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Diffstat (limited to 'tools/perf/util/expr.y')
| -rw-r--r-- | tools/perf/util/expr.y | 301 |
1 files changed, 301 insertions, 0 deletions
diff --git a/tools/perf/util/expr.y b/tools/perf/util/expr.y new file mode 100644 index 000000000..635e56235 --- /dev/null +++ b/tools/perf/util/expr.y @@ -0,0 +1,301 @@ +/* Simple expression parser */ +%{ +#define YYDEBUG 1 +#include <assert.h> +#include <math.h> +#include <stdlib.h> +#include "util/debug.h" +#define IN_EXPR_Y 1 +#include "expr.h" +%} + +%define api.pure full + +%parse-param { double *final_val } +%parse-param { struct expr_parse_ctx *ctx } +%parse-param { bool compute_ids } +%parse-param {void *scanner} +%lex-param {void* scanner} + +%union { + double num; + char *str; + struct ids { + /* + * When creating ids, holds the working set of event ids. NULL + * implies the set is empty. + */ + struct hashmap *ids; + /* + * The metric value. When not creating ids this is the value + * read from a counter, a constant or some computed value. When + * creating ids the value is either a constant or BOTTOM. NAN is + * used as the special BOTTOM value, representing a "set of all + * values" case. + */ + double val; + } ids; +} + +%token ID NUMBER MIN MAX IF ELSE LITERAL D_RATIO SOURCE_COUNT EXPR_ERROR +%left MIN MAX IF +%left '|' +%left '^' +%left '&' +%left '<' '>' +%left '-' '+' +%left '*' '/' '%' +%left NEG NOT +%type <num> NUMBER LITERAL +%type <str> ID +%destructor { free ($$); } <str> +%type <ids> expr if_expr +%destructor { ids__free($$.ids); } <ids> + +%{ +static void expr_error(double *final_val __maybe_unused, + struct expr_parse_ctx *ctx __maybe_unused, + bool compute_ids __maybe_unused, + void *scanner, + const char *s) +{ + pr_debug("%s\n", s); +} + +/* + * During compute ids, the special "bottom" value uses NAN to represent the set + * of all values. NAN is selected as it isn't a useful constant value. + */ +#define BOTTOM NAN + +/* During computing ids, does val represent a constant (non-BOTTOM) value? */ +static bool is_const(double val) +{ + return isfinite(val); +} + +static struct ids union_expr(struct ids ids1, struct ids ids2) +{ + struct ids result = { + .val = BOTTOM, + .ids = ids__union(ids1.ids, ids2.ids), + }; + return result; +} + +static struct ids handle_id(struct expr_parse_ctx *ctx, char *id, + bool compute_ids, bool source_count) +{ + struct ids result; + + if (!compute_ids) { + /* + * Compute the event's value from ID. If the ID isn't known then + * it isn't used to compute the formula so set to NAN. + */ + struct expr_id_data *data; + + result.val = NAN; + if (expr__resolve_id(ctx, id, &data) == 0) { + result.val = source_count + ? expr_id_data__source_count(data) + : expr_id_data__value(data); + } + result.ids = NULL; + free(id); + } else { + /* + * Set the value to BOTTOM to show that any value is possible + * when the event is computed. Create a set of just the ID. + */ + result.val = BOTTOM; + result.ids = ids__new(); + if (!result.ids || ids__insert(result.ids, id)) { + pr_err("Error creating IDs for '%s'", id); + free(id); + } + } + return result; +} + +/* + * If we're not computing ids or $1 and $3 are constants, compute the new + * constant value using OP. Its invariant that there are no ids. If computing + * ids for non-constants union the set of IDs that must be computed. + */ +#define BINARY_LONG_OP(RESULT, OP, LHS, RHS) \ + if (!compute_ids || (is_const(LHS.val) && is_const(RHS.val))) { \ + assert(LHS.ids == NULL); \ + assert(RHS.ids == NULL); \ + RESULT.val = (long)LHS.val OP (long)RHS.val; \ + RESULT.ids = NULL; \ + } else { \ + RESULT = union_expr(LHS, RHS); \ + } + +#define BINARY_OP(RESULT, OP, LHS, RHS) \ + if (!compute_ids || (is_const(LHS.val) && is_const(RHS.val))) { \ + assert(LHS.ids == NULL); \ + assert(RHS.ids == NULL); \ + RESULT.val = LHS.val OP RHS.val; \ + RESULT.ids = NULL; \ + } else { \ + RESULT = union_expr(LHS, RHS); \ + } + +%} +%% + +start: if_expr +{ + if (compute_ids) + ctx->ids = ids__union($1.ids, ctx->ids); + + if (final_val) + *final_val = $1.val; +} +; + +if_expr: expr IF expr ELSE if_expr +{ + if (fpclassify($3.val) == FP_ZERO) { + /* + * The IF expression evaluated to 0 so treat as false, take the + * ELSE and discard everything else. + */ + $$.val = $5.val; + $$.ids = $5.ids; + ids__free($1.ids); + ids__free($3.ids); + } else if (!compute_ids || is_const($3.val)) { + /* + * If ids aren't computed then treat the expression as true. If + * ids are being computed and the IF expr is a non-zero + * constant, then also evaluate the true case. + */ + $$.val = $1.val; + $$.ids = $1.ids; + ids__free($3.ids); + ids__free($5.ids); + } else if ($1.val == $5.val) { + /* + * LHS == RHS, so both are an identical constant. No need to + * evaluate any events. + */ + $$.val = $1.val; + $$.ids = NULL; + ids__free($1.ids); + ids__free($3.ids); + ids__free($5.ids); + } else { + /* + * Value is either the LHS or RHS and we need the IF expression + * to compute it. + */ + $$ = union_expr($1, union_expr($3, $5)); + } +} +| expr +; + +expr: NUMBER +{ + $$.val = $1; + $$.ids = NULL; +} +| ID { $$ = handle_id(ctx, $1, compute_ids, /*source_count=*/false); } +| SOURCE_COUNT '(' ID ')' { $$ = handle_id(ctx, $3, compute_ids, /*source_count=*/true); } +| expr '|' expr { BINARY_LONG_OP($$, |, $1, $3); } +| expr '&' expr { BINARY_LONG_OP($$, &, $1, $3); } +| expr '^' expr { BINARY_LONG_OP($$, ^, $1, $3); } +| expr '<' expr { BINARY_OP($$, <, $1, $3); } +| expr '>' expr { BINARY_OP($$, >, $1, $3); } +| expr '+' expr { BINARY_OP($$, +, $1, $3); } +| expr '-' expr { BINARY_OP($$, -, $1, $3); } +| expr '*' expr { BINARY_OP($$, *, $1, $3); } +| expr '/' expr +{ + if (fpclassify($3.val) == FP_ZERO) { + pr_debug("division by zero\n"); + YYABORT; + } else if (!compute_ids || (is_const($1.val) && is_const($3.val))) { + assert($1.ids == NULL); + assert($3.ids == NULL); + $$.val = $1.val / $3.val; + $$.ids = NULL; + } else { + /* LHS and/or RHS need computing from event IDs so union. */ + $$ = union_expr($1, $3); + } +} +| expr '%' expr +{ + if (fpclassify($3.val) == FP_ZERO) { + pr_debug("division by zero\n"); + YYABORT; + } else if (!compute_ids || (is_const($1.val) && is_const($3.val))) { + assert($1.ids == NULL); + assert($3.ids == NULL); + $$.val = (long)$1.val % (long)$3.val; + $$.ids = NULL; + } else { + /* LHS and/or RHS need computing from event IDs so union. */ + $$ = union_expr($1, $3); + } +} +| D_RATIO '(' expr ',' expr ')' +{ + if (fpclassify($5.val) == FP_ZERO) { + /* + * Division by constant zero always yields zero and no events + * are necessary. + */ + assert($5.ids == NULL); + $$.val = 0.0; + $$.ids = NULL; + ids__free($3.ids); + } else if (!compute_ids || (is_const($3.val) && is_const($5.val))) { + assert($3.ids == NULL); + assert($5.ids == NULL); + $$.val = $3.val / $5.val; + $$.ids = NULL; + } else { + /* LHS and/or RHS need computing from event IDs so union. */ + $$ = union_expr($3, $5); + } +} +| '-' expr %prec NEG +{ + $$.val = -$2.val; + $$.ids = $2.ids; +} +| '(' if_expr ')' +{ + $$ = $2; +} +| MIN '(' expr ',' expr ')' +{ + if (!compute_ids) { + $$.val = $3.val < $5.val ? $3.val : $5.val; + $$.ids = NULL; + } else { + $$ = union_expr($3, $5); + } +} +| MAX '(' expr ',' expr ')' +{ + if (!compute_ids) { + $$.val = $3.val > $5.val ? $3.val : $5.val; + $$.ids = NULL; + } else { + $$ = union_expr($3, $5); + } +} +| LITERAL +{ + $$.val = $1; + $$.ids = NULL; +} +; + +%% |