[nfc][ctx_prof] Change some internal "set" types

- the set used for targets under a callsite is simpler to use if iterators
  are stable (it gets manipulated during updates)
- the set used to fetch the transitive closure of GUIDs under a node can
  be left as a choice to the user.

Author: mtrofin

llvm/include/llvm/Analysis/CtxProfAnalysis.h

@@ -9,7 +9,6 @@
 #ifndef LLVM_ANALYSIS_CTXPROFANALYSIS_H
 #define LLVM_ANALYSIS_CTXPROFANALYSIS_H
 
-#include "llvm/ADT/DenseMap.h"
 #include "llvm/IR/GlobalValue.h"
 #include "llvm/IR/InstrTypes.h"
 #include "llvm/IR/IntrinsicInst.h"

llvm/include/llvm/ProfileData/PGOCtxProfReader.h

@@ -15,13 +15,11 @@
 #ifndef LLVM_PROFILEDATA_CTXINSTRPROFILEREADER_H
 #define LLVM_PROFILEDATA_CTXINSTRPROFILEREADER_H
 
-#include "llvm/ADT/DenseSet.h"
 #include "llvm/Bitstream/BitstreamReader.h"
 #include "llvm/IR/GlobalValue.h"
 #include "llvm/ProfileData/PGOCtxProfWriter.h"
 #include "llvm/Support/Error.h"
 #include <map>
-#include <vector>
 
 namespace llvm {
 /// A node (context) in the loaded contextual profile, suitable for mutation
@@ -34,7 +32,7 @@ namespace llvm {
 class PGOCtxProfContext final {
 public:
   using CallTargetMapTy = std::map<GlobalValue::GUID, PGOCtxProfContext>;
-  using CallsiteMapTy = DenseMap<uint32_t, CallTargetMapTy>;
+  using CallsiteMapTy = std::map<uint32_t, CallTargetMapTy>;
 
 private:
   friend class PGOCtxProfileReader;
@@ -97,7 +95,16 @@ class PGOCtxProfContext final {
     return Callsites.find(I)->second;
   }
 
-  void getContainedGuids(DenseSet<GlobalValue::GUID> &Guids) const;
+  /// Insert this node's GUID as well as the GUIDs of the transitive closure of
+  /// child nodes, into the provided set (technically, all that is required of
+  /// `TSetOfGUIDs` is to have an `insert(GUID)` member)
+  template <class TSetOfGUIDs>
+  void getContainedGuids(TSetOfGUIDs &Guids) const {
+    Guids.insert(GUID);
+    for (const auto &[_, Callsite] : Callsites)
+      for (const auto &[_, Callee] : Callsite)
+        Callee.getContainedGuids(Guids);
+  }
 };
 
 class PGOCtxProfileReader final {

llvm/lib/ProfileData/PGOCtxProfReader.cpp

@@ -44,14 +44,6 @@ PGOCtxProfContext::getOrEmplace(uint32_t Index, GlobalValue::GUID G,
   return Iter->second;
 }
 
-void PGOCtxProfContext::getContainedGuids(
-    DenseSet<GlobalValue::GUID> &Guids) const {
-  Guids.insert(GUID);
-  for (const auto &[_, Callsite] : Callsites)
-    for (const auto &[_, Callee] : Callsite)
-      Callee.getContainedGuids(Guids);
-}
-
 Expected<BitstreamEntry> PGOCtxProfileReader::advance() {
   return Cursor.advance(BitstreamCursor::AF_DontAutoprocessAbbrevs);
 }

llvm/lib/Transforms/IPO/FunctionImport.cpp

@@ -722,7 +722,7 @@ class WorkloadImportsManager : public ModuleImportsManager {
       return;
     }
     const auto &CtxMap = *Ctx;
-    DenseSet<GlobalValue::GUID> ContainedGUIDs;
+    SetVector<GlobalValue::GUID> ContainedGUIDs;
     for (const auto &[RootGuid, Root] : CtxMap) {
       // Avoid ContainedGUIDs to get in/out of scope. Reuse its memory for
       // subsequent roots, but clear its contents.