X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FCodeGen%2FLiveVariables.cpp;h=789eddc427747386ffefea72ea2d07f2e1d631f6;hb=c496875f0c205ffadcec8060e1170e1c58e4eb55;hp=348ed3a0f9329d4fe5641eadcff8db2eb9766862;hpb=7806c0778f22552ebe6711f3dc43887dc6097bfc;p=oota-llvm.git

diff --git a/lib/CodeGen/LiveVariables.cpp b/lib/CodeGen/LiveVariables.cpp
index 348ed3a0f93..789eddc4277 100644
--- a/lib/CodeGen/LiveVariables.cpp
+++ b/lib/CodeGen/LiveVariables.cpp
@@ -27,17 +27,17 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/CodeGen/LiveVariables.h"
+#include "llvm/ADT/DepthFirstIterator.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/ADT/SmallSet.h"
 #include "llvm/CodeGen/MachineInstr.h"
 #include "llvm/CodeGen/MachineRegisterInfo.h"
 #include "llvm/CodeGen/Passes.h"
 #include "llvm/Support/Debug.h"
+#include "llvm/Support/ErrorHandling.h"
 #include "llvm/Target/TargetInstrInfo.h"
 #include "llvm/Target/TargetMachine.h"
-#include "llvm/Support/ErrorHandling.h"
-#include "llvm/ADT/DepthFirstIterator.h"
-#include "llvm/ADT/SmallPtrSet.h"
-#include "llvm/ADT/SmallSet.h"
-#include "llvm/ADT/STLExtras.h"
 #include <algorithm>
 using namespace llvm;
 
@@ -65,6 +65,7 @@ LiveVariables::VarInfo::findKill(const MachineBasicBlock *MBB) const {
 }
 
 void LiveVariables::VarInfo::dump() const {
+#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
   dbgs() << "  Alive in blocks: ";
   for (SparseBitVector<>::iterator I = AliveBlocks.begin(),
            E = AliveBlocks.end(); I != E; ++I)
@@ -77,6 +78,7 @@ void LiveVariables::VarInfo::dump() const {
       dbgs() << "\n    #" << i << ": " << *Kills[i];
     dbgs() << "\n";
   }
+#endif
 }
 
 /// getVarInfo - Get (possibly creating) a VarInfo object for the given vreg.
@@ -501,8 +503,6 @@ bool LiveVariables::runOnMachineFunction(MachineFunction &mf) {
   MRI = &mf.getRegInfo();
   TRI = MF->getTarget().getRegisterInfo();
 
-  ReservedRegisters = TRI->getReservedRegs(mf);
-
   unsigned NumRegs = TRI->getNumRegs();
   PhysRegDef  = new MachineInstr*[NumRegs];
   PhysRegUse  = new MachineInstr*[NumRegs];
@@ -586,7 +586,7 @@ bool LiveVariables::runOnMachineFunction(MachineFunction &mf) {
         unsigned MOReg = UseRegs[i];
         if (TargetRegisterInfo::isVirtualRegister(MOReg))
           HandleVirtRegUse(MOReg, MBB, MI);
-        else if (!ReservedRegisters[MOReg])
+        else if (!MRI->isReserved(MOReg))
           HandlePhysRegUse(MOReg, MI);
       }
 
@@ -599,7 +599,7 @@ bool LiveVariables::runOnMachineFunction(MachineFunction &mf) {
         unsigned MOReg = DefRegs[i];
         if (TargetRegisterInfo::isVirtualRegister(MOReg))
           HandleVirtRegDef(MOReg, MI);
-        else if (!ReservedRegisters[MOReg])
+        else if (!MRI->isReserved(MOReg))
           HandlePhysRegDef(MOReg, MI, Defs);
       }
       UpdatePhysRegDefs(MI, Defs);
@@ -619,29 +619,6 @@ bool LiveVariables::runOnMachineFunction(MachineFunction &mf) {
                                 MBB);
     }
 
-    // Finally, if the last instruction in the block is a return, make sure to
-    // mark it as using all of the live-out values in the function.
-    // Things marked both call and return are tail calls; do not do this for
-    // them.  The tail callee need not take the same registers as input
-    // that it produces as output, and there are dependencies for its input
-    // registers elsewhere.
-    if (!MBB->empty() && MBB->back().isReturn()
-        && !MBB->back().isCall()) {
-      MachineInstr *Ret = &MBB->back();
-
-      for (MachineRegisterInfo::liveout_iterator
-           I = MF->getRegInfo().liveout_begin(),
-           E = MF->getRegInfo().liveout_end(); I != E; ++I) {
-        assert(TargetRegisterInfo::isPhysicalRegister(*I) &&
-               "Cannot have a live-out virtual register!");
-        HandlePhysRegUse(*I, Ret);
-
-        // Add live-out registers as implicit uses.
-        if (!Ret->readsRegister(*I))
-          Ret->addOperand(MachineOperand::CreateReg(*I, false, true));
-      }
-    }
-
     // MachineCSE may CSE instructions which write to non-allocatable physical
     // registers across MBBs. Remember if any reserved register is liveout.
     SmallSet<unsigned, 4> LiveOuts;
@@ -806,18 +783,44 @@ void LiveVariables::addNewBlock(MachineBasicBlock *BB,
                                 MachineBasicBlock *SuccBB) {
   const unsigned NumNew = BB->getNumber();
 
-  // All registers used by PHI nodes in SuccBB must be live through BB.
-  for (MachineBasicBlock::iterator BBI = SuccBB->begin(),
-         BBE = SuccBB->end(); BBI != BBE && BBI->isPHI(); ++BBI)
+  SmallSet<unsigned, 16> Defs, Kills;
+
+  MachineBasicBlock::iterator BBI = SuccBB->begin(), BBE = SuccBB->end();
+  for (; BBI != BBE && BBI->isPHI(); ++BBI) {
+    // Record the def of the PHI node.
+    Defs.insert(BBI->getOperand(0).getReg());
+
+    // All registers used by PHI nodes in SuccBB must be live through BB.
     for (unsigned i = 1, e = BBI->getNumOperands(); i != e; i += 2)
       if (BBI->getOperand(i+1).getMBB() == BB)
         getVarInfo(BBI->getOperand(i).getReg()).AliveBlocks.set(NumNew);
+  }
+
+  // Record all vreg defs and kills of all instructions in SuccBB.
+  for (; BBI != BBE; ++BBI) {
+    for (MachineInstr::mop_iterator I = BBI->operands_begin(),
+         E = BBI->operands_end(); I != E; ++I) {
+      if (I->isReg() && TargetRegisterInfo::isVirtualRegister(I->getReg())) {
+        if (I->isDef())
+          Defs.insert(I->getReg());
+        else if (I->isKill())
+          Kills.insert(I->getReg());
+      }
+    }
+  }
 
   // Update info for all live variables
   for (unsigned i = 0, e = MRI->getNumVirtRegs(); i != e; ++i) {
     unsigned Reg = TargetRegisterInfo::index2VirtReg(i);
+
+    // If the Defs is defined in the successor it can't be live in BB.
+    if (Defs.count(Reg))
+      continue;
+
+    // If the register is either killed in or live through SuccBB it's also live
+    // through BB.
     VarInfo &VI = getVarInfo(Reg);
-    if (!VI.AliveBlocks.test(NumNew) && VI.isLiveIn(*SuccBB, Reg, *MRI))
+    if (Kills.count(Reg) || VI.AliveBlocks.test(SuccBB->getNumber()))
       VI.AliveBlocks.set(NumNew);
   }
 }