Invention Grant
US08171260B2 Fetching all or portion of instructions in memory line up to branch instruction based on branch prediction and size indicator stored in branch target buffer indexed by fetch address 有权
根据存储在由抓取地址索引的分支目标缓冲区中的分支预测和大小指示符,将内存行中的所有或部分指令取出到分支指令

  • Patent Title: Fetching all or portion of instructions in memory line up to branch instruction based on branch prediction and size indicator stored in branch target buffer indexed by fetch address
  • Patent Title (中): 根据存储在由抓取地址索引的分支目标缓冲区中的分支预测和大小指示符,将内存行中的所有或部分指令取出到分支指令
  • Application No.: US12489889
    Application Date: 2009-06-23
  • Publication No.: US08171260B2
    Publication Date: 2012-05-01
  • Inventor: Anatoly GelmanRussell Lawrence Schnapp
  • Applicant: Anatoly GelmanRussell Lawrence Schnapp
  • Applicant Address: US TX Carrollton
  • Assignee: STMicroelectronics, Inc.
  • Current Assignee: STMicroelectronics, Inc.
  • Current Assignee Address: US TX Carrollton
  • Main IPC: G06F9/38
  • IPC: G06F9/38
Fetching all or portion of instructions in memory line up to branch instruction based on branch prediction and size indicator stored in branch target buffer indexed by fetch address
Abstract:
The invention provides a method and apparatus for branch prediction in a processor. A fetch-block branch target buffer is used in an early stage of pipeline processing before the instruction is decoded, which stores information about a control transfer instruction for a “block” of instruction memory. The block of instruction memory is represented by a block entry in the fetch-block branch target buffer. The block entry represents one recorded control-transfer instruction (such as a branch instruction) and a set of sequentially preceding instructions, up to a fixed maximum length N. Indexing into the fetch-block branch target buffer yields an answer whether the block entry represents memory that contains a previously executed a control-transfer instruction, a length value representing the amount of memory that contains the instructions represented by the block, and an indicator for the type of control-transfer instruction that terminates the block, its target and outcome. Both the decode and execution pipelines include correction capabilities for modifying the block branch target buffer dependent on the results of the instruction decode and execution and can include a mechanism to correct malformed instructions.
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