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It decides which functions need stack protection. It sets the `needStackProtection` flags on all function which contain stack-allocated values for which an buffer overflow could occur. Within safe swift code there shouldn't be any buffer overflows. But if the address of a stack variable is converted to an unsafe pointer, it's not in the control of the compiler anymore. This means, if there is any `address_to_pointer` instruction for an `alloc_stack`, such a function is marked for stack protection. Another case is `index_addr` for non-tail allocated memory. This pattern appears if pointer arithmetic is done with unsafe pointers in swift code. If the origin of an unsafe pointer can only be tracked to a function argument, the pass tries to find the root stack allocation for such an argument by doing an inter-procedural analysis. If this is not possible, the fallback is to move the argument into a temporary `alloc_stack` and do the unsafe pointer operations on the temporary. rdar://93677524
12 lines
390 B
CMake
12 lines
390 B
CMake
# This source file is part of the Swift.org open source project
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#
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# Copyright (c) 2014 - 2022 Apple Inc. and the Swift project authors
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# Licensed under Apache License v2.0 with Runtime Library Exception
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#
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# See http://swift.org/LICENSE.txt for license information
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# See http://swift.org/CONTRIBUTORS.txt for Swift project authors
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swift_compiler_sources(Optimizer
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StackProtection.swift
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)
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