[IR] Delete MODULE_CODE_DEPLIB

[MaskRay]

Summary

In 2012 (rL168694), it was considered "never used and has bit-rotted".
Now is 2020.

[merge_guards_bot]

Unit tests: fail. 62194 tests passed, 1 failed and 815 were skipped.

failed: libc++.std/thread/thread_mutex/thread_mutex_requirements/thread_timedmutex_requirements/thread_timedmutex_recursive/try_lock_until.pass.cpp

clang-tidy: pass.

clang-format: pass.

Build artifacts: diff.json, clang-tidy.txt, clang-format.patch, CMakeCache.txt, console-log.txt, test-results.xml

Pre-merge checks is in beta. Report issue. Please join beta or enable it for your project.

[mehdi_amini]

llvm/lib/Bitcode/Reader/BitcodeReader.cpp

3605

Isn't this breaking bitcode backward compatibility?

[void]

llvm/lib/Bitcode/Reader/BitcodeReader.cpp

3605

This used to be okay when changing major versions. I'm not too familiar with the current versioning system though or whether that's still the policy.

[mehdi_amini]

llvm/lib/Bitcode/Reader/BitcodeReader.cpp

3605

It changed when we changed the version numbering to not have major/minor anymore. At the time (IIRC) we considered we would break compatibility only if it is really motivated. The current section of the developer policy: https://llvm.org/docs/DeveloperPolicy.html#ir-backwards-compatibility

[MaskRay]

llvm/lib/Bitcode/Reader/BitcodeReader.cpp

3605

Is this a case that "really no one makes use of the feature"? It was planned to be removed in 4.0

[mehdi_amini]

llvm/lib/Bitcode/Reader/BitcodeReader.cpp

3605

Anything that was "planned to be removed in 4.0" is now supported "forever" until we make an explicit choice to break backward compatibility.

The reason is that "4.0" was used during the development of the 3.x versions as "this future major breaking change version". At the time the major number was used to indicate the compatibility. When we reached 3.9 we decided to change the numbering, instead of going to 3.10 we went to 4.0 but after changing the meaning of the major number to not mean anything anymore with respect to bitcode backward compatibility.

[dexonsmith]

Anything that was "planned to be removed in 4.0" is now supported "forever" until we make an explicit choice to break backward compatibility.

As Mehdi pointed out, the right fix is probably to update the comment(s) to something like:

// Deprecated, but still needed to read old bitcode files.

[mehdi_amini]

Sent https://reviews.llvm.org/D82514 to cleanup

llvm/docs/BitCodeFormat.rst

 
 The ``SECTIONNAME`` record (code 5) contains a variable number of values
 representing the bytes of a single section name string. There should be one
 ``SECTIONNAME`` record for each section name referenced (e.g., in global
 variable or function ``section`` attributes) within the module. These records
 can be referenced by the 1-based index in the *section* fields of ``GLOBALVAR``
 or ``FUNCTION`` records.
 
-MODULE_CODE_DEPLIB Record
-^^^^^^^^^^^^^^^^^^^^^^^^^
-
-``[DEPLIB, ...string...]``
-
-The ``DEPLIB`` record (code 6) contains a variable number of values representing
-the bytes of a single dependent library name string, one of the libraries
-mentioned in a ``deplibs`` declaration.  There should be one ``DEPLIB`` record
-for each library name referenced.
-
 MODULE_CODE_GLOBALVAR Record
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 ``[GLOBALVAR, strtab offset, strtab size, pointer type, isconst, initid, linkage, alignment, section, visibility, threadlocal, unnamed_addr, externally_initialized, dllstorageclass, comdat, attributes, preemptionspecifier]``
 
