Revert "Query the StringMap only once when creating MDString (NFC)"

This reverts commit r261030 and r261036.
(The revision was marked "approved" on phabricator, but some concerns
were raised on the mailing list. Thanks D. Blaikie for notifying me.)

From: Mehdi Amini <mehdi.amini@apple.com>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@261055 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/llvm/IR/Metadata.h b/include/llvm/IR/Metadata.h
index a514b60..df8ce35 100644 (file)
--- a/include/llvm/IR/Metadata.h
+++ b/include/llvm/IR/Metadata.h
@@ -592,11 +592,9 @@ class MDString : public Metadata {
 
   StringMapEntry<MDString> *Entry;
   MDString() : Metadata(MDStringKind, Uniqued), Entry(nullptr) {}
+  MDString(MDString &&) : Metadata(MDStringKind, Uniqued) {}
 
 public:
-  // This is a "default" move ctor, MSVC does not support "= default" here
-  MDString(MDString &&R)
-      : Metadata(MDStringKind, Uniqued), Entry(std::move(R.Entry)) {}
   static MDString *get(LLVMContext &Context, StringRef Str);
   static MDString *get(LLVMContext &Context, const char *Str) {
     return get(Context, Str ? StringRef(Str) : StringRef());

diff --git a/lib/IR/Metadata.cpp b/lib/IR/Metadata.cpp
index ddb9cc4..cc0c568 100644 (file)
--- a/lib/IR/Metadata.cpp
+++ b/lib/IR/Metadata.cpp
@@ -397,12 +397,17 @@ void ValueAsMetadata::handleRAUW(Value *From, Value *To) {
 
 MDString *MDString::get(LLVMContext &Context, StringRef Str) {
   auto &Store = Context.pImpl->MDStringCache;
-  auto I = Store.insert(std::make_pair(Str, MDString()));
-  auto &MapEntry = I.first->getValue();
-  if (!I.second)
-    return &MapEntry;
-  MapEntry.Entry = &*I.first;
-  return &MapEntry;
+  auto I = Store.find(Str);
+  if (I != Store.end())
+    return &I->second;
+
+  auto *Entry =
+      StringMapEntry<MDString>::Create(Str, Store.getAllocator(), MDString());
+  bool WasInserted = Store.insert(Entry);
+  (void)WasInserted;
+  assert(WasInserted && "Expected entry to be inserted");
+  Entry->second.Entry = Entry;
+  return &Entry->second;
 }
 
 StringRef MDString::getString() const {