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[dsymutil] Fix line table sequence mapping for stmt_sequence attributes #143656

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[dsymutil] Fix line table sequence mapping for stmt_sequence attributes #143656

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33 changes: 31 additions & 2 deletions llvm/lib/DWARFLinker/Classic/DWARFLinker.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2297,8 +2297,37 @@ void DWARFLinker::DIECloner::generateLineTableForUnit(CompileUnit &Unit) {

// Create a map of stmt sequence offsets to original row indices.
DenseMap<uint64_t, unsigned> SeqOffToOrigRow;
for (const DWARFDebugLine::Sequence &Seq : LT->Sequences)
SeqOffToOrigRow[Seq.StmtSeqOffset] = Seq.FirstRowIndex;
// The DWARF parser's discovery of sequences can be incomplete. To
// ensure all DW_AT_LLVM_stmt_sequence attributes can be patched, we
// build a map from both the parser's results and a manual
// reconstruction.
if (!LT->Rows.empty()) {
// First, trust the sequences that the DWARF parser did identify.
for (const DWARFDebugLine::Sequence &Seq : LT->Sequences)
SeqOffToOrigRow.try_emplace(Seq.StmtSeqOffset, Seq.FirstRowIndex);

// Second, manually find sequence boundaries and match them to the
// sorted attributes to handle sequences the parser might have missed.
auto StmtAttrs = Unit.getStmtSeqListAttributes();
llvm::sort(StmtAttrs,
[](const PatchLocation &A, const PatchLocation &B) {
return A.get() < B.get();
});

std::vector<size_t> SeqStartRows;
SeqStartRows.push_back(0);
for (size_t i = 0; i < LT->Rows.size() - 1; ++i)
if (LT->Rows[i].EndSequence)
SeqStartRows.push_back(i + 1);

// Correlate the sorted attributes with the reconstructed sequence
// starts. This provides a partial mapping if counts are mismatched,
// maximizing the number of correctly patched attributes.
size_t NumMappings = std::min(StmtAttrs.size(), SeqStartRows.size());
for (size_t i = 0; i < NumMappings; ++i) {
SeqOffToOrigRow.try_emplace(StmtAttrs[i].get(), SeqStartRows[i]);
}
}

// Create a map of original row indices to new row indices.
DenseMap<size_t, size_t> OrigRowToNewRow;
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7 changes: 6 additions & 1 deletion llvm/test/tools/dsymutil/ARM/stmt-seq-macho.test
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Expand Up @@ -4,7 +4,12 @@
# RUN: yaml2obj %t/stmt_seq_macho.exe.yaml -o %t/stmt_seq_macho.exe
# RUN: yaml2obj %t/stmt_seq_macho.o.yaml -o %t/stmt_seq_macho.o
# RUN: dsymutil --flat --verify-dwarf=none -oso-prepend-path %t %t/stmt_seq_macho.exe -o %t/stmt_seq_macho.dSYM
# RUN: llvm-dwarfdump --debug-info --debug-line -v %t/stmt_seq_macho.dSYM | sort | FileCheck %s -check-prefix=CHECK_DSYM
# RUN: llvm-dwarfdump --debug-info --debug-line -v %t/stmt_seq_macho.dSYM > %t/stmt_seq_macho.dSYM.txt
# RUN: cat %t/stmt_seq_macho.dSYM.txt | sort | FileCheck %s -check-prefix=CHECK_DSYM
# RUN: cat %t/stmt_seq_macho.dSYM.txt | FileCheck %s -check-prefix=CHECK_NO_INVALID_OFFSET

# CHECK_NO_INVALID_OFFSET-NOT: DW_AT_LLVM_stmt_sequence{{.*}}0xffffffff


# CHECK_DSYM: DW_AT_LLVM_stmt_sequence [DW_FORM_sec_offset] ([[OFFSET1:(0x[0-9a-f]+)]])
# CHECK_DSYM: DW_AT_LLVM_stmt_sequence [DW_FORM_sec_offset] ([[OFFSET2:(0x[0-9a-f]+)]])
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