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, 38 insertions, 7 deletions

diff --git a/llvm/lib/CodeGen/MIRParser/MIParser.cpp b/llvm/lib/CodeGen/MIRParser/MIParser.cpp
index c58d192284d..70dca277733 100644
--- a/llvm/lib/CodeGen/MIRParser/MIParser.cpp
+++ b/llvm/lib/CodeGen/MIRParser/MIParser.cpp
@@ -229,6 +229,7 @@ public:
   bool parseMemoryOperandFlag(MachineMemOperand::Flags &Flags);
   bool parseMemoryPseudoSourceValue(const PseudoSourceValue *&PSV);
   bool parseMachinePointerInfo(MachinePointerInfo &Dest);
+  bool parseOptionalScope(LLVMContext &Context, SyncScope::ID &SSID);
   bool parseOptionalAtomicOrdering(AtomicOrdering &Order);
   bool parseMachineMemoryOperand(MachineMemOperand *&Dest);
 
@@ -318,6 +319,10 @@ private:
   ///
   /// Return true if the name isn't a name of a bitmask target flag.
   bool getBitmaskTargetFlag(StringRef Name, unsigned &Flag);
+
+  /// parseStringConstant
+  ///   ::= StringConstant
+  bool parseStringConstant(std::string &Result);
 };
 
 } // end anonymous namespace
@@ -2135,6 +2140,26 @@ bool MIParser::parseMachinePointerInfo(MachinePointerInfo &Dest) {
   return false;
 }
 
+bool MIParser::parseOptionalScope(LLVMContext &Context,
+                                  SyncScope::ID &SSID) {
+  SSID = SyncScope::System;
+  if (Token.is(MIToken::Identifier) && Token.stringValue() == "syncscope") {
+    lex();
+    if (expectAndConsume(MIToken::lparen))
+      return error("expected '(' in syncscope");
+
+    std::string SSN;
+    if (parseStringConstant(SSN))
+      return true;
+
+    SSID = Context.getOrInsertSyncScopeID(SSN);
+    if (expectAndConsume(MIToken::rparen))
+      return error("expected ')' in syncscope");
+  }
+
+  return false;
+}
+
 bool MIParser::parseOptionalAtomicOrdering(AtomicOrdering &Order) {
   Order = AtomicOrdering::NotAtomic;
   if (Token.isNot(MIToken::Identifier))
@@ -2174,12 +2199,10 @@ bool MIParser::parseMachineMemoryOperand(MachineMemOperand *&Dest) {
     Flags |= MachineMemOperand::MOStore;
   lex();
 
-  // Optional "singlethread" scope.
-  SynchronizationScope Scope = SynchronizationScope::CrossThread;
-  if (Token.is(MIToken::Identifier) && Token.stringValue() == "singlethread") {
-    Scope = SynchronizationScope::SingleThread;
-    lex();
-  }
+  // Optional synchronization scope.
+  SyncScope::ID SSID;
+  if (parseOptionalScope(MF.getFunction()->getContext(), SSID))
+    return true;
 
   // Up to two atomic orderings (cmpxchg provides guarantees on failure).
   AtomicOrdering Order, FailureOrder;
@@ -2244,7 +2267,7 @@ bool MIParser::parseMachineMemoryOperand(MachineMemOperand *&Dest) {
   if (expectAndConsume(MIToken::rparen))
     return true;
   Dest = MF.getMachineMemOperand(Ptr, Flags, Size, BaseAlignment, AAInfo, Range,
-                                 Scope, Order, FailureOrder);
+                                 SSID, Order, FailureOrder);
   return false;
 }
 
@@ -2457,6 +2480,14 @@ bool MIParser::getBitmaskTargetFlag(StringRef Name, unsigned &Flag) {
   return false;
 }
 
+bool MIParser::parseStringConstant(std::string &Result) {
+  if (Token.isNot(MIToken::StringConstant))
+    return error("expected string constant");
+  Result = Token.stringValue();
+  lex();
+  return false;
+}
+
 bool llvm::parseMachineBasicBlockDefinitions(PerFunctionMIParsingState &PFS,
                                              StringRef Src,
                                              SMDiagnostic &Error) {