[ThinLTO][Bitcode] Add 'entrycount' to FS_COMBINED_PROFILE. NFC

[evgeny777]

Summary

This field has been missing from abbreviation for a while, however things still work because abbreviation has array field at the end. I don't see how this can be tested unless llvm-bcanalyzer is taught to dump abbreviations.

[tejohnson]

Interesting - does this mean we just encoded it with a VBR 4 (what numrefs was to be encoded with), and everything else just got shifted down in the encoding (so immutablerefcnt got encoded as the first VBR 8 in the array at the end)? Unfortunate that there isn't a way to test for this.

lgtm

[evgeny777]

Interesting - does this mean we just encoded it with a VBR 4 (what numrefs was to be encoded with)

Exactly.

lib/Bitcode/Writer/BitcodeWriter.cpp

void IndexBitcodeWriter::writeCombinedGlobalValueSummary() {
   // Abbrev for FS_COMBINED_PROFILE.
   Abbv = std::make_shared<BitCodeAbbrev>();
   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED_PROFILE));
   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // fflags
+  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // entrycount
   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // immutablerefcnt
   // numrefs x valueid, n x (valueid, hotness)
   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
   unsigned FSCallsProfileAbbrev = Stream.EmitAbbrev(std::move(Abbv));
 
   // Abbrev for FS_COMBINED_GLOBALVAR_INIT_REFS.