[lld-macho] Fix assertion when two symbols at same addr have unwind info
If there are multiple symbols at the same address, our unwind info implementation assumes that we always register unwind entries to a single canonical symbol. This assumption was violated by the `registerEhFrame` code. Fixes #56570. Reviewed By: #lld-macho, thakis Differential Revision: https://reviews.llvm.org/D130208
This commit is contained in:
Jez Ng
parent
1da3119025
commit
241f62d8d3
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@ -1528,6 +1528,13 @@ void ObjFile::registerEhFrames(Section &ehFrameSection) {
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Defined *funcSym;
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if (funcAddrRelocIt != isec->relocs.end()) {
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funcSym = targetSymFromCanonicalSubtractor(isec, funcAddrRelocIt);
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// Canonicalize the symbol. If there are multiple symbols at the same
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// address, we want both `registerEhFrame` and `registerCompactUnwind`
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// to register the unwind entry under same symbol.
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// This is not particularly efficient, but we should run into this case
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// infrequently (only when handling the output of `ld -r`).
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funcSym = findSymbolAtOffset(cast<ConcatInputSection>(funcSym->isec),
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funcSym->value);
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} else {
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funcSym = findSymbolAtAddress(sections, funcAddr);
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ehRelocator.makePcRel(funcAddrOff, funcSym, target->p2WordSize);
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@ -211,7 +211,7 @@ void UnwindInfoSection::addSymbol(const Defined *d) {
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// we use that as the key here.
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auto p = symbols.insert({{d->isec, d->value}, d});
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// If we have multiple symbols at the same address, only one of them can have
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// an associated CUE.
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// an associated unwind entry.
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if (!p.second && d->unwindEntry) {
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assert(!p.first->second->unwindEntry);
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p.first->second = d;
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@ -0,0 +1,159 @@
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--- !mach-o
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FileHeader:
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magic: 0xFEEDFACF
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cputype: 0x1000007
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cpusubtype: 0x3
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filetype: 0x1
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ncmds: 4
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sizeofcmds: 384
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flags: 0x2000
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reserved: 0x0
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LoadCommands:
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- cmd: LC_SEGMENT_64
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cmdsize: 312
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segname: ''
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vmaddr: 0
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vmsize: 96
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filesize: 96
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maxprot: 7
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nsects: 3
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flags: 0
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Sections:
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segname: __TEXT
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addr: 0x0
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size: 2
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offset: 0x1C0
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align: 0
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reloff: 0x0
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nreloc: 0
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flags: 0x80000400
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reserved1: 0x0
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reserved2: 0x0
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reserved3: 0x0
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content: '9090'
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- sectname: __eh_frame
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segname: __TEXT
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addr: 0x8
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size: 56
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offset: 0x1C8
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align: 3
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reloff: 0x220
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nreloc: 4
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flags: 0x0
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reserved1: 0x0
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reserved2: 0x0
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reserved3: 0x0
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content: 1400000000000000017A520001781001100C0708900100001C00000004000000F8FFFFFFFFFFFFFF0100000000000000000E080000000000
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relocations:
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- address: 0x1C
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symbolnum: 3
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pcrel: false
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length: 2
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extern: true
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type: 5
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scattered: false
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value: 0
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- address: 0x1C
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symbolnum: 4
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pcrel: false
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length: 2
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extern: true
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type: 0
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scattered: false
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value: 0
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- address: 0x20
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symbolnum: 4
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pcrel: false
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length: 3
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extern: true
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type: 5
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scattered: false
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value: 0
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- address: 0x20
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symbolnum: 2
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pcrel: false
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length: 3
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extern: true
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type: 0
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scattered: false
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value: 0
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- sectname: __compact_unwind
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segname: __LD
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addr: 0x40
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size: 32
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offset: 0x200
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align: 3
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reloff: 0x240
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nreloc: 1
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flags: 0x2000000
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reserved1: 0x0
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reserved2: 0x0
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reserved3: 0x0
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content: '0000000000000000010000000000010200000000000000000000000000000000'
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relocations:
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- address: 0x0
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symbolnum: 2
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pcrel: false
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length: 3
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extern: true
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type: 0
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scattered: false
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value: 0
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- cmd: LC_SYMTAB
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cmdsize: 24
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symoff: 584
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nsyms: 5
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stroff: 664
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strsize: 40
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- cmd: LC_BUILD_VERSION
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cmdsize: 32
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platform: 1
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minos: 659200
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sdk: 0
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ntools: 1
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Tools:
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- tool: 3
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version: 50069504
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- cmd: LC_DATA_IN_CODE
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cmdsize: 16
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dataoff: 584
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datasize: 0
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LinkEditData:
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NameList:
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n_type: 0xE
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n_sect: 1
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n_desc: 0
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n_value: 0
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- n_strx: 10
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n_type: 0xE
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n_sect: 1
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n_desc: 0
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n_value: 1
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- n_strx: 16
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n_type: 0xE
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n_sect: 1
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n_desc: 0
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n_value: 1
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- n_strx: 21
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n_type: 0xE
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n_sect: 2
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n_desc: 0
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n_value: 8
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- n_strx: 31
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n_type: 0xE
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n_sect: 2
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n_desc: 0
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n_value: 32
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StringTable:
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- ' '
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- _spacer
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- ltmp1
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- _foo
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- EH_Frame1
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- func.eh
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- ''
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...
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@ -0,0 +1,26 @@
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## When changing the assembly input, uncomment these lines to re-generate the
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## YAML.
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# COM: llvm-mc --emit-dwarf-unwind=always -filetype=obj -triple=x86_64-apple-macos10.15 %s -o %t.o
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# COM: ld -r %t.o -o %t-r.o
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# COM: obj2yaml %t-r.o > %S/Inputs/double-unwind-info.yaml
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# RUN: yaml2obj %S/Inputs/double-unwind-info.yaml > %t-r.o
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# RUN: %lld -dylib -lSystem %t-r.o -o /dev/null
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.text
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## eh_frame function address relocations are only emitted if the function isn't
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## at address 0x0.
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_spacer:
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nop
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## Check that we perform unwind info registration correctly when there are
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## multiple symbols at the same address. This would previously hit an assertion
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## error (PR56570).
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_foo:
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ltmp1:
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.cfi_startproc
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.cfi_def_cfa_offset 8
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nop
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.cfi_endproc
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.subsections_via_symbols
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