1 files changed, 147 insertions, 0 deletions
diff --git a/llvm/lib/CodeGen/LiveRegUnits.cpp b/llvm/lib/CodeGen/LiveRegUnits.cpp
new file mode 100644
index 000000000000..97763def1f40
--- /dev/null
+++ b/llvm/lib/CodeGen/LiveRegUnits.cpp
@@ -0,0 +1,147 @@
+//===- LiveRegUnits.cpp - Register Unit Set -------------------------------===//
+//
+// 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 imlements the LiveRegUnits set.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/CodeGen/LiveRegUnits.h"
+
+#include "llvm/CodeGen/MachineBasicBlock.h"
+#include "llvm/CodeGen/MachineFrameInfo.h"
+#include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/CodeGen/MachineInstrBundle.h"
+#include "llvm/CodeGen/MachineOperand.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/CodeGen/TargetRegisterInfo.h"
+#include "llvm/MC/MCRegisterInfo.h"
+
+using namespace llvm;
+
+void LiveRegUnits::removeRegsNotPreserved(const uint32_t *RegMask) {
+  for (unsigned U = 0, E = TRI->getNumRegUnits(); U != E; ++U) {
+    for (MCRegUnitRootIterator RootReg(U, TRI); RootReg.isValid(); ++RootReg) {
+      if (MachineOperand::clobbersPhysReg(RegMask, *RootReg))
+        Units.reset(U);
+    }
+  }
+}
+
+void LiveRegUnits::addRegsInMask(const uint32_t *RegMask) {
+  for (unsigned U = 0, E = TRI->getNumRegUnits(); U != E; ++U) {
+    for (MCRegUnitRootIterator RootReg(U, TRI); RootReg.isValid(); ++RootReg) {
+      if (MachineOperand::clobbersPhysReg(RegMask, *RootReg))
+        Units.set(U);
+    }
+  }
+}
+
+void LiveRegUnits::stepBackward(const MachineInstr &MI) {
+  // Remove defined registers and regmask kills from the set.
+  for (ConstMIBundleOperands O(MI); O.isValid(); ++O) {
+    if (O->isReg()) {
+      if (!O->isDef() || O->isDebug())
+        continue;
+      Register Reg = O->getReg();
+      if (!Register::isPhysicalRegister(Reg))
+        continue;
+      removeReg(Reg);
+    } else if (O->isRegMask())
+      removeRegsNotPreserved(O->getRegMask());
+  }
+
+  // Add uses to the set.
+  for (ConstMIBundleOperands O(MI); O.isValid(); ++O) {
+    if (!O->isReg() || !O->readsReg() || O->isDebug())
+      continue;
+    Register Reg = O->getReg();
+    if (!Register::isPhysicalRegister(Reg))
+      continue;
+    addReg(Reg);
+  }
+}
+
+void LiveRegUnits::accumulate(const MachineInstr &MI) {
+  // Add defs, uses and regmask clobbers to the set.
+  for (ConstMIBundleOperands O(MI); O.isValid(); ++O) {
+    if (O->isReg()) {
+      Register Reg = O->getReg();
+      if (!Register::isPhysicalRegister(Reg))
+        continue;
+      if (!O->isDef() && !O->readsReg())
+        continue;
+      addReg(Reg);
+    } else if (O->isRegMask())
+      addRegsInMask(O->getRegMask());
+  }
+}
+
+/// Add live-in registers of basic block \p MBB to \p LiveUnits.
+static void addBlockLiveIns(LiveRegUnits &LiveUnits,
+                            const MachineBasicBlock &MBB) {
+  for (const auto &LI : MBB.liveins())
+    LiveUnits.addRegMasked(LI.PhysReg, LI.LaneMask);
+}
+
+/// Adds all callee saved registers to \p LiveUnits.
+static void addCalleeSavedRegs(LiveRegUnits &LiveUnits,
+                               const MachineFunction &MF) {
+  const MachineRegisterInfo &MRI = MF.getRegInfo();
+  for (const MCPhysReg *CSR = MRI.getCalleeSavedRegs(); CSR && *CSR; ++CSR)
+    LiveUnits.addReg(*CSR);
+}
+
+void LiveRegUnits::addPristines(const MachineFunction &MF) {
+  const MachineFrameInfo &MFI = MF.getFrameInfo();
+  if (!MFI.isCalleeSavedInfoValid())
+    return;
+  /// This function will usually be called on an empty object, handle this
+  /// as a special case.
+  if (empty()) {
+    /// Add all callee saved regs, then remove the ones that are saved and
+    /// restored.
+    addCalleeSavedRegs(*this, MF);
+    /// Remove the ones that are not saved/restored; they are pristine.
+    for (const CalleeSavedInfo &Info : MFI.getCalleeSavedInfo())
+      removeReg(Info.getReg());
+    return;
+  }
+  /// If a callee-saved register that is not pristine is already present
+  /// in the set, we should make sure that it stays in it. Precompute the
+  /// set of pristine registers in a separate object.
+  /// Add all callee saved regs, then remove the ones that are saved+restored.
+  LiveRegUnits Pristine(*TRI);
+  addCalleeSavedRegs(Pristine, MF);
+  /// Remove the ones that are not saved/restored; they are pristine.
+  for (const CalleeSavedInfo &Info : MFI.getCalleeSavedInfo())
+    Pristine.removeReg(Info.getReg());
+  addUnits(Pristine.getBitVector());
+}
+
+void LiveRegUnits::addLiveOuts(const MachineBasicBlock &MBB) {
+  const MachineFunction &MF = *MBB.getParent();
+
+  addPristines(MF);
+
+  // To get the live-outs we simply merge the live-ins of all successors.
+  for (const MachineBasicBlock *Succ : MBB.successors())
+    addBlockLiveIns(*this, *Succ);
+
+  // For the return block: Add all callee saved registers.
+  if (MBB.isReturnBlock()) {
+    const MachineFrameInfo &MFI = MF.getFrameInfo();
+    if (MFI.isCalleeSavedInfoValid())
+      addCalleeSavedRegs(*this, MF);
+  }
+}
+
+void LiveRegUnits::addLiveIns(const MachineBasicBlock &MBB) {
+  const MachineFunction &MF = *MBB.getParent();
+  addPristines(MF);
+  addBlockLiveIns(*this, MBB);
+}