CodeGen: Push the ModuleSlotTracker through Metadata

For another 1% speedup on the testcase in PR23865, push the
`ModuleSlotTracker` through to metadata-related printing in
`MachineBasicBlock::print()`.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@240848 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/IR/Metadata.h

@@ -27,8 +27,11 @@
 #include <type_traits>
 
 namespace llvm {
+
 class LLVMContext;
 class Module;
+class ModuleSlotTracker;
+
 template<typename ValueSubClass, typename ItemParentClass>
   class SymbolTableListTraits;
 
@@ -129,7 +132,11 @@ public:
   ///
   /// If \c M is provided, metadata nodes will be numbered canonically;
   /// otherwise, pointer addresses are substituted.
+  /// @{
   void printAsOperand(raw_ostream &OS, const Module *M = nullptr) const;
+  void printAsOperand(raw_ostream &OS, ModuleSlotTracker &MST,
+                      const Module *M = nullptr) const;
+  /// @}
 };
 
 #define HANDLE_METADATA(CLASS) class CLASS;

include/llvm/IR/ModuleSlotTracker.h

@@ -41,8 +41,13 @@ public:
 
   /// Construct a slot tracker from a module.
   ///
-  /// If \a M is \c nullptr, uses a null slot tracker.
-  explicit ModuleSlotTracker(const Module *M);
+  /// If \a M is \c nullptr, uses a null slot tracker.  Otherwise, initializes
+  /// a slot tracker, and initializes all metadata slots.  \c
+  /// ShouldInitializeAllMetadata defaults to true because this is expected to
+  /// be shared between multiple callers, and otherwise MDNode references will
+  /// not match up.
+  explicit ModuleSlotTracker(const Module *M,
+                             bool ShouldInitializeAllMetadata = true);
 
   /// Destructor to clean up storage.
   ~ModuleSlotTracker();