[llvm-commits] [llvm] r160194 - /llvm/trunk/lib/CodeGen/TwoAddressInstructionPass.cpp

[Chandler Carruth]

Author: chandlerc
Date: Fri Jul 13 16:18:38 2012
New Revision: 160194

URL: http://llvm.org/viewvc/llvm-project?rev=160194&view=rev
Log:
Use the LiveVariables information to efficiently get local kills. This
removes the largest scaling problem in the test cases from PR13225 when
ASan is switched to insert basic blocks in the natural CFG order.

It may also solve some scaling problems for more normal code with large
numbers of basic blocks and variables.

Modified:
    llvm/trunk/lib/CodeGen/TwoAddressInstructionPass.cpp

Modified: llvm/trunk/lib/CodeGen/TwoAddressInstructionPass.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/TwoAddressInstructionPass.cpp?rev=160194&r1=160193&r2=160194&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/TwoAddressInstructionPass.cpp (original)
+++ llvm/trunk/lib/CodeGen/TwoAddressInstructionPass.cpp Fri Jul 13 16:18:38 2012
@@ -483,32 +483,6 @@
   return false;
 }
 
-/// findLocalKill - Look for an instruction below MI in the MBB that kills the
-/// specified register. Returns null if there are any other Reg use between the
-/// instructions.
-static
-MachineInstr *findLocalKill(unsigned Reg, MachineBasicBlock *MBB,
-                            MachineInstr *MI, MachineRegisterInfo *MRI,
-                            DenseMap<MachineInstr*, unsigned> &DistanceMap) {
-  MachineInstr *KillMI = 0;
-  for (MachineRegisterInfo::use_nodbg_iterator
-         UI = MRI->use_nodbg_begin(Reg),
-         UE = MRI->use_nodbg_end(); UI != UE; ++UI) {
-    MachineInstr *UseMI = &*UI;
-    if (UseMI == MI || UseMI->getParent() != MBB)
-      continue;
-    if (DistanceMap.count(UseMI))
-      continue;
-    if (!UI.getOperand().isKill())
-      return 0;
-    if (KillMI)
-      return 0;  // -O0 kill markers cannot be trusted?
-    KillMI = UseMI;
-  }
-
-  return KillMI;
-}
-
 /// findOnlyInterestingUse - Given a register, if has a single in-basic block
 /// use, return the use instruction if it's a copy or a two-address use.
 static
@@ -905,13 +879,18 @@
                                      MachineBasicBlock::iterator &mi,
                                      MachineBasicBlock::iterator &nmi,
                                      unsigned Reg) {
+  // Bail immediately if we don't have LV available. We use it to find kills
+  // efficiently.
+  if (!LV)
+    return false;
+
   MachineInstr *MI = &*mi;
   DenseMap<MachineInstr*, unsigned>::iterator DI = DistanceMap.find(MI);
   if (DI == DistanceMap.end())
     // Must be created from unfolded load. Don't waste time trying this.
     return false;
 
-  MachineInstr *KillMI = findLocalKill(Reg, MBB, mi, MRI, DistanceMap);
+  MachineInstr *KillMI = LV->getVarInfo(Reg).findKill(MBB);
   if (!KillMI || KillMI->isCopy() || KillMI->isCopyLike())
     // Don't mess with copies, they may be coalesced later.
     return false;
@@ -1012,19 +991,9 @@
   MBB->splice(KillPos, MBB, From, To);
   DistanceMap.erase(DI);
 
-  if (LV) {
-    // Update live variables
-    LV->removeVirtualRegisterKilled(Reg, KillMI);
-    LV->addVirtualRegisterKilled(Reg, MI);
-  } else {
-    for (unsigned i = 0, e = KillMI->getNumOperands(); i != e; ++i) {
-      MachineOperand &MO = KillMI->getOperand(i);
-      if (!MO.isReg() || !MO.isUse() || MO.getReg() != Reg)
-        continue;
-      MO.setIsKill(false);
-    }
-    MI->addRegisterKilled(Reg, 0);
-  }
+  // Update live variables
+  LV->removeVirtualRegisterKilled(Reg, KillMI);
+  LV->addVirtualRegisterKilled(Reg, MI);
 
   return true;
 }
@@ -1061,13 +1030,18 @@
                                      MachineBasicBlock::iterator &mi,
                                      MachineBasicBlock::iterator &nmi,
                                      unsigned Reg) {
+  // Bail immediately if we don't have LV available. We use it to find kills
+  // efficiently.
+  if (!LV)
+    return false;
+
   MachineInstr *MI = &*mi;
   DenseMap<MachineInstr*, unsigned>::iterator DI = DistanceMap.find(MI);
   if (DI == DistanceMap.end())
     // Must be created from unfolded load. Don't waste time trying this.
     return false;
 
-  MachineInstr *KillMI = findLocalKill(Reg, MBB, mi, MRI, DistanceMap);
+  MachineInstr *KillMI = LV->getVarInfo(Reg).findKill(MBB);
   if (!KillMI || KillMI->isCopy() || KillMI->isCopyLike())
     // Don't mess with copies, they may be coalesced later.
     return false;
@@ -1165,19 +1139,10 @@
   nmi = llvm::prior(InsertPos); // Backtrack so we process the moved instr.
   DistanceMap.erase(DI);
 
-  if (LV) {
-    // Update live variables
-    LV->removeVirtualRegisterKilled(Reg, KillMI);
-    LV->addVirtualRegisterKilled(Reg, MI);
-  } else {
-    for (unsigned i = 0, e = KillMI->getNumOperands(); i != e; ++i) {
-      MachineOperand &MO = KillMI->getOperand(i);
-      if (!MO.isReg() || !MO.isUse() || MO.getReg() != Reg)
-        continue;
-      MO.setIsKill(false);
-    }
-    MI->addRegisterKilled(Reg, 0);
-  }
+  // Update live variables
+  LV->removeVirtualRegisterKilled(Reg, KillMI);
+  LV->addVirtualRegisterKilled(Reg, MI);
+
   return true;
 }