公开(公告)号：US6079005A

公开(公告)日：2000-06-20

申请号：US975224

申请日：1997-11-20

申请人： David B. Witt ,  Thang M. Tran

发明人： David B. Witt ,  Thang M. Tran

IPC分类号： G06F9/32 ,  G06F9/38 ,  G06F12/10

CPC分类号： G06F9/3806 ,  G06F12/1054 ,  G06F9/30058

摘要： A microprocessor employs a branch prediction unit including a branch prediction storage which stores the index portion of branch target addresses and an instruction cache which is virtually indexed and physically tagged. The branch target index (if predicted-taken), or the sequential index (if predicted not-taken) is provided as the index to the instruction cache. The selected physical tag is provided to a reverse translation lookaside buffer (TLB) which translates the physical tag to a virtual page number. Concatenating the virtual page number to the virtual index from the instruction cache (and the offset portion, generated from the branch prediction) results in the branch target address being generated. In one embodiment, a current page register stores the most recently translated virtual page number and the corresponding real page number. The branch prediction unit predicts that each fetch address will continue to reside in the current page and uses the virtual page number from the current page to form the branch Target address. The physical tag from the fetched cache line is compared to the corresponding real page number to verify that the fetch address is actually still within the current page. When a mismatch is detected between the corresponding real page number and the physical tag from the fetched cache line, the branch target address is corrected with the linear page number provided by the reverse TLB and the current page register is updated.

摘要翻译： 微处理器采用分支预测单元，该分支预测单元包括分支预测存储器，该分支预测存储器存储分支目标地址的索引部分和虚拟索引并被物理标记的指令高速缓存。 提供分支目标索引（如果预测取得）或顺序索引（如果预测未被采用）作为指令高速缓存的索引。 所选择的物理标签被提供给反向翻译后备缓冲器（TLB），其将物理标签转换成虚拟页码。 将虚拟页号连接到来自指令高速缓存（以及从分支预测生成的偏移部分）的虚拟索引导致生成分支目标地址。 在一个实施例中，当前页面寄存器存储最近翻译的虚拟页面号码和相应的真实页面号码。 分支预测单元预测每个获取地址将继续驻留在当前页面中，并且使用当前页面中的虚拟页面号来形成分支目标地址。 将获取的高速缓存行中的物理标记与相应的实际页码进行比较，以验证提取地址实际上仍在当前页面中。 当在相应的实际页码与来自取出的高速缓存行的物理标记之间检测到不匹配时，用反向TLB提供的线性页码修正分支目标地址，并更新当前页寄存器。

公开(公告)号：US6014734A

公开(公告)日：2000-01-11

申请号：US153770

申请日：1998-09-15

申请人： Thang M. Tran ,  Rupaka Mahalingaiah

发明人： Thang M. Tran ,  Rupaka Mahalingaiah

IPC分类号： G01R31/3185 ,  G06F9/30 ,  G06F9/38 ,  G06F11/267

CPC分类号： G06F9/3806 ,  G06F9/30054 ,  G06F9/30152 ,  G06F9/3816 ,  G06F9/382 ,  G06F9/3832 ,  G06F9/3844 ,  G06F9/3848 ,  G01R31/318533 ,  G06F11/2236

摘要： A microprocessor is provided which is configured to predict return addresses for return instructions according to a return stack storage included therein. The return stack storage is a stack structure configured to store return addresses associated with previously detected call instructions. Return addresses may be predicted for return instructions early in the instruction processing pipeline of the microprocessor. In one embodiment, the return stack storage additionally stores a call tag and a return tag with each return address. The call tag and return tag respectively identify call and return instructions associated with the return address. These tags may be compared to a branch tag conveyed to the return prediction unit upon detection of a branch misprediction. The results of the comparisons may be used to adjust the contents of the return stack storage with respect to the misprediction. The microprocessor may continue to predict return addresses correctly following a mispredicted branch instruction.

