Initial implementation of 'fence' instruction, the new C++0x-style replacement for llvm.memory.barrier.

This is just a LangRef entry and reading/writing/memory representation; optimizer+codegen support coming soon.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@136009 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 44 insertions, 0 deletions

diff --git a/lib/AsmParser/LLParser.cpp b/lib/AsmParser/LLParser.cpp
index 7164ae1ba5..76771c29ba 100644
--- a/lib/AsmParser/LLParser.cpp
+++ b/lib/AsmParser/LLParser.cpp
@@ -1145,6 +1145,32 @@ bool LLParser::ParseOptionalCommaAlign(unsigned &Alignment,
   return false;
 }
 
+/// ParseScopeAndOrdering
+///   if isAtomic: ::= 'singlethread'? AtomicOrdering
+///   else: ::=
+///
+/// This sets Scope and Ordering to the parsed values.
+bool LLParser::ParseScopeAndOrdering(bool isAtomic, SynchronizationScope &Scope,
+                                     AtomicOrdering &Ordering) {
+  if (!isAtomic)
+    return false;
+
+  Scope = CrossThread;
+  if (EatIfPresent(lltok::kw_singlethread))
+    Scope = SingleThread;
+  switch (Lex.getKind()) {
+  default: return TokError("Expected ordering on atomic instruction");
+  case lltok::kw_unordered: Ordering = Unordered; break;
+  case lltok::kw_monotonic: Ordering = Monotonic; break;
+  case lltok::kw_acquire: Ordering = Acquire; break;
+  case lltok::kw_release: Ordering = Release; break;
+  case lltok::kw_acq_rel: Ordering = AcquireRelease; break;
+  case lltok::kw_seq_cst: Ordering = SequentiallyConsistent; break;
+  }
+  Lex.Lex();
+  return false;
+}
+
 /// ParseOptionalStackAlignment
 ///   ::= /* empty */
 ///   ::= 'alignstack' '(' 4 ')'
@@ -2924,6 +2950,7 @@ int LLParser::ParseInstruction(Instruction *&Inst, BasicBlock *BB,
   case lltok::kw_alloca:         return ParseAlloc(Inst, PFS);
   case lltok::kw_load:           return ParseLoad(Inst, PFS, false);
   case lltok::kw_store:          return ParseStore(Inst, PFS, false);
+  case lltok::kw_fence:          return ParseFence(Inst, PFS);
   case lltok::kw_volatile:
     if (EatIfPresent(lltok::kw_load))
       return ParseLoad(Inst, PFS, true);
@@ -3633,6 +3660,23 @@ int LLParser::ParseStore(Instruction *&Inst, PerFunctionState &PFS,
   return AteExtraComma ? InstExtraComma : InstNormal;
 }
 
+/// ParseFence
+///   ::= 'fence' 'singlethread'? AtomicOrdering
+int LLParser::ParseFence(Instruction *&Inst, PerFunctionState &PFS) {
+  AtomicOrdering Ordering = NotAtomic;
+  SynchronizationScope Scope = CrossThread;
+  if (ParseScopeAndOrdering(true /*Always atomic*/, Scope, Ordering))
+    return true;
+
+  if (Ordering == Unordered)
+    return TokError("fence cannot be unordered");
+  if (Ordering == Monotonic)
+    return TokError("fence cannot be monotonic");
+
+  Inst = new FenceInst(Context, Ordering, Scope);
+  return InstNormal;
+}
+
 /// ParseGetElementPtr
 ///   ::= 'getelementptr' 'inbounds'? TypeAndValue (',' TypeAndValue)*
 int LLParser::ParseGetElementPtr(Instruction *&Inst, PerFunctionState &PFS) {