Smart contracts, predominantly written in Solidity and deployed on blockchains such as Ethereum, are immutable after deployment, making functional correctness critical. However, existing evaluations of Solidity code generation rely largely on surface-level metrics (e.g., BLEU, CrystalBLEU) or manual inspection, which correlate poorly with functional correctness. In contrast to Python, Solidity lacks large-scale, execution-based benchmarks, limiting systematic evaluation of large language models for smart contract development. We introduce SolBench, a comprehensive benchmark and automated testing pipeline for Solidity that emphasizes functional correctness via differential fuzzing. SolBench consists of 28825 functions extracted from 7604 real-world smart contracts collected from Etherscan (genesis-2024), spanning ten application domains. We benchmark 14 diverse LLMs, covering open and closed models, 1.3B-671B parameters, and both general-purpose and code-specialized architectures. The dominant failure mode is missing critical intra-contract information, such as state variables and type definitions. Providing full-contract context improves accuracy but incurs prohibitive inference costs. To address this, we propose Retrieval-Augmented Repair (RAR), a cost-effective framework that integrates execution feedback into code repair. RAR uses compiler and runtime error messages to retrieve only the minimal contract snippets needed to correct a target function, avoiding full-context inference. This significantly reduces input length while improving functional correctness. We further analyze retrieval and repair strategies within RAR, demonstrating consistent gains in accuracy and efficiency. SolBench and RAR enable principled, execution-based evaluation and economical improvement of Solidity code generation. Dataset and code are publicly available at https://github.com/ZaoyuChen/SolBench.