[Frontend] Generate an interface hash for emit-module-separately jobs #38939
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@swift-ci Please smoke test |
xymus
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| // Enable interface hash computation for primaries or emit-module-separately, | ||
| // but not in WMO, as it's only currently needed for incremental mode. | ||
| if (forPrimary || | ||
| typeOpts.SkipFunctionBodies == FunctionBodySkipping::NonInlinableWithoutTypes) { |
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Can we use FrontOptions::ActionType::EmitModuleOnly here instead?
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We can if we don't mind turning on interface hashing in some non-incremental builds. EmitModuleOnly is used when we skip compilation, it's already pretty common before the emit-module-separately work afaict. It looks like the stdlib is built this way via CMake and a lot of tests just do an -emit-module without an -emit-library, so they are considered EmitModuleOnly.
What do you think? Can we turn on interface hashing in more cases or should we keep limiting it only to emit-module-separately builds with the check on -experimental-skip-non-inlinable-function-bodies-without-types or some new flag?
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Merging to move on with testing on the driver side. I'll be happy to revisit if we have a better way to differentiate incremental emit-module jobs. |
Uses the newer `-experimental-skip-non-inlinable-function-bodies-without-types` which was introduced here: swiftlang/swift#34612. This should improve LLDB usage in some cases. When using WMO, it has two downsides in Swift 5.5, both introduced by swiftlang/swift#38939: - The swiftmodules will have swiftdeps info embedded in them, which is only needed for incremental compilation - Interface hashing is enabled, which again is only needed for incremental compilation This is because the swift compiler only expects `-experimental-skip-non-inlinable-function-bodies-without-types` to be used with the new `emit-module-separately` incremental build.
We need emit-module jobs created for an emit-module-separately incremental build to generate the interface has for this build mode to support fine-grained incremental builds.
I used
typeOpts.SkipFunctionBodies == FunctionBodySkipping::NonInlinableWithoutTypesas an heuristic to differentiate this emit-module-separately job from other kind of emit-module jobs. This flag should be passed to the compiler only in this build mode. In the future, we may want to have a flag dedicated to identifying jobs used in an incremental build from those from WMO as we move away from merge-module.