 The ``GLOBALVAR`` record (code 7) marks the declaration or definition of a
 global variable. The operand fields are:
 

llvm/include/llvm/Bitcode/LLVMBitCodes.h

 /// MODULE blocks have a number of optional fields and subblocks.
 enum ModuleCodes {
   MODULE_CODE_VERSION = 1,     // VERSION:     [version#]
   MODULE_CODE_TRIPLE = 2,      // TRIPLE:      [strchr x N]
   MODULE_CODE_DATALAYOUT = 3,  // DATALAYOUT:  [strchr x N]
   MODULE_CODE_ASM = 4,         // ASM:         [strchr x N]
   MODULE_CODE_SECTIONNAME = 5, // SECTIONNAME: [strchr x N]
 
-  // FIXME: Remove DEPLIB in 4.0.
-  MODULE_CODE_DEPLIB = 6, // DEPLIB:      [strchr x N]
-
   // GLOBALVAR: [pointer type, isconst, initid,
   //             linkage, alignment, section, visibility, threadlocal]
   MODULE_CODE_GLOBALVAR = 7,
 
   // FUNCTION:  [type, callingconv, isproto, linkage, paramattrs, alignment,
   //             section, visibility, gc, unnamed_addr]
   MODULE_CODE_FUNCTION = 8,
 

llvm/lib/AsmParser/LLLexer.cpp

#define KEYWORD(STR)                                                           \
   KEYWORD(from);
   KEYWORD(tail);
   KEYWORD(musttail);
   KEYWORD(notail);
   KEYWORD(target);
   KEYWORD(triple);
   KEYWORD(source_filename);
   KEYWORD(unwind);
-  KEYWORD(deplibs);             // FIXME: Remove in 4.0.
   KEYWORD(datalayout);
   KEYWORD(volatile);
   KEYWORD(atomic);
   KEYWORD(unordered);
   KEYWORD(monotonic);
   KEYWORD(acquire);
   KEYWORD(release);
   KEYWORD(acq_rel);

llvm/lib/AsmParser/LLParser.h

private:
 
     // Top-Level Entities
     bool ParseTopLevelEntities();
     bool ValidateEndOfModule();
     bool ValidateEndOfIndex();
     bool ParseTargetDefinition();
     bool ParseModuleAsm();
     bool ParseSourceFileName();
-    bool ParseDepLibs();        // FIXME: Remove in 4.0.
     bool ParseUnnamedType();
     bool ParseNamedType();
     bool ParseDeclare();
     bool ParseDefine();
 
     bool ParseGlobalType(bool &IsConstant);
     bool ParseUnnamedGlobal();
     bool ParseNamedGlobal();

llvm/lib/AsmParser/LLParser.cpp

while (true) {
     case lltok::kw_declare: if (ParseDeclare()) return true; break;
     case lltok::kw_define:  if (ParseDefine()) return true; break;
     case lltok::kw_module:  if (ParseModuleAsm()) return true; break;
     case lltok::kw_target:  if (ParseTargetDefinition()) return true; break;
     case lltok::kw_source_filename:
       if (ParseSourceFileName())
         return true;
       break;
-    case lltok::kw_deplibs: if (ParseDepLibs()) return true; break;
     case lltok::LocalVarID: if (ParseUnnamedType()) return true; break;
     case lltok::LocalVar:   if (ParseNamedType()) return true; break;
     case lltok::GlobalID:   if (ParseUnnamedGlobal()) return true; break;
     case lltok::GlobalVar:  if (ParseNamedGlobal()) return true; break;
     case lltok::ComdatVar:  if (parseComdat()) return true; break;
     case lltok::exclaim:    if (ParseStandaloneMetadata()) return true; break;
     case lltok::SummaryID:
       if (ParseSummaryEntry())
bool LLParser::ParseSourceFileName() {
   if (ParseToken(lltok::equal, "expected '=' after source_filename") ||
       ParseStringConstant(SourceFileName))
     return true;
   if (M)
     M->setSourceFileName(SourceFileName);
   return false;
 }
 
