[DWARFLinker] Constrain a function's high_pc to its own symbol (#215952) - #13867
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JDevlieghere wants to merge 1 commit into
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[DWARFLinker] Constrain a function's high_pc to its own symbol (#215952)#13867JDevlieghere wants to merge 1 commit into
JDevlieghere wants to merge 1 commit into
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…215952) Mach-O objects built with .subsections_via_symbols make every symbol an independently placeable atom, and the linker packs atoms without preserving the spacing they had in the object file. I have an example where the compiler describes such a subprogram as extending past its own atom. While it's debatable whether that's a good idea, it's not invalid in the object file. However, once linked, it is invalid. We can make dsymutil resilient against this by looking at the size of the symbol in the debug map and adjusting the end_pc. I'm doing so conservatively so that only a collision is repaired. Already overlapping/invalid ranges remain untouched. rdar://184768778 (cherry picked from commit 5e8490a)
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Mach-O objects built with .subsections_via_symbols make every symbol an independently placeable atom, and the linker packs atoms without preserving the spacing they had in the object file.
I have an example where the compiler describes such a subprogram as extending past its own atom. While it's debatable whether that's a good idea, it's not invalid in the object file. However, once linked, it is invalid.
We can make dsymutil resilient against this by looking at the size of the symbol in the debug map and adjusting the end_pc. I'm doing so conservatively so that only a collision is repaired. Already overlapping/invalid ranges remain untouched.
rdar://184768778
(cherry picked from commit 5e8490a)