1 files changed, 157 insertions, 0 deletions
diff --git a/llvm/lib/Target/ARM/MVETailPredUtils.h b/llvm/lib/Target/ARM/MVETailPredUtils.h
new file mode 100644
index 000000000000..9ab5d92729fe
--- /dev/null
+++ b/llvm/lib/Target/ARM/MVETailPredUtils.h
@@ -0,0 +1,157 @@
+//===-- MVETailPredUtils.h - Tail predication utility functions -*- C++-*-===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+//
+// This file contains utility functions for low overhead and tail predicated
+// loops, shared between the ARMLowOverheadLoops pass and anywhere else that
+// needs them.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIB_TARGET_ARM_MVETAILPREDUTILS_H
+#define LLVM_LIB_TARGET_ARM_MVETAILPREDUTILS_H
+
+#include "llvm/CodeGen/MachineInstr.h"
+#include "llvm/CodeGen/MachineInstrBuilder.h"
+#include "llvm/CodeGen/MachineOperand.h"
+#include "llvm/CodeGen/TargetInstrInfo.h"
+
+namespace llvm {
+
+static inline unsigned VCTPOpcodeToLSTP(unsigned Opcode, bool IsDoLoop) {
+  switch (Opcode) {
+  default:
+    llvm_unreachable("unhandled vctp opcode");
+    break;
+  case ARM::MVE_VCTP8:
+    return IsDoLoop ? ARM::MVE_DLSTP_8 : ARM::MVE_WLSTP_8;
+  case ARM::MVE_VCTP16:
+    return IsDoLoop ? ARM::MVE_DLSTP_16 : ARM::MVE_WLSTP_16;
+  case ARM::MVE_VCTP32:
+    return IsDoLoop ? ARM::MVE_DLSTP_32 : ARM::MVE_WLSTP_32;
+  case ARM::MVE_VCTP64:
+    return IsDoLoop ? ARM::MVE_DLSTP_64 : ARM::MVE_WLSTP_64;
+  }
+  return 0;
+}
+
+static inline unsigned getTailPredVectorWidth(unsigned Opcode) {
+  switch (Opcode) {
+  default:
+    llvm_unreachable("unhandled vctp opcode");
+  case ARM::MVE_VCTP8:
+    return 16;
+  case ARM::MVE_VCTP16:
+    return 8;
+  case ARM::MVE_VCTP32:
+    return 4;
+  case ARM::MVE_VCTP64:
+    return 2;
+  }
+  return 0;
+}
+
+static inline bool isVCTP(const MachineInstr *MI) {
+  switch (MI->getOpcode()) {
+  default:
+    break;
+  case ARM::MVE_VCTP8:
+  case ARM::MVE_VCTP16:
+  case ARM::MVE_VCTP32:
+  case ARM::MVE_VCTP64:
+    return true;
+  }
+  return false;
+}
+
+static inline bool isLoopStart(MachineInstr &MI) {
+  return MI.getOpcode() == ARM::t2DoLoopStart ||
+         MI.getOpcode() == ARM::t2DoLoopStartTP ||
+         MI.getOpcode() == ARM::t2WhileLoopStart;
+}
+
+// WhileLoopStart holds the exit block, so produce a cmp lr, 0 and then a
+// beq that branches to the exit branch.
+inline void RevertWhileLoopStart(MachineInstr *MI, const TargetInstrInfo *TII,
+                        unsigned BrOpc = ARM::t2Bcc) {
+  MachineBasicBlock *MBB = MI->getParent();
+
+  // Cmp
+  MachineInstrBuilder MIB =
+      BuildMI(*MBB, MI, MI->getDebugLoc(), TII->get(ARM::t2CMPri));
+  MIB.add(MI->getOperand(0));
+  MIB.addImm(0);
+  MIB.addImm(ARMCC::AL);
+  MIB.addReg(ARM::NoRegister);
+
+  // Branch
+  MIB = BuildMI(*MBB, MI, MI->getDebugLoc(), TII->get(BrOpc));
+  MIB.add(MI->getOperand(1)); // branch target
+  MIB.addImm(ARMCC::EQ);      // condition code
+  MIB.addReg(ARM::CPSR);
+
+  MI->eraseFromParent();
+}
+
+inline void RevertDoLoopStart(MachineInstr *MI, const TargetInstrInfo *TII) {
+  MachineBasicBlock *MBB = MI->getParent();
+  BuildMI(*MBB, MI, MI->getDebugLoc(), TII->get(ARM::tMOVr))
+      .add(MI->getOperand(0))
+      .add(MI->getOperand(1))
+      .add(predOps(ARMCC::AL));
+
+  MI->eraseFromParent();
+}
+
+inline void RevertLoopDec(MachineInstr *MI, const TargetInstrInfo *TII,
+                          bool SetFlags = false) {
+  MachineBasicBlock *MBB = MI->getParent();
+
+  MachineInstrBuilder MIB =
+      BuildMI(*MBB, MI, MI->getDebugLoc(), TII->get(ARM::t2SUBri));
+  MIB.add(MI->getOperand(0));
+  MIB.add(MI->getOperand(1));
+  MIB.add(MI->getOperand(2));
+  MIB.addImm(ARMCC::AL);
+  MIB.addReg(0);
+
+  if (SetFlags) {
+    MIB.addReg(ARM::CPSR);
+    MIB->getOperand(5).setIsDef(true);
+  } else
+    MIB.addReg(0);
+
+  MI->eraseFromParent();
+}
+
+// Generate a subs, or sub and cmp, and a branch instead of an LE.
+inline void RevertLoopEnd(MachineInstr *MI, const TargetInstrInfo *TII,
+                          unsigned BrOpc = ARM::t2Bcc, bool SkipCmp = false) {
+  MachineBasicBlock *MBB = MI->getParent();
+
+  // Create cmp
+  if (!SkipCmp) {
+    MachineInstrBuilder MIB =
+        BuildMI(*MBB, MI, MI->getDebugLoc(), TII->get(ARM::t2CMPri));
+    MIB.add(MI->getOperand(0));
+    MIB.addImm(0);
+    MIB.addImm(ARMCC::AL);
+    MIB.addReg(ARM::NoRegister);
+  }
+
+  // Create bne
+  MachineInstrBuilder MIB =
+      BuildMI(*MBB, MI, MI->getDebugLoc(), TII->get(BrOpc));
+  MIB.add(MI->getOperand(1)); // branch target
+  MIB.addImm(ARMCC::NE);      // condition code
+  MIB.addReg(ARM::CPSR);
+  MI->eraseFromParent();
+}
+
+} // end namespace llvm
+
+#endif // LLVM_LIB_TARGET_ARM_MVETAILPREDUTILS_H