[llvm-commits] [llvm] r102678 - /llvm/trunk/lib/CodeGen/SelectionDAG/InstrEmitter.cpp

[Dan Gohman]

Author: djg
Date: Thu Apr 29 19:08:21 2010
New Revision: 102678

URL: http://llvm.org/viewvc/llvm-project?rev=102678&view=rev
Log:
Set register kill flags on the SelectionDAG path, at least in the
easy cases.

Modified:
    llvm/trunk/lib/CodeGen/SelectionDAG/InstrEmitter.cpp

Modified: llvm/trunk/lib/CodeGen/SelectionDAG/InstrEmitter.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/InstrEmitter.cpp?rev=102678&r1=102677&r2=102678&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/InstrEmitter.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/InstrEmitter.cpp Thu Apr 29 19:08:21 2010
@@ -296,8 +296,19 @@
     }
   }
 
+  // If this value has only one use, that use is a kill. This is a
+  // conservative approximation. Tied operands are never killed, so we need
+  // to check that. And that means we need to determine the index of the
+  // operand.
+  unsigned Idx = MI->getNumOperands();
+  while (Idx > 0 &&
+         MI->getOperand(Idx-1).isReg() && MI->getOperand(Idx-1).isImplicit())
+    --Idx;
+  bool isTied = MI->getDesc().getOperandConstraint(Idx, TOI::TIED_TO) != -1;
+  bool isKill = Op.hasOneUse() && !isTied;
+
   MI->addOperand(MachineOperand::CreateReg(VReg, isOptDef,
-                                           false/*isImp*/, false/*isKill*/,
+                                           false/*isImp*/, isKill,
                                            false/*isDead*/, false/*isUndef*/,
                                            false/*isEarlyClobber*/,
                                            0/*SubReg*/, IsDebug));