[BlockExtractor] Expose a constructor for the group extraction

[qcolombet]

Summary

NFC

[volkan]

LGTM

include/llvm/Transforms/IPO.h

 
 /// createBlockExtractorPass - This pass extracts all the specified blocks
 /// from the functions in the module.
 ///
 ModulePass *createBlockExtractorPass();
 ModulePass *
 createBlockExtractorPass(const SmallVectorImpl<BasicBlock *> &BlocksToExtract,
                          bool EraseFunctions);
+ModulePass *
+createBlockExtractorPass(const SmallVectorImpl<SmallVector<BasicBlock *, 16>>
+                             &GroupsOfBlocksToExtract,
+                         bool EraseFunctions);
 
 /// createStripDeadPrototypesPass - This pass removes any function declarations
 /// (prototypes) that are not used.
 ModulePass *createStripDeadPrototypesPass();
 
 //===----------------------------------------------------------------------===//
 /// createReversePostOrderFunctionAttrsPass - This pass walks SCCs of the call
 /// graph in RPO to deduce and propagate function attributes. Currently it

lib/Transforms/IPO/BlockExtractor.cpp

 namespace {
 class BlockExtractor : public ModulePass {
   SmallVector<SmallVector<BasicBlock *, 16>, 4> GroupsOfBlocks;
   bool EraseFunctions;
   /// Map a function name to groups of blocks.
   SmallVector<std::pair<std::string, SmallVector<std::string, 4>>, 4>
       BlocksByName;
 
+  void init(const SmallVectorImpl<SmallVector<BasicBlock *, 16>>
+                &GroupsOfBlocksToExtract) {
+    for (const SmallVectorImpl<BasicBlock *> &GroupOfBlocks :
+         GroupsOfBlocksToExtract) {
+      SmallVector<BasicBlock *, 16> NewGroup;
+      NewGroup.append(GroupOfBlocks.begin(), GroupOfBlocks.end());
+      GroupsOfBlocks.emplace_back(NewGroup);
+    }
+    if (!BlockExtractorFile.empty())
+      loadFile();
+  }
+
 public:
   static char ID;
   BlockExtractor(const SmallVectorImpl<BasicBlock *> &BlocksToExtract,
                  bool EraseFunctions)
       : ModulePass(ID), EraseFunctions(EraseFunctions) {
     // We want one group per element of the input list.
+    SmallVector<SmallVector<BasicBlock *, 16>, 4> MassagedGroupsOfBlocks;
     for (BasicBlock *BB : BlocksToExtract) {
       SmallVector<BasicBlock *, 16> NewGroup;
       NewGroup.push_back(BB);
-      GroupsOfBlocks.push_back(NewGroup);
+      MassagedGroupsOfBlocks.push_back(NewGroup);
     }
-    if (!BlockExtractorFile.empty())
-      loadFile();
+    init(MassagedGroupsOfBlocks);
   }
+
+  BlockExtractor(const SmallVectorImpl<SmallVector<BasicBlock *, 16>>
+                     &GroupsOfBlocksToExtract,
+                 bool EraseFunctions)
+      : ModulePass(ID), EraseFunctions(EraseFunctions) {
+    init(GroupsOfBlocksToExtract);
+  }
+
   BlockExtractor() : BlockExtractor(SmallVector<BasicBlock *, 0>(), false) {}
   bool runOnModule(Module &M) override;
 
 private:
   void loadFile();
   void splitLandingPadPreds(Function &F);
 };
 } // end anonymous namespace
 
 char BlockExtractor::ID = 0;
 INITIALIZE_PASS(BlockExtractor, "extract-blocks",
                 "Extract basic blocks from module", false, false)
 
 ModulePass *llvm::createBlockExtractorPass() { return new BlockExtractor(); }
 ModulePass *llvm::createBlockExtractorPass(
     const SmallVectorImpl<BasicBlock *> &BlocksToExtract, bool EraseFunctions) {
   return new BlockExtractor(BlocksToExtract, EraseFunctions);
 }
+ModulePass *llvm::createBlockExtractorPass(
+    const SmallVectorImpl<SmallVector<BasicBlock *, 16>>
+        &GroupsOfBlocksToExtract,
+    bool EraseFunctions) {
+  return new BlockExtractor(GroupsOfBlocksToExtract, EraseFunctions);
+}
 
 /// Gets all of the blocks specified in the input file.
 void BlockExtractor::loadFile() {
   auto ErrOrBuf = MemoryBuffer::getFile(BlockExtractorFile);
   if (ErrOrBuf.getError())
     report_fatal_error("BlockExtractor couldn't load the file.");
   // Read the file.
   auto &Buf = *ErrOrBuf;