[llvm-commits] [llvm] r144569 - /llvm/trunk/lib/CodeGen/TwoAddressInstructionPass.cpp

[Evan Cheng]

Author: evancheng
Date: Mon Nov 14 15:11:15 2011
New Revision: 144569

URL: http://llvm.org/viewvc/llvm-project?rev=144569&view=rev
Log:
Avoid dereferencing off the beginning of lists.

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=144569&r1=144568&r2=144569&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/TwoAddressInstructionPass.cpp (original)
+++ llvm/trunk/lib/CodeGen/TwoAddressInstructionPass.cpp Mon Nov 14 15:11:15 2011
@@ -999,10 +999,8 @@
   }
 
   // Move debug info as well.
-  if (From != MBB->begin()) {
-    while (llvm::prior(From)->isDebugValue())
-      --From;
-  }
+  while (From != MBB->begin() && llvm::prior(From)->isDebugValue())
+    --From;
 
   // Copies following MI may have been moved as well.
   nmi = To;
@@ -1146,9 +1144,8 @@
 
   // Move the old kill above MI, don't forget to move debug info as well.
   MachineBasicBlock::iterator InsertPos = mi;
-  if (InsertPos != MBB->begin())
-    while (llvm::prior(InsertPos)->isDebugValue())
-      --InsertPos;
+  while (InsertPos != MBB->begin() && llvm::prior(InsertPos)->isDebugValue())
+    --InsertPos;
   MachineBasicBlock::iterator From = KillMI;
   MachineBasicBlock::iterator To = llvm::next(From);
   while (llvm::prior(From)->isDebugValue())