[llvm] [GSYM] Use debug line offsets during GSYM creation (PR #129196)

[Zhaoxuan Jiang via llvm-commits]

================
@@ -317,8 +317,20 @@ static void convertFunctionLineTable(OutputAggregator &Out, CUInfo &CUI,
   const object::SectionedAddress SecAddress{
       StartAddress, object::SectionedAddress::UndefSection};
 
+  // Attempt to retrieve DW_AT_LLVM_stmt_sequence if present.
+  std::optional<uint64_t> StmtSeqOffset;
+  if (auto StmtSeqAttr = Die.find(llvm::dwarf::DW_AT_LLVM_stmt_sequence)) {
+    // The `DW_AT_LLVM_stmt_sequence` attribute might be set to `UINT64_MAX`
+    // when it refers to an empty line sequence. In such cases, the DWARF linker
+    // will exclude the empty sequence from the final output and assign
+    // `UINT64_MAX` to the `DW_AT_LLVM_stmt_sequence` attribute.
+    auto StmtSeqVal = dwarf::toSectionOffset(StmtSeqAttr, UINT64_MAX);
+    if (StmtSeqVal != UINT32_MAX)
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nocchijiang wrote:

IIUC:

```suggestion
    if (StmtSeqVal != UINT64_MAX)
```

https://github.com/llvm/llvm-project/pull/129196