[Source manager] Improve the performance of findBufferContainingLocInternal #68971
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…ternal() This function was performing a linear scan through the set of known buffers to find the buffer containing a given source location. This linear scan can show up in hot loops, and the number of buffers in a program is increasing due to macros, so this has become a performance problem. Replace the linear scan with a logarithmic lookup into a sorted vector of the buffer IDs, with a one-element most-recently-used cache so that repeated lookups in the same buffer require constant time. This mirrors what we already do with source files in a module. Unfortunately, we cannot reuse that code because there is no link from buffers to source files. We should look to consolidate this in the future. Fixes rdar://116184248.
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@swift-ci please smoke test |
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@swift-ci please test compiler performance |
tshortli
approved these changes
Oct 4, 2023
This was referenced Oct 5, 2023
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Infrastructure failure in trying to post the performance results. Digging in, this didn't make a difference in aggregate, I suspect because none of the test projects there have a huge number of Swift files in a single target. |
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This function was performing a linear scan through the set of known buffers to find the buffer containing a given source location. This linear scan can show up in hot loops, and the number of buffers in a program is increasing due to macros, so this has become a performance problem.
Replace the linear scan with a logarithmic lookup into a sorted vector of the buffer IDs, with a one-element most-recently-used cache so that repeated lookups in the same buffer require constant time.
This mirrors what we already do with source files in a module. Unfortunately, we cannot reuse that code because there is no link from buffers to source files. We should look to consolidate this in the future.
Fixes rdar://116184248.