1 files changed, 16 insertions, 0 deletions
diff --git a/llvm/lib/Target/X86/X86TargetMachine.cpp b/llvm/lib/Target/X86/X86TargetMachine.cpp
index 569c0408f30..95e7021dce5 100644
--- a/llvm/lib/Target/X86/X86TargetMachine.cpp
+++ b/llvm/lib/Target/X86/X86TargetMachine.cpp
@@ -16,6 +16,7 @@
 #include "llvm/PassManager.h"
 #include "llvm/CodeGen/MachineFunction.h"
 #include "llvm/CodeGen/Passes.h"
+#include "llvm/Support/CommandLine.h"
 #include "llvm/Support/FormattedStream.h"
 #include "llvm/Target/TargetOptions.h"
 #include "llvm/Target/TargetRegistry.h"
@@ -92,6 +93,16 @@ X86TargetMachine::X86TargetMachine(const Target &T, StringRef TT,
 }
 
 //===----------------------------------------------------------------------===//
+// Command line options for x86
+//===----------------------------------------------------------------------===//
+bool UseVZeroUpper;
+
+static cl::opt<bool, true>
+VZeroUpper("x86-use-vzeroupper",
+  cl::desc("Minimize AVX to SSE transition penalty"),
+  cl::location(UseVZeroUpper), cl::init(false));
+
+//===----------------------------------------------------------------------===//
 // Pass Pipeline Configuration
 //===----------------------------------------------------------------------===//
 
@@ -125,6 +136,11 @@ bool X86TargetMachine::addPreEmitPass(PassManagerBase &PM,
     PM.add(createSSEDomainFixPass());
     return true;
   }
+
+  if (Subtarget.hasAVX() && UseVZeroUpper) {
+    PM.add(createX86IssueVZeroUpperPass());
+    return true;
+  }
   return false;
 }