| 摘要 |
An apparatus stores state information corresponding to various stack items, indicative of the value of the stack items. The state information may be retained even if the stack items are popped from the stack. When a stack item is to be pushed to the same stack location, if the state information corresponding to the item previously in that location is still valid, the apparatus determines if the stack item being pushed is the same as the previous stack item. If so, the instruction to perform the push may be eliminated and the stack pointer may be adjusted. In one embodiment, the apparatus includes a code translator configured to translate from a stack-based instruction sequence to a register based instruction sequence. Registers are used to store one or more items at the top of the stack, and a stack transform is used to map the registers to stack locations. The stack transform may also be used to track state information for the stack items which the code translator is able to track. For example, in one embodiment, the code translator is able to track constants and variables from a local variable array. If the stack transform entry to be allocated to a push has valid state information, and that state information matches state information corresponding to the stack item being pushed, the push may be eliminated from the translated code sequence. |
