Revert "ValueMapper: Make LocalAsMetadata match function-local Values"

This reverts commit r265631, since it caused bot failures:
http://lab.llvm.org:8011/builders/clang-ppc64be-linux/builds/3256
http://lab.llvm.org:8011/builders/clang-cmake-aarch64-42vma/builds/7272

Looks like something is depending on the old behaviour.  I'll try to
track it down and recommit.

llvm-svn: 265637

1 files changed, 16 insertions, 38 deletions

diff --git a/llvm/lib/Transforms/Utils/ValueMapper.cpp b/llvm/lib/Transforms/Utils/ValueMapper.cpp
index 5a92b4c01c0..59870f81c3b 100644
--- a/llvm/lib/Transforms/Utils/ValueMapper.cpp
+++ b/llvm/lib/Transforms/Utils/ValueMapper.cpp
@@ -86,9 +86,6 @@ public:
   /// (not an MDNode, or MDNode::isResolved() returns true).
   Metadata *mapMetadata(const Metadata *MD);
 
-  // Map LocalAsMetadata, which never gets memoized.
-  Metadata *mapLocalAsMetadata(const LocalAsMetadata &LAM);
-
 private:
   Value *mapBlockAddress(const BlockAddress &BA);
 
@@ -297,27 +294,18 @@ Value *Mapper::mapValue(const Value *V) {
 
   if (const auto *MDV = dyn_cast<MetadataAsValue>(V)) {
     const Metadata *MD = MDV->getMetadata();
-
-    // Locals shouldn't be memoized.  Return nullptr if mapLocalAsMetadata()
-    // returns nullptr; otherwise bridge back to the Value hierarchy.
-    if (auto *LAM = dyn_cast<LocalAsMetadata>(MD)) {
-      if (auto *MappedMD = mapLocalAsMetadata(*LAM)) {
-        if (LAM == MappedMD)
-          return const_cast<Value *>(V);
-        return MetadataAsValue::get(V->getContext(), MappedMD);
-      }
-      return nullptr;
-    }
-
     // If this is a module-level metadata and we know that nothing at the module
     // level is changing, then use an identity mapping.
-    if (Flags & RF_NoModuleLevelChanges)
+    if (!isa<LocalAsMetadata>(MD) && (Flags & RF_NoModuleLevelChanges))
       return VM[V] = const_cast<Value *>(V);
 
-    // Map the metadata and turn it into a value.
+    // FIXME: be consistent with function-local values for LocalAsMetadata by
+    // returning nullptr when LocalAsMetadata is missing.  Adding a mapping is
+    // expensive.
     auto *MappedMD = mapMetadata(MD);
-    if (MD == MappedMD)
+    if (MD == MappedMD || (!MappedMD && (Flags & RF_IgnoreMissingLocals)))
       return VM[V] = const_cast<Value *>(V);
+
     return VM[V] = MetadataAsValue::get(V->getContext(), MappedMD);
   }
 
@@ -635,16 +623,21 @@ Optional<Metadata *> Mapper::mapSimpleMetadata(const Metadata *MD) {
   if (isa<MDString>(MD))
     return mapToSelf(MD);
 
-  if (auto *CMD = dyn_cast<ConstantAsMetadata>(MD)) {
+  if (isa<ConstantAsMetadata>(MD))
     if ((Flags & RF_NoModuleLevelChanges))
       return mapToSelf(MD);
 
+  // FIXME: Assert that this is not LocalAsMetadata.  It should be handled
+  // elsewhere.
+  if (const auto *VMD = dyn_cast<ValueAsMetadata>(MD)) {
     // Disallow recursion into metadata mapping through mapValue.
     VM.disableMapMetadata();
-    Value *MappedV = mapValue(CMD->getValue());
+    Value *MappedV = mapValue(VMD->getValue());
     VM.enableMapMetadata();
 
-    if (CMD->getValue() == MappedV)
+    // FIXME: Always use "ignore" behaviour.  There should only be globals here.
+    if (VMD->getValue() == MappedV ||
+        (!MappedV && (Flags & RF_IgnoreMissingLocals)))
       return mapToSelf(MD);
 
     return mapToMetadata(MD, MappedV ? ValueAsMetadata::get(MappedV) : nullptr);
@@ -666,24 +659,9 @@ Metadata *llvm::MapMetadata(const Metadata *MD, ValueToValueMapTy &VM,
   return Mapper(VM, Flags, TypeMapper, Materializer).mapMetadata(MD);
 }
 
-Metadata *Mapper::mapLocalAsMetadata(const LocalAsMetadata &LAM) {
-  if (Optional<Metadata *> NewMD = VM.getMappedMD(&LAM))
-    return *NewMD;
-
-  // Lookup the mapping for the value itself, and return the appropriate
-  // metadata.
-  if (Value *V = mapValue(LAM.getValue())) {
-    if (V == LAM.getValue())
-      return const_cast<LocalAsMetadata *>(&LAM);
-    return ValueAsMetadata::get(V);
-  }
-  return nullptr;
-}
-
 Metadata *Mapper::mapMetadata(const Metadata *MD) {
-  if (auto *LAM = dyn_cast<LocalAsMetadata>(MD))
-    return mapLocalAsMetadata(*LAM);
-
+  // FIXME: First check for and deal with LocalAsMetadata, so that
+  // mapSimpleMetadata() doesn't need to deal with it.
   if (Optional<Metadata *> NewMD = mapSimpleMetadata(MD))
     return *NewMD;