commit ecdefb5df755b260b79b94ab98acfe6fcee3318d
author Chris Lattner <sabre@nondot.org> Wed May 28 05:30:41 2008 +0000
committer Chris Lattner <sabre@nondot.org> Wed May 28 05:30:41 2008 +0000
tree 04ed8a680061a240d69816fdee875dd3e196d4cf
parent f8910ab6db9ae6baff10fbe96029b2005085e7b5

Implement PR2370: memmove(x,x,size) -> noop.

llvm-svn: 51636

llvm/lib/Transforms/Scalar/InstructionCombining.cpp

diff --git a/llvm/lib/Transforms/Scalar/InstructionCombining.cpp b/llvm/lib/Transforms/Scalar/InstructionCombining.cpp
index 2020415..8c2dc3e 100644
--- a/llvm/lib/Transforms/Scalar/InstructionCombining.cpp
+++ b/llvm/lib/Transforms/Scalar/InstructionCombining.cpp
@@ -9131,6 +9131,10 @@
           CI.setOperand(0, Intrinsic::getDeclaration(M, MemCpyID));
           Changed = true;
         }
+
+      // memmove(x,x,size) -> noop.
+      if (MMI->getSource() == MMI->getDest())
+        return EraseInstFromFunction(CI);
     }
 
     // If we can determine a pointer alignment that is bigger than currently