[PATCH] D74923: [DebugInfo]: Do not start parsing macinfo/macinfo.dwo if the section's are empty.

[Sourabh Singh Tomar via Phabricator via llvm-commits]

SouraVX added a comment.

In D74923#1885240 <https://reviews.llvm.org/D74923#1885240>, @dblaikie wrote:

> Does this matter? "parsing" an empty section would be successfully parsing zero contributions & dumping nothing. That seems like a fine implementation & avoids needing this special case to check the section size first.


Sort of, consider this for a moment -- 
First we try to parse macinfo --- which for now is empty. assume
then `Macro` is constructed due to this call.

  const DWARFDebugMacro *DWARFContext::getDebugMacinfo() {
    if (Macro)
      return Macro.get();
  DWARFDataExtractor MacinfoData(*DObj, DObj->getMacinfoSection(), isLittleEndian(),
                                   0);
    Macro.reset(new DWARFDebugMacro());
    Macro->parse(*this, MacinfoData, &Offset);
    return Macro.get();

Now after wards we try to parse/dump macro section using mostly similar function then,

  const DWARFDebugMacro *DWARFContext::getDebugMacro() {
  if (Macro)  -- since this is constructed previously, function call will return from here it self. hence no contents dumped
      return Macro.get();
  DWARFDataExtractor MacroData(*DObj, DObj->getMacroSection(), isLittleEndian(),
                                   0);
    ...

BTW, in current implementation, My checks are heavy or the empty Macro construction/parsing/dumping is heavy ??


Repository:
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