1 files changed, 111 insertions, 0 deletions
diff --git a/lib/CodeGen/LiveRegUnits.cpp b/lib/CodeGen/LiveRegUnits.cpp
new file mode 100644
index 0000000..6221ca2
--- /dev/null
+++ b/lib/CodeGen/LiveRegUnits.cpp
@@ -0,0 +1,111 @@
+//===-- LiveInterval.cpp - Live Interval Representation -------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the LiveRegUnits utility for tracking liveness of
+// physical register units across machine instructions in forward or backward
+// order.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/CodeGen/LiveRegUnits.h"
+#include "llvm/CodeGen/MachineInstrBundle.h"
+using namespace llvm;
+
+/// Return true if the given MachineOperand clobbers the given register unit.
+/// A register unit is only clobbered if all its super-registers are clobbered.
+static bool operClobbersUnit(const MachineOperand *MO, unsigned Unit,
+                             const MCRegisterInfo *MCRI) {
+  for (MCRegUnitRootIterator RI(Unit, MCRI); RI.isValid(); ++RI) {
+    for (MCSuperRegIterator SI(*RI, MCRI, true); SI.isValid(); ++SI) {
+      if (!MO->clobbersPhysReg(*SI))
+        return false;
+    }
+  }
+  return true;
+}
+
+/// We assume the high bits of a physical super register are not preserved
+/// unless the instruction has an implicit-use operand reading the
+/// super-register or a register unit for the upper bits is available.
+void LiveRegUnits::removeRegsInMask(const MachineOperand &Op,
+                                    const MCRegisterInfo &MCRI) {
+  SparseSet<unsigned>::iterator LUI = LiveUnits.begin();
+  while (LUI != LiveUnits.end()) {
+    if (operClobbersUnit(&Op, *LUI, &MCRI))
+      LUI = LiveUnits.erase(LUI);
+    else
+      ++LUI;
+  }
+}
+
+void LiveRegUnits::stepBackward(const MachineInstr &MI,
+                                const MCRegisterInfo &MCRI) {
+  // Remove defined registers and regmask kills from the set.
+  for (ConstMIBundleOperands O(&MI); O.isValid(); ++O) {
+    if (O->isReg()) {
+      if (!O->isDef())
+        continue;
+      unsigned Reg = O->getReg();
+      if (Reg == 0)
+        continue;
+      removeReg(Reg, MCRI);
+    } else if (O->isRegMask()) {
+      removeRegsInMask(*O, MCRI);
+    }
+  }
+  // Add uses to the set.
+  for (ConstMIBundleOperands O(&MI); O.isValid(); ++O) {
+    if (!O->isReg() || !O->readsReg() || O->isUndef())
+      continue;
+    unsigned Reg = O->getReg();
+    if (Reg == 0)
+      continue;
+    addReg(Reg, MCRI);
+  }
+}
+
+/// Uses with kill flag get removed from the set, defs added. If possible
+/// use StepBackward() instead of this function because some kill flags may
+/// be missing.
+void LiveRegUnits::stepForward(const MachineInstr &MI,
+                               const MCRegisterInfo &MCRI) {
+  SmallVector<unsigned, 4> Defs;
+  // Remove killed registers from the set.
+  for (ConstMIBundleOperands O(&MI); O.isValid(); ++O) {
+    if (O->isReg()) {
+      unsigned Reg = O->getReg();
+      if (Reg == 0)
+        continue;
+      if (O->isDef()) {
+        if (!O->isDead())
+          Defs.push_back(Reg);
+      } else {
+        if (!O->isKill())
+          continue;
+        assert(O->isUse());
+        removeReg(Reg, MCRI);
+      }
+    } else if (O->isRegMask()) {
+      removeRegsInMask(*O, MCRI);
+    }
+  }
+  // Add defs to the set.
+  for (unsigned i = 0, e = Defs.size(); i != e; ++i) {
+    addReg(Defs[i], MCRI);
+  }
+}
+
+/// Adds all registers in the live-in list of block @p BB.
+void LiveRegUnits::addLiveIns(const MachineBasicBlock *MBB,
+                              const MCRegisterInfo &MCRI) {
+  for (MachineBasicBlock::livein_iterator L = MBB->livein_begin(),
+         LE = MBB->livein_end(); L != LE; ++L) {
+    addReg(*L, MCRI);
+  }
+}