[MachO] Fix symbol merging during symtab parsing #465
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This file really suffered from the Great Reformat. I'm adding a few early returns to give the deeply nested code some more breathing room.
git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@373803 91177308-0d34-0410-b5e6-96231b3b80d8 (cherry picked from commit 582965dc3ea03188e87738d83cef2912da6545ea) (cherry picked from commit 5e0386a1400c009afe99e217e89e085f742bafc4) apple-llvm-split-commit: cfd351c8d978959b5263f6fdb467569f39e5c0d4 apple-llvm-split-dir: lldb/ (cherry picked from commit af2e99e)
The symtab parser in ObjectFileMachO has logic to coalesce debug (STAB) and non-debug symbols, based on the address and the symbol name for static (STSYM) and global symbols (GSYM) respectively. It makes the assumption that the debug variant is always encountered first. Rather than creating a second entry in the symbol table for the non-debug symbol, the latter gets merged into the existing debug symbol. This breaks when the linker emits the non-debug symbol first. We'd end up with two entries in the symbol table, each containing part of the information LLDB relies on. Indeed, commenting out the merging logic breaks the test suite spectacularly. This patch solves that problem by always parsing the debug symbols first. This guarantees that the assumption for merging holds. I'm not particularly happy with adding a lambda, but after numerous attempts this is the best solution I could come up with. The symtab parsing logic is pretty complex in that it touches a lot of things. I've experienced first hand that it's very easy to break things. I believe this approach strikes a balance between fixing the issue while limiting the risk of regressions. Differential revision: https://reviews.llvm.org/D68536 git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@373994 91177308-0d34-0410-b5e6-96231b3b80d8 (cherry picked from commit a8446221d1f565cbd2696ab71d42b4bf29b994e1) (cherry picked from commit 569ae2622aeca76cc79285686b742ba89055944d) apple-llvm-split-commit: c7ca5246795eb58c3cbd272368c667510efbbe20 apple-llvm-split-dir: lldb/ (cherry picked from commit e341a70)
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The symtab parser in ObjectFileMachO has logic to coalesce debug (STAB)
and non-debug symbols, based on the address and the symbol name for
static (STSYM) and global symbols (GSYM) respectively. It makes the
assumption that the debug variant is always encountered first. Rather
than creating a second entry in the symbol table for the non-debug
symbol, the latter gets merged into the existing debug symbol.
This breaks when the linker emits the non-debug symbol first. We'd end
up with two entries in the symbol table, each containing part of the
information LLDB relies on. Indeed, commenting out the merging logic
breaks the test suite spectacularly.
This patch solves that problem by always parsing the debug symbols
first. This guarantees that the assumption for merging holds.