摘要翻译： 提供微处理器，其被配置为根据其中包括的返回堆栈存储来预测返回指令的返回地址。 返回栈存储器是被配置为存储与先前检测到的调用指令相关联的返回地址的堆栈结构。 可以在微处理器的指令处理流水线的早期为返回指令预测返回地址。 在一个实施例中，返回堆栈存储器另外存储具有每个返回地址的呼叫标签和返回标签。 呼叫标签和返回标签分别标识与返回地址相关联的呼叫和返回指令。 这些标签可以与检测到分支错误预测时传送到返回预测单元的分支标签进行比较。 可以使用比较结果来调整返回堆栈存储器相对于错误预测的内容。 微处理器可以在错误预测的分支指令之后继续正确地预测返回地址。

公开(公告)号：US5954816A

公开(公告)日：1999-09-21

申请号：US972988

申请日：1997-11-19

申请人： Thang M. Tran ,  David E. Kroesche ,  Karthikeyan Muthusamy ,  Andrew McBride

发明人： Thang M. Tran ,  David E. Kroesche ,  Karthikeyan Muthusamy ,  Andrew McBride

IPC分类号： G06F9/38

CPC分类号： G06F9/3844 ,  G06F9/30054 ,  G06F9/3806

摘要： A branch prediction unit includes a branch prediction entry corresponding to a group of contiguous instruction bytes. The branch prediction entry stores branch predictions corresponding to branch instructions within the group of contiguous instruction bytes. Additionally, the branch prediction entry stores a set of branch selectors corresponding to the group of contiguous instruction bytes. The branch selectors identify which branch prediction is to be selected if the corresponding byte (or bytes) is selected by the offset portion of the fetch address. Still further, a predicted branch selector is stored. The predicted branch selector is used to select a branch prediction for forming the fetch address. In parallel, a selected branch selector is selected from the set of branch selectors. The predicted branch selector is verified using the selected branch selector. If the selected branch selector and the predicted branch selector mismatch, the correct branch prediction is generated and the predicted branch selector is updated to indicate the selected branch selector.

摘要翻译： 分支预测单元包括对应于一组相邻指令字节的分支预测条目。 分支预测条目存储对应于连续指令字节组内的分支指令的分支预测。 此外，分支预测条目存储对应于该组连续指令字节的一组分支选择器。 如果通过提取地址的偏移部分选择了相应的字节（或字节），则分支选择器识别要选择哪个分支预测。 此外，存储预测分支选择器。 预测分支选择器用于选择用于形成取出地址的分支预测。 并行地，从分支选择器组中选择选择的分支选择器。 使用所选择的分支选择器验证预测分支选择器。 如果所选择的分支选择器和预测分支选择器不匹配，则生成正确的分支预测，并且更新预测分支选择器以指示所选择的分支选择器。

公开(公告)号：US5903910A

公开(公告)日：1999-05-11

申请号：US561073

申请日：1995-11-20

申请人： Thang M. Tran ,  Marty L. Pflum ,  David B. Witt ,  William M. Johnson

发明人： Thang M. Tran ,  Marty L. Pflum ,  David B. Witt ,  William M. Johnson

IPC分类号： G06F9/30 ,  G06F9/38 ,  G06F12/08 ,  G06F12/00

CPC分类号： G06F9/30167 ,  G06F12/0875 ,  G06F9/30163 ,  G06F9/3824 ,  G06F9/3867

摘要： A microprocessor including a pair of caches is provided. One of the pair of caches is accessed by stack-relative memory accesses from the decode stage of the instruction processing pipeline. The second of the pair of caches is accessed by memory accesses from the execute stage of the instruction processing pipeline. When a miss is detected in the first of the pair of caches, the stack-relative memory access which misses is conveyed to the execute stage of the instruction processing pipeline. When the stack-relative memory access accesses the second of the pair of caches, the cache line containing the access is transmitted to the first of the pair of caches for storage. The first of the pair of caches selects a victim line for replacement when the data is transferred from the second of the pair of caches. If the victim line has been modified while stored in the first cache, then the victim line is stored in a copyback buffer. A signal is asserted by the first cache to inform the second cache of the need to perform a victim line copyback. Requests from the execute stage of the instruction processing pipeline are stalled to allow the copyback to occur.

