[Mlir-commits] [mlir] [mlir][Ptr] Init the Ptr dialect with the `!ptr.ptr` type. (PR #86860)

[Mehdi Amini]

================
@@ -0,0 +1,182 @@
+//===- PtrTypes.cpp - Pointer dialect types ---------------------*- C++ -*-===//
+//
+// This file is licensed under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines the Ptr dialect types.
+//
+//===----------------------------------------------------------------------===//
+
+#include "mlir/Dialect/Ptr/IR/PtrTypes.h"
+#include "llvm/ADT/TypeSwitch.h"
+
+using namespace mlir;
+using namespace mlir::ptr;
+
+//===----------------------------------------------------------------------===//
+// Pointer type
+//===----------------------------------------------------------------------===//
+
+constexpr const static unsigned kDefaultPointerSizeBits = 64;
+constexpr const static unsigned kBitsInByte = 8;
+constexpr const static unsigned kDefaultPointerAlignment = 8;
+
+/// Returns the part of the data layout entry that corresponds to `pos` for the
+/// given `type` by interpreting the list of entries `params`. For the pointer
+/// type in the default address space, returns the default value if the entries
+/// do not provide a custom one, for other address spaces returns std::nullopt.
+static std::optional<uint64_t>
+getPointerDataLayoutEntry(DataLayoutEntryListRef params, PtrType type,
+                          PtrDLEntryPos pos) {
+  // First, look for the entry for the pointer in the current address space.
+  Attribute currentEntry;
+  for (DataLayoutEntryInterface entry : params) {
+    if (!entry.isTypeEntry())
+      continue;
+    if (cast<PtrType>(entry.getKey().get<Type>()).getMemorySpace() ==
+        type.getMemorySpace()) {
+      currentEntry = entry.getValue();
+      break;
+    }
+  }
+  bool isSizeOrIndex =
+      pos == PtrDLEntryPos::Size || pos == PtrDLEntryPos::Index;
+  if (currentEntry) {
+    std::optional<uint64_t> value = extractPointerSpecValue(currentEntry, pos);
+    // If the optional `PtrDLEntryPos::Index` entry is not available, use the
+    // pointer size as the index bitwidth.
+    if (!value && pos == PtrDLEntryPos::Index)
+      value = extractPointerSpecValue(currentEntry, PtrDLEntryPos::Size);
+    return *value / (isSizeOrIndex ? 1 : kBitsInByte);
+  }
+
+  // If not found, and this is the pointer to the default memory space, assume
+  // 64-bit pointers.
+  if (type.getMemorySpace() == type.getDefaultMemorySpace())
+    return isSizeOrIndex ? kDefaultPointerSizeBits : kDefaultPointerAlignment;
+
+  return std::nullopt;
+}
+
+uint64_t PtrType::getAddressSpace() const { return 0; }
+
+Attribute PtrType::getDefaultMemorySpace() const { return nullptr; }
+
+bool PtrType::areCompatible(DataLayoutEntryListRef oldLayout,
+                            DataLayoutEntryListRef newLayout) const {
+  for (DataLayoutEntryInterface newEntry : newLayout) {
+    if (!newEntry.isTypeEntry())
+      continue;
+    unsigned size = kDefaultPointerSizeBits;
+    unsigned abi = kDefaultPointerAlignment;
+    auto newType = llvm::cast<PtrType>(newEntry.getKey().get<Type>());
+    const auto *it =
+        llvm::find_if(oldLayout, [&](DataLayoutEntryInterface entry) {
+          if (auto type = llvm::dyn_cast_if_present<Type>(entry.getKey())) {
+            return llvm::cast<PtrType>(type).getMemorySpace() ==
+                   newType.getMemorySpace();
+          }
+          return false;
+        });
+    if (it == oldLayout.end()) {
+      it = llvm::find_if(oldLayout, [&](DataLayoutEntryInterface entry) {
+        if (auto type = llvm::dyn_cast_if_present<Type>(entry.getKey())) {
+          auto ptrTy = llvm::cast<PtrType>(type);
+          return ptrTy.getMemorySpace() == ptrTy.getDefaultMemorySpace();
+        }
+        return false;
+      });
+    }
+    if (it != oldLayout.end()) {
+      size = *extractPointerSpecValue(*it, PtrDLEntryPos::Size);
+      abi = *extractPointerSpecValue(*it, PtrDLEntryPos::Abi);
+    }
+
+    Attribute newSpec = llvm::cast<DenseIntElementsAttr>(newEntry.getValue());
+    unsigned newSize = *extractPointerSpecValue(newSpec, PtrDLEntryPos::Size);
+    unsigned newAbi = *extractPointerSpecValue(newSpec, PtrDLEntryPos::Abi);
+    if (size != newSize || abi < newAbi || abi % newAbi != 0)
+      return false;
+  }
+  return true;
+}
+
+uint64_t PtrType::getABIAlignment(const DataLayout &dataLayout,
+                                  DataLayoutEntryListRef params) const {
+  if (std::optional<uint64_t> alignment =
+          getPointerDataLayoutEntry(params, *this, PtrDLEntryPos::Abi))
+    return *alignment;
+
+  return dataLayout.getTypeABIAlignment(
+      get(getContext(), getDefaultMemorySpace()));
+}
+
+std::optional<uint64_t>
+PtrType::getIndexBitwidth(const DataLayout &dataLayout,
+                          DataLayoutEntryListRef params) const {
+  if (std::optional<uint64_t> indexBitwidth =
+          getPointerDataLayoutEntry(params, *this, PtrDLEntryPos::Index))
+    return *indexBitwidth;
+
+  return dataLayout.getTypeIndexBitwidth(
+      get(getContext(), getDefaultMemorySpace()));
+}
+
+llvm::TypeSize PtrType::getTypeSizeInBits(const DataLayout &dataLayout,
+                                          DataLayoutEntryListRef params) const {
+  if (std::optional<uint64_t> size =
+          getPointerDataLayoutEntry(params, *this, PtrDLEntryPos::Size))
+    return llvm::TypeSize::getFixed(*size);
+
+  // For other memory spaces, use the size of the pointer to the default memory
+  // space.
+  return dataLayout.getTypeSizeInBits(
+      get(getContext(), getDefaultMemorySpace()));
+}
+
+uint64_t PtrType::getPreferredAlignment(const DataLayout &dataLayout,
+                                        DataLayoutEntryListRef params) const {
+  if (std::optional<uint64_t> alignment =
+          getPointerDataLayoutEntry(params, *this, PtrDLEntryPos::Preferred))
+    return *alignment;
+
+  return dataLayout.getTypePreferredAlignment(
+      get(getContext(), getDefaultMemorySpace()));
----------------
joker-eph wrote:

I don't understand how that does not just infinitely recurse?

I would think we'd end up here at some point: https://github.com/llvm/llvm-project/blob/main/mlir/lib/Interfaces/DataLayoutInterfaces.cpp#L219

https://github.com/llvm/llvm-project/pull/86860