Add function importing info from samplepgo profile to the module summary.

Summary: For SamplePGO, the profile may contain cross-module inline stacks. As we need to make sure the profile annotation happens when all the hot inline stacks are expanded, we need to pass this info to the module importer so that it can import proper functions if necessary. This patch implemented this feature by emitting cross-module targets as part of function entry metadata. In the module-summary phase, the metadata is used to build call edges that points to functions need to be imported.

Reviewers: mehdi_amini, tejohnson

Reviewed By: tejohnson

Subscribers: davidxl, llvm-commits

Differential Revision: https://reviews.llvm.org/D30053

llvm-svn: 296498

1 files changed, 15 insertions, 2 deletions

diff --git a/llvm/lib/IR/Function.cpp b/llvm/lib/IR/Function.cpp
index 0c6b3520dad..7b5d49c34b3 100644
--- a/llvm/lib/IR/Function.cpp
+++ b/llvm/lib/IR/Function.cpp
@@ -1259,9 +1259,10 @@ void Function::setValueSubclassDataBit(unsigned Bit, bool On) {
     setValueSubclassData(getSubclassDataFromValue() & ~(1 << Bit));
 }
 
-void Function::setEntryCount(uint64_t Count) {
+void Function::setEntryCount(uint64_t Count,
+                             const DenseSet<GlobalValue::GUID> *S) {
   MDBuilder MDB(getContext());
-  setMetadata(LLVMContext::MD_prof, MDB.createFunctionEntryCount(Count));
+  setMetadata(LLVMContext::MD_prof, MDB.createFunctionEntryCount(Count, S));
 }
 
 Optional<uint64_t> Function::getEntryCount() const {
@@ -1278,6 +1279,18 @@ Optional<uint64_t> Function::getEntryCount() const {
   return None;
 }
 
+DenseSet<GlobalValue::GUID> Function::getImportGUIDs() const {
+  DenseSet<GlobalValue::GUID> R;
+  if (MDNode *MD = getMetadata(LLVMContext::MD_prof))
+    if (MDString *MDS = dyn_cast<MDString>(MD->getOperand(0)))
+      if (MDS->getString().equals("function_entry_count"))
+        for (unsigned i = 2; i < MD->getNumOperands(); i++)
+          R.insert(mdconst::extract<ConstantInt>(MD->getOperand(i))
+                       ->getValue()
+                       .getZExtValue());
+  return R;
+}
+
 void Function::setSectionPrefix(StringRef Prefix) {
   MDBuilder MDB(getContext());
   setMetadata(LLVMContext::MD_section_prefix,