Handle cases when joining live intervals of two virtual registers.

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

diff --git a/lib/CodeGen/LiveIntervalAnalysis.cpp b/lib/CodeGen/LiveIntervalAnalysis.cpp
index 29c095a1aa470024a7188a78573d5252c49d5b28..ce2e4290b164636711f24daa164ee4f8e3ce3e96 100644 (file)
--- a/lib/CodeGen/LiveIntervalAnalysis.cpp
+++ b/lib/CodeGen/LiveIntervalAnalysis.cpp
@@ -959,7 +959,29 @@ bool LiveIntervals::JoinCopy(MachineInstr *CopyMI,
 
   DOUT << "\n\t\tJoined.  Result = "; DestInt.print(DOUT, mri_);
   DOUT << "\n";
-  
+
+  // Live range has been lengthened due to colaescing, eliminate the
+  // unnecessary kills at the end of the source live ranges.
+  LiveVariables::VarInfo& svi = lv_->getVarInfo(repSrcReg);
+  for (unsigned i = 0, e = svi.Kills.size(); i != e; ++i) {
+    MachineInstr *Kill = svi.Kills[i];
+    if (Kill == CopyMI || isRemoved(Kill))
+      continue;
+    if (DestInt.liveAt(getInstructionIndex(Kill) + InstrSlots::NUM))
+      unsetRegisterKill(Kill, repSrcReg);
+  }
+  if (MRegisterInfo::isVirtualRegister(repDstReg)) {
+    // If both are virtual registers...
+    LiveVariables::VarInfo& dvi = lv_->getVarInfo(repDstReg);
+    for (unsigned i = 0, e = dvi.Kills.size(); i != e; ++i) {
+      MachineInstr *Kill = dvi.Kills[i];
+      if (Kill == CopyMI || isRemoved(Kill))
+        continue;
+      if (DestInt.liveAt(getInstructionIndex(Kill) + InstrSlots::NUM))
+        unsetRegisterKill(Kill, repDstReg);
+    }
+  }
+
   // If the intervals were swapped by Join, swap them back so that the register
   // mapping (in the r2i map) is correct.
   if (Swapped) SrcInt.swap(DestInt);
@@ -1471,6 +1493,17 @@ LiveIntervals::hasRegisterUse(unsigned Reg, unsigned Start, unsigned End) {
   return false;
 }
 
+/// unsetRegisterKill - Unset IsKill property of all uses of specific register
+/// of the specific instruction.
+void LiveIntervals::unsetRegisterKill(MachineInstr *MI, unsigned Reg) {
+  for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
+    MachineOperand &MO = MI->getOperand(i);
+    if (MO.isReg() && MO.isUse() && MO.isKill() && MO.getReg() &&
+        mri_->regsOverlap(rep(MO.getReg()), Reg))
+      MO.unsetIsKill();
+  }
+}
+
 LiveInterval LiveIntervals::createInterval(unsigned reg) {
   float Weight = MRegisterInfo::isPhysicalRegister(reg) ?
                        HUGE_VALF : 0.0F;