/* Simple expression parser */
%{
#ifndef NDEBUG
#define YYDEBUG 1
#endif
#include <assert.h>
#include <math.h>
#include <stdlib.h>
#include "util/debug.h"
#define IN_EXPR_Y 1
#include "expr.h"
#include "expr-bison.h"
int expr_lex(YYSTYPE * yylval_param , void *yyscanner);
%}
%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 HAS_EVENT STRCMP_CPUID_STR 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 __maybe_unused,
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_OP(RESULT, OP, LHS, RHS) \
if (!compute_ids || (is_const(LHS.val) && is_const(RHS.val))) { \
assert(LHS.ids == NULL); \
assert(RHS.ids == NULL); \
if (isnan(LHS.val) || isnan(RHS.val)) { \
RESULT.val = NAN; \
} else { \
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 ')' { $$ = handle_id(ctx, $3, compute_ids, /*source_count=*/true); }
| HAS_EVENT '(' ID ')'
{
$$.val = expr__has_event(ctx, compute_ids, $3);
$$.ids = NULL;
free($3);
}
| STRCMP_CPUID_STR '(' ID ')'
{
$$.val = expr__strcmp_cpuid_str(ctx, compute_ids, $3);
$$.ids = NULL;
free($3);
}
| expr '|' expr
{
if (is_const($1.val) && is_const($3.val)) {
assert($1.ids == NULL);
assert($3.ids == NULL);
$$.ids = NULL;
$$.val = (fpclassify($1.val) == FP_ZERO && fpclassify($3.val) == FP_ZERO) ? 0 : 1;
} else if (is_const($1.val)) {
assert($1.ids == NULL);
if (fpclassify($1.val) == FP_ZERO) {
$$ = $3;
} else {
$$.val = 1;
$$.ids = NULL;
ids__free($3.ids);
}
} else if (is_const($3.val)) {
assert($3.ids == NULL);
if (fpclassify($3.val) == FP_ZERO) {
$$ = $1;
} else {
$$.val = 1;
$$.ids = NULL;
ids__free($1.ids);
}
} else {
$$ = union_expr($1, $3);
}
}
| expr '&' expr
{
if (is_const($1.val) && is_const($3.val)) {
assert($1.ids == NULL);
assert($3.ids == NULL);
$$.val = (fpclassify($1.val) != FP_ZERO && fpclassify($3.val) != FP_ZERO) ? 1 : 0;
$$.ids = NULL;
} else if (is_const($1.val)) {
assert($1.ids == NULL);
if (fpclassify($1.val) != FP_ZERO) {
$$ = $3;
} else {
$$.val = 0;
$$.ids = NULL;
ids__free($3.ids);
}
} else if (is_const($3.val)) {
assert($3.ids == NULL);
if (fpclassify($3.val) != FP_ZERO) {
$$ = $1;
} else {
$$.val = 0;
$$.ids = NULL;
ids__free($1.ids);
}
} else {
$$ = union_expr($1, $3);
}
}
| expr '^' expr
{
if (is_const($1.val) && is_const($3.val)) {
assert($1.ids == NULL);
assert($3.ids == NULL);
$$.val = (fpclassify($1.val) == FP_ZERO) != (fpclassify($3.val) == FP_ZERO) ? 1 : 0;
$$.ids = NULL;
} else {
$$ = union_expr($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($$, *, $1, $3); }
| expr '/' expr
{
if (fpclassify($3.val) == FP_ZERO) {
pr_debug("division by zero\n");
assert($3.ids == NULL);
if (compute_ids)
ids__free($1.ids);
$$.val = NAN;
$$.ids = NULL;
} else if (!compute_ids || (is_const($1.val) && is_const($3.val))) {
assert($1.ids == NULL);
assert($3.ids == NULL);
$$.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;
}
;
%%
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