[SIL] Allow giving debug names to SILBasicBlocks

Author: ktoso

include/swift/SIL/SILBasicBlock.h

@@ -107,6 +107,9 @@ public SwiftObjectHeader {
   ///          debug output.
   int getDebugID() const;
 
+  void setDebugName(llvm::StringRef name);
+  Optional<llvm::StringRef> getDebugName() const;
+
   SILFunction *getParent() { return Parent; }
   const SILFunction *getParent() const { return Parent; }
 

include/swift/SIL/SILModule.h

@@ -163,6 +163,8 @@ class SILModule {
       llvm::ilist<SILDifferentiabilityWitness>;
   using CoverageMapCollectionType =
       llvm::MapVector<StringRef, SILCoverageMap *>;
+  using BasicBlockNameMapType =
+      llvm::DenseMap<const SILBasicBlock *, llvm::StringRef>;
 
   enum class LinkingMode : uint8_t {
     /// Link functions with non-public linkage. Used by the mandatory pipeline.
@@ -360,6 +362,10 @@ class SILModule {
   /// Action to be executed for serializing the SILModule.
   ActionCallback SerializeSILAction;
 
+#if NDEBUG
+  BasicBlockNameMapType basicBlockNames;
+#endif
+
   SILModule(llvm::PointerUnion<FileUnit *, ModuleDecl *> context,
             Lowering::TypeConverter &TC, const SILOptions &Options);
 
@@ -447,6 +453,23 @@ class SILModule {
   void setSerialized() { serialized = true; }
   bool isSerialized() const { return serialized; }
 
+  void setBasicBlockName(const SILBasicBlock *block, StringRef name) {
+    #if NDEBUG
+    basicBlockNames[block] = name;
+    #endif
+  }
+  Optional<StringRef> getBasicBlockName(const SILBasicBlock *block) {
+    #if NDEBUG
+    auto Known = basicBlockNames.find(block);
+    if (Known == basicBlockNames.end())
+      return None;
+
+    return Known->second;
+    #else
+    return None;
+    #endif
+  }
+
   /// Serialize a SIL module using the configured SerializeSILAction.
   void serialize();
 

lib/SIL/IR/SILBasicBlock.cpp

@@ -67,6 +67,14 @@ int SILBasicBlock::getDebugID() const {
   llvm_unreachable("block not in function's block list");
 }
 
+void SILBasicBlock::setDebugName(llvm::StringRef name) {
+  getModule().setBasicBlockName(this, name);
+}
+
+Optional<llvm::StringRef> SILBasicBlock::getDebugName() const {
+  return getModule().getBasicBlockName(this);
+}
+
 SILModule &SILBasicBlock::getModule() const {
   return getParent()->getModule();
 }

lib/SIL/IR/SILPrinter.cpp

@@ -816,6 +816,12 @@ class SILPrinter : public SILInstructionVisitor<SILPrinter> {
       for (auto Id : PredIDs)
         *this << ' ' << Id;
     }
+
+    // If the basic block has a name available, print it as well
+    auto debugName = BB->getDebugName();
+    if (debugName.hasValue()) {
+      *this << " /// " << debugName.getValue();
+    }
     *this << '\n';
 
     const auto &SM = BB->getModule().getASTContext().SourceMgr;

lib/SILGen/SILGenFunction.h

@@ -818,6 +818,7 @@ class LLVM_LIBRARY_VISIBILITY SILGenFunction
   /// are created by different emissions; it's just a little
   /// counter-intuitive within a single emission.)
   SILBasicBlock *createBasicBlock();
+  SILBasicBlock *createBasicBlock(llvm::StringRef debugName);
   SILBasicBlock *createBasicBlockAfter(SILBasicBlock *afterBB);
   SILBasicBlock *createBasicBlockBefore(SILBasicBlock *beforeBB);
 

lib/SILGen/SILGenStmt.cpp

@@ -58,6 +58,12 @@ SILBasicBlock *SILGenFunction::createBasicBlock() {
   }
 }
 
+SILBasicBlock *SILGenFunction::createBasicBlock(llvm::StringRef debugName) {
+  auto block = createBasicBlock();
+  block->setDebugName(debugName);
+  return block;
+}
+
 SILBasicBlock *SILGenFunction::createBasicBlock(FunctionSection section) {
   switch (section) {
   case FunctionSection::Ordinary: {