Enhance synchscope representation

  OpenCL 2.0 introduces the notion of memory scopes in atomic operations to
  global and local memory. These scopes restrict how synchronization is
  achieved, which can result in improved performance.

  This change extends existing notion of synchronization scopes in LLVM to
  support arbitrary scopes expressed as target-specific strings, in addition to
  the already defined scopes (single thread, system).

  The LLVM IR and MIR syntax for expressing synchronization scopes has changed
  to use *syncscope("<scope>")*, where <scope> can be "singlethread" (this
  replaces *singlethread* keyword), or a target-specific name. As before, if
  the scope is not specified, it defaults to CrossThread/System scope.

  Implementation details:
    - Mapping from synchronization scope name/string to synchronization scope id
      is stored in LLVM context;
    - CrossThread/System and SingleThread scopes are pre-defined to efficiently
      check for known scopes without comparing strings;
    - Synchronization scope names are stored in SYNC_SCOPE_NAMES_BLOCK in
      the bitcode.

Differential Revision: https://reviews.llvm.org/D21723

llvm-svn: 307722

1 files changed, 14 insertions, 0 deletions

diff --git a/llvm/lib/IR/LLVMContextImpl.h b/llvm/lib/IR/LLVMContextImpl.h
index 395beb57fe3..e413a4f3443 100644
--- a/llvm/lib/IR/LLVMContextImpl.h
+++ b/llvm/lib/IR/LLVMContextImpl.h
@@ -1297,6 +1297,20 @@ public:
   void getOperandBundleTags(SmallVectorImpl<StringRef> &Tags) const;
   uint32_t getOperandBundleTagID(StringRef Tag) const;
 
+  /// A set of interned synchronization scopes.  The StringMap maps
+  /// synchronization scope names to their respective synchronization scope IDs.
+  StringMap<SyncScope::ID> SSC;
+
+  /// getOrInsertSyncScopeID - Maps synchronization scope name to
+  /// synchronization scope ID.  Every synchronization scope registered with
+  /// LLVMContext has unique ID except pre-defined ones.
+  SyncScope::ID getOrInsertSyncScopeID(StringRef SSN);
+
+  /// getSyncScopeNames - Populates client supplied SmallVector with
+  /// synchronization scope names registered with LLVMContext.  Synchronization
+  /// scope names are ordered by increasing synchronization scope IDs.
+  void getSyncScopeNames(SmallVectorImpl<StringRef> &SSNs) const;
+
   /// Maintain the GC name for each function.
   ///
   /// This saves allocating an additional word in Function for programs which