3 files changed, 73 insertions, 10 deletions

diff --git a/llvm/lib/AsmParser/LLParser.cpp b/llvm/lib/AsmParser/LLParser.cpp
index 60808755acc..323bb5430c4 100644
--- a/llvm/lib/AsmParser/LLParser.cpp
+++ b/llvm/lib/AsmParser/LLParser.cpp
@@ -575,7 +575,6 @@ bool LLParser::parseComdat() {
 bool LLParser::ParseMDString(MDString *&Result) {
   std::string Str;
   if (ParseStringConstant(Str)) return true;
-  llvm::UpgradeMDStringConstant(Str);
   Result = MDString::get(Context, Str);
   return false;
 }
diff --git a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
index dcaaa7d2975..99bd0b1fbd7 100644
--- a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
+++ b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -166,6 +166,8 @@ class BitcodeReader : public GVMaterializer {
 
   SmallVector<Instruction*, 64> InstsWithTBAATag;
 
+  bool HasSeenOldLoopTags = false;
+
   /// The set of attributes by index.  Index zero in the file is for null, and
   /// is thus not represented here.  As such all indices are off by one.
   std::vector<AttributeSet> MAttributes;
@@ -2385,7 +2387,10 @@ std::error_code BitcodeReader::parseMetadata(bool ModuleLevel) {
     }
     case bitc::METADATA_STRING: {
       std::string String(Record.begin(), Record.end());
-      llvm::UpgradeMDStringConstant(String);
+
+      // Test for upgrading !llvm.loop.
+      HasSeenOldLoopTags |= mayBeOldLoopAttachmentTag(String);
+
       Metadata *MD = MDString::get(Context, String);
       MetadataList.assignValue(MD, NextMetadataNo++);
       break;
@@ -3956,9 +3961,15 @@ std::error_code BitcodeReader::parseMetadataAttachment(Function &F) {
         MDNode *MD = dyn_cast_or_null<MDNode>(Node);
         if (!MD)
           return error("Invalid metadata attachment");
+
+        if (HasSeenOldLoopTags && I->second == LLVMContext::MD_loop)
+          MD = upgradeInstructionLoopAttachment(*MD);
+
         Inst->setMetadata(I->second, MD);
-        if (I->second == LLVMContext::MD_tbaa)
+        if (I->second == LLVMContext::MD_tbaa) {
           InstsWithTBAATag.push_back(Inst);
+          continue;
+        }
       }
       break;
     }
diff --git a/llvm/lib/IR/AutoUpgrade.cpp b/llvm/lib/IR/AutoUpgrade.cpp
index 12c354c89b2..b9cee43b4db 100644
--- a/llvm/lib/IR/AutoUpgrade.cpp
+++ b/llvm/lib/IR/AutoUpgrade.cpp
@@ -894,11 +894,64 @@ bool llvm::UpgradeDebugInfo(Module &M) {
   return RetCode;
 }
 
-void llvm::UpgradeMDStringConstant(std::string &String) {
-  const std::string OldPrefix = "llvm.vectorizer.";
-  if (String == "llvm.vectorizer.unroll") {
-    String = "llvm.loop.interleave.count";
-  } else if (String.find(OldPrefix) == 0) {
-    String.replace(0, OldPrefix.size(), "llvm.loop.vectorize.");
-  }
+static bool isOldLoopArgument(Metadata *MD) {
+  auto *T = dyn_cast_or_null<MDTuple>(MD);
+  if (!T)
+    return false;
+  if (T->getNumOperands() < 1)
+    return false;
+  auto *S = dyn_cast_or_null<MDString>(T->getOperand(0));
+  if (!S)
+    return false;
+  return S->getString().startswith("llvm.vectorizer.");
+}
+
+static MDString *upgradeLoopTag(LLVMContext &C, StringRef OldTag) {
+  StringRef OldPrefix = "llvm.vectorizer.";
+  assert(OldTag.startswith(OldPrefix) && "Expected old prefix");
+
+  if (OldTag == "llvm.vectorizer.unroll")
+    return MDString::get(C, "llvm.loop.interleave.count");
+
+  return MDString::get(
+      C, (Twine("llvm.loop.vectorize.") + OldTag.drop_front(OldPrefix.size()))
+             .str());
+}
+
+static Metadata *upgradeLoopArgument(Metadata *MD) {
+  auto *T = dyn_cast_or_null<MDTuple>(MD);
+  if (!T)
+    return MD;
+  if (T->getNumOperands() < 1)
+    return MD;
+  auto *OldTag = dyn_cast_or_null<MDString>(T->getOperand(0));
+  if (!OldTag)
+    return MD;
+  if (!OldTag->getString().startswith("llvm.vectorizer."))
+    return MD;
+
+  // This has an old tag.  Upgrade it.
+  SmallVector<Metadata *, 8> Ops;
+  Ops.reserve(T->getNumOperands());
+  Ops.push_back(upgradeLoopTag(T->getContext(), OldTag->getString()));
+  for (unsigned I = 1, E = T->getNumOperands(); I != E; ++I)
+    Ops.push_back(T->getOperand(I));
+
+  return MDTuple::get(T->getContext(), Ops);
+}
+
+MDNode *llvm::upgradeInstructionLoopAttachment(MDNode &N) {
+  auto *T = dyn_cast<MDTuple>(&N);
+  if (!T)
+    return &N;
+
+  if (!llvm::any_of(T->operands(), isOldLoopArgument))
+    return &N;
+
+  SmallVector<Metadata *, 8> Ops;
+  Ops.reserve(T->getNumOperands());
+  for (Metadata *MD : T->operands())
+    Ops.push_back(upgradeLoopArgument(MD));
+
+  return MDTuple::get(T->getContext(), Ops);
 }