Refactor linalg lowering to LLVM

The linalg.view type used to be lowered to a struct containing a data pointer, offset, sizes/strides information. This was problematic when passing to external functions due to ABI, struct padding and alignment issues.

The linalg.view type is now lowered to LLVMIR as a *pointer* to a struct containing the data pointer, offset and sizes/strides. This simplifies the interfacing with external library functions and makes it trivial to add new functions without creating a shim that would go from a value type struct to a pointer type.

The consequences are that:
1. lowering explicitly uses llvm.alloca in lieu of llvm.undef and performs the proper llvm.load/llvm.store where relevant.
2. the shim creation function `getLLVMLibraryCallDefinition` disappears.
3. views are passed by pointer, scalars are passed by value. In the future, other structs will be passed by pointer (on a per-need basis).

PiperOrigin-RevId: 264183671

3 files changed, 142 insertions, 133 deletions

diff --git a/mlir/lib/Conversion/GPUToCUDA/ConvertLaunchFuncToCudaCalls.cpp b/mlir/lib/Conversion/GPUToCUDA/ConvertLaunchFuncToCudaCalls.cpp
index b3864a39560..a3b80b1e9e0 100644
--- a/mlir/lib/Conversion/GPUToCUDA/ConvertLaunchFuncToCudaCalls.cpp
+++ b/mlir/lib/Conversion/GPUToCUDA/ConvertLaunchFuncToCudaCalls.cpp
@@ -111,7 +111,8 @@ private:
   Value *allocatePointer(OpBuilder &builder, Location loc) {
     auto one = builder.create<LLVM::ConstantOp>(loc, getInt32Type(),
                                                 builder.getI32IntegerAttr(1));
-    return builder.create<LLVM::AllocaOp>(loc, getPointerPointerType(), one);
+    return builder.create<LLVM::AllocaOp>(loc, getPointerPointerType(), one,
+                                          /*alignment=*/0);
   }
 
   void declareCudaFunctions(Location loc);
@@ -233,13 +234,13 @@ GpuLaunchFuncToCudaCallsPass::setupParamsArray(gpu::LaunchFuncOp launchOp,
   auto arraySize = builder.create<LLVM::ConstantOp>(
       loc, getInt32Type(),
       builder.getI32IntegerAttr(launchOp.getNumKernelOperands()));
-  auto array =
-      builder.create<LLVM::AllocaOp>(loc, getPointerPointerType(), arraySize);
+  auto array = builder.create<LLVM::AllocaOp>(loc, getPointerPointerType(),
+                                              arraySize, /*alignment=*/0);
   for (int idx = 0, e = launchOp.getNumKernelOperands(); idx < e; ++idx) {
     auto operand = launchOp.getKernelOperand(idx);
     auto llvmType = operand->getType().cast<LLVM::LLVMType>();
-    auto memLocation =
-        builder.create<LLVM::AllocaOp>(loc, llvmType.getPointerTo(), one);
+    auto memLocation = builder.create<LLVM::AllocaOp>(
+        loc, llvmType.getPointerTo(), one, /*alignment=*/1);
     builder.create<LLVM::StoreOp>(loc, operand, memLocation);
     auto casted =
         builder.create<LLVM::BitcastOp>(loc, getPointerType(), memLocation);
@@ -267,8 +268,8 @@ Value *GpuLaunchFuncToCudaCallsPass::generateKernelNameConstant(
   auto kernelNameSize = builder.create<LLVM::ConstantOp>(
       loc, getInt32Type(),
       builder.getI32IntegerAttr(kernelFunction.getName().size() + 1));
-  auto kernelName =
-      builder.create<LLVM::AllocaOp>(loc, getPointerType(), kernelNameSize);
+  auto kernelName = builder.create<LLVM::AllocaOp>(
+      loc, getPointerType(), kernelNameSize, /*alignment=*/1);
   for (auto byte : llvm::enumerate(kernelFunction.getName())) {
     auto index = builder.create<LLVM::ConstantOp>(
         loc, getInt32Type(), builder.getI32IntegerAttr(byte.index()));
diff --git a/mlir/lib/Conversion/StandardToLLVM/ConvertStandardToLLVM.cpp b/mlir/lib/Conversion/StandardToLLVM/ConvertStandardToLLVM.cpp
index 9ba06db7aba..4240e3e7ae7 100644
--- a/mlir/lib/Conversion/StandardToLLVM/ConvertStandardToLLVM.cpp
+++ b/mlir/lib/Conversion/StandardToLLVM/ConvertStandardToLLVM.cpp
@@ -808,10 +808,7 @@ struct LoadOpLowering : public LoadStoreOpLowering<LoadOp> {
 
     Value *dataPtr = getDataPtr(op->getLoc(), type, transformed.memref(),
                                 transformed.indices(), rewriter, getModule());
-    auto elementType = lowering.convertType(type.getElementType());
-
-    rewriter.replaceOpWithNewOp<LLVM::LoadOp>(op, elementType,
-                                              ArrayRef<Value *>{dataPtr});
+    rewriter.replaceOpWithNewOp<LLVM::LoadOp>(op, dataPtr);
     return matchSuccess();
   }
 };
diff --git a/mlir/lib/Linalg/Transforms/LowerToLLVMDialect.cpp b/mlir/lib/Linalg/Transforms/LowerToLLVMDialect.cpp
index de183f8f76e..05bdf24a975 100644
--- a/mlir/lib/Linalg/Transforms/LowerToLLVMDialect.cpp
+++ b/mlir/lib/Linalg/Transforms/LowerToLLVMDialect.cpp
@@ -117,21 +117,22 @@ static Type convertLinalgType(Type t, LLVMTypeConverter &lowering) {
   if (t.isa<RangeType>())
     return LLVMType::getStructTy(int64Ty, int64Ty, int64Ty);
 
-  // View descriptor contains the pointer to the data buffer, followed by a
-  // 64-bit integer containing the distance between the beginning of the buffer
-  // and the first element to be accessed through the view, followed by two
-  // arrays, each containing as many 64-bit integers as the rank of the View.
-  // The first array represents the size, in number of original elements, of the
-  // view along the given dimension.  When taking the view, the size is the
-  // difference between the upper and the lower bound of the range.  The second
-  // array represents the "stride" (in tensor abstraction sense), i.e. the
-  // number of consecutive elements of the underlying buffer that separate two
-  // consecutive elements addressable through the view along the given
-  // dimension.  When taking the view, the strides are constructed as products
-  // of the original sizes along the trailing dimensions, multiplied by the view
-  // step.  For example, a view of a MxN memref with ranges {0:M:1}, {0:N:1},
-  // i.e. the view of a complete memref, will have strides N and 1.  A view with
-  // ranges {0:M:2}, {0:N:3} will have strides 2*N and 3.
+  // A linalg.view type converts to a *pointer to* a view descriptor. The view
+  // descriptor contains the pointer to the data buffer, followed by a 64-bit
+  // integer containing the distance between the beginning of the buffer and the
+  // first element to be accessed through the view, followed by two arrays, each
+  // containing as many 64-bit integers as the rank of the View. The first array
+  // represents the size, in number of original elements, of the view along the
+  // given dimension.  When taking the view, the size is the difference between
+  // the upper and the lower bound of the range. The second array represents the
+  // "stride" (in tensor abstraction sense), i.e. the number of consecutive
+  // elements of the underlying buffer that separate two consecutive elements
+  // addressable through the view along the given dimension.  When taking the
+  // view, the strides are constructed as products of the original sizes along
+  // the trailing dimensions, multiplied by the view step.  For example, a view
+  // of a MxN memref with ranges {0:M:1}, {0:N:1}, i.e. the view of a complete
+  // memref, will have strides N and 1.  A view with ranges {0:M:2}, {0:N:3}
+  // will have strides 2*N and 3.
   //
   // template <typename Elem, size_t Rank>
   // struct {
@@ -139,16 +140,24 @@ static Type convertLinalgType(Type t, LLVMTypeConverter &lowering) {
   //   int64_t offset;
   //   int64_t sizes[Rank];
   //   int64_t strides[Rank];
-  // };
+  // } *;
   if (auto viewType = t.dyn_cast<ViewType>()) {
     auto ptrTy = getPtrToElementType(viewType, lowering);
     auto arrayTy = LLVMType::getArrayTy(int64Ty, viewType.getRank());
-    return LLVMType::getStructTy(ptrTy, int64Ty, arrayTy, arrayTy);
+    return LLVMType::getStructTy(ptrTy, int64Ty, arrayTy, arrayTy)
+        .getPointerTo();
   }
 
   return Type();
 }
 
+static constexpr int kPtrPosInBuffer = 0;
+static constexpr int kSizePosInBuffer = 1;
+static constexpr int kPtrPosInView = 0;
+static constexpr int kOffsetPosInView = 1;
+static constexpr int kSizePosInView = 2;
+static constexpr int kStridePosInView = 3;
+
 // Create an array attribute containing integer attributes with values provided
 // in `position`.
 static ArrayAttr positionAttr(Builder &builder, ArrayRef<int> position) {
@@ -192,10 +201,9 @@ public:
                     llvm::divideCeil(vectorType.getElementTypeBitWidth(), 8);
     else
       elementSize = llvm::divideCeil(elementType.getIntOrFloatBitWidth(), 8);
-    auto bufferType = allocOp.getResult()->getType().cast<BufferType>();
+    auto bufferType = allocOp.getBufferType();
     auto elementPtrType = getPtrToElementType(bufferType, lowering);
-    auto bufferDescriptorType =
-        convertLinalgType(allocOp.getResult()->getType(), lowering);
+    auto bufferDescriptorTy = convertLinalgType(bufferType, lowering);
 
     // Emit IR for creating a new buffer descriptor with an underlying malloc.
     edsc::ScopedContext context(rewriter, op->getLoc());
@@ -212,11 +220,11 @@ public:
             .getOperation()
             ->getResult(0);
     allocated = bitcast(elementPtrType, allocated);
-    Value *desc = undef(bufferDescriptorType);
-    desc = insertvalue(bufferDescriptorType, desc, allocated,
-                       positionAttr(rewriter, 0));
-    desc = insertvalue(bufferDescriptorType, desc, size,
-                       positionAttr(rewriter, 1));
+    Value *desc = undef(bufferDescriptorTy);
+    desc = insertvalue(bufferDescriptorTy, desc, allocated,
+                       positionAttr(rewriter, kPtrPosInBuffer));
+    desc = insertvalue(bufferDescriptorTy, desc, size,
+                       positionAttr(rewriter, kSizePosInBuffer));
     rewriter.replaceOp(op, desc);
     return matchSuccess();
   }
@@ -246,13 +254,15 @@ public:
 
     // Get MLIR types for extracting element pointer.
     auto deallocOp = cast<BufferDeallocOp>(op);
-    auto elementPtrTy = getPtrToElementType(
-        deallocOp.getOperand()->getType().cast<BufferType>(), lowering);
+    auto elementPtrTy =
+        getPtrToElementType(deallocOp.getBufferType(), lowering);
 
     // Emit MLIR for buffer_dealloc.
+    BufferDeallocOpOperandAdaptor adaptor(operands);
     edsc::ScopedContext context(rewriter, op->getLoc());
-    Value *casted = bitcast(voidPtrTy, extractvalue(elementPtrTy, operands[0],
-                                                    positionAttr(rewriter, 0)));
+    Value *casted =
+        bitcast(voidPtrTy, extractvalue(elementPtrTy, adaptor.buffer(),
+                                        positionAttr(rewriter, 0)));
     llvm_call(ArrayRef<Type>(), rewriter.getSymbolRefAttr(freeFunc), casted);
     rewriter.replaceOp(op, llvm::None);
     return matchSuccess();
@@ -270,8 +280,10 @@ public:
                   ConversionPatternRewriter &rewriter) const override {
     auto int64Ty = lowering.convertType(rewriter.getIntegerType(64));
     edsc::ScopedContext context(rewriter, op->getLoc());
+    BufferSizeOpOperandAdaptor adaptor(operands);
     rewriter.replaceOp(
-        op, {extractvalue(int64Ty, operands[0], positionAttr(rewriter, 1))});
+        op, {extractvalue(int64Ty, adaptor.buffer(),
+                          positionAttr(rewriter, kSizePosInBuffer))});
     return matchSuccess();
   }
 };
@@ -288,11 +300,11 @@ public:
     auto dimOp = cast<linalg::DimOp>(op);
     auto indexTy = lowering.convertType(rewriter.getIndexType());
     edsc::ScopedContext context(rewriter, op->getLoc());
-    rewriter.replaceOp(
-        op,
-        {extractvalue(
-            indexTy, operands[0],
-            positionAttr(rewriter, {2, static_cast<int>(dimOp.getIndex())}))});
+    auto pos = positionAttr(
+        rewriter, {kSizePosInView, static_cast<int>(dimOp.getIndex())});
+    linalg::DimOpOperandAdaptor adaptor(operands);
+    Value *viewDescriptor = llvm_load(adaptor.view());
+    rewriter.replaceOp(op, {extractvalue(indexTy, viewDescriptor, pos)});
     return matchSuccess();
   }
 };
@@ -311,7 +323,7 @@ public:
   // current view indices.  Use the base offset and strides stored in the view
   // descriptor to emit IR iteratively computing the actual offset, followed by
   // a getelementptr. This must be called under an edsc::ScopedContext.
-  Value *obtainDataPtr(Operation *op, Value *viewDescriptor,
+  Value *obtainDataPtr(Operation *op, Value *viewDescriptorPtr,
                        ArrayRef<Value *> indices,
                        ConversionPatternRewriter &rewriter) const {
     auto loadOp = cast<Op>(op);
@@ -323,10 +335,13 @@ public:
 
     // Linearize subscripts as:
     //   base_offset + SUM_i index_i * stride_i.
-    Value *base = extractvalue(elementTy, viewDescriptor, pos(0));
-    Value *offset = extractvalue(int64Ty, viewDescriptor, pos(1));
+    Value *viewDescriptor = llvm_load(viewDescriptorPtr);
+    Value *base = extractvalue(elementTy, viewDescriptor, pos(kPtrPosInView));
+    Value *offset =
+        extractvalue(int64Ty, viewDescriptor, pos(kOffsetPosInView));
     for (int i = 0, e = loadOp.getRank(); i < e; ++i) {
-      Value *stride = extractvalue(int64Ty, viewDescriptor, pos({3, i}));
+      Value *stride =
+          extractvalue(int64Ty, viewDescriptor, pos({kStridePosInView, i}));
       Value *additionalOffset = mul(indices[i], stride);
       offset = add(offset, additionalOffset);
     }
@@ -344,9 +359,8 @@ class LoadOpConversion : public LoadStoreOpConversion<linalg::LoadOp> {
                   ConversionPatternRewriter &rewriter) const override {
     edsc::ScopedContext edscContext(rewriter, op->getLoc());
     auto elementTy = lowering.convertType(*op->result_type_begin());
-    Value *viewDescriptor = operands[0];
-    ArrayRef<Value *> indices = operands.drop_front();
-    auto ptr = obtainDataPtr(op, viewDescriptor, indices, rewriter);
+    linalg::LoadOpOperandAdaptor adaptor(operands);
+    auto ptr = obtainDataPtr(op, adaptor.view(), adaptor.indices(), rewriter);
     rewriter.replaceOp(op, {llvm_load(elementTy, ptr)});
     return matchSuccess();
   }
@@ -368,18 +382,23 @@ public:
     edsc::ScopedContext context(rewriter, op->getLoc());
 
     // Fill in an aggregate value of the descriptor.
+    RangeOpOperandAdaptor adaptor(operands);
     Value *desc = undef(rangeDescriptorTy);
-    desc = insertvalue(rangeDescriptorTy, desc, operands[0],
-                       positionAttr(rewriter, 0));
-    desc = insertvalue(rangeDescriptorTy, desc, operands[1],
-                       positionAttr(rewriter, 1));
-    desc = insertvalue(rangeDescriptorTy, desc, operands[2],
-                       positionAttr(rewriter, 2));
+    desc = insertvalue(desc, adaptor.min(), positionAttr(rewriter, 0));
+    desc = insertvalue(desc, adaptor.max(), positionAttr(rewriter, 1));
+    desc = insertvalue(desc, adaptor.step(), positionAttr(rewriter, 2));
     rewriter.replaceOp(op, desc);
     return matchSuccess();
   }
 };
 
+/// Conversion pattern that transforms a linalg.slice op into:
+///   1. A function entry `alloca` operation to allocate a ViewDescriptor.
+///   2. A load of the ViewDescriptor from the pointer allocated in 1.
+///   3. Updates to the ViewDescriptor to introduce the data ptr, offset, size
+///      and stride corresponding to the
+///   4. A store of the resulting ViewDescriptor to the alloca'ed pointer.
+/// The linalg.slice op is replaced by the alloca'ed pointer.
 class SliceOpConversion : public LLVMOpLowering {
 public:
   explicit SliceOpConversion(MLIRContext *context, LLVMTypeConverter &lowering_)
@@ -390,7 +409,8 @@ public:
                   ConversionPatternRewriter &rewriter) const override {
     SliceOpOperandAdaptor adaptor(operands);
     auto sliceOp = cast<SliceOp>(op);
-    auto viewDescriptorTy = convertLinalgType(sliceOp.getViewType(), lowering);
+    auto viewDescriptorPtrTy =
+        convertLinalgType(sliceOp.getViewType(), lowering);
     auto viewType = sliceOp.getBaseViewType();
     auto int64Ty = lowering.convertType(rewriter.getIntegerType(64));
 
@@ -399,26 +419,36 @@ public:
     auto pos = [&rewriter](ArrayRef<int> values) {
       return positionAttr(rewriter, values);
     };
-    // Helper function to obtain the ptr of the given `view`.
-    auto getViewPtr = [pos, this](ViewType type, Value *view) -> Value * {
-      auto elementPtrTy = getPtrToElementType(type, lowering);
-      return extractvalue(elementPtrTy, view, pos(0));
-    };
 
     edsc::ScopedContext context(rewriter, op->getLoc());
-    // Declare the view descriptor and insert data ptr.
-    Value *desc = undef(viewDescriptorTy);
-    desc = insertvalue(viewDescriptorTy, desc,
-                       getViewPtr(viewType, adaptor.view()), pos(0));
+    // Declare the view descriptor and insert data ptr *at the entry block of
+    // the function*, which is the preferred location for LLVM's analyses.
+    auto ip = rewriter.getInsertionPoint();
+    auto ib = rewriter.getInsertionBlock();
+    rewriter.setInsertionPointToStart(
+        &op->getParentOfType<FuncOp>().getBlocks().front());
+    Value *one =
+        constant(int64Ty, rewriter.getIntegerAttr(rewriter.getIndexType(), 1));
+    // Alloca with proper alignment.
+    Value *allocatedDesc =
+        llvm_alloca(viewDescriptorPtrTy, one, /*alignment=*/8);
+    Value *desc = llvm_load(allocatedDesc);
+    rewriter.setInsertionPoint(ib, ip);
+
+    Value *baseDesc = llvm_load(adaptor.view());
+
+    auto ptrPos = pos(kPtrPosInView);
+    auto elementTy = getPtrToElementType(sliceOp.getViewType(), lowering);
+    desc = insertvalue(desc, extractvalue(elementTy, baseDesc, ptrPos), ptrPos);
 
     // TODO(ntv): extract sizes and emit asserts.
     SmallVector<Value *, 4> strides(viewType.getRank());
     for (int i = 0, e = viewType.getRank(); i < e; ++i) {
-      strides[i] = extractvalue(int64Ty, adaptor.view(), pos({3, i}));
+      strides[i] = extractvalue(int64Ty, baseDesc, pos({kStridePosInView, i}));
     }
 
     // Compute and insert base offset.
-    Value *baseOffset = extractvalue(int64Ty, adaptor.view(), pos(1));
+    Value *baseOffset = extractvalue(int64Ty, baseDesc, pos(kOffsetPosInView));
     for (int i = 0, e = viewType.getRank(); i < e; ++i) {
       Value *indexing = adaptor.indexings()[i];
       Value *min =
@@ -428,7 +458,7 @@ public:
       Value *product = mul(min, strides[i]);
       baseOffset = add(baseOffset, product);
     }
-    desc = insertvalue(viewDescriptorTy, desc, baseOffset, pos(1));
+    desc = insertvalue(desc, baseOffset, pos(kOffsetPosInView));
 
     // Compute and insert view sizes (max - min along the range) and strides.
     // Skip the non-range operands as they will be projected away from the view.
@@ -443,14 +473,15 @@ public:
         Value *step = extractvalue(int64Ty, rangeDescriptor, pos(2));
         Value *size = sub(max, min);
         Value *stride = mul(strides[i], step);
-        desc = insertvalue(viewDescriptorTy, desc, size, pos({2, numNewDims}));
-        desc =
-            insertvalue(viewDescriptorTy, desc, stride, pos({3, numNewDims}));
+        desc = insertvalue(desc, size, pos({kSizePosInView, numNewDims}));
+        desc = insertvalue(desc, stride, pos({kStridePosInView, numNewDims}));
         ++numNewDims;
       }
     }
 
-    rewriter.replaceOp(op, desc);
+    // Store back in alloca'ed region.
+    llvm_store(desc, allocatedDesc);
+    rewriter.replaceOp(op, allocatedDesc);
     return matchSuccess();
   }
 };
@@ -463,16 +494,21 @@ class StoreOpConversion : public LoadStoreOpConversion<linalg::StoreOp> {
   matchAndRewrite(Operation *op, ArrayRef<Value *> operands,
                   ConversionPatternRewriter &rewriter) const override {
     edsc::ScopedContext edscContext(rewriter, op->getLoc());
-    Value *data = operands[0];
-    Value *viewDescriptor = operands[1];
-    ArrayRef<Value *> indices = operands.drop_front(2);
-    Value *ptr = obtainDataPtr(op, viewDescriptor, indices, rewriter);
-    llvm_store(data, ptr);
+    linalg::StoreOpOperandAdaptor adaptor(operands);
+    Value *ptr = obtainDataPtr(op, adaptor.view(), adaptor.indices(), rewriter);
+    llvm_store(adaptor.value(), ptr);
     rewriter.replaceOp(op, llvm::None);
     return matchSuccess();
   }
 };
 
+/// Conversion pattern that transforms a linalg.view op into:
+///   1. A function entry `alloca` operation to allocate a ViewDescriptor.
+///   2. A load of the ViewDescriptor from the pointer allocated in 1.
+///   3. Updates to the ViewDescriptor to introduce the data ptr, offset, size
+///      and stride.
+///   4. A store of the resulting ViewDescriptor to the alloca'ed pointer.
+/// The linalg.view op is replaced by the alloca'ed pointer.
 class ViewOpConversion : public LLVMOpLowering {
 public:
   explicit ViewOpConversion(MLIRContext *context, LLVMTypeConverter &lowering_)
@@ -482,7 +518,9 @@ public:
   matchAndRewrite(Operation *op, ArrayRef<Value *> operands,
                   ConversionPatternRewriter &rewriter) const override {
     auto viewOp = cast<ViewOp>(op);
-    auto viewDescriptorTy = convertLinalgType(viewOp.getViewType(), lowering);
+    ViewOpOperandAdaptor adaptor(operands);
+    auto viewDescriptorPtrTy =
+        convertLinalgType(viewOp.getViewType(), lowering);
     auto elementTy = getPtrToElementType(viewOp.getViewType(), lowering);
     auto int64Ty = lowering.convertType(rewriter.getIntegerType(64));
 
@@ -490,21 +528,34 @@ public:
       return positionAttr(rewriter, values);
     };
 
-    // First operand to `view` is the buffer descriptor.
-    Value *bufferDescriptor = operands[0];
+    Value *bufferDescriptor = adaptor.buffer();
+    auto bufferTy = getPtrToElementType(
+        viewOp.buffer()->getType().cast<BufferType>(), lowering);
 
     // Declare the descriptor of the view.
     edsc::ScopedContext context(rewriter, op->getLoc());
-    Value *desc = undef(viewDescriptorTy);
+    auto ip = rewriter.getInsertionPoint();
+    auto ib = rewriter.getInsertionBlock();
+    rewriter.setInsertionPointToStart(
+        &op->getParentOfType<FuncOp>().getBlocks().front());
+    Value *one =
+        constant(int64Ty, rewriter.getIntegerAttr(rewriter.getIndexType(), 1));
+    // Alloca for proper alignment.
+    Value *allocatedDesc =
+        llvm_alloca(viewDescriptorPtrTy, one, /*alignment=*/8);
+    Value *desc = llvm_load(allocatedDesc);
+    rewriter.setInsertionPoint(ib, ip);
 
     // Copy the buffer pointer from the old descriptor to the new one.
-    Value *buffer = extractvalue(elementTy, bufferDescriptor, pos(0));
-    desc = insertvalue(viewDescriptorTy, desc, buffer, pos(0));
+    Value *bufferAsViewElementType =
+        bitcast(elementTy,
+                extractvalue(bufferTy, bufferDescriptor, pos(kPtrPosInBuffer)));
+    desc = insertvalue(desc, bufferAsViewElementType, pos(kPtrPosInView));
 
     // Zero base offset.
     auto indexTy = rewriter.getIndexType();
     Value *baseOffset = constant(int64Ty, IntegerAttr::get(indexTy, 0));
-    desc = insertvalue(viewDescriptorTy, desc, baseOffset, pos(1));
+    desc = insertvalue(desc, baseOffset, pos(kOffsetPosInView));
 
     // Compute and insert view sizes (max - min along the range).
     int numRanges = llvm::size(viewOp.ranges());
@@ -514,18 +565,20 @@ public:
       Value *rangeDescriptor = operands[1 + i];
       Value *step = extractvalue(int64Ty, rangeDescriptor, pos(2));
       Value *stride = mul(runningStride, step);
-      desc = insertvalue(viewDescriptorTy, desc, stride, pos({3, i}));
+      desc = insertvalue(desc, stride, pos({kStridePosInView, i}));
       // Update size.
       Value *min = extractvalue(int64Ty, rangeDescriptor, pos(0));
       Value *max = extractvalue(int64Ty, rangeDescriptor, pos(1));
       Value *size = sub(max, min);
-      desc = insertvalue(viewDescriptorTy, desc, size, pos({2, i}));
+      desc = insertvalue(desc, size, pos({kSizePosInView, i}));
       // Update stride for the next dimension.
       if (i > 0)
         runningStride = mul(runningStride, max);
     }
 
-    rewriter.replaceOp(op, desc);
+    // Store back in alloca'ed region.
+    llvm_store(desc, allocatedDesc);
+    rewriter.replaceOp(op, allocatedDesc);
     return matchSuccess();
   }
 };
@@ -585,32 +638,6 @@ getLLVMLibraryCallDeclaration(Operation *op, LLVMTypeConverter &lowering,
   return libFn;
 }
 
-static void getLLVMLibraryCallDefinition(FuncOp fn,
-                                         LLVMTypeConverter &lowering) {
-  // Generate the implementation function definition.
-  auto implFn = getLLVMLibraryCallImplDefinition(fn);
-
-  // Generate the function body.
-  OpBuilder builder(fn.addEntryBlock());
-  edsc::ScopedContext scope(builder, fn.getLoc());
-  SmallVector<Value *, 4> implFnArgs;
-
-  // Create a constant 1.
-  auto one = constant(LLVMType::getInt64Ty(lowering.getDialect()),
-                      IntegerAttr::get(IndexType::get(fn.getContext()), 1));
-  for (auto arg : fn.getArguments()) {
-    // Allocate a stack for storing the argument value. The stack is passed to
-    // the implementation function.
-    auto alloca =
-        llvm_alloca(arg->getType().cast<LLVMType>().getPointerTo(), one)
-            .getValue();
-    implFnArgs.push_back(alloca);
-    llvm_store(arg, alloca);
-  }
-  llvm_call(ArrayRef<Type>(), builder.getSymbolRefAttr(implFn), implFnArgs);
-  llvm_return{ArrayRef<Value *>()};
-}
-
 namespace {
 // The conversion class from Linalg to LLVMIR.
 class LinalgTypeConverter : public LLVMTypeConverter {
@@ -622,16 +649,6 @@ public:
       return result;
     return convertLinalgType(t, *this);
   }
-
-  void addLibraryFnDeclaration(FuncOp fn) { libraryFnDeclarations.insert(fn); }
-
-  ArrayRef<FuncOp> getLibraryFnDeclarations() {
-    return libraryFnDeclarations.getArrayRef();
-  }
-
-private:
-  /// List of library functions declarations needed during dialect conversion
-  llvm::SetVector<FuncOp> libraryFnDeclarations;
 };
 } // end anonymous namespace
 
@@ -652,7 +669,6 @@ public:
     auto f = getLLVMLibraryCallDeclaration<LinalgOp>(op, lowering, rewriter);
     if (!f)
       return matchFailure();
-    static_cast<LinalgTypeConverter &>(lowering).addLibraryFnDeclaration(f);
 
     auto fAttr = rewriter.getSymbolRefAttr(f);
     auto named = rewriter.getNamedAttr("callee", fAttr);
@@ -727,11 +743,6 @@ void LowerLinalgToLLVMPass::runOnModule() {
   if (failed(applyPartialConversion(module, target, patterns, &converter))) {
     signalPassFailure();
   }
-
-  // Emit the function body of any Library function that was declared.
-  for (auto fn : converter.getLibraryFnDeclarations()) {
-    getLLVMLibraryCallDefinition(fn, converter);
-  }
 }
 
 std::unique_ptr<ModulePassBase> mlir::linalg::createLowerLinalgToLLVMPass() {