Bitcode: Remove reader support for MODULE_CODE_PURGEVALS.

[pcc]

Summary

Support for writing this module code was removed in r73220, which was well
before the LLVM 3.0 release, so we do not need to be able to understand it
for backwards compatibility.

[mehdi_amini]

I trust you on checking the branching point for 3.0 ;)

llvm/docs/BitCodeFormat.rst

* *dllstorageclass*: If present, an encoding of the
   :ref:`dllstorageclass<bcdllstorageclass>` of the alias
 
 * *threadlocal*: If present, an encoding of the
   :ref:`thread local property<bcthreadlocal>` of the alias
 
 * *unnamed_addr*: If present, an encoding of the
   :ref:`unnamed_addr<bcunnamedaddr>` attribute of this alias
 
-MODULE_CODE_PURGEVALS Record
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-``[PURGEVALS, numvals]``
-
-The ``PURGEVALS`` record (code 10) resets the module-level value list to the
-size given by the single operand value. Module-level value list items are added
-by ``GLOBALVAR``, ``FUNCTION``, and ``ALIAS`` records.  After a ``PURGEVALS``
-record is seen, new value indices will start from the given *numvals* value.
-
 .. _MODULE_CODE_GCNAME:
 
 MODULE_CODE_GCNAME Record
 ^^^^^^^^^^^^^^^^^^^^^^^^^
 
 ``[GCNAME, ...string...]``
 
 The ``GCNAME`` record (code 11) contains a variable number of values

llvm/include/llvm/Bitcode/LLVMBitCodes.h

enum ModuleCodes {
 
   // FUNCTION:  [type, callingconv, isproto, linkage, paramattrs, alignment,
   //             section, visibility, gc, unnamed_addr]
   MODULE_CODE_FUNCTION = 8,
 
   // ALIAS: [alias type, aliasee val#, linkage, visibility]
   MODULE_CODE_ALIAS_OLD = 9,
 
-  // MODULE_CODE_PURGEVALS: [numvals]
-  MODULE_CODE_PURGEVALS = 10,
-
   MODULE_CODE_GCNAME = 11, // GCNAME: [strchr x N]
   MODULE_CODE_COMDAT = 12, // COMDAT: [selection_kind, name]
 
   MODULE_CODE_VSTOFFSET = 13, // VSTOFFSET: [offset]
 
   // ALIAS: [alias value type, addrspace, aliasee val#, linkage, visibility]
   MODULE_CODE_ALIAS = 14,
 

llvm/lib/Bitcode/Reader/BitcodeReader.cpp

case bitc::MODULE_CODE_ALIAS_OLD: {
       if (OpNum != Record.size())
         NewGA->setThreadLocalMode(getDecodedThreadLocalMode(Record[OpNum++]));
       if (OpNum != Record.size())
         NewGA->setUnnamedAddr(getDecodedUnnamedAddrType(Record[OpNum++]));
       ValueList.push_back(NewGA);
       IndirectSymbolInits.push_back(std::make_pair(NewGA, Val));
       break;
     }
-    /// MODULE_CODE_PURGEVALS: [numvals]
-    case bitc::MODULE_CODE_PURGEVALS:
-      // Trim down the value list to the specified size.
-      if (Record.size() < 1 || Record[0] > ValueList.size())
-        return error("Invalid record");
-      ValueList.shrinkTo(Record[0]);
-      break;
     /// MODULE_CODE_VSTOFFSET: [offset]
     case bitc::MODULE_CODE_VSTOFFSET:
       if (Record.size() < 1)
         return error("Invalid record");
       // Note that we subtract 1 here because the offset is relative to one word
       // before the start of the identification or module block, which was
       // historically always the start of the regular bitcode header.
       VSTOffset = Record[0] - 1;

llvm/tools/llvm-bcanalyzer/llvm-bcanalyzer.cpp

default: return nullptr;
       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, PURGEVALS)
       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)
     }
   case bitc::IDENTIFICATION_BLOCK_ID:
     switch (CodeID) {