Resynthesis and retiming for optimum partial scan
DAC '94 Proceedings of the 31st annual Design Automation Conference
Retiming sequential circuits for low power
ICCAD '93 Proceedings of the 1993 IEEE/ACM international conference on Computer-aided design
Razor: A Low-Power Pipeline Based on Circuit-Level Timing Speculation
Proceedings of the 36th annual IEEE/ACM International Symposium on Microarchitecture
EVAL: Utilizing processors with variation-induced timing errors
Proceedings of the 41st annual IEEE/ACM International Symposium on Microarchitecture
Circuit techniques for dynamic variation tolerance
Proceedings of the 46th Annual Design Automation Conference
Tribeca: design for PVT variations with local recovery and fine-grained adaptation
Proceedings of the 42nd Annual IEEE/ACM International Symposium on Microarchitecture
DynaTune: circuit-level optimization for timing speculation considering dynamic path behavior
Proceedings of the 2009 International Conference on Computer-Aided Design
Slack redistribution for graceful degradation under voltage overscaling
Proceedings of the 2010 Asia and South Pacific Design Automation Conference
Re-synthesis for cost-efficient circuit-level timing speculation
Proceedings of the 48th Design Automation Conference
Recovery-based design for variation-tolerant SoCs
Proceedings of the 49th Annual Design Automation Conference
CCP: common case promotion for improved timing error resilience with energy efficiency
Proceedings of the 2012 ACM/IEEE international symposium on Low power electronics and design
On logic synthesis for timing speculation
Proceedings of the International Conference on Computer-Aided Design
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Recovery based design (RBD) is a promising approach for the design of energy-efficient circuits under variations. RBD instruments circuits with mechanisms to identify and correct timing violations, thereby allowing reduced guard bands or design margins. In addition, RBD enables aggressive voltage overscaling to a point where timing errors occur even under nominal conditions. A major barrier to the widespread adoption of RBD is that traditional design practices and synthesis tools result in circuits with so-called"path walls", leading to an explosion in the number of timing errors beyond a certain critical operating voltage. To alleviate this effect, previous techniques focused on combinational circuit optimizations such as sizing, use of dual Vth cells, re-structuring, etc. to favorably reshape the path delay distribution. However, these techniques are limited by the inherent sequential structure of the circuit, which defines the boundaries of the combinational logic. In this work, we explore a completely different approach to synthesize circuits for RBD. We propose the use of retiming, a well-known and powerful sequential optimization technique to redefine the boundaries of combinational logic, thereby creating new opportunities for RBD that cannot be explored by previous techniques. We make the key observation that, in retiming circuits with RBD (unlike classical retiming), it is acceptable for a few paths in the circuit to exceed the clock period. Using this insight, we propose a synthesis methodology, Relax-and-Retime, wherein the original circuit is relaxed by ignoring timing constraints on selected paths that are bottlenecks to retiming. When classical minimum period retiming is employed on this relaxed circuit, the path wall is shifted to a lower delay, thus allowing additional voltage overscaling. The Relax-and-Retime methodology judiciously selects bottleneck paths by trading off recovery overheads caused by timing errors due to these paths with the opportunities for retiming. We utilize the proposed methodology to synthesize a wide range of benchmarks including arithmetic circuits, ISCAS89 benchmarks and modules from the UltraSPARC T1 processor. Our results demonstrate 9-25% (average of 15.3%) improvement in overall energy compared to a well-optimized baseline with RBD.