SwiftCompilerSources: added OwnershipUtils for ForwardingInstruction. #68885
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SwiftCompilerSources/Sources/Optimizer/Utilities/OwnershipUtils.swift
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| // | ||
| // This walker is used to query basic lifetime attributes on values, such as "escaping" or "lexical". It must be precise for correctness and is performance critical. | ||
| // | ||
| // TODO: Ideally, this would be defined alongside ForwardingInstruction, but basic data structures and utilities are not available in the SIL module. |
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Are the walkers really part of SIL? You can also view them as utility, based on ForwardingInstruction.
Anyway, if we want we can easily move the WalkUtils into SIL
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Any walker that is required for well-formed SIL is part of SIL. In this case, the behavior of the walker will change SIL semantics, so it's definitely part of SIL. If the walker, "stops early" and we fail to see that some value has a pointer-escape, then we lose information needed for correctness. We also cache some information about lifetimes as instruction flags, and that cache needs to be consistent with the walker.
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Note that I'm not too concerned about the final resting place for new lifetime utilities because I expect them to change a lot in the next few months.
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| extension Value { | ||
| public var forwardingInstruction: ForwardingInstruction? { |
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Though it's a bit lengthy, I think that definingForwardingInstruction would make it a bit clearer.
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I don't care much about the name here, but I'm worried that people will think they can use definingForwardingInstruction the same way they use definingInstruction. But it doesn't work that way. For terminator results, you cannot use the forwarding instruction as an insertion point.
atrick
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SwiftCompilerSources/Sources/Optimizer/Utilities/OwnershipUtils.swift
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| return tpei.tupleOperand | ||
| case let sei as SelectEnumInst: | ||
| return sei.enumOperand | ||
| default: |
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This can be the default implementation
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This could be combined with ValueUseDefWalker if the latter is refactored to classsify instructions by projections and aggegation (which always forward) vs. other arbitrary hard-coded instruction types. It would also need to limit the walk to real operands (which are always forwarded). Then this walker can call into the default walk for projections and track the projection path. The current implementation is however simpler and more efficient.
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Adding unit tests is taking longer than expected. I'll put them in a follow-up PR. |
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@swift-ci test |
Add SwiftCompilerSources bridging for operand ownership and forwarding instructions.
This needs to be in place to bootstrap lifetime diagnostics. We'll start adding unit tests as we explore different diagnostic test cases.