1 files changed, 41 insertions, 0 deletions
diff --git a/lib/CodeGen/GlobalISel/CombinerHelper.cpp b/lib/CodeGen/GlobalISel/CombinerHelper.cpp
new file mode 100644
index 000000000000..44e904a6391b
--- /dev/null
+++ b/lib/CodeGen/GlobalISel/CombinerHelper.cpp
@@ -0,0 +1,41 @@
+//== ---lib/CodeGen/GlobalISel/GICombinerHelper.cpp --------------------- == //
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+#include "llvm/CodeGen/GlobalISel/CombinerHelper.h"
+#include "llvm/CodeGen/GlobalISel/MachineIRBuilder.h"
+#include "llvm/CodeGen/GlobalISel/Utils.h"
+#include "llvm/CodeGen/MachineInstr.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
+
+#define DEBUG_TYPE "gi-combine"
+
+using namespace llvm;
+
+CombinerHelper::CombinerHelper(MachineIRBuilder &B) :
+  Builder(B), MRI(Builder.getMF().getRegInfo()) {}
+
+bool CombinerHelper::tryCombineCopy(MachineInstr &MI) {
+  if (MI.getOpcode() != TargetOpcode::COPY)
+    return false;
+  unsigned DstReg = MI.getOperand(0).getReg();
+  unsigned SrcReg = MI.getOperand(1).getReg();
+  LLT DstTy = MRI.getType(DstReg);
+  LLT SrcTy = MRI.getType(SrcReg);
+  // Simple Copy Propagation.
+  // a(sx) = COPY b(sx) -> Replace all uses of a with b.
+  if (DstTy.isValid() && SrcTy.isValid() && DstTy == SrcTy) {
+    MI.eraseFromParent();
+    MRI.replaceRegWith(DstReg, SrcReg);
+    return true;
+  }
+  return false;
+}
+
+bool CombinerHelper::tryCombine(MachineInstr &MI) {
+  return tryCombineCopy(MI);
+}