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[lld][WebAssembly] Handle TLS symbols in older object file
In older versions of llvm (e.g. llvm 13), symbols were not individually flagged as TLS. In this case, the indent was to implicitly mark any symbols defined in TLS segments as TLS. However, we were not performing this implicit conversion if the segment was explicitly marked as TLS As it happens, llvm 13 was branched between the addition of the segment flag and the addition of the symbol flag. See: - segment flag added: https://reviews.llvm.org/D102202 - symbol flag added: https://reviews.llvm.org/D109426 Testing this is tricky because the assembler will imply the TLS status of the symbol based on the segment its declared in, so we are forced to use a yaml file here. Fixes: emscripten-core/emscripten#15891 Differential Revision: https://reviews.llvm.org/D118414
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Original file line number | Diff line number | Diff line change |
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# RUN: yaml2obj %s -o %t.o | ||
# RUN: wasm-ld --shared-memory -o %t.wasm %t.o | ||
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# Verify compatability with older object files that didn't mark individual | ||
# symbols as TLS. In this case the symbol `bar` is being used in a TLS-only | ||
# relocation (R_WASM_MEMORY_ADDR_TLS_SLEB) but is not itself marked as TLS. | ||
# However, because it is defined in a section (`.mydata`) that *is* marked as | ||
# TLS we implicitly mark bar as TLS. | ||
# | ||
# We had a regression where llvm-13-generated object files were being rejected | ||
# with: "R_WASM_MEMORY_ADDR_TLS_SLEB cannot be used against non-TLS symbol" | ||
# This test verifies that this error is not triggered. | ||
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--- !WASM | ||
FileHeader: | ||
Version: 0x1 | ||
Sections: | ||
- Type: TYPE | ||
Signatures: | ||
- Index: 0 | ||
ParamTypes: [] | ||
ReturnTypes: [] | ||
- Type: IMPORT | ||
Imports: | ||
- Module: env | ||
Field: __linear_memory | ||
Kind: MEMORY | ||
Memory: | ||
Minimum: 0x1 | ||
- Type: FUNCTION | ||
FunctionTypes: [ 0 ] | ||
- Type: DATACOUNT | ||
Count: 1 | ||
- Type: CODE | ||
Relocations: | ||
- Type: R_WASM_MEMORY_ADDR_TLS_SLEB | ||
Index: 1 | ||
Offset: 0x4 | ||
Functions: | ||
- Index: 0 | ||
Locals: [] | ||
Body: 4180808080001A0B | ||
- Type: DATA | ||
Segments: | ||
- SectionOffset: 6 | ||
InitFlags: 0 | ||
Offset: | ||
Opcode: I32_CONST | ||
Value: 0 | ||
Content: '00000000' | ||
- Type: CUSTOM | ||
Name: linking | ||
Version: 2 | ||
SymbolTable: | ||
- Index: 0 | ||
Kind: FUNCTION | ||
Name: _start | ||
Flags: [ ] | ||
Function: 0 | ||
- Index: 1 | ||
Kind: DATA | ||
Name: bar | ||
Flags: [ ] | ||
Segment: 0 | ||
Size: 4 | ||
SegmentInfo: | ||
- Index: 0 | ||
Name: .mydata | ||
Alignment: 0 | ||
Flags: [ TLS ] | ||
- Type: CUSTOM | ||
Name: target_features | ||
Features: | ||
- Prefix: USED | ||
Name: "atomics" | ||
- Prefix: USED | ||
Name: "bulk-memory" | ||
... |
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