Bitcode: Merge the code for parsing global value module codes in the summary bitcode reader. NFCI.

[pcc]

Summary

This code will need to be taught to handle string tables and it's better if
there is only one copy of it.

[tejohnson]

LGTM

llvm/trunk/lib/Bitcode/Reader/BitcodeReader.cpp

case BitstreamEntry::Record: {
         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;
           break;
-        // GLOBALVAR: [pointer type, isconst, initid,
-        //             linkage, alignment, section, visibility, threadlocal,
-        //             unnamed_addr, externally_initialized, dllstorageclass,
-        //             comdat]
-        case bitc::MODULE_CODE_GLOBALVAR: {
-          if (Record.size() < 6)
-            return error("Invalid record");
-          uint64_t RawLinkage = Record[3];
-          GlobalValue::LinkageTypes Linkage = getDecodedLinkage(RawLinkage);
-          ValueIdToLinkageMap[ValueId++] = Linkage;
-          break;
-        }
-        // FUNCTION:  [type, callingconv, isproto, linkage, paramattr,
-        //             alignment, section, visibility, gc, unnamed_addr,
-        //             prologuedata, dllstorageclass, comdat, prefixdata]
-        case bitc::MODULE_CODE_FUNCTION: {
-          if (Record.size() < 8)
-            return error("Invalid record");
-          uint64_t RawLinkage = Record[3];
-          GlobalValue::LinkageTypes Linkage = getDecodedLinkage(RawLinkage);
-          ValueIdToLinkageMap[ValueId++] = Linkage;
-          break;
-        }
-        // ALIAS: [alias type, addrspace, aliasee val#, linkage, visibility,
-        // dllstorageclass]
+        // GLOBALVAR: [pointer type, isconst,     initid,       linkage, ...]
+        // FUNCTION:  [type,         callingconv, isproto,      linkage, ...]
+        // ALIAS:     [alias type,   addrspace,   aliasee val#, linkage, ...]
+        case bitc::MODULE_CODE_GLOBALVAR:
+        case bitc::MODULE_CODE_FUNCTION:
         case bitc::MODULE_CODE_ALIAS: {
-          if (Record.size() < 6)
+          if (Record.size() <= 3)
             return error("Invalid record");
           uint64_t RawLinkage = Record[3];
           GlobalValue::LinkageTypes Linkage = getDecodedLinkage(RawLinkage);
           ValueIdToLinkageMap[ValueId++] = Linkage;
           break;
         }
         }
       }