 } else { \141 RESULT = union_expr(LHS, RHS); \142 }143 144%}145%%146 147start: if_expr148{149 if (compute_ids)150 ctx->ids = ids__union($1.ids, ctx->ids);151 152 if (final_val)153 *final_val = $1.val;154}155;156 157if_expr: expr IF expr ELSE if_expr158{159 if (fpclassify($3.val) == FP_ZERO) {160 /*161 * The IF expression evaluated to 0 so treat as false, take the162 * ELSE and discard everything else.163 */164 $$.val = $5.val;165 $$.ids = $5.ids;166 ids__free($1.ids);167 ids__free($3.ids);168 } else if (!compute_ids || is_const($3.val)) {169 /*170 * If ids aren't computed then treat the expression as true. If171 * ids are being computed and the IF expr is a non-zero172 * constant, then also evaluate the true case.173 */174 $$.val = $1.val;175 $$.ids = $1.ids;176 ids__free($3.ids);177 ids__free($5.ids);178 } else if ($1.val == $5.val) {179 /*180 * LHS == RHS, so both are an identical constant. No need to181 * evaluate any events.182 */183 $$.val = $1.val;184 $$.ids = NULL;185 ids__free($1.ids);186 ids__free($3.ids);187 ids__free($5.ids);188 } else {189 /*190 * Value is either the LHS or RHS and we need the IF expression191 * to compute it.192 */193 $$ = union_expr($1, union_expr($3, $5));194 }195}196| expr197;198 199expr: NUMBER200{201 $$.val = $1;202 $$.ids = NULL;203}204| ID { $$ = handle_id(ctx, $1, compute_ids, /*source_count=*/false); }205| SOURCE_COUNT '(' ID ')' { $$ = handle_id(ctx, $3, compute_ids, /*source_count=*/true); }206| HAS_EVENT '(' ID ')'207{208 $$.val = expr__has_event(ctx, compute_ids, $3);209 $$.ids = NULL;210 free($3);211}212| STRCMP_CPUID_STR '(' ID ')'213{214 $$.val = expr__strcmp_cpuid_str(ctx, compute_ids, $3);215 $$.ids = NULL;216 free($3);217}218| expr '|' expr219{220 if (is_const($1.val) && is_const($3.val)) {221 assert($1.ids == NULL);222 assert($3.ids == NULL);223 $$.ids = NULL;224 $$.val = (fpclassify($1.val) == FP_ZERO && fpclassify($3.val) == FP_ZERO) ? 0 : 1;225 } else if (is_const($1.val)) {226 assert($1.ids == NULL);227 if (fpclassify($1.val) == FP_ZERO) {228 $$ = $3;229 } else {230 $$.val = 1;231 $$.ids = NULL;232 ids__free($3.ids);233 }234 } else if (is_const($3.val)) {235 assert($3.ids == NULL);236 if (fpclassify($3.val) == FP_ZERO) {237 $$ = $1;238 } else {239 $$.val = 1;240 $$.ids = NULL;241 ids__free($1.ids);242 }243 } else {244 $$ = union_expr($1, $3);245 }246}247| expr '&' expr248{249 if (is_const($1.val) && is_const($3.val)) {250 assert($1.ids == NULL);251 assert($3.ids == NULL);252 $$.val = (fpclassify($1.val) != FP_ZERO && fpclassify($3.val) != FP_ZERO) ? 1 : 0;253 $$.ids = NULL;254 } else if (is_const($1.val)) {255 assert($1.ids == NULL);256 if (fpclassify($1.val) != FP_ZERO) {257 $$ = $3;258 } else {259 $$.val = 0;260 $$.ids = NULL;261 ids__free($3.ids);262 }263 } else if (is_const($3.val)) {264 assert($3.ids == NULL);265 if (fpclassify($3.val) != FP_ZERO) {266 $$ = $1;267 } else {268 $$.val = 0;269 $$.ids = NULL;270 ids__free($1.ids);271 }272 } else {273 $$ = union_expr($1, $3);274 }275}276| expr '^' expr277{278 if (is_const($1.val) && is_const($3.val)) {279 assert($1.ids == NULL);280 assert($3.ids == NULL);281 $$.val = (fpclassify($1.val) == FP_ZERO) != (fpclassify($3.val) == FP_ZERO) ? 1 : 0;282 $$.ids = NULL;283 } else {284 $$ = union_expr($1, $3);285 }286}287| expr '<' expr { BINARY_OP($$, <, $1, $3); }288| expr '>' expr { BINARY_OP($$, >, $1, $3); }289| expr '+' expr { BINARY_OP($$, +, $1, $3); }290| expr '-' expr { BINARY_OP($$, -, $1, $3); }291| expr '*' expr { BINARY_OP($$, *, $1, $3); }292| expr '/' expr293{294 if (fpclassify($3.val) == FP_ZERO) {295 pr_debug("division by zero\n");296 assert($3.ids == NULL);297 if (compute_ids)298 ids__free($1.ids);299 $$.val = NAN;300 $$.ids = NULL;301 } else if (!compute_ids || (is_const($1.val) && is_const($3.val))) {302 assert($1.ids == NULL);303 assert($3.ids == NULL);304 $$.val = $1.val / $3.val;305 $$.ids = NULL;306 } else {307 /* LHS and/or RHS need computing from event IDs so union. */308 $$ = union_expr($1, $3);309 }310}311| expr '%' expr312{313 if (fpclassify($3.val) == FP_ZERO) {314 pr_debug("division by zero\n");315 YYABORT;316 } else if (!compute_ids || (is_const($1.val) && is_const($3.val))) {317 assert($1.ids == NULL);318 assert($3.ids == NULL);319 $$.val = (long)$1.val % (long)$3.val;320 $$.ids = NULL;321 } else {322 /* LHS and/or RHS need computing from event IDs so union. */323 $$ = union_expr($1, $3);324 }325}326| D_RATIO '(' expr ',' expr ')'327{328 if (fpclassify($5.val) == FP_ZERO) {329 /*330 * Division by constant zero always yields zero and no events331 * are necessary.332 */333 assert($5.ids == NULL);334 $$.val = 0.0;335 $$.ids = NULL;336 ids__free($3.ids);337 } else if (!compute_ids || (is_const($3.val) && is_const($5.val))) {338 assert($3.ids == NULL);339 assert($5.ids == NULL);340 $$.val = $3.val / $5.val;341 $$.ids = NULL;342 } else {343 /* LHS and/or RHS need computing from event IDs so union. */344 $$ = union_expr($3, $5);345 }346}347| '-' expr %prec NEG348{349 $$.val = -$2.val;350 $$.ids = $2.ids;351}352| '(' if_expr ')'353{354 $$ = $2;355}356| MIN '(' expr ',' expr ')'357{358 if (!compute_ids) {359 $$.val = $3.val < $5.val ? $3.val : $5.val;360 $$.ids = NULL;361 } else {362 $$ = union_expr($3, $5);363 }364}365| MAX '(' expr ',' expr ')'366{367 if (!compute_ids) {368 $$.val = $3.val > $5.val ? $3.val : $5.val;369 $$.ids = NULL;370 } else {371 $$ = union_expr($3, $5);372 }373}374| LITERAL375{376 $$.val = $1;377 $$.ids = NULL;378}379;380 381%%382