公开(公告)号：US5142631A

公开(公告)日：1992-08-25

申请号：US306773

申请日：1989-02-03

申请人： John E. Murray ,  Mark A. Firstenberg ,  David B. Fite ,  Michael M. McKeon ,  Wiliam R. Grundmann ,  David A. Webb, Jr. ,  Ronald M. Salett ,  Tryggve Fossum ,  Dwight P. Manley ,  Ricky C. Hetherington

发明人： John E. Murray ,  Mark A. Firstenberg ,  David B. Fite ,  Michael M. McKeon ,  Wiliam R. Grundmann ,  David A. Webb, Jr. ,  Ronald M. Salett ,  Tryggve Fossum ,  Dwight P. Manley ,  Ricky C. Hetherington

IPC分类号： G06F9/38

CPC分类号： G06F9/355 ,  G06F9/345 ,  G06F9/3836 ,  G06F9/3838 ,  G06F9/3857

摘要： A method is provided for preprocessing multiple instructions prior to execution of such instructions in a digital computer having an instruction decoder, an instruction execution unit, and multiple general purpose registers which are read to produce memory addresses during the preprocessing. The method comprises: (1) avoiding the preprocessing of a current instruction to read a general purpose register to produce a memory address prior to the modification of the contents of that register by a preceding instruction by (a) generating a composite write mask having a bit set for each general purpose register whose contents are to be modified by at least one of a plurality of decoded by not-yet-executed instructions preceding the current instruction, and (b) stalling the preprocessing of the current instruction when a general purpose register to be read by the current instruction is a register having a bit set in the write mask, and/or (2) avoiding the preprocessing of a current instruction which modifies the contents of a general purpose register that is to be read by a preceding instruction by (a) generating a composite read mask having a bit set for each general purpose register to be read by at least one of a plurality of decoded but not-yet-executed instructions preceding the current instruction, and (b) stalling the preprocessing of the current instruction when a general purpose register whose contents are to be modified by the current instruction is a register having a bit set in the read mask.