Lookup hint information

An apparatus comprising:

• a first-level cache comprising a plurality of first-level cache entries for storing cached data;
• a second-level cache comprising a plurality of second-level cache entries for storing cached data;
• and
• cache control circuitry to:
• perform a first-level cache lookup of the first-level cache based on a lookup address, to determine whether the first-level cache stores valid cached data corresponding to the lookup address;
• when lookup hint information associated with the lookup address is available, determine based on the lookup hint information whether to activate or deactivate a second-level cache lookup of the second-level cache, the lookup hint information indicative of whether the second-level cache is predicted to store valid cached data associated with the lookup address;
• and
• when the second-level cache lookup is activated, perform the second-level cache lookup of the second-level cache based on the lookup address to determine whether the second-level cache stores valid cached data corresponding to the lookup address;
• in which:
• the cache control circuitry is configured to determine based on the first-level cache lookup whether the lookup hint information is available, and when the lookup hint information is available, to obtain the lookup hint information associated with the lookup address from a first-level cache entry identified as corresponding to the lookup address in the first-level cache lookup.

An apparatus comprising:

• a first-level cache comprising a plurality of first-level cache entries for storing cached data;
• a second-level cache comprising a plurality of second-level cache entries for storing cached data;
• and
• cache control circuitry to:
• perform a first-level cache lookup of the first-level cache based on a lookup address, to determine whether the first-level cache stores valid cached data corresponding to the lookup address;
• when lookup hint information associated with the lookup address is available, determine based on the lookup hint information whether to activate or deactivate a second-level cache lookup of the second-level cache, the lookup hint information indicative of whether the second-level cache is predicted to store valid cached data associated with the lookup address;
• and
• when the second-level cache lookup is activated, perform the second-level cache lookup of the second-level cache based on the lookup address to determine whether the second-level cache stores valid cached data corresponding to the lookup address;
• and
• branch prediction circuitry to determine a predicted branch instruction behavior associated with the lookup address based on branch prediction information indicated by valid cached data identified as corresponding to the lookup address in at least one of the first-level cache lookup and the second-level cache lookup.