High-Level Synthesis of Efficient Pipelines with Visibility Control

2026-07-21

AI Summary

This work addresses the limitations of existing high-level synthesis (HLS) tools in balancing sequential semantics with fine-grained control over pipeline design, which hinders optimization of power, performance, and area (PPA). The paper proposes a novel HLS approach based on visibility control that preserves a sequential programming model while enabling precise manipulation of pipeline structures and hazard-handling mechanisms through a unified visibility abstraction. This framework encompasses strategies such as stall insertion, bypassing, speculative execution, delayed commit, and register renaming. Experimental results on a RISC-V core, histogram computation, and an AES accelerator demonstrate that the generated pipelines significantly outperform those from state-of-the-art sequential-semantics-preserving HLS tools, achieving PPA metrics close to hand-optimized RTL implementations and enabling efficient design space exploration.

Abstract

High-level synthesis (HLS) raises the abstraction of hardware design from concurrent register-transfer level (RTL) programs to sequential programs. Among the forms of parallelism HLS exploits, pipelining demands fine-grained control over pipeline structure and hazard resolution to achieve competitive power, performance, and area (PPA). However, existing tools either lack such control or sacrifice sequential semantics to provide it. We present an HLS tool that embeds fine-grained pipeline control in a sequential programming model, enabling rapid design-space exploration. The tool builds on visibility control, a novel programming abstraction that unifies hazard resolution strategies including stalling, bypassing, speculation, deferred commit, and register renaming. We evaluate on in-order RISC-V cores, histograms, and an AES accelerator. On RISC-V cores, we implement stall, bypass, speculation, and register renaming; on histograms, we implement scheduling strategies that previously required RTL or concurrent programming models. Compiled pipelines outperform HLS tools with sequential semantics and achieve PPA comparable to hand-written RTL.

Problem

• High-Level Synthesis
• Pipelining
• Visibility Control
• Hazard Resolution
• Sequential Semantics

Innovation

• visibility control
• high-level synthesis
• pipeline hazard resolution
• sequential programming model
• design-space exploration