[Lldb-commits] [PATCH] D143932: Further delay simulator SDK filepath discovery until needed

[Jason Molenda via Phabricator via lldb-commits]

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In https://reviews.llvm.org/D122373 I changed how the apple simulator platform plugins would find the SDK path given the name of an SDK -- so we would wait until we were actually Creating the plugin to call `xcrun` to find the full path.  If a system doesn't have a given SDK installed, this xcrun call can be very slow, so delaying that search until we know we need a specific simulator platform to be selected, avoided that problem.

I have a new way of hitting this now, and need to make it even more lazy.  `qProcessInfo` can give lldb a list of addresses of binaries to load -- and in the case of the kernel, the address is the address of a *kernelset*.  We need some Mach-O fileset specific code to find the kernel in the fileset.  So ProcessGDBRemote force-creates every platform, and asks it, "can you do something with this address that might be a fileset".  PlatformDarwinKernel knows how to do something.  But every platform is force-Created, so if the create is expensive (as it is with the simulator platforms), we have a big delay if some SDKs aren't installed on the system.

This patch moves the expansion of (primary sdk name, seconary sdk name) -> sdk filepath until it's actually used by the simulator platform methods -- much later than the CreateInstance, when the platform is actually being used.  It will only be calculated once.

I'd call it a NFC change tbh, but it does avoid a very expensive external cost so it's not completely accurate.  It's a big important for this use case.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D143932

Files:
  lldb/source/Plugins/Platform/MacOSX/PlatformAppleSimulator.cpp
  lldb/source/Plugins/Platform/MacOSX/PlatformAppleSimulator.h

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