[PATCH] D67697: [Alignment] Add a None() member function

[Guillaume Chatelet via Phabricator via llvm-commits]

gchatelet updated this revision to Diff 220630.
gchatelet added a comment.

- Adding documentation


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D67697/new/

https://reviews.llvm.org/D67697

Files:
  llvm/include/llvm/Support/Alignment.h
  llvm/unittests/Support/AlignmentTest.cpp


Index: llvm/unittests/Support/AlignmentTest.cpp
===================================================================
--- llvm/unittests/Support/AlignmentTest.cpp
+++ llvm/unittests/Support/AlignmentTest.cpp
@@ -28,7 +28,10 @@
   return Out;
 }
 
-TEST(AlignmentTest, AlignDefaultCTor) { EXPECT_EQ(Align().value(), 1ULL); }
+TEST(AlignmentTest, AlignDefaultCTor) {
+  EXPECT_EQ(Align().value(), 1ULL);
+  EXPECT_EQ(Align::None().value(), 1ULL);
+}
 
 TEST(AlignmentTest, MaybeAlignDefaultCTor) {
   EXPECT_FALSE(MaybeAlign().hasValue());
Index: llvm/include/llvm/Support/Alignment.h
===================================================================
--- llvm/include/llvm/Support/Alignment.h
+++ llvm/include/llvm/Support/Alignment.h
@@ -55,7 +55,7 @@
 
 public:
   /// Default is byte-aligned.
-  Align() = default;
+  constexpr Align() = default;
   /// Do not perform checks in case of copy/move construct/assign, because the
   /// checks have been performed when building `Other`.
   Align(const Align &Other) = default;
@@ -73,6 +73,13 @@
   /// This is a hole in the type system and should not be abused.
   /// Needed to interact with C for instance.
   uint64_t value() const { return uint64_t(1) << ShiftValue; }
+
+  /// Returns a default constructed Align which corresponds to no alignment.
+  /// This is useful to test for unalignment as it conveys clear semantic.
+  /// `if (A != llvm::Align::None())`
+  /// would be better than
+  /// `if (A > llvm::Align(1))`
+  constexpr static const Align None() { return llvm::Align(); }
 };
 
 /// Treats the value 0 as a 1, so Align is always at least 1.


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