Tomorrow's architecture seminar

[Alaa Alameldeen <alaa@xxxxxxxxxxx>]

Tomorrow's architecture seminar (1:30 PM in 2310) might be of
interest to the PL seminar audience. It is a practice talk for
the upcoming CGO conference (International Symposium on Code
Generation and Optimization). You are all welcome to attend.
The title and abstract are attached.

-Alaa

Dynamic Binary Translation for Accumulator-Oriented Architectures

By: Ho-Seop Kim, UW-Madison

A dynamic binary translation system for a co-designed virtual machine is 
described and evaluated. The underlying hardware directly executes an 
accumulator-oriented instruction set that exposes instruction dependence 
chains (strands) to a distributed microarchitecture containing a simple 
instruction pipeline. To support conventional program binaries, a source 
instruction set (Alpha in our study) is dynamically translated to the 
target accumulator instruction set. The binary translator identifies 
chains of inter-instruction dependences and assigns them to dependence- 
carrying accumulators. Because the underlying superscalar 
microarchitecture is capable of dynamic instruction scheduling, the 
binary translation system does not perform aggressive optimizations or 
reschedule code; this significantly reduces binary translation overhead.

Detailed timing simulation of the dynamically translated code running on 
an accumulator-based distributed microarchitecture shows the overall 
system is capable of achieving similar performance to an ideal out-of- 
order superscalar processor, ignoring the significant clock frequency 
advantages that the accumulator-based hardware is likely to have. As 
part of the study, we evaluate an instruction set modification that 
simplifies precise trap implementation. This approach significantly 
reduces the number of instructions required for register state copying, 
thereby improving performance. We also observe that translation chaining 
methods can have substantial impact on the performance, and we evaluate 
a number of chaining methods.