+/*
+ * compare_tev_args is reflexive, transitive and antisymmetric.
+ * I can proof it but this margin is too narrow to contain.
+ */
+static int compare_tev_args(const void *ptev1, const void *ptev2)
+{
+ int i, ret;
+ const struct probe_trace_event *tev1 =
+ *(const struct probe_trace_event **)ptev1;
+ const struct probe_trace_event *tev2 =
+ *(const struct probe_trace_event **)ptev2;
+
+ ret = tev2->nargs - tev1->nargs;
+ if (ret)
+ return ret;
+
+ for (i = 0; i < tev1->nargs; i++) {
+ struct probe_trace_arg *arg1, *arg2;
+ struct probe_trace_arg_ref *ref1, *ref2;
+
+ arg1 = &tev1->args[i];
+ arg2 = &tev2->args[i];
+
+ ret = strcmp(arg1->value, arg2->value);
+ if (ret)
+ return ret;
+
+ ref1 = arg1->ref;
+ ref2 = arg2->ref;
+
+ while (ref1 && ref2) {
+ ret = ref2->offset - ref1->offset;
+ if (ret)
+ return ret;
+
+ ref1 = ref1->next;
+ ref2 = ref2->next;
+ }
+
+ if (ref1 || ref2)
+ return ref2 ? 1 : -1;
+ }
+
+ return 0;
+}
+
+/*
+ * Assign a type number to each tevs in a pev.
+ * mapping is an array with same slots as tevs in that pev.
+ * nr_types will be set to number of types.
+ */
+static int map_prologue(struct perf_probe_event *pev, int *mapping,
+ int *nr_types)
+{
+ int i, type = 0;
+ struct probe_trace_event **ptevs;
+
+ size_t array_sz = sizeof(*ptevs) * pev->ntevs;
+
+ ptevs = malloc(array_sz);
+ if (!ptevs) {
+ pr_debug("No ehough memory: alloc ptevs failed\n");
+ return -ENOMEM;
+ }
+
+ pr_debug("In map_prologue, ntevs=%d\n", pev->ntevs);
+ for (i = 0; i < pev->ntevs; i++)
+ ptevs[i] = &pev->tevs[i];
+
+ qsort(ptevs, pev->ntevs, sizeof(*ptevs),
+ compare_tev_args);
+
+ for (i = 0; i < pev->ntevs; i++) {
+ int n;
+
+ n = ptevs[i] - pev->tevs;
+ if (i == 0) {
+ mapping[n] = type;
+ pr_debug("mapping[%d]=%d\n", n, type);
+ continue;
+ }
+
+ if (compare_tev_args(ptevs + i, ptevs + i - 1) == 0)
+ mapping[n] = type;
+ else
+ mapping[n] = ++type;
+
+ pr_debug("mapping[%d]=%d\n", n, mapping[n]);
+ }
+ free(ptevs);
+ *nr_types = type + 1;
+
+ return 0;
+}
+