摘要翻译： 提供了包括一对高速缓存的微处理器。 一对缓存中的一个通过来自指令处理流水线的解码级的堆栈相对存储器访问进行访问。 该对高速缓存中的第二个由指令处理流水线的执行阶段的存储器访问访问。 当在一对高速缓存中的第一个中检测到未命中时，丢失的堆栈相对存储器访问被传送到指令处理流水线的执行阶段。 当堆栈相对存储器访问访问该对高速缓存中的第二个时，包含访问的高速缓存行被发送到该对高速缓存中的第一个用于存储。 一对缓存中的第一个在从一对缓存中的第二个数据传输数据时选择一个受害者行进行替换。 如果受害者行已被存储在第一个缓存中被修改，那么受害者行将被存储在一个副本缓冲区中。 一个信号由第一个缓存断言，通知第二个缓存是否需要执行受害线回拷。 来自指令处理流水线的执行阶段的请求被停止以允许发生回拷。

公开(公告)号：US5822574A

公开(公告)日：1998-10-13

申请号：US819109

申请日：1997-03-17

申请人： Thang M. Tran

发明人： Thang M. Tran

IPC分类号： G06F9/38

CPC分类号： G06F9/30036 ,  G06F9/3806 ,  G06F9/3836 ,  G06F9/3838 ,  G06F9/384 ,  G06F9/3853 ,  G06F9/3855 ,  G06F9/3857

摘要： A superscalar microprocessor is provided having functional units which receive a pointer (a reorder buffer tag) which is compared to the reorder buffer tags of the instructions currently being executed. The pointer identifies the oldest outstanding branch instruction. If a functional unit's reorder buffer tag matches the pointer, then that functional unit conveys its corrected fetch address to the instruction fetching mechanism of the superscalar microprocessor (i.e. the branch prediction unit). The superscalar microprocessor also includes a load/store unit which receives a pair of pointers identifying the oldest outstanding instructions which are not in condition for retirement. The load/store unit compares these pointers with the reorder buffer tags of load instructions that miss the data cache and store instructions. A match must be found before the associated instruction is presented to the data cache and the main memory system. The pointer-compare mechanism provides an ordering mechanism for load instructions that miss the data cache and store instructions.

摘要翻译： 提供了一种超标量微处理器，其具有接收与当前正在执行的指令的重排序缓冲器标签相比较的指针（重排序缓冲器标签）的功能单元。 指针标识最旧的未完成的分支指令。 如果功能单元的重新排序缓冲器标签与指针匹配，则该功能单元将其校正的提取地址传送到超标量微处理器（即，分支预测单元）的指令获取机制。 超标量微处理器还包括一个加载/存储单元，其接收一对指示符，用于标识不符合退休条件的最旧的未完成指令。 加载/存储单元将这些指针与错过数据高速缓存和存储指令的加载指令的重新排序缓冲区标记进行比较。 在将相关指令提供给数据高速缓存和主存储器系统之前，必须找到匹配项。 指针比较机制为缺少数据高速缓存和存储指令的加载指令提供了排序机制。

公开(公告)号：US5752259A

公开(公告)日：1998-05-12

申请号：US621960

申请日：1996-03-26

申请人： Thang M. Tran

发明人： Thang M. Tran

IPC分类号： G06F9/38 ,  G06F12/08 ,  G06F12/00

CPC分类号： G06F9/3814 ,  G06F12/0851 ,  G06F12/0864 ,  G06F12/0875 ,  G06F9/3802 ,  G06F9/3806

摘要： An apparatus including a banked instruction cache and a branch prediction unit is provided. The banked instruction cache allows multiple instruction fetch addresses (comprising consecutive instruction blocks from the predicted instruction stream being executed by the microprocessor) to be fetched concurrently. The instruction cache provides an instruction block corresponding to one of the multiple fetch addresses to the instruction processing pipeline of the microprocessor during each consecutive clock cycle, while additional instruction fetch addresses from the predicted instruction stream are fetched. Preferably, the instruction cache includes at least a number of banks equal to the number of clock cycles consumed by an instruction cache access. In this manner, instructions may be provided during each consecutive clock cycle even though instruction cache access time is greater than the clock cycle time of the microprocessor. Because consecutive instruction blocks from the instruction stream are fetched concurrently, the branch prediction unit stores a prediction for a non-consecutive instruction block with each instruction block. For example, for an instruction cache having a cache access time which is twice the clock cycle time, a prediction for the second consecutive instruction block following a particular instruction block within the predicted instruction stream is stored. When a pair of consecutive instruction blocks are fetched, predictions for a second pair of consecutive instruction blocks within the instruction stream subsequent to the pair of consecutive instruction blocks are formed from the branch prediction information stored with respect to the pair of consecutive instruction blocks.

