Lower memcpy if it makes sense.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@42864 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp
index 2311f1e..5ff9714 100644
--- a/lib/Transforms/Scalar/InstructionCombining.cpp
+++ b/lib/Transforms/Scalar/InstructionCombining.cpp
@@ -7669,6 +7669,52 @@
MI->setAlignment(ConstantInt::get(Type::Int32Ty, Align));
Changed = true;
}
+
+ // If MemCpyInst length is 1/2/4/8 bytes then replace memcpy with load/store
+ ConstantInt *MemOpLength = dyn_cast<ConstantInt>(CI.getOperand(3));
+ if (isa<MemCpyInst>(MI))
+ if (MemOpLength) {
+ unsigned Size = MemOpLength->getZExtValue();
+ unsigned Align = cast<ConstantInt>(CI.getOperand(4))->getZExtValue();
+ const PointerType *PTy = cast<PointerType>(CI.getOperand(1)->getType());
+ const Type *MTy = PTy->getElementType();
+ PointerType *NewPtrTy = NULL;
+ if (MTy == Type::Int8Ty) {
+ if (Size == 8)
+ NewPtrTy = PointerType::get(Type::Int64Ty);
+ else if (Size == 4)
+ NewPtrTy = PointerType::get(Type::Int32Ty);
+ else if (Size == 2)
+ NewPtrTy = PointerType::get(Type::Int16Ty);
+ else if (Size == 1)
+ NewPtrTy = PointerType::get(Type::Int8Ty);
+ } else if (MTy == Type::Int16Ty) {
+ if (Size == 4)
+ NewPtrTy = PointerType::get(Type::Int64Ty);
+ else if (Size == 2)
+ NewPtrTy = PointerType::get(Type::Int32Ty);
+ else if (Size == 1)
+ NewPtrTy = PointerType::get(Type::Int16Ty);
+ } else if (MTy == Type::Int32Ty) {
+ if (Size == 2)
+ NewPtrTy = PointerType::get(Type::Int64Ty);
+ else if (Size == 1)
+ NewPtrTy = PointerType::get(Type::Int32Ty);
+ } else if (MTy == Type::Int64Ty) {
+ if (Size == 1)
+ NewPtrTy = PointerType::get(Type::Int64Ty);
+ }
+ if (NewPtrTy)
+ {
+ Value *Src = InsertCastBefore(Instruction::BitCast, CI.getOperand(2), NewPtrTy, CI);
+ Value *Dest = InsertCastBefore(Instruction::BitCast, CI.getOperand(1), NewPtrTy, CI);
+ Value *L = new LoadInst(Src, "tmp", false, Align, &CI);
+ Value *NS = new StoreInst(L, Dest, false, Align, &CI);
+ CI.replaceAllUsesWith(NS);
+ Changed = true;
+ return EraseInstFromFunction(CI);
+ }
+ }
} else if (isa<MemSetInst>(MI)) {
unsigned Alignment = GetOrEnforceKnownAlignment(MI->getDest(), TD);
if (MI->getAlignment()->getZExtValue() < Alignment) {