[llvm-commits] [llvm] r103726 - in /llvm/trunk: include/llvm/CodeGen/MachineRegisterInfo.h lib/CodeGen/MachineCSE.cpp lib/CodeGen/MachineRegisterInfo.cpp

[Dan Gohman]

Author: djg
Date: Thu May 13 14:24:00 2010
New Revision: 103726

URL: http://llvm.org/viewvc/llvm-project?rev=103726&view=rev
Log:
Add a utility function for conservatively clearing kill flags, and make
use of it in MachineCSE.

Modified:
    llvm/trunk/include/llvm/CodeGen/MachineRegisterInfo.h
    llvm/trunk/lib/CodeGen/MachineCSE.cpp
    llvm/trunk/lib/CodeGen/MachineRegisterInfo.cpp

Modified: llvm/trunk/include/llvm/CodeGen/MachineRegisterInfo.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/CodeGen/MachineRegisterInfo.h?rev=103726&r1=103725&r2=103726&view=diff
==============================================================================
--- llvm/trunk/include/llvm/CodeGen/MachineRegisterInfo.h (original)
+++ llvm/trunk/include/llvm/CodeGen/MachineRegisterInfo.h Thu May 13 14:24:00 2010
@@ -162,6 +162,12 @@
   /// register or null if none is found.  This assumes that the code is in SSA
   /// form, so there should only be one definition.
   MachineInstr *getVRegDef(unsigned Reg) const;
+
+  /// clearKillFlags - Iterate over all the uses of the given register and
+  /// clear the kill flag from the MachineOperand. This function is used by
+  /// optimization passes which extend register lifetimes and need only
+  /// preserve conservative kill flag information.
+  void clearKillFlags(unsigned Reg) const;
   
 #ifndef NDEBUG
   void dumpUses(unsigned RegNo) const;

Modified: llvm/trunk/lib/CodeGen/MachineCSE.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/MachineCSE.cpp?rev=103726&r1=103725&r2=103726&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/MachineCSE.cpp (original)
+++ llvm/trunk/lib/CodeGen/MachineCSE.cpp Thu May 13 14:24:00 2010
@@ -112,6 +112,7 @@
       DEBUG(dbgs() << "Coalescing: " << *DefMI);
       DEBUG(dbgs() << "*** to: " << *MI);
       MO.setReg(SrcReg);
+      MRI->clearKillFlags(SrcReg);
       if (NewRC != SRC)
         MRI->setRegClass(SrcReg, NewRC);
       DefMI->eraseFromParent();
@@ -365,8 +366,10 @@
 
     // Actually perform the elimination.
     if (DoCSE) {
-      for (unsigned i = 0, e = CSEPairs.size(); i != e; ++i)
+      for (unsigned i = 0, e = CSEPairs.size(); i != e; ++i) {
         MRI->replaceRegWith(CSEPairs[i].first, CSEPairs[i].second);
+        MRI->clearKillFlags(CSEPairs[i].second);
+      }
       MI->eraseFromParent();
       ++NumCSEs;
     } else {

Modified: llvm/trunk/lib/CodeGen/MachineRegisterInfo.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/MachineRegisterInfo.cpp?rev=103726&r1=103725&r2=103726&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/MachineRegisterInfo.cpp (original)
+++ llvm/trunk/lib/CodeGen/MachineRegisterInfo.cpp Thu May 13 14:24:00 2010
@@ -133,6 +133,15 @@
   return ++UI == use_nodbg_end();
 }
 
+/// clearKillFlags - Iterate over all the uses of the given register and
+/// clear the kill flag from the MachineOperand. This function is used by
+/// optimization passes which extend register lifetimes and need only
+/// preserve conservative kill flag information.
+void MachineRegisterInfo::clearKillFlags(unsigned Reg) const {
+  for (use_iterator UI = use_begin(Reg), UE = use_end(); UI != UE; ++UI)
+    UI.getOperand().setIsKill(false);
+}
+
 bool MachineRegisterInfo::isLiveIn(unsigned Reg) const {
   for (livein_iterator I = livein_begin(), E = livein_end(); I != E; ++I)
     if (I->first == Reg || I->second == Reg)