[NFCI]Remove EntryCount from FunctionSummary and clean up surrounding synthetic count passes. (#107471)

The primary motivation is to remove `EntryCount` from `FunctionSummary`.
This frees 8 bytes out of `sizeof(FunctionSummary)` (136 bytes as of
https://github.com/llvm/llvm-project/commit/64498c54831bed9cf069e0923b9b73678c6451d8).

While I'm at it, this PR clean up {SummaryBasedOptimizations,
SyntheticCountsPropagation} since they were not used and there are no
plans to further invest on them.

With this patch, bitcode writer writes a placeholder 0 at the byte
offset of `EntryCount` and bitcode reader can parse the function entry
count at the correct byte offset. Added a TODO to stop writing
`EntryCount` and bump bitcode version

1 files changed, 4 insertions, 4 deletions

diff --git a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
index e52757f..250ba42 100644
--- a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
+++ b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -7686,8 +7686,8 @@ Error ModuleSummaryIndexBitcodeReader::parseEntireSummary(unsigned ID) {
         PendingAllocs.clear();
       }
       auto FS = std::make_unique<FunctionSummary>(
-          Flags, InstCount, getDecodedFFlags(RawFunFlags), /*EntryCount=*/0,
-          std::move(Refs), std::move(Calls), std::move(PendingTypeTests),
+          Flags, InstCount, getDecodedFFlags(RawFunFlags), std::move(Refs),
+          std::move(Calls), std::move(PendingTypeTests),
           std::move(PendingTypeTestAssumeVCalls),
           std::move(PendingTypeCheckedLoadVCalls),
           std::move(PendingTypeTestAssumeConstVCalls),
@@ -7832,8 +7832,8 @@ Error ModuleSummaryIndexBitcodeReader::parseEntireSummary(unsigned ID) {
       ValueInfo VI = std::get<0>(getValueInfoFromValueId(ValueID));
       setSpecialRefs(Refs, NumRORefs, NumWORefs);
       auto FS = std::make_unique<FunctionSummary>(
-          Flags, InstCount, getDecodedFFlags(RawFunFlags), EntryCount,
-          std::move(Refs), std::move(Edges), std::move(PendingTypeTests),
+          Flags, InstCount, getDecodedFFlags(RawFunFlags), std::move(Refs),
+          std::move(Edges), std::move(PendingTypeTests),
           std::move(PendingTypeTestAssumeVCalls),
           std::move(PendingTypeCheckedLoadVCalls),
           std::move(PendingTypeTestAssumeConstVCalls),