kernel/trace/trace_events_filter.c

160  * @invert: What to assign a program entry for its branch condition
168 static void update_preds(struct prog_entry *prog, int N, int invert)
174 	prog[t].when_to_branch = invert;
229  *  predicate, when_to_branch, invert, target
234  * The "invert" holds whether the value should be reversed before testing.
241  * The possible invert values are 1 and 0. The number of "!"s that are in scope
242  * before the predicate determines the invert value, if the number is odd then
243  * the invert value is 1 and 0 otherwise. This means the invert value only
247  * The top of the stack and "invert" are initialized to zero.
254  *    gets the current invert value, and the loop continues to the next token.
255  *    The top of the stack saves the "invert" value to keep track of what
260  * #3 If the token is an "!", the current "invert" value gets inverted, and
262  *    this "invert" value is only valid for the current program entry,
268  *    current value of "invert". The target is currently assigned to the
274  * #6 The invert variable is reset to the current value saved on the top of
277  * #7 The top of the stack holds not only the current invert value, but also
283  *    the program, and the current value of "invert".  More will be described
292  *    this time with an inverted value of "invert" (that is !invert). This is
325  * That entry's "when_to_branch" is set to the value passed in (the "invert"
326  * or "!invert"). Then it sets the current program entry's target to the saved
337  *  update_preds(prog, 2, 0); // invert = 0 as we are processing "&&"
343  * update_preds(prog, 2, 1); // invert = 1 as we are now processing "||"
440  * program to that does: "when_to_branch ^= invert;" will do the
480 	int invert = 0;
519 			*(++top) = invert;
524 			invert = !invert;
533 		inverts[N] = invert;				/* #4 */
569 			invert = *top & INVERT;
572 				update_preds(prog, N - 1, invert);
580 				update_preds(prog, N - 1, !invert);
629 		invert = inverts[i] ^ prog[i].when_to_branch;
630 		prog[i].when_to_branch = invert;