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.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@142787 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Utils/Local.cpp b/lib/Transforms/Utils/Local.cpp
index 7034feb..134ab71 100644
--- a/lib/Transforms/Utils/Local.cpp
+++ b/lib/Transforms/Utils/Local.cpp
@@ -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;
}