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

2 files changed, 59 insertions, 0 deletions

diff --git a/lib/Bitcode/Reader/BitcodeReader.cpp b/lib/Bitcode/Reader/BitcodeReader.cpp
index 914c6c1..2029f43 100644
--- a/lib/Bitcode/Reader/BitcodeReader.cpp
+++ b/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -131,6 +131,27 @@ static int GetDecodedBinaryOpcode(unsigned Val, Type *Ty) {
   }
 }
 
+static AtomicOrdering GetDecodedOrdering(unsigned Val) {
+  switch (Val) {
+  case bitc::ORDERING_NOTATOMIC: return NotAtomic;
+  case bitc::ORDERING_UNORDERED: return Unordered;
+  case bitc::ORDERING_MONOTONIC: return Monotonic;
+  case bitc::ORDERING_ACQUIRE: return Acquire;
+  case bitc::ORDERING_RELEASE: return Release;
+  case bitc::ORDERING_ACQREL: return AcquireRelease;
+  default: // Map unknown orderings to sequentially-consistent.
+  case bitc::ORDERING_SEQCST: return SequentiallyConsistent;
+  }
+}
+
+static SynchronizationScope GetDecodedSynchScope(unsigned Val) {
+  switch (Val) {
+  case bitc::SYNCHSCOPE_SINGLETHREAD: return SingleThread;
+  default: // Map unknown scopes to cross-thread.
+  case bitc::SYNCHSCOPE_CROSSTHREAD: return CrossThread;
+  }
+}
+
 namespace llvm {
 namespace {
   /// @brief A class for maintaining the slot number definition
@@ -2534,6 +2555,18 @@ bool BitcodeReader::ParseFunctionBody(Function *F) {
       InstructionList.push_back(I);
       break;
     }
+    case bitc::FUNC_CODE_INST_FENCE: { // FENCE:[ordering, synchscope]
+      if (2 != Record.size())
+        return Error("Invalid FENCE record");
+      AtomicOrdering Ordering = GetDecodedOrdering(Record[0]);
+      if (Ordering == NotAtomic || Ordering == Unordered ||
+          Ordering == Monotonic)
+        return Error("Invalid FENCE record");
+      SynchronizationScope SynchScope = GetDecodedSynchScope(Record[1]);
+      I = new FenceInst(Context, Ordering, SynchScope);
+      InstructionList.push_back(I);
+      break;
+    }
     case bitc::FUNC_CODE_INST_CALL: {
       // CALL: [paramattrs, cc, fnty, fnid, arg0, arg1...]
       if (Record.size() < 3)
diff --git a/lib/Bitcode/Writer/BitcodeWriter.cpp b/lib/Bitcode/Writer/BitcodeWriter.cpp
index 4dfa0ba..9df3c17 100644
--- a/lib/Bitcode/Writer/BitcodeWriter.cpp
+++ b/lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -101,6 +101,27 @@ static unsigned GetEncodedBinaryOpcode(unsigned Opcode) {
   }
 }
 
+static unsigned GetEncodedOrdering(AtomicOrdering Ordering) {
+  switch (Ordering) {
+  default: llvm_unreachable("Unknown atomic ordering");
+  case NotAtomic: return bitc::ORDERING_NOTATOMIC;
+  case Unordered: return bitc::ORDERING_UNORDERED;
+  case Monotonic: return bitc::ORDERING_MONOTONIC;
+  case Acquire: return bitc::ORDERING_ACQUIRE;
+  case Release: return bitc::ORDERING_RELEASE;
+  case AcquireRelease: return bitc::ORDERING_ACQREL;
+  case SequentiallyConsistent: return bitc::ORDERING_SEQCST;
+  }
+}
+
+static unsigned GetEncodedSynchScope(SynchronizationScope SynchScope) {
+  switch (SynchScope) {
+  default: llvm_unreachable("Unknown synchronization scope");
+  case SingleThread: return bitc::SYNCHSCOPE_SINGLETHREAD;
+  case CrossThread: return bitc::SYNCHSCOPE_CROSSTHREAD;
+  }
+}
+
 static void WriteStringRecord(unsigned Code, StringRef Str,
                               unsigned AbbrevToUse, BitstreamWriter &Stream) {
   SmallVector<unsigned, 64> Vals;
@@ -1147,6 +1168,11 @@ static void WriteInstruction(const Instruction &I, unsigned InstID,
     Vals.push_back(Log2_32(cast<StoreInst>(I).getAlignment())+1);
     Vals.push_back(cast<StoreInst>(I).isVolatile());
     break;
+  case Instruction::Fence:
+    Code = bitc::FUNC_CODE_INST_FENCE;
+    Vals.push_back(GetEncodedOrdering(cast<FenceInst>(I).getOrdering()));
+    Vals.push_back(GetEncodedSynchScope(cast<FenceInst>(I).getSynchScope()));
+    break;
   case Instruction::Call: {
     const CallInst &CI = cast<CallInst>(I);
     PointerType *PTy = cast<PointerType>(CI.getCalledValue()->getType());