Abstract: Disclosed herein are quantum dot devices, as well as related computing devices and methods. For example, in some embodiments, a quantum dot device may include: a quantum well stack; a first gate above the quantum well stack, wherein the first gate includes a first gate metal and a first gate dielectric; and a second gate above the quantum well stack, wherein the second gate includes a second gate metal and a second gate dielectric, and the first gate is at least partially between a portion of the second gate and the quantum well stack.

Abstract: A processor is configured with a first level branch prediction cache configured to store branch prediction information corresponding to a group of instructions. In addition, a second level branch prediction cache is utilized to store branch prediction information which is evicted from the first level cache. The second level branch prediction cache is configured to store only a subset of the information which is evicted from the first level cache. Branch prediction information which is evicted from the first level cache and not stored in the second level cache is discarded. Upon a miss in the first level cache, a determination is made as to whether the second level cache contains branch prediction information corresponding to the miss. If corresponding branch prediction information is detected in the second level cache, the detected branch prediction information is used to rebuild complete branch prediction information.

Abstract: A branch prediction unit includes a local branch prediction and a global branch prediction. A global branch prediction utilizes a global history shift register to record the behavior of conditional branches. In some cases, a conditional branch may behave in a static manner, either always being taken or not taken, while resident in an instruction cache. Such static behaving conditional branches do not need a global history for prediction and contend with other conditional branches for global branch history training. By utilizing a dynamic branch classification scheme, branches requiring global history prediction can be identified and static behaving conditional branches may be prevented from polluting the global history. All conditional branches are initially classified as local and do not participate in global history training. Only after two mispredictions are branches recognized as exhibiting dynamic behavior and classified as global.

Abstract: A microprocessor capable of caching victimized branch prediction information is disclosed. Branch prediction information is generated as branch instructions are executed over time. This prediction information is stored in a branch target buffer. The storage locations within the branch target buffer correspond to cache line locations within the microprocessor's instructions cache. Instead of discarding branch prediction information corresponding to instructions that are replaced or discarded from the instruction cache, the branch prediction information is stored in a victim branch prediction cache. Address information may also be stored to identify which instructions the prediction information corresponds to. The microprocessor's instruction cache is configured to receive and store instruction bytes, and the branch target array is coupled to the instruction cache and configured to store branch target information corresponding to the stored instruction bytes.

Abstract: A method for efficiently storing and determining predicted next fetch addresses is disclosed. Predicted fetch addresses are generated by a number of independent sources. Predicted fetch addresses for indirect branch instructions are stored in a indirect branch target cache. Predicted fetch addresses for direct branch instructions are calculated using an “on-the-fly” direct branch adder. Predicted fetch addresses for return instructions are stored in a return stack. Predicted fetch addresses for sequential instructions are calculated on-the-fly using a sequential address adder. A branch selector array is used to store selector bits that indicate which of the above sources should be selected for the next predicted fetch address. The selector bits each correspond to particular instruction bytes stored in an instruction cache. Predecode bits indicative of branch instructions and instruction boundaries may also be stored in the instruction cache.

Abstract: A microprocessor configured to reduce variance in the length of variable length instructions by compressing multiple prefix bytes into a single byte is disclosed. The microprocessor is configured with a predecode unit and an instruction cache. The predecode unit is configured to receive variable length instructions, each having a variable number of prefix bytes. The predecode unit is configured to detect the prefix bytes and compress them into one compressed prefix byte for each instruction. The instruction cache is coupled to the predecode unit and is configured to receive and store the instructions and compressed prefix bytes from the predecode unit. The instruction cache may be configured to output one of the instructions and any corresponding compressed prefix bytes in response to receiving a fetch address. A computer system, method, and software program configured to compress prefix bytes are also disclosed.

Abstract: A microprocessor capable of out-of-order instruction decoding and in-order dependency checking is disclosed. The microprocessor may include an instruction cache, two decode units, a reorder queue, and dependency checking logic. The instruction cache is configured to output cache line portions to the decode units. The decode units operate independently and in parallel. One of the decode units may be a split decoder that receives all instruction bytes from instructions that extend across cache line portion boundaries. The split decode unit may be configured to reassemble the instruction bytes into instructions. These instructions are then decoded by the split decode unit. A reorder queue may be used to store the decoded instructions according to their relative cache line positions. The decoded instructions are read out of the reorder queue in program order, thereby enabling the dependency checking logic to perform dependency checking in program order.

Abstract: A way prediction structure is provided which predicts a way of an associative cache in which an access will hit, and causes the data bytes from the predicted way to be conveyed as the output of the cache. The typical tag comparisons to the request address are bypassed for data byte selection, causing the access time of the associative cache to be substantially the access time of the direct-mapped way prediction array within the way prediction structure. Also included in the way prediction structure is a way prediction control unit configured to update the way prediction array when an incorrect way prediction is detected. The clock cycle of a superscalar microprocessor including the way prediction structure with its caches may be increased if the cache access time is limiting the clock cycle. Additionally, the associative cache may be retained in the high frequency superscalar microprocessor (which might otherwise employ a direct-mapped cache for access time reasons).

Abstract: A superscalar microprocessor employing a way prediction structure is provided. The way prediction structure predicts a way of an associative cache in which an access will hit, and causes the data bytes from the predicted way to be conveyed as the output of the cache. The typical tag comparisons to the request address are bypassed for data byte selection, causing the access time of the associative cache to be substantially the access time of the direct-mapped way prediction array within the way prediction structure. Also included in the way prediction structure is a way prediction control unit configured to update the way prediction array when an incorrect way prediction is detected. The clock cycle of the superscalar microprocessor including the way prediction structure with its caches may be increased if the cache access time is limiting the clock cycle.