[llvm] r294452 - [InstCombineCalls] Remove zero length atomic memcpy intrinsics

[Igor Laevsky via llvm-commits]

Author: igor.laevsky
Date: Wed Feb  8 08:23:47 2017
New Revision: 294452

URL: http://llvm.org/viewvc/llvm-project?rev=294452&view=rev
Log:
[InstCombineCalls] Remove zero length atomic memcpy intrinsics

Differential Revision: https://reviews.llvm.org/D28909


Modified:
    llvm/trunk/include/llvm/IR/IntrinsicInst.h
    llvm/trunk/lib/Transforms/InstCombine/InstCombineCalls.cpp

Modified: llvm/trunk/include/llvm/IR/IntrinsicInst.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/IR/IntrinsicInst.h?rev=294452&r1=294451&r2=294452&view=diff
==============================================================================
--- llvm/trunk/include/llvm/IR/IntrinsicInst.h (original)
+++ llvm/trunk/include/llvm/IR/IntrinsicInst.h Wed Feb  8 08:23:47 2017
@@ -191,6 +191,32 @@ namespace llvm {
     }
   };
 
+  /// This class represents atomic memcpy intrinsic
+  /// TODO: Integrate this class into MemIntrinsic hierarchy.
+  class ElementAtomicMemCpyInst : public IntrinsicInst {
+  public:
+    Value *getRawDest() const { return getArgOperand(0); }
+    Value *getRawSource() const { return getArgOperand(1); }
+
+    Value *getNumElements() const { return getArgOperand(2); }
+    void setNumElements(Value *V) { setArgOperand(2, V); }
+
+    uint64_t getSrcAlignment() const { return getParamAlignment(1); }
+    uint64_t getDstAlignment() const { return getParamAlignment(2); }
+
+    uint64_t getElementSizeInBytes() const {
+      Value *Arg = getArgOperand(3);
+      return cast<ConstantInt>(Arg)->getZExtValue();
+    }
+
+    static inline bool classof(const IntrinsicInst *I) {
+      return I->getIntrinsicID() == Intrinsic::memcpy_element_atomic;
+    }
+    static inline bool classof(const Value *V) {
+      return isa<IntrinsicInst>(V) && classof(cast<IntrinsicInst>(V));
+    }
+  };
+
   /// This is the common base class for memset/memcpy/memmove.
   class MemIntrinsic : public IntrinsicInst {
   public:

Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineCalls.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineCalls.cpp?rev=294452&r1=294451&r2=294452&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineCalls.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineCalls.cpp Wed Feb  8 08:23:47 2017
@@ -1835,6 +1835,12 @@ Instruction *InstCombiner::visitCallInst
     if (Changed) return II;
   }
 
+  if (auto *AMI = dyn_cast<ElementAtomicMemCpyInst>(II)) {
+    if (Constant *C = dyn_cast<Constant>(AMI->getNumElements()))
+      if (C->isNullValue())
+        return eraseInstFromFunction(*AMI);
+  }
+
   if (Instruction *I = SimplifyNVVMIntrinsic(II, *this))
     return I;