)]}' { "commit": "76dd742f7b32e4d3acf50fab1dbbd897f215837e", "tree": "7615d664966b39302c45ff409448013047b288e6", "parents": [ "bad3df476457db2fd7dd36729c47fb1d2bddad3a" ], "author": { "name": "Zhaoxuan Jiang", "email": "jiangzhaoxuan94@gmail.com", "time": "Fri Aug 15 04:49:09 2025 +0800" }, "committer": { "name": "GitHub", "email": "noreply@github.com", "time": "Thu Aug 14 13:49:09 2025 -0700" }, "message": "[CGData] Lazy loading support for stable function map (#151660)\n\nThe stable function map could be huge for a large application. Fully\nloading it is slow and consumes a significant amount of memory, which is\nunnecessary and drastically slows down compilation especially for\nnon-LTO and distributed-ThinLTO setups. This patch introduces an opt-in\nlazy loading support for the stable function map. The detailed changes\nare:\n\n- `StableFunctionMap`\n- The map now stores entries in an `EntryStorage` struct, which includes\noffsets for serialized entries and a `std::once_flag` for thread-safe\nlazy loading.\n- The underlying map type is changed from `DenseMap` to\n`std::unordered_map` for compatibility with `std::once_flag`.\n- `contains()`, `size()` and `at()` are implemented to only load\nrequested entries on demand.\n\n- Lazy Loading Mechanism\n- When reading indexed codegen data, if the newly-introduced\n`-indexed-codegen-data-lazy-loading` flag is set, the stable function\nmap is not fully deserialized up front. The binary format for the stable\nfunction map now includes offsets and sizes to support lazy loading.\n- The safety of lazy loading is guarded by the once flag per function\nhash. This guarantees that even in a multi-threaded environment, the\ndeserialization for a given function hash will happen exactly once. The\nfirst thread to request it performs the load, and subsequent threads\nwill wait for it to complete before using the data. For single-threaded\nbuilds, the overhead is negligible (a single check on the once flag).\nFor multi-threaded scenarios, users can omit the flag to retain the\nprevious eager-loading behavior.", "tree_diff": [ { "type": "modify", "old_id": "38b96b72ccac6b85fdebc3797af32c9a95ffead8", "old_mode": 33188, "old_path": "llvm/include/llvm/CGData/CodeGenData.h", "new_id": "e44497a40824515a1078baaa3693e641346a2c03", "new_mode": 33188, "new_path": "llvm/include/llvm/CGData/CodeGenData.h" }, { "type": "modify", "old_id": "94de4c0b017a2aaad578aeff7bde8c118de0b064", "old_mode": 33188, "old_path": "llvm/include/llvm/CGData/CodeGenData.inc", "new_id": "d5fbe2fb97718247f0a9455ed425cfb927284caf", "new_mode": 33188, "new_path": "llvm/include/llvm/CGData/CodeGenData.inc" }, { "type": "modify", "old_id": "bcb72e82169733b361718f6d5037a3e9614e58ef", "old_mode": 33188, "old_path": "llvm/include/llvm/CGData/StableFunctionMap.h", "new_id": "ea3523c3a32993f4979702e421909dfb854de4bb", "new_mode": 33188, 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