[lldb] Assortment of cherry-picks from upstream LLVM #10866
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Michael137
commented
Jun 18, 2025
Michael137
commented
- IR checker changes
- Fix for upcoming [libc++] Avoid type-punning between __hash_value_type and pair llvm/llvm-project#143501
- Fix for [lldb] wrong std::deque size llvm/llvm-project#144555
Currently when jitting expressions, LLDB scans the IR instructions of the `$__lldb_expr` and will insert a call to a utility function for each load/store instruction. The purpose of the utility funciton is to dereference the load/store operand. If that operand was an invalid pointer the utility function would trap and LLDB asks the IR checker whether it was responsible for the trap, in which case it prints out an error message saying the expression dereferenced an invalid pointer. This is a lot of setup for not much gain. In fact, creating/running this utility expression shows up as ~2% of the expression evaluation time (though we cache them for subsequent expressions). And the error message we get out of it is arguably less useful than if we hadn't instrumented the IR. It was also untested. Before: ``` (lldb) expr int a = *returns_invalid_ptr() error: Execution was interrupted, reason: Attempted to dereference an invalid pointer.. The process has been returned to the state before expression evaluation. ``` After: ``` (lldb) expr int a = *returns_invalid_ptr() error: Expression execution was interrupted: EXC_BAD_ACCESS (code=1, address=0x5). The process has been returned to the state before expression evaluation. ``` This patch removes this IR checker. (cherry picked from commit 0a7b0c8)
…argets/frames (llvm#144503) There's no need to create this utility function (and run it) for targets/frames that aren't Objective-C/Objective-C++. (cherry picked from commit 4ced29b)
…le::value_type (llvm#144517) llvm#143501 changes usage of `__hash_value_type` in libcxx to an empty tag type. This type will no longer have a definition in DWARF. Currently the LLDB unordered_map formatter deduces the map's `element_type` by looking at the `__cc_` member of `__hash_value_type`. But that will no longer work because we only have its forward declaration. Since what we're really after is the type that `__hash_value_type` is wrapping, we can just look at the `__hash_table::value_type` typedef. With llvm#143501 that will now point to the `std::pair` element type (which used to be what we got from `__cc_`). TBD: need to double-check this works for older layouts. Quick glance at the code makes me suspicious of cases like `unordered_map<std::pair<int, int>, int>` (cherry picked from commit 382e3fd)
…ng changes Cherry-picked the LLDB parts from: ``` commit c7df106 Author: Peng Liu <[email protected]> Date: Wed Nov 13 05:08:08 2024 -0500 Unify naming of internal pointer members in std::vector and std::__split_buffer (llvm#115517) ``` Addresses llvm#144555
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@swift-ci test |
adrian-prantl
approved these changes
Jun 18, 2025
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Not entirely sure if that test failure is related. |
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@swift-ci test macOS |
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failing test was in https://ci.swift.org/job/apple-llvm-project-pr-macos/7613/ |
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