| Issue |
125529
|
| Summary |
Inconsistent section-alignment values in RuntimeDyld
|
| Labels |
new issue
|
| Assignees |
|
| Reporter |
JohnReppy
|
## Summary
The alignment values given for sections as arguments to `RTDyldMemoryManager::reserveAllocationSpace` are smaller than the values supplied when calling `RTDyldMemoryManager::allocateDataSection`. This inconsistency means that the amount of reserved space may not be sufficient for the later allocations.
## Details
This bug is in LLVM 18.1.8. I am cross compiling from x86_64 to aarch64 on macOS (so the object-file format is MachO). Our version of LLVM is slightly modified to support a specialized calling convention, but is otherwise a stock installation.
I added debug output to `RuntimeDyld.cpp` where these functions are called and get the following output:
```console
# RuntimeDyldImpl::loadObjectImpl: CodeAlign = 4; RODataAlign = 1; RWDataAlign = 1
# RuntimeDyldImpl::emitSection: Name = __text; Alignment = 8
# RuntimeDyldImpl::emitSection: Name = __const; Alignment = 8
```
I believe that the issue is related to the fact that different algorithms are used to compute the alignment in the two situations. Specifically, the `allocateDataSection` method bumps up the alignment by the stub alignment (which is always 8 bytes for Mach).
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