[llvm-commits] [llvm] r110589 - /llvm/trunk/lib/CodeGen/TwoAddressInstructionPass.cpp

[Jakob Stoklund Olesen]

Author: stoklund
Date: Mon Aug  9 15:19:16 2010
New Revision: 110589

URL: http://llvm.org/viewvc/llvm-project?rev=110589&view=rev
Log:
A REG_SEQUENCE instruction may use the same register twice.

If we are emitting COPY instructions for the REG_SEQUENCE, make sure the kill
flag goes on the last COPY. Otherwise we may be using a killed register.

<rdar://problem/8287792>

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=110589&r1=110588&r2=110589&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/TwoAddressInstructionPass.cpp (original)
+++ llvm/trunk/lib/CodeGen/TwoAddressInstructionPass.cpp Mon Aug  9 15:19:16 2010
@@ -1446,7 +1446,17 @@
         //
         // If the REG_SEQUENCE doesn't kill its source, keeping live variables
         // correctly up to date becomes very difficult. Insert a copy.
-        //
+
+        // Defer any kill flag to the last operand using SrcReg. Otherwise, we
+        // might insert a COPY that uses SrcReg after is was killed.
+        if (isKill)
+          for (unsigned j = i + 2; j < e; j += 2)
+            if (MI->getOperand(j).getReg() == SrcReg) {
+              MI->getOperand(j).setIsKill();
+              isKill = false;
+              break;
+            }
+
         MachineBasicBlock::iterator InsertLoc = MI;
         MachineInstr *CopyMI = BuildMI(*MI->getParent(), InsertLoc,
                                 MI->getDebugLoc(), TII->get(TargetOpcode::COPY))