MachineRegisterInfo: Introduce isPhysRegUsed()

[oota-llvm.git] / lib / CodeGen / LivePhysRegs.cpp

diff --git a/lib/CodeGen/LivePhysRegs.cpp b/lib/CodeGen/LivePhysRegs.cpp
index 2e103333c7888453932371e5d8890c502ac957e7..cbd98e3f3450f152d92b4056aa6429af25efe1ef 100644 (file)
--- a/lib/CodeGen/LivePhysRegs.cpp
+++ b/lib/CodeGen/LivePhysRegs.cpp
@@ -9,26 +9,32 @@
 //
 // This file implements the LivePhysRegs utility for tracking liveness of
 // physical registers across machine instructions in forward or backward order.
+// A more detailed description can be found in the corresponding header file.
 //
 //===----------------------------------------------------------------------===//
 
 #include "llvm/CodeGen/LivePhysRegs.h"
+#include "llvm/CodeGen/MachineFrameInfo.h"
+#include "llvm/CodeGen/MachineFunction.h"
 #include "llvm/CodeGen/MachineInstrBundle.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/raw_ostream.h"
 using namespace llvm;
 
 
-/// 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.
-
 /// \brief Remove all registers from the set that get clobbered by the register
 /// mask.
-void LivePhysRegs::removeRegsInMask(const MachineOperand &MO) {
+/// The clobbers set will be the list of live registers clobbered
+/// by the regmask.
+void LivePhysRegs::removeRegsInMask(const MachineOperand &MO,
+        SmallVectorImpl<std::pair<unsigned, const MachineOperand*>> *Clobbers) {
   SparseSet<unsigned>::iterator LRI = LiveRegs.begin();
   while (LRI != LiveRegs.end()) {
-    if (MO.clobbersPhysReg(*LRI))
+    if (MO.clobbersPhysReg(*LRI)) {
+      if (Clobbers)
+        Clobbers->push_back(std::make_pair(*LRI, &MO));
       LRI = LiveRegs.erase(LRI);
-    else
+    } else
       ++LRI;
   }
 }
@@ -46,7 +52,7 @@ void LivePhysRegs::stepBackward(const MachineInstr &MI) {
         continue;
       removeReg(Reg);
     } else if (O->isRegMask())
-      removeRegsInMask(*O);
+      removeRegsInMask(*O, nullptr);
   }
 
   // Add uses to the set.
@@ -64,8 +70,8 @@ void LivePhysRegs::stepBackward(const MachineInstr &MI) {
 /// killed-uses, add defs. This is the not recommended way, because it depends
 /// on accurate kill flags. If possible use stepBackwards() instead of this
 /// function.
-void LivePhysRegs::stepForward(const MachineInstr &MI) {
-  SmallVector<unsigned, 4> Defs;
+void LivePhysRegs::stepForward(const MachineInstr &MI,
+        SmallVectorImpl<std::pair<unsigned, const MachineOperand*>> &Clobbers) {
   // Remove killed registers from the set.
   for (ConstMIBundleOperands O(&MI); O.isValid(); ++O) {
     if (O->isReg()) {
@@ -73,8 +79,9 @@ void LivePhysRegs::stepForward(const MachineInstr &MI) {
       if (Reg == 0)
         continue;
       if (O->isDef()) {
-        if (!O->isDead())
-          Defs.push_back(Reg);
+        // Note, dead defs are still recorded.  The caller should decide how to
+        // handle them.
+        Clobbers.push_back(std::make_pair(Reg, &*O));
       } else {
         if (!O->isKill())
           continue;
@@ -82,10 +89,78 @@ void LivePhysRegs::stepForward(const MachineInstr &MI) {
         removeReg(Reg);
       }
     } else if (O->isRegMask())
-      removeRegsInMask(*O);
+      removeRegsInMask(*O, &Clobbers);
   }
 
   // Add defs to the set.
-  for (unsigned i = 0, e = Defs.size(); i != e; ++i)
-    addReg(Defs[i]);
+  for (auto Reg : Clobbers) {
+    // Skip dead defs.  They shouldn't be added to the set.
+    if (Reg.second->isReg() && Reg.second->isDead())
+      continue;
+    addReg(Reg.first);
+  }
+}
+
+/// Prin the currently live registers to OS.
+void LivePhysRegs::print(raw_ostream &OS) const {
+  OS << "Live Registers:";
+  if (!TRI) {
+    OS << " (uninitialized)\n";
+    return;
+  }
+
+  if (empty()) {
+    OS << " (empty)\n";
+    return;
+  }
+
+  for (const_iterator I = begin(), E = end(); I != E; ++I)
+    OS << " " << PrintReg(*I, TRI);
+  OS << "\n";
+}
+
+/// Dumps the currently live registers to the debug output.
+void LivePhysRegs::dump() const {
+#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
+  dbgs() << "  " << *this;
+#endif
+}
+
+/// Add live-in registers of basic block \p MBB to \p LiveRegs.
+static void addLiveIns(LivePhysRegs &LiveRegs, const MachineBasicBlock &MBB) {
+  for (unsigned Reg : make_range(MBB.livein_begin(), MBB.livein_end()))
+    LiveRegs.addReg(Reg);
+}
+
+/// Add pristine registers to the given \p LiveRegs. This function removes
+/// actually saved callee save registers when \p InPrologueEpilogue is false.
+static void addPristines(LivePhysRegs &LiveRegs, const MachineFunction &MF,
+                         const TargetRegisterInfo &TRI) {
+  const MachineFrameInfo &MFI = *MF.getFrameInfo();
+  if (!MFI.isCalleeSavedInfoValid())
+    return;
+
+  for (const MCPhysReg *CSR = TRI.getCalleeSavedRegs(&MF); CSR && *CSR; ++CSR)
+    LiveRegs.addReg(*CSR);
+  for (const CalleeSavedInfo &Info : MFI.getCalleeSavedInfo())
+    LiveRegs.removeReg(Info.getReg());
+}
+
+void LivePhysRegs::addLiveOuts(const MachineBasicBlock *MBB,
+                               bool AddPristines) {
+  if (AddPristines) {
+    const MachineFunction &MF = *MBB->getParent();
+    addPristines(*this, MF, *TRI);
+  }
+  for (const MachineBasicBlock *Succ : MBB->successors())
+    ::addLiveIns(*this, *Succ);
+}
+
+void LivePhysRegs::addLiveIns(const MachineBasicBlock *MBB,
+                              bool AddPristines) {
+  if (AddPristines) {
+    const MachineFunction &MF = *MBB->getParent();
+    addPristines(*this, MF, *TRI);
+  }
+  ::addLiveIns(*this, *MBB);
 }