[llvm] [llvm-objcopy] Support SREC output format (PR #75874)

[James Henderson via llvm-commits]

================
@@ -2813,6 +2813,244 @@ Error IHexWriter::finalize() {
   return Error::success();
 }
 
+Error SRECSectionWriterBase::visit(const StringTableSection &Sec) {
+  // Check that sizer has already done its work
+  assert(Sec.Size == Sec.StrTabBuilder.getSize());
+  // we don't need to write anything here the real writer has already done it.
+  return Error::success();
+}
+
+Error SRECSectionWriterBase::visit(const Section &Sec) {
+  writeSection(Sec, Sec.Contents);
+  return Error::success();
+}
+
+Error SRECSectionWriterBase::visit(const OwnedDataSection &Sec) {
+  writeSection(Sec, Sec.Data);
+  return Error::success();
+}
+
+Error SRECSectionWriterBase::visit(const DynamicRelocationSection &Sec) {
+  writeSection(Sec, Sec.Contents);
+  return Error::success();
+}
+
+void SRECSectionWriter::writeRecord(SRecord &Record, uint64_t Off) {
+  SRecLineData Data = Record.toString();
+  memcpy(Out.getBufferStart() + Off, Data.data(), Data.size());
+}
+
+void SRECSectionWriter::writeRecords(uint32_t Entry) {
+  Type = std::max(Type, SRecord::getType(Entry));
+  uint64_t Off = HeaderSize;
+  for (SRecord &Record : Records) {
+    Record.Type = Type;
+    writeRecord(Record, Off);
+    Off += Record.getSize();
+  }
+  Offset = Off;
+}
+
+void SRECSectionWriterBase::writeRecords(uint32_t Entry) {
+  // The ELF header could contain an entry point outside of the sections we have
+  // seen that does not fit the current record Type
----------------
jh7370 wrote:

```suggestion
  // seen that does not fit the current record Type.
```

https://github.com/llvm/llvm-project/pull/75874