[PATCH] D117262: [NFC] Store Address's alignment into PointerIntPairs

[Arthur Eubanks via Phabricator via cfe-commits]

aeubanks updated this revision to Diff 399840.
aeubanks added a comment.

update


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D117262/new/

https://reviews.llvm.org/D117262

Files:
  clang/lib/CodeGen/Address.h


Index: clang/lib/CodeGen/Address.h
===================================================================
--- clang/lib/CodeGen/Address.h
+++ clang/lib/CodeGen/Address.h
@@ -14,30 +14,37 @@
 #ifndef LLVM_CLANG_LIB_CODEGEN_ADDRESS_H
 #define LLVM_CLANG_LIB_CODEGEN_ADDRESS_H
 
-#include "llvm/IR/Constants.h"
 #include "clang/AST/CharUnits.h"
+#include "llvm/ADT/PointerIntPair.h"
+#include "llvm/IR/Constants.h"
+#include "llvm/Support/MathExtras.h"
 
 namespace clang {
 namespace CodeGen {
 
 /// An aligned address.
 class Address {
-  llvm::Value *Pointer;
-  llvm::Type *ElementType;
-  CharUnits Alignment;
+  // Int portion stores upper 3 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;
 
 protected:
   Address(std::nullptr_t) : Pointer(nullptr), ElementType(nullptr) {}
 
 public:
   Address(llvm::Value *pointer, llvm::Type *elementType, CharUnits alignment)
-      : Pointer(pointer), ElementType(elementType), Alignment(alignment) {
+      : Pointer(pointer), ElementType(elementType) {
     assert(pointer != nullptr && "Pointer cannot be null");
     assert(elementType != nullptr && "Element type cannot be null");
     assert(llvm::cast<llvm::PointerType>(pointer->getType())
                ->isOpaqueOrPointeeTypeMatches(elementType) &&
            "Incorrect pointer element type");
-    assert(!alignment.isZero() && "Alignment cannot be zero");
+    assert(alignment.isPowerOfTwo() && "Alignment cannot be zero");
+    auto AlignLog = llvm::Log2_64(alignment.getQuantity());
+    assert(AlignLog < (1 << 6) && "cannot fit alignment into 6 bits");
+    Pointer.setInt(AlignLog >> 3);
+    ElementType.setInt(AlignLog & 7);
   }
 
   // Deprecated: Use constructor with explicit element type instead.
@@ -46,11 +53,11 @@
                 Alignment) {}
 
   static Address invalid() { return Address(nullptr); }
-  bool isValid() const { return Pointer != nullptr; }
+  bool isValid() const { return Pointer.getPointer() != nullptr; }
 
   llvm::Value *getPointer() const {
     assert(isValid());
-    return Pointer;
+    return Pointer.getPointer();
   }
 
   /// Return the type of the pointer value.
@@ -61,7 +68,7 @@
   /// Return the type of the values stored in this address.
   llvm::Type *getElementType() const {
     assert(isValid());
-    return ElementType;
+    return ElementType.getPointer();
   }
 
   /// Return the address space that this address resides in.
@@ -77,19 +84,21 @@
   /// Return the alignment of this pointer.
   CharUnits getAlignment() const {
     assert(isValid());
-    return Alignment;
+    unsigned AlignLog = (Pointer.getInt() << 3) | ElementType.getInt();
+    return CharUnits::fromQuantity(1 << AlignLog);
   }
 
   /// Return address with different pointer, but same element type and
   /// alignment.
   Address withPointer(llvm::Value *NewPointer) const {
-    return Address(NewPointer, ElementType, Alignment);
+    return Address(NewPointer, ElementType.getPointer(), getAlignment());
   }
 
   /// Return address with different alignment, but same pointer and element
   /// type.
   Address withAlignment(CharUnits NewAlignment) const {
-    return Address(Pointer, ElementType, NewAlignment);
+    return Address(Pointer.getPointer(), ElementType.getPointer(),
+                   NewAlignment);
   }
 };
 


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