Coarse-grained reconfigurable architecture (CGRA) has become a promising candidate for data-intensive computing due to its flexibility and high energy efficiency. CGRA compilers map data flow graphs (DFGs) extracted from applications onto CGRAs, playing a fundamental role in fully exploiting hardware resources for acceleration. Yet the existing compilers are time-demanding and cannot guarantee optimal results due to the traversal search of enormous search spaces brought about by the spatio-temporal flexibility of CGRA structures and the complexity of DFGs. Inspired by the amazing progress in reinforcement learning (RL) and Monte-Carlo tree search (MCTS) for real-world problems, we consider constructing a compiler that can learn from past experiences and comprehensively understand the target DFG and CGRA. In this paper, we propose an architecture-aware compiler for CGRAs based on RL and MCTS, called MapZero - a framework to automatically extract the characteristics of DFG and CGRA hardware and map operations onto varied CGRA fabrics. We apply Graph Attention Network to generate an adaptive embedding for DFGs and also model the functionality and interconnection status of the CGRA, aiming at training an RL agent to perform placement and routing intelligently. Experimental results show that MapZero can generate superior-quality mappings and reduce compilation time hundreds of times compared to state-of-the-art methods. MapZero can find high-quality mappings very quickly when the feasible solution space is rather small and all other compilers fail. We also demonstrate the scalability and broad applicability of our framework.

Modern out-of-order processors call for more aggressive scheduling techniques such as priority scheduling and out-of-order commit to make use of increasing core resources. Since these approaches prioritize the issue or commit of certain instructions, they face the conundrum of providing the capacity efficiency of scheduling structures while preserving the ideal ordering of instructions. Traditional collapsible queues are too expensive for today's processors, while state-of-the-art queue designs compromise with the pseudo-ordering of instructions, leading to performance degradation as well as other limitations. In this paper, we present Orinoco, a microarchitecture/circuit co-design that supports ordered issue and unordered commit with non-collapsible queues. We decouple the temporal ordering of instructions from their queue positions by introducing an age matrix with the bit count encoding, along with a commit dependency matrix and a memory disambiguation matrix to determine instructions to prioritize issue or commit. We leverage the Processing-in-Memory (PIM) approach and efficiently implement the matrix schedulers as 8T SRAM arrays. Orinoco achieves an average IPC improvement of 14.8% over the baseline in-order commit core with the state-of-the-art scheduler while incurring overhead equivalent to a few kilobytes of SRAM.