Title
Increasing the number of effective registers in a low-power processor using a windowed register file
Abstract
Low-power embedded processors utilize compact instruction encodings to achieve small code size. Instruction sizes of 8 to 16 bits are common. Such encodings place tight restrictions on the number of bits available to encode operand specifiers, and thus on the number of architected registers. The central problem with this approach is that performance and power are often sacrificed as the burden of operand supply is shifted from the register file to the memory due to the limited number of registers. In this paper, we investigate the use of a windowed register file to address this problem by providing more registers than allowed in the encoding. The registers are organized as a set of identical register windows where at each point in the execution there is a single active window. Special window management instructions are used to change the active window and to transfer values between windows. The goal of this design is to give the appearance of a large register file without compromising the instruction encoding. To support the windowed register file, we designed and implemented a novel graph partitioning based compiler algorithm that partitions virtual registers within a given procedure across multiple windows. On a 16-bit embedded processor with a parameterized register window, an average of 10% improvement in application performance and 7% reduction in system power was achieved as an eight-register design was scaled from one to four windows.
Year
DOI
Venue
2003
10.1145/951710.951729
CASES
Keywords
Field
DocType
low-power processor,register file,identical register windows,windowed register file,large register file,parameterized register window,multiple windows,virtual register,single active window,active window,effective register,architected register,embedded processor,register window,graph partitioning
Status register,Register allocation,Instruction register,Computer science,Parallel computing,Register file,Control register,Real-time computing,Register window,Register renaming,Processor register,Computer hardware
Conference
ISBN
Citations 
PageRank 
1-58113-676-5
6
0.67
References 
Authors
15
7
Name
Order
Citations
PageRank
Rajiv A. Ravindran121311.13
Robert M. Senger229423.55
Eric D. Marsman311510.30
Ganesh S. Dasika438724.30
Matthew R. Guthaus515519.14
Scott Mahlke64811312.08
Richard B. Brown747364.00