[NFC][RemoteInspection] Add an opaque AddressSpace field to RemoteAddress #82997
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This patch changes RemoteAbsolutePointer to store both the symbol and the resolved address. This allows us to retire some ugly workarounds to deal with non-symbolic addresses and it fixes code paths that would need these workarounds, but haven't implemented them yet (i.e., the pack shape handling in the symbolicReferenceResolver in MetadatyaReader. Addresses parts of rdar://146273066. rdar://153687085 (cherry picked from commit 9381a54) (cherry picked from commit a6eafcb)
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The Offset field of a DynamicRelocation is either an offset or a remote address, but was being treated only as a remote address on getDynamicSymbol.
…ress Add an extra opaque field to AddressSpace, which can be used by clients of RemoteInspection to distinguish between different address spaces. LLDB employs an optimization where it reads memory from files instead of the running process whenever it can to speed up memory reads (these can be slow when debugging something over a network). To do this, it needs to keep track whether an address originated from a process or a file. It currently distinguishes addresses by setting an unused high bit on the address, but because of pointer authentication this is not a reliable solution. In order to keep this optimization working, this patch adds an extra opaque AddressSpace field to RemoteAddress, which LLDB can use on its own implementation of MemoryReader to distinguish between addresses. This patch is NFC for the other RemoteInspection clients, as it adds extra information to RemoteAddress, which is entirely optional and if unused should not change the behavior of the library. Although this patch is quite big the changes are largely mechanical, replacing threading StoredPointer with RemoteAddress. rdar://148361743 (cherry picked from commit 58df553) (cherry picked from commit 8f3862b)
Sometimes it makes sense to compares addresses from different address spaces. rdar://148361743 (cherry picked from commit c97dfd6)
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tbkka
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Jul 14, 2025
| return RemoteAddress(Data - rhs, getAddressSpace()); | ||
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| RemoteAddress operator-(const RemoteAddress &rhs) const { |
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The difference between two addresses should be an integer, not an address.
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It's useful to have these math operations return an address as an API because they're pretty much always used to calculate a new address at some offset from the current address.
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Actually, you are right Tim, this shouldn't be the return of comparing two addresses. I will update this
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I have a PR on main fixing this #83040
mikeash
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Jul 14, 2025
tbkka
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Jul 14, 2025
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LLDB employs an optimization where it reads memory from files instead of the running process whenever it can to speed up memory reads (these can be slow when debugging something over a network). To do this, it needs to keep track whether an address originated from a process or a file. It currently distinguishes addresses by setting an unused high bit on the address, but because of pointer authentication this is not a reliable solution.
In order to keep this optimization working, the main commit adds an extra opaque AddressSpace field to RemoteAddress, which LLDB can use on its own implementation of MemoryReader to distinguish between addresses, the others are commits supporting that change.
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StoredPointerwithRemoteAddress, using the newRemoteAddressconstructor, etc) and are NFC for other remote mirrors clients.