1 files changed, 69 insertions, 0 deletions
diff --git a/llvm/lib/Target/ARM/ARMMacroFusion.cpp b/llvm/lib/Target/ARM/ARMMacroFusion.cpp
new file mode 100644
index 000000000000..38bf28ba8219
--- /dev/null
+++ b/llvm/lib/Target/ARM/ARMMacroFusion.cpp
@@ -0,0 +1,69 @@
+//===- ARMMacroFusion.cpp - ARM Macro Fusion ----------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+/// \file This file contains the ARM implementation of the DAG scheduling
+///  mutation to pair instructions back to back.
+//
+//===----------------------------------------------------------------------===//
+
+#include "ARMMacroFusion.h"
+#include "ARMSubtarget.h"
+#include "llvm/CodeGen/MacroFusion.h"
+#include "llvm/CodeGen/TargetInstrInfo.h"
+
+namespace llvm {
+
+// Fuse AES crypto encoding or decoding.
+static bool isAESPair(const MachineInstr *FirstMI,
+                      const MachineInstr &SecondMI) {
+  // Assume the 1st instr to be a wildcard if it is unspecified.
+  switch(SecondMI.getOpcode()) {
+  // AES encode.
+  case ARM::AESMC :
+    return FirstMI == nullptr || FirstMI->getOpcode() == ARM::AESE;
+  // AES decode.
+  case ARM::AESIMC:
+    return FirstMI == nullptr || FirstMI->getOpcode() == ARM::AESD;
+  }
+
+  return false;
+}
+
+// Fuse literal generation.
+static bool isLiteralsPair(const MachineInstr *FirstMI,
+                           const MachineInstr &SecondMI) {
+  // Assume the 1st instr to be a wildcard if it is unspecified.
+  if ((FirstMI == nullptr || FirstMI->getOpcode() == ARM::MOVi16) &&
+      SecondMI.getOpcode() == ARM::MOVTi16)
+    return true;
+
+  return false;
+}
+
+/// Check if the instr pair, FirstMI and SecondMI, should be fused
+/// together. Given SecondMI, when FirstMI is unspecified, then check if
+/// SecondMI may be part of a fused pair at all.
+static bool shouldScheduleAdjacent(const TargetInstrInfo &TII,
+                                   const TargetSubtargetInfo &TSI,
+                                   const MachineInstr *FirstMI,
+                                   const MachineInstr &SecondMI) {
+  const ARMSubtarget &ST = static_cast<const ARMSubtarget&>(TSI);
+
+  if (ST.hasFuseAES() && isAESPair(FirstMI, SecondMI))
+    return true;
+  if (ST.hasFuseLiterals() && isLiteralsPair(FirstMI, SecondMI))
+    return true;
+
+  return false;
+}
+
+std::unique_ptr<ScheduleDAGMutation> createARMMacroFusionDAGMutation () {
+  return createMacroFusionDAGMutation(shouldScheduleAdjacent);
+}
+
+} // end namespace llvm