[PATCH] D144686: [CodeGen] Remove the template specialization of `Address` that stores alignment information into pointers

[Akira Hatanaka via Phabricator via cfe-commits]

ahatanak updated this revision to Diff 500222.
ahatanak added a comment.

Remove AddressImpl altogether.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D144686/new/

https://reviews.llvm.org/D144686

Files:
  clang/lib/CodeGen/Address.h


Index: clang/lib/CodeGen/Address.h
===================================================================
--- clang/lib/CodeGen/Address.h
+++ clang/lib/CodeGen/Address.h
@@ -25,80 +25,20 @@
 // Indicates whether a pointer is known not to be null.
 enum KnownNonNull_t { NotKnownNonNull, KnownNonNull };
 
-// We try to save some space by using 6 bits over two PointerIntPairs to store
-// the alignment. However, some arches don't support 3 bits in a PointerIntPair
-// so we fallback to storing the alignment separately.
-template <typename T, bool = alignof(llvm::Value *) >= 8> class AddressImpl {};
-
-template <typename T> class AddressImpl<T, false> {
+/// An aligned address.
+class Address {
   llvm::PointerIntPair<llvm::Value *, 1, bool> PointerAndKnownNonNull;
   llvm::Type *ElementType;
   CharUnits Alignment;
 
-public:
-  AddressImpl(llvm::Value *Pointer, llvm::Type *ElementType,
-              CharUnits Alignment, KnownNonNull_t IsKnownNonNull)
-      : PointerAndKnownNonNull(Pointer, IsKnownNonNull),
-        ElementType(ElementType), Alignment(Alignment) {}
-  llvm::Value *getPointer() const {
-    return PointerAndKnownNonNull.getPointer();
-  }
-  llvm::Type *getElementType() const { return ElementType; }
-  CharUnits getAlignment() const { return Alignment; }
-  KnownNonNull_t isKnownNonNull() const {
-    return (KnownNonNull_t)PointerAndKnownNonNull.getInt();
-  }
-  void setKnownNonNull() { PointerAndKnownNonNull.setInt(true); }
-};
-
-template <typename T> class AddressImpl<T, true> {
-  // Int portion stores the non-null bit and the upper 2 bits of the log of the
-  // alignment.
-  llvm::PointerIntPair<llvm::Value *, 3, unsigned> Pointer;
-  // Int portion stores lower 3 bits of the log of the alignment.
-  llvm::PointerIntPair<llvm::Type *, 3, unsigned> ElementType;
-
-public:
-  AddressImpl(llvm::Value *Pointer, llvm::Type *ElementType,
-              CharUnits Alignment, KnownNonNull_t IsKnownNonNull)
-      : Pointer(Pointer), ElementType(ElementType) {
-    if (Alignment.isZero()) {
-      this->Pointer.setInt(IsKnownNonNull << 2);
-      return;
-    }
-    // Currently the max supported alignment is exactly 1 << 32 and is
-    // guaranteed to be a power of 2, so we can store the log of the alignment
-    // into 5 bits.
-    assert(Alignment.isPowerOfTwo() && "Alignment cannot be zero");
-    auto AlignLog = llvm::Log2_64(Alignment.getQuantity());
-    assert(AlignLog < (1 << 5) && "cannot fit alignment into 5 bits");
-    this->Pointer.setInt(IsKnownNonNull << 2 | AlignLog >> 3);
-    this->ElementType.setInt(AlignLog & 7);
-  }
-  llvm::Value *getPointer() const { return Pointer.getPointer(); }
-  llvm::Type *getElementType() const { return ElementType.getPointer(); }
-  CharUnits getAlignment() const {
-    unsigned AlignLog = ((Pointer.getInt() & 0x3) << 3) | ElementType.getInt();
-    return CharUnits::fromQuantity(CharUnits::QuantityType(1) << AlignLog);
-  }
-  KnownNonNull_t isKnownNonNull() const {
-    return (KnownNonNull_t)(!!(Pointer.getInt() & 0x4));
-  }
-  void setKnownNonNull() { Pointer.setInt(Pointer.getInt() | 0x4); }
-};
-
-/// An aligned address.
-class Address {
-  AddressImpl<void> A;
-
 protected:
-  Address(std::nullptr_t)
-      : A(nullptr, nullptr, CharUnits::Zero(), NotKnownNonNull) {}
+  Address(std::nullptr_t) : ElementType(nullptr) {}
 
 public:
   Address(llvm::Value *Pointer, llvm::Type *ElementType, CharUnits Alignment,
           KnownNonNull_t IsKnownNonNull = NotKnownNonNull)
-      : A(Pointer, ElementType, Alignment, IsKnownNonNull) {
+      : PointerAndKnownNonNull(Pointer, IsKnownNonNull),
+        ElementType(ElementType), Alignment(Alignment) {
     assert(Pointer != nullptr && "Pointer cannot be null");
     assert(ElementType != nullptr && "Element type cannot be null");
     assert(llvm::cast<llvm::PointerType>(Pointer->getType())
@@ -107,11 +47,13 @@
   }
 
   static Address invalid() { return Address(nullptr); }
-  bool isValid() const { return A.getPointer() != nullptr; }
+  bool isValid() const {
+    return PointerAndKnownNonNull.getPointer() != nullptr;
+  }
 
   llvm::Value *getPointer() const {
     assert(isValid());
-    return A.getPointer();
+    return PointerAndKnownNonNull.getPointer();
   }
 
   /// Return the type of the pointer value.
@@ -122,7 +64,7 @@
   /// Return the type of the values stored in this address.
   llvm::Type *getElementType() const {
     assert(isValid());
-    return A.getElementType();
+    return ElementType;
   }
 
   /// Return the address space that this address resides in.
@@ -138,7 +80,7 @@
   /// Return the alignment of this pointer.
   CharUnits getAlignment() const {
     assert(isValid());
-    return A.getAlignment();
+    return Alignment;
   }
 
   /// Return address with different pointer, but same element type and
@@ -159,13 +101,13 @@
   /// Whether the pointer is known not to be null.
   KnownNonNull_t isKnownNonNull() const {
     assert(isValid());
-    return A.isKnownNonNull();
+    return (KnownNonNull_t)PointerAndKnownNonNull.getInt();
   }
 
   /// Set the non-null bit.
   Address setKnownNonNull() {
     assert(isValid());
-    A.setKnownNonNull();
+    PointerAndKnownNonNull.setInt(true);
     return *this;
   }
 };

_______________________________________________
cfe-commits mailing list
cfe-commits@lists.llvm.org
https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits