Make specifying the function in bbsection profile a noop, when no other directives are specified.

Author: rlavaee

llvm/include/llvm/CodeGen/BasicBlockSectionsProfileReader.h

@@ -68,17 +68,13 @@ class BasicBlockSectionsProfileReader {
 
   BasicBlockSectionsProfileReader() = default;
 
-  // Returns true if basic block sections profile exist for function \p
-  // FuncName.
+  // Returns true if function \p FuncName is hot based on the basic block
+  // section profile.
   bool isFunctionHot(StringRef FuncName) const;
 
-  // Returns a pair with first element representing whether basic block sections
-  // profile exist for the function \p FuncName, and the second element
-  // representing the basic block sections profile (cluster info) for this
-  // function. If the first element is true and the second element is empty, it
-  // means unique basic block sections are desired for all basic blocks of the
-  // function.
-  std::pair<bool, SmallVector<BBClusterInfo>>
+  // Returns the cluster info for the function \p FuncName. Returns an empty
+  // vector if function has no cluster info.
+  SmallVector<BBClusterInfo>
   getClusterInfoForFunction(StringRef FuncName) const;
 
   // Returns the path clonings for the given function.
@@ -190,7 +186,7 @@ class BasicBlockSectionsProfileReaderWrapperPass : public ImmutablePass {
 
   bool isFunctionHot(StringRef FuncName) const;
 
-  std::pair<bool, SmallVector<BBClusterInfo>>
+  SmallVector<BBClusterInfo>
   getClusterInfoForFunction(StringRef FuncName) const;
 
   SmallVector<SmallVector<unsigned>>

llvm/lib/CodeGen/BasicBlockSections.cpp

@@ -314,11 +314,9 @@ bool BasicBlockSections::handleBBSections(MachineFunction &MF) {
 
   DenseMap<UniqueBBID, BBClusterInfo> FuncClusterInfo;
   if (BBSectionsType == BasicBlockSection::List) {
-    auto [HasProfile, ClusterInfo] =
+    auto ClusterInfo =
         getAnalysis<BasicBlockSectionsProfileReaderWrapperPass>()
             .getClusterInfoForFunction(MF.getName());
-    if (!HasProfile)
-      return false;
     for (auto &BBClusterInfo : ClusterInfo) {
       FuncClusterInfo.try_emplace(BBClusterInfo.BBID, BBClusterInfo);
     }

llvm/lib/CodeGen/BasicBlockSectionsProfileReader.cpp

@@ -58,22 +58,21 @@ BasicBlockSectionsProfileReader::parseUniqueBBID(StringRef S) const {
 }
 
 bool BasicBlockSectionsProfileReader::isFunctionHot(StringRef FuncName) const {
-  return getClusterInfoForFunction(FuncName).first;
+  return !getClusterInfoForFunction(FuncName).empty();
 }
 
-std::pair<bool, SmallVector<BBClusterInfo>>
+SmallVector<BBClusterInfo>
 BasicBlockSectionsProfileReader::getClusterInfoForFunction(
     StringRef FuncName) const {
   auto R = ProgramPathAndClusterInfo.find(getAliasName(FuncName));
-  return R != ProgramPathAndClusterInfo.end()
-             ? std::pair(true, R->second.ClusterInfo)
-             : std::pair(false, SmallVector<BBClusterInfo>());
+  return R != ProgramPathAndClusterInfo.end() ? R->second.ClusterInfo : SmallVector<BBClusterInfo>();
 }
 
 SmallVector<SmallVector<unsigned>>
 BasicBlockSectionsProfileReader::getClonePathsForFunction(
     StringRef FuncName) const {
-  return ProgramPathAndClusterInfo.lookup(getAliasName(FuncName)).ClonePaths;
+  auto R = ProgramPathAndClusterInfo.find(getAliasName(FuncName));
+  return R != ProgramPathAndClusterInfo.end() ? R->second.ClonePaths : SmallVector<SmallVector<unsigned>>();
 }
 
 uint64_t BasicBlockSectionsProfileReader::getEdgeCount(
@@ -494,7 +493,7 @@ bool BasicBlockSectionsProfileReaderWrapperPass::isFunctionHot(
   return BBSPR.isFunctionHot(FuncName);
 }
 
-std::pair<bool, SmallVector<BBClusterInfo>>
+SmallVector<BBClusterInfo>
 BasicBlockSectionsProfileReaderWrapperPass::getClusterInfoForFunction(
     StringRef FuncName) const {
   return BBSPR.getClusterInfoForFunction(FuncName);