[llvm-commits] [llvm] r142787 - in /llvm/trunk: lib/Transforms/Utils/Local.cpp test/Transforms/DeadStoreElimination/simple.ll

[Nick Lewycky]

Author: nicholas
Date: Sun Oct 23 23:35:36 2011
New Revision: 142787

URL: http://llvm.org/viewvc/llvm-project?rev=142787&view=rev
Log:
A dead malloc, a free(NULL) and a free(undef) are all trivially dead
instructions.

This doesn't introduce any optimizations we weren't doing before (except
potentially due to pass ordering issues), now passes will eliminate them sooner
as part of their own cleanups.

Modified:
    llvm/trunk/lib/Transforms/Utils/Local.cpp
    llvm/trunk/test/Transforms/DeadStoreElimination/simple.ll

Modified: llvm/trunk/lib/Transforms/Utils/Local.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/Local.cpp?rev=142787&r1=142786&r2=142787&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Utils/Local.cpp (original)
+++ llvm/trunk/lib/Transforms/Utils/Local.cpp Sun Oct 23 23:35:36 2011
@@ -28,6 +28,7 @@
 #include "llvm/Analysis/DIBuilder.h"
 #include "llvm/Analysis/Dominators.h"
 #include "llvm/Analysis/InstructionSimplify.h"
+#include "llvm/Analysis/MemoryBuiltins.h"
 #include "llvm/Analysis/ProfileInfo.h"
 #include "llvm/Analysis/ValueTracking.h"
 #include "llvm/Target/TargetData.h"
@@ -257,6 +258,13 @@
         II->getIntrinsicID() == Intrinsic::lifetime_end)
       return isa<UndefValue>(II->getArgOperand(1));
   }
+
+  if (extractMallocCall(I)) return true;
+
+  if (CallInst *CI = isFreeCall(I))
+    if (Constant *C = dyn_cast<Constant>(CI->getArgOperand(0)))
+      return C->isNullValue() || isa<UndefValue>(C);
+
   return false;
 }
 

Modified: llvm/trunk/test/Transforms/DeadStoreElimination/simple.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/DeadStoreElimination/simple.ll?rev=142787&r1=142786&r2=142787&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/DeadStoreElimination/simple.ll (original)
+++ llvm/trunk/test/Transforms/DeadStoreElimination/simple.ll Sun Oct 23 23:35:36 2011
@@ -257,5 +257,4 @@
   ret void
 }
 ; CHECK: @test20
-; CHECK-NOT: store
-; CHECK: ret void
+; CHECK-NEXT: ret void