[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, 1 insertions, 17 deletions

diff --git a/llvm/lib/Transforms/Utils/FunctionImportUtils.cpp b/llvm/lib/Transforms/Utils/FunctionImportUtils.cpp
index 87be6be01885..766c7501550d 100644
--- a/llvm/lib/Transforms/Utils/FunctionImportUtils.cpp
+++ b/llvm/lib/Transforms/Utils/FunctionImportUtils.cpp
@@ -220,24 +220,8 @@ FunctionImportGlobalProcessing::getLinkage(const GlobalValue *SGV,
 void FunctionImportGlobalProcessing::processGlobalForThinLTO(GlobalValue &GV) {
 
   ValueInfo VI;
-  if (GV.hasName()) {
+  if (GV.hasName())
     VI = ImportIndex.getValueInfo(GV.getGUID());
-    // Set synthetic function entry counts.
-    if (VI && ImportIndex.hasSyntheticEntryCounts()) {
-      if (Function *F = dyn_cast<Function>(&GV)) {
-        if (!F->isDeclaration()) {
-          for (const auto &S : VI.getSummaryList()) {
-            auto *FS = cast<FunctionSummary>(S->getBaseObject());
-            if (FS->modulePath() == M.getModuleIdentifier()) {
-              F->setEntryCount(Function::ProfileCount(FS->entryCount(),
-                                                      Function::PCT_Synthetic));
-              break;
-            }
-          }
-        }
-      }
-    }
-  }
 
   // We should always have a ValueInfo (i.e. GV in index) for definitions when
   // we are exporting, and also when importing that value.