[runtime] Move xamarin_create_managed_ref internal call to managed code. #11271
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Move the xamarin_create_managed_ref internal call to managed code, to ease things with CoreCLR. In order to preserve performance, this wasn't a straight forward port. * monotouch_create_managed_ref used to detect if there already was a GCHandle for a native object. To avoid a managed->native transition, this logic has now been moved into the code that sets the GCHandle (the xamarinSetGCHandle:flags: / xamarin_set_gchandle_trampoline code), and these methods return a value saying whether the GCHandle was set or not. * xamarin_create_gchandle will check the retain count to determine whether to create a weak or a strong GCHandle for the managed object. In this particular case we should never need to create a strong GCHandle, which means that we don't need to check the retain count (saving a managed->native transition). Performance measurements: slightly faster in all test cases I could come up with. * 'new NSObject ()': 3% faster * 'new CustomObject ()': 6% faster * Creating an NSObject in native code, and getting the managed wrapper: 0.6% faster * Creating a CustomObject in native code (the type being defined in managed code): 2% faster All measurements done in an iOS simulator on an iMac Pro.
spouliot
approved these changes
Apr 21, 2021
❌ Tests failed on Build ❌Tests failed on Build. API diff✅ API Diff from stable View API diffTest results22 tests failed, 77 tests passed.Failed tests
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✅ Tests passed on Build. ✅Tests passed on Build. API diff✅ API Diff from stable View API diff🎉 All 102 tests passed 🎉 |
tj-devel709
approved these changes
Apr 22, 2021
dalexsoto
approved these changes
Apr 22, 2021
filipnavara
reviewed
Apr 23, 2021
| bool | ||
| xamarin_set_gchandle_with_flags_safe (id self, GCHandle gchandle, enum XamarinGCHandleFlags flags) | ||
| { | ||
| // COOP: no managed memory access: any mode |
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This comment sounds outdated.
mandel-macaque
approved these changes
Apr 23, 2021
| enum XamarinGCHandleFlags : uint32_t { | ||
| XamarinGCHandleFlags_None = 0, | ||
| XamarinGCHandleFlags_WeakGCHandle = 1, | ||
| XamarinGCHandleFlags_HasManagedRef = 2, | ||
| XamarinGCHandleFlags_InitialSet = 4, |
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These are flags, so 1 + 2 = 3.
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Move the xamarin_create_managed_ref internal call to managed code, to ease things
with CoreCLR.
In order to preserve performance, this wasn't a straight forward port.
monotouch_create_managed_ref used to detect if there already was a GCHandle for
a native object. To avoid a managed->native transition, this logic has now been
moved into the code that sets the GCHandle (the
xamarinSetGCHandle:flags:/xamarin_set_gchandle_trampolinecode), and these methods return a value saying whether the GCHandle was set or
not.
xamarin_create_gchandle will check the retain count to determine whether to create
a weak or a strong GCHandle for the managed object. In this particular case we
should never need to create a strong GCHandle, which means that we don't need to
check the retain count (saving a managed->native transition).
Performance measurements: slightly faster in all test cases I could come up with.'new NSObject ()': 3% faster'new CustomObject ()': 6% fasterCreating an NSObject in native code, and getting the managed wrapper: 0.6% fasterCreating a CustomObject in native code (the type being defined in managed code): 2% fasterAll measurements done in an iOS simulator on an iMac Pro.Using the new perftest (#11298), I get very similar numbers for both old code and new code: https://gist.github.com/rolfbjarne/e0fc2ae0f21da15062b4f051138679af (multiple runs). Sometimes the old code is faster, sometimes the new code is faster (although the old code tends to be the one who wins).
In any case there aren't any significant performance hits due to this change, so it should be good to go.
The next failure is now: