[LV] Avoid redundant operations manipulating masks

The Loop Vectorizer generates redundant operations when manipulating masks:
AND with true, OR with false, compare equal to true. Instead of relying on
a subsequent pass to clean them up, this patch avoids generating them.

Use null (no-mask) to represent all-one full masks, instead of a constant
all-one vector, following the convention of masked gathers and scatters.

Preparing for a follow-up VPlan patch in which these mask manipulating
operations are modeled using recipes.

Differential Revision: https://reviews.llvm.org/D35725

llvm-svn: 309558

1 files changed, 2 insertions, 0 deletions

diff --git a/llvm/lib/IR/IRBuilder.cpp b/llvm/lib/IR/IRBuilder.cpp
index b7fa07c6ffa..89338c8b849 100644
--- a/llvm/lib/IR/IRBuilder.cpp
+++ b/llvm/lib/IR/IRBuilder.cpp
@@ -356,6 +356,7 @@ CallInst *IRBuilderBase::CreateMaskedLoad(Value *Ptr, unsigned Align,
   PointerType *PtrTy = cast<PointerType>(Ptr->getType());
   Type *DataTy = PtrTy->getElementType();
   assert(DataTy->isVectorTy() && "Ptr should point to a vector");
+  assert(Mask && "Mask should not be all-ones (null)");
   if (!PassThru)
     PassThru = UndefValue::get(DataTy);
   Type *OverloadedTypes[] = { DataTy, PtrTy };
@@ -375,6 +376,7 @@ CallInst *IRBuilderBase::CreateMaskedStore(Value *Val, Value *Ptr,
   PointerType *PtrTy = cast<PointerType>(Ptr->getType());
   Type *DataTy = PtrTy->getElementType();
   assert(DataTy->isVectorTy() && "Ptr should point to a vector");
+  assert(Mask && "Mask should not be all-ones (null)");
   Type *OverloadedTypes[] = { DataTy, PtrTy };
   Value *Ops[] = { Val, Ptr, getInt32(Align), Mask };
   return CreateMaskedIntrinsic(Intrinsic::masked_store, Ops, OverloadedTypes);