[ThinLTO] Compute synthetic function entry count

Summary:
This patch computes the synthetic function entry count on the whole
program callgraph (based on module summary) and writes the entry counts
to the summary. After function importing, this count gets attached to
the IR as metadata. Since it adds a new field to the summary, this bumps
up the version.

Reviewers: tejohnson

Subscribers: mehdi_amini, inglorion, llvm-commits

Differential Revision: https://reviews.llvm.org/D43521

llvm-svn: 349076

1 files changed, 17 insertions, 2 deletions

diff --git a/llvm/lib/Transforms/Utils/FunctionImportUtils.cpp b/llvm/lib/Transforms/Utils/FunctionImportUtils.cpp
index 70be86d8d6c..a9772e31da5 100644
--- a/llvm/lib/Transforms/Utils/FunctionImportUtils.cpp
+++ b/llvm/lib/Transforms/Utils/FunctionImportUtils.cpp
@@ -203,11 +203,26 @@ FunctionImportGlobalProcessing::getLinkage(const GlobalValue *SGV,
 
 void FunctionImportGlobalProcessing::processGlobalForThinLTO(GlobalValue &GV) {
 
-  // Check the summaries to see if the symbol gets resolved to a known local
-  // definition.
   ValueInfo VI;
   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 (auto &S : VI.getSummaryList()) {
+            FunctionSummary *FS = dyn_cast<FunctionSummary>(S->getBaseObject());
+            if (FS->modulePath() == M.getModuleIdentifier()) {
+              F->setEntryCount(Function::ProfileCount(FS->entryCount(),
+                                                      Function::PCT_Synthetic));
+              break;
+            }
+          }
+        }
+      }
+    }
+    // Check the summaries to see if the symbol gets resolved to a known local
+    // definition.
     if (VI && VI.isDSOLocal()) {
       GV.setDSOLocal(true);
       if (GV.hasDLLImportStorageClass())