[lld] [lld][ELF] Add --debug-names to create merged .debug_names. (PR #86508)

[David Blaikie via llvm-commits]

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@@ -2734,14 +2734,99 @@ static uint32_t getDebugNamesHeaderSize(uint32_t augmentationStringSize) {
          /* Augmentation string */ augmentationStringSize;
 }
 
+static Expected<DebugNamesBaseSection::IndexEntry *>
+readEntry(uint64_t &offset, const DWARFDebugNames::NameIndex &ni,
+          uint64_t entriesBase, DWARFDataExtractor &namesExtractor,
+          const LLDDWARFSection &namesSec) {
+  std::string errMsg;
+  auto ie = makeThreadLocal<DebugNamesBaseSection::IndexEntry>();
+  ie->poolOffset = offset;
+  Error err = Error::success();
+  uint64_t ulebVal = namesExtractor.getULEB128(&offset, &err);
+  if (err) {
+    errMsg = ": invalid abbrev code in entry: ";
+    errMsg.append(toString(std::move(err)));
+    return createStringError(inconvertibleErrorCode(), errMsg.c_str());
+  }
+  if (ulebVal < UINT32_MAX)
+    ie->abbrevCode = static_cast<uint32_t>(ulebVal);
+  else {
+    errMsg = ": abbrev code in entry too large for DWARF32: ";
+    errMsg.append(std::to_string(ulebVal));
+    return createStringError(inconvertibleErrorCode(), errMsg.c_str());
+  }
+  auto it = ni.getAbbrevs().find_as(ie->abbrevCode);
+  if (it == ni.getAbbrevs().end()) {
+    errMsg = ": entry abbrev code not found in abbrev table: ";
+    errMsg.append(std::to_string(ie->abbrevCode));
+    return createStringError(inconvertibleErrorCode(), errMsg.c_str());
+  }
+
+  DebugNamesBaseSection::AttrValue attr, cuAttr = {0, 0};
+  for (DWARFDebugNames::AttributeEncoding a : it->Attributes) {
+    if (a.Index == dwarf::DW_IDX_parent) {
+      if (a.Form == dwarf::DW_FORM_ref4) {
+        attr.attrValue = namesExtractor.getU32(&offset, &err);
+        attr.attrSize = 4;
+        ie->parentOffset = entriesBase + attr.attrValue;
+      } else if (a.Form != DW_FORM_flag_present) {
+        errMsg = ": invalid form for DW_IDX_parent";
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dwblaikie wrote:

Presumably should just return immediately here, with the string error?

And then there's no reason for `errMsg` to have such a wide scope (or possibly to exist at all)

https://github.com/llvm/llvm-project/pull/86508