-/// toplevelentity
-///   ::= 'deplibs' '=' '[' ']'
-///   ::= 'deplibs' '=' '[' STRINGCONSTANT (',' STRINGCONSTANT)* ']'
-/// FIXME: Remove in 4.0. Currently parse, but ignore.
-bool LLParser::ParseDepLibs() {
-  assert(Lex.getKind() == lltok::kw_deplibs);
-  Lex.Lex();
-  if (ParseToken(lltok::equal, "expected '=' after deplibs") ||
-      ParseToken(lltok::lsquare, "expected '=' after deplibs"))
-    return true;
-
-  if (EatIfPresent(lltok::rsquare))
-    return false;
-
-  do {
-    std::string Str;
-    if (ParseStringConstant(Str)) return true;
-  } while (EatIfPresent(lltok::comma));
-
-  return ParseToken(lltok::rsquare, "expected ']' at end of list");
-}
-
 /// ParseUnnamedType:
 ///   ::= LocalVarID '=' 'type' type
 bool LLParser::ParseUnnamedType() {
   LocTy TypeLoc = Lex.getLoc();
   unsigned TypeID = Lex.getUIntVal();
   Lex.Lex(); // eat LocalVarID;
 
   if (ParseToken(lltok::equal, "expected '=' after name") ||

llvm/lib/AsmParser/LLToken.h

enum Kind {
   kw_from,
   kw_tail,
   kw_musttail,
   kw_notail,
   kw_target,
   kw_triple,
   kw_source_filename,
   kw_unwind,
-  kw_deplibs, // FIXME: Remove in 4.0
   kw_datalayout,
   kw_volatile,
   kw_atomic,
   kw_unordered,
   kw_monotonic,
   kw_acquire,
   kw_release,
   kw_acq_rel,

llvm/lib/Bitcode/Reader/BitcodeAnalyzer.cpp

case bitc::MODULE_BLOCK_ID:
     switch (CodeID) {
     default:
       return None;
       STRINGIFY_CODE(MODULE_CODE, VERSION)
       STRINGIFY_CODE(MODULE_CODE, TRIPLE)
       STRINGIFY_CODE(MODULE_CODE, DATALAYOUT)
       STRINGIFY_CODE(MODULE_CODE, ASM)
       STRINGIFY_CODE(MODULE_CODE, SECTIONNAME)
-      STRINGIFY_CODE(MODULE_CODE, DEPLIB) // FIXME: Remove in 4.0
       STRINGIFY_CODE(MODULE_CODE, GLOBALVAR)
       STRINGIFY_CODE(MODULE_CODE, FUNCTION)
       STRINGIFY_CODE(MODULE_CODE, ALIAS)
       STRINGIFY_CODE(MODULE_CODE, GCNAME)
       STRINGIFY_CODE(MODULE_CODE, VSTOFFSET)
       STRINGIFY_CODE(MODULE_CODE, METADATA_VALUES_UNUSED)
       STRINGIFY_CODE(MODULE_CODE, SOURCE_FILENAME)
       STRINGIFY_CODE(MODULE_CODE, HASH)

llvm/lib/Bitcode/Reader/BitcodeReader.cpp

while (true) {
     }
     case bitc::MODULE_CODE_ASM: {  // ASM: [strchr x N]
       std::string S;
       if (convertToString(Record, 0, S))
         return error("Invalid record");
       TheModule->setModuleInlineAsm(S);
       break;
     }
-    case bitc::MODULE_CODE_DEPLIB: {  // DEPLIB: [strchr x N]
-      // FIXME: Remove in 4.0.
-      std::string S;
-      if (convertToString(Record, 0, S))
-        return error("Invalid record");
-      // Ignore value.
-      break;
-    }
     case bitc::MODULE_CODE_SECTIONNAME: {  // SECTIONNAME: [strchr x N]
       std::string S;
       if (convertToString(Record, 0, S))
         return error("Invalid record");
       SectionTable.push_back(S);
       break;
     }
     case bitc::MODULE_CODE_GCNAME: {  // SECTIONNAME: [strchr x N]