摘要翻译： 提供一种包括分组指令高速缓存和分支预测单元的装置。 存储的指令高速缓存允许同时取出多​​个指令获取地址（包括来自由微处理器执行的预测指令流的连续指令块）。 指令高速缓冲存储器在每个连续的时钟周期期间向微处理器的指令处理流水线提供与多个提取地址中的一个相对应的指令块，同时提取来自预测指令流的附加指令提取地址。 优选地，指令高速缓存包括等于指令高速缓存访​​问消耗的时钟周期的数量的至少一组存储体。 以这种方式，即使指令高速缓存访​​问时间大于微处理器的时钟周期时间，也可以在每个连续时钟周期期间提供指令。 由于来自指令流的连续的指令块被同时取出，所以分支预测单元存储具有每个指令块的非连续指令块的预测。 例如，对于具有两倍于时钟周期时间的高速缓存访​​问时间的指令高速缓存，存储在预测指令流内的特定指令块之后的第二连续指令块的预测。 当取出一对连续的指令块时，根据相对于一对连续指令块存储的分支预测信息，形成在该连续指令块对之后的指令流内的第二对连续指令块的预测。

公开(公告)号：US5687110A

公开(公告)日：1997-11-11

申请号：US603802

申请日：1996-02-20

申请人： Thang M. Tran ,  Andrew McBride

发明人： Thang M. Tran ,  Andrew McBride

IPC分类号： G06F9/38 ,  G11C7/00

CPC分类号： G06F9/3844 ,  G06F9/3857 ,  G06F9/3863

摘要： A memory including first storage circuits for storing first values and second storages circuit for storing second values is provided. The first value may be retired branch prediction information, while the second value may be speculative branch prediction information. The speculative branch prediction information is updated when the corresponding instructions are fetched, and the retired branch prediction value is updated when the corresponding branch instruction is retired. The speculative branch prediction information is used to form branch predictions. Therefore, the speculatively fetched and executed branches influence subsequent branch predictions. Upon detection of a mispredicted branch or an instruction which causes an exception, the speculative branch prediction information is updated to the corresponding retired branch prediction information. An update circuit is coupled between the first and second storage circuits for transmitting the updated information upon assertion of a control signal. The control signal may be asserted to cause the update of each speculative branch prediction by the corresponding retired branch prediction. The updates occur substantially simultaneously, restoring any corruption to speculative branch predictions due to speculatively fetched branch instructions which were flushed from the instruction processing pipeline. Although discussed herein in terms of a branch prediction array, the memory may be adapted to many other applications.

摘要翻译： 提供了包括用于存储第一值的第一存储电路和用于存储第二值的第二存储电路的存储器。 第一值可以是退休分支预测信息，而第二值可以是推测性分支预测信息。 当对应的指令被取出时，推测分支预测信息被更新，并且当对应的分支指令退出时，退出的分支预测值被更新。 推测分支预测信息用于形成分支预测。 因此，推测取得和执行的分支影响后续的分支预测。 在检测到错误的分支或引起异常的指令时，将推测性分支预测信息更新为相应的退出分支预测信息。 更新电路耦合在第一和第二存储电路之间，用于在断言控制信号时发送更新的信息。 控制信号可以被断言，以通过相应的退役分支预测使每个推测分支预测的更新。 这些更新基本上同时发生，由于从指令处理流水线刷新的推测性获取的分支指令，将任何损坏恢复到推测性分支预测。 尽管这里在分支预测阵列方面进行了讨论，但存储器可以适用于许多其他应用。

公开(公告)号：US5619464A

公开(公告)日：1997-04-08

申请号：US473103

申请日：1995-06-07

申请人： Thang M. Tran

发明人： Thang M. Tran

IPC分类号： G11C7/12 ,  G11C7/22 ,  G11C13/00

CPC分类号： G11C7/22 ,  G11C7/12

摘要： A RAM array circuit is provided which includes a memory array formed by several RAM cell columns. A particular cell within each column and row may be selected for access (either read or write) by an address decode circuit. The RAM array circuit employs a self-time column having a delay characteristic which is approximately equal to that of each of the RAM cell columns. The rising edge of a single-phase clock is used to precharge each RAM cell column as well as the self-time column. As the self-time column is precharged to a high level, the self-time control circuit disables the precharge and enables the array access for read or write. When a particular row is selected by the address decoding mechanism, the self-time column is discharged. Once the self-time column has discharged, a sense amplifier is enabled to read data from the array. Access is then disabled and precharge is again enabled upon the next rising edge of the clock.

