Broaden use of SearchValues in TryFindNextPossibleStartingPosition in Regex

[stephentoub]

Replaces #89140. That PR changed how we emit custom IndexOf helpers, such that if we could fully enumerate the set and it contained a small enough number of characters, we would have the whole thing vectorized by first doing an ASCII-based search and then falling back to a probabilistic map search. But we then decided to move that approach down into SearchValues itself, via #89155. This means we can simplify TryFindNextPossibleStartingPosition in Regex to not track AsciiSet specially and instead just increase the number of characters we query the set for (from 5 to 128). That way, we'll use SearchValues rather than emitting our own helper up until a (semi-arbitrary) point where we deem it impossible or infeasible to enumerate all the chars that make up the set.

[stephentoub]

Replaces #89140. That PR changed how we emit custom IndexOf helpers, such that if we could fully enumerate the set and it contained a small enough number of characters, we would have the whole thing vectorized by first doing an ASCII-based search and then falling back to a probabilistic map search. But we then decided to move that approach down into SearchValues itself, via #89155. This means we can simplify TryFindNextPossibleStartingPosition in Regex to not track AsciiSet specially and instead just increase the number of characters we query the set for (from 5 to 128). That way, we'll use SearchValues rather than emitting our own helper up until a (semi-arbitrary) point where we deem it impossible or infeasible to enumerate all the chars that make up the set.

[stephentoub]

Replaces #89140. That PR changed how we emit custom IndexOf helpers, such that if we could fully enumerate the set and it contained a small enough number of characters, we would have the whole thing vectorized by first doing an ASCII-based search and then falling back to a probabilistic map search. But we then decided to move that approach down into SearchValues itself, via #89155. This means we can simplify TryFindNextPossibleStartingPosition in Regex to not track AsciiSet specially and instead just increase the number of characters we query the set for (from 5 to 128). That way, we'll use SearchValues rather than emitting our own helper up until a (semi-arbitrary) point where we deem it impossible or infeasible to enumerate all the chars that make up the set.

[stephentoub]

Replaces #89140. That PR changed how we emit custom IndexOf helpers, such that if we could fully enumerate the set and it contained a small enough number of characters, we would have the whole thing vectorized by first doing an ASCII-based search and then falling back to a probabilistic map search. But we then decided to move that approach down into SearchValues itself, via #89155. This means we can simplify TryFindNextPossibleStartingPosition in Regex to not track AsciiSet specially and instead just increase the number of characters we query the set for (from 5 to 128). That way, we'll use SearchValues rather than emitting our own helper up until a (semi-arbitrary) point where we deem it impossible or infeasible to enumerate all the chars that make up the set.

[stephentoub]

Replaces #89140. That PR changed how we emit custom IndexOf helpers, such that if we could fully enumerate the set and it contained a small enough number of characters, we would have the whole thing vectorized by first doing an ASCII-based search and then falling back to a probabilistic map search. But we then decided to move that approach down into SearchValues itself, via #89155. This means we can simplify TryFindNextPossibleStartingPosition in Regex to not track AsciiSet specially and instead just increase the number of characters we query the set for (from 5 to 128). That way, we'll use SearchValues rather than emitting our own helper up until a (semi-arbitrary) point where we deem it impossible or infeasible to enumerate all the chars that make up the set.

[stephentoub]

Replaces #89140. That PR changed how we emit custom IndexOf helpers, such that if we could fully enumerate the set and it contained a small enough number of characters, we would have the whole thing vectorized by first doing an ASCII-based search and then falling back to a probabilistic map search. But we then decided to move that approach down into SearchValues itself, via #89155. This means we can simplify TryFindNextPossibleStartingPosition in Regex to not track AsciiSet specially and instead just increase the number of characters we query the set for (from 5 to 128). That way, we'll use SearchValues rather than emitting our own helper up until a (semi-arbitrary) point where we deem it impossible or infeasible to enumerate all the chars that make up the set.

[stephentoub]

Replaces #89140. That PR changed how we emit custom IndexOf helpers, such that if we could fully enumerate the set and it contained a small enough number of characters, we would have the whole thing vectorized by first doing an ASCII-based search and then falling back to a probabilistic map search. But we then decided to move that approach down into SearchValues itself, via #89155. This means we can simplify TryFindNextPossibleStartingPosition in Regex to not track AsciiSet specially and instead just increase the number of characters we query the set for (from 5 to 128). That way, we'll use SearchValues rather than emitting our own helper up until a (semi-arbitrary) point where we deem it impossible or infeasible to enumerate all the chars that make up the set.