🍒[cxx-interop][IRGen] Do not try to retain/release a null pointer #73515
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This teaches IRGen to only emit a lifetime operation (retain or release) for a C++ foreign reference type if the pointer is not `nullptr`.
Previously the compiler would in some cases emit a release call for `nullptr`, which breaks the assumption that the argument to a custom release function is `_Nonnull`. For instance:
```
var globalOptional: MyRefType? = nil
func foo() { globalOptional = MyRefType.create() }
```
When emitting IR for the assignment operation to `globalOptional`, the compiler would emit code to first retrieve the existing value of `globalOptional` and release it. If the value is `nil`, it does not need to be released.
rdar://97532642
(cherry picked from commit bd6da5d)
This also re-enables a test that was disabled since 2022. rdar://97532642 (cherry picked from commit ef47dd6)
|
@swift-ci please test |
DougGregor
approved these changes
May 8, 2024
rdar://95738946 (cherry picked from commit 961a2e2)
This adjusts the test to be correct on 32-bit platforms. rdar://127795392 (cherry picked from commit d84cbac)
When compiling with optimizations, the compiler might reorder some instructions, leading to test failures. rdar://127795755 (cherry picked from commit 27829b7)
|
@swift-ci please test |
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Explanation: This teaches IRGen to only emit a lifetime operation (retain or release) for a C++ foreign reference type if the pointer is not
nullptr.Scope: IRGen of lifetime operations for C++ foreign reference types is changed.
Risk: Low, only affects C++ reference types, and only takes effect when C++ interop is enabled.
Testing: Added compiler tests.
Issue: rdar://97532642
Reviewer: @rjmccall @beccadax @zoecarver
Original PR: #73366