[PATCH] D157913: [Coverage] Allow Clang coverage to be used with debug info correlation.
Ellis Hoag via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Tue Sep 19 11:04:28 PDT 2023
ellis added a comment.
In D157913#4648296 <https://reviews.llvm.org/D157913#4648296>, @zequanwu wrote:
> For some unknown reasons, linker still generates __llvm_prf_names section in the final binary on mac even if the object file doesn't have this section. And I cannot use llvm-objdump to get anything from that section.
>
> $ llvm-readelf -S ../tmp/a.out
> ...
> Section {
> Index: 15
> Name: __llvm_prf_names (5F 5F 6C 6C 76 6D 5F 70 72 66 5F 6E 61 6D 65 73)
> Segment: __DATA (5F 5F 44 41 54 41 00 00 00 00 00 00 00 00 00 00)
> Address: 0x100018000
> Size: 0x0
> Offset: 98304
> Alignment: 0
> RelocationOffset: 0x0
> RelocationCount: 0
> Type: Regular (0x0)
> Attributes [ (0x0)
> ]
> Reserved1: 0x0
> Reserved2: 0x0
> Reserved3: 0x0
> }
> ...
> $ llvm-objdump --section=__llvm_prf_names --full-contents ../tmp/a.out
> ../tmp/a.out: file format mach-o arm64
>
> I will delete the test for now as it's not working on mac: `compiler-rt/test/profile/Darwin/coverage-debug-info-correlate.cpp`
I have seen that MachO sections remain in the header even if the size is zero which seems to be the case here. You could use `llvm-objdump` to verify that the section exists but the size is zero.
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https://reviews.llvm.org/D157913/new/
https://reviews.llvm.org/D157913
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