commit a935db8ea28ee73be647e8aa46ce59baf9279306
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 972f570b46f92773f937cbd48c623bf3bcd70108
parent e5ab3355ba30d6d45ce67482039ee567f3763284

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



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@51636 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Transforms/Scalar/InstructionCombining.cpp

diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp
index 2020415..8c2dc3e 100644
--- a/lib/Transforms/Scalar/InstructionCombining.cpp
+++ b/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