摘要翻译： 提供了一种RAM阵列电路，其包括由几个RAM单元列形成的存储器阵列。 每个列和行中的特定单元可以被选择用于由地址解码电路进行访问（读或写）。 RAM阵列电路采用具有近似等于每个RAM单元列的延迟特性的自身时间列。 单相时钟的上升沿用于对每个RAM单元列以及自身时间列进行预充电。 当自身时间列被预充电到高电平时，自身时间控制电路禁止预充电，并使阵列访问能够进行读或写。 当通过地址解码机制选择特定行时，自身时间列被排出。 一旦自身时间列放电，读出放大器就可以从阵列中读取数据。 然后禁用访问，并在时钟的下一个上升沿再次启用预充电。

公开(公告)号：US09110656B2

公开(公告)日：2015-08-18

申请号：US13210566

申请日：2011-08-16

申请人： Thang M. Tran ,  Trinh Huy H. Nguyen

发明人： Thang M. Tran ,  Trinh Huy H. Nguyen

IPC分类号： G06F9/30 ,  G06F9/38

CPC分类号： G06F9/30087 ,  G06F9/3814 ,  G06F9/3824 ,  G06F9/3838 ,  G06F9/3851 ,  G06F9/3891

摘要： A processor configured to provide instructions of a first instruction type to a first execution unit, and a second execution queue configured to provide instructions of a second instruction type to a second execution unit. A first instruction of the second instruction type is received. The first instruction is decoded by the decode/issue unit to determine operands of the first instruction. The operands of the first instruction are determined to include a dependency on a second instruction of the first instruction type stored in a first entry of the first execution queue. The first instruction is stored in a first entry of the second execution queue. A synchronization indicator corresponding to the first instruction in a second entry of the first execution queue is set immediately adjacent the first entry of the first execution queue, which indicates that the first instruction is stored in another execution queue.

摘要翻译： 一种处理器，被配置为向第一执行单元提供第一指令类型的指令，以及第二执行队列，被配置为向第二执行单元提供第二指令类型的指令。 接收第二指令类型的第一指令。 第一指令由解码/发布单元解码以确定第一指令的操作数。 第一指令的操作数被确定为包括对存储在第一执行队列的第一条目中的第一指令类型的第二指令的依赖性。 第一个指令存储在第二个执行队列的第一个条目中。 与第一执行队列的第二条目中的第一指令相对应的同步指示符被设置为紧邻第一执行队列的第一条目，其指示第一指令被存储在另一个执行队列中。

公开(公告)号：US09092225B2

公开(公告)日：2015-07-28

申请号：US13362720

申请日：2012-01-31

申请人： Thang M. Tran ,  Michael B. Schinzler

发明人： Thang M. Tran ,  Michael B. Schinzler

IPC分类号： G06F9/38

CPC分类号： G06F9/3851 ,  G06F9/3804 ,  G06F9/381

摘要： In a processing system capable of single and multi-thread execution, a branch prediction unit can be configured to detect hard to predict branches and loop instructions. In a dual-threading (simultaneous multi-threading) configuration, one instruction queues (IQ) is used for each thread and instructions are alternately sent from each IQ to decode units. In single thread mode, the second IQ can be used to store the “not predicted path” of the hard-to-predict branch or the “fall-through” path of the loop. On mis-prediction, the mis-prediction penalty is reduced by getting the instructions from IQ instead of instruction cache.

摘要翻译： 在能够进行单线程和多线程执行的处理系统中，分支预测单元可以被配置为检测难以预测分支和循环指令。 在双线程（同时多线程）配置中，每个线程都使用一个指令队列（IQ），并将指令从每个IQ交替发送到解码单元。 在单线程模式中，第二个IQ可用于存储难以预测的分支的“未预测路径”或循环的“直通”路径。 在误预测中，通过从IQ而不是指令高速缓存获取指令来减少错误预测损失。