[llvm-commits] [llvm] r51636 - in /llvm/trunk: lib/Transforms/Scalar/InstructionCombining.cpp test/Transforms/InstCombine/memmove.ll

[Chris Lattner]

Author: lattner
Date: Wed May 28 00:30:41 2008
New Revision: 51636

URL: http://llvm.org/viewvc/llvm-project?rev=51636&view=rev
Log:
Implement PR2370: memmove(x,x,size) -> noop.


Modified:
    llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp
    llvm/trunk/test/Transforms/InstCombine/memmove.ll

Modified: llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp?rev=51636&r1=51635&r2=51636&view=diff

==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp Wed May 28 00:30:41 2008
@@ -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

Modified: llvm/trunk/test/Transforms/InstCombine/memmove.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/memmove.ll?rev=51636&r1=51635&r2=51636&view=diff

==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/memmove.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/memmove.ll Wed May 28 00:30:41 2008
@@ -34,3 +34,9 @@
 	ret i32 0
 }
 
+; PR2370
+define void @test4(i8* %a) {
+        tail call void @llvm.memmove.i32( i8* %a, i8* %a, i32 100, i32 1 )
+        ret void
+}
+