I cannot find a libgcc function for this builtin. Therefor expanding it to a noop (which is how it use to be treated). If someone who knows the x86 backend better than me could tell me how to get a lock prefix on an instruction, that would be nice to complete x86 support.

llvm-svn: 47213

1 files changed, 4 insertions, 0 deletions

diff --git a/llvm/lib/Target/CBackend/CBackend.cpp b/llvm/lib/Target/CBackend/CBackend.cpp
index d434eb9786d..334f6fe54f9 100644
--- a/llvm/lib/Target/CBackend/CBackend.cpp
+++ b/llvm/lib/Target/CBackend/CBackend.cpp
@@ -2459,6 +2459,7 @@ void CWriter::lowerIntrinsics(Function &F) {
         if (Function *F = CI->getCalledFunction())
           switch (F->getIntrinsicID()) {
           case Intrinsic::not_intrinsic:
+          case Intrinsic::memory_barrier:
           case Intrinsic::vastart:
           case Intrinsic::vacopy:
           case Intrinsic::vaend:
@@ -2544,6 +2545,9 @@ void CWriter::visitCallInst(CallInst &I) {
         WroteCallee = true;
         break;
       }
+      case Intrinsic::memory_barrier:
+        Out << "0; __sync_syncronize()";
+        return;
       case Intrinsic::vastart:
         Out << "0; ";