TrailingObjects::FixedSizeStorage constexpr fixes + tests

Summary:
This change fixes issues with `LLVM_CONSTEXPR` functions and
`TrailingObjects::FixedSizeStorage`. In particular, some of the
functions marked `LLVM_CONSTEXPR` used by `FixedSizeStorage` were not
implemented such that they evaluate successfully as part of a constant
expression despite constant arguments.

This change also implements a more traditional template-meta path to
accommodate MSVC, and adds unit tests for `FixedSizeStorage`.

Drive-by fix: the access control for members of `TrailingObjectsImpl` is
tightened.

Reviewers: faisalv, rsmith, aaron.ballman

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D22668

llvm-svn: 277270

1 files changed, 47 insertions, 0 deletions

diff --git a/llvm/unittests/Support/TrailingObjectsTest.cpp b/llvm/unittests/Support/TrailingObjectsTest.cpp
index a1d3e7b3c86..65fdcb93623 100644
--- a/llvm/unittests/Support/TrailingObjectsTest.cpp
+++ b/llvm/unittests/Support/TrailingObjectsTest.cpp
@@ -41,6 +41,9 @@ public:
   unsigned numShorts() const { return NumShorts; }
 
   // Pull some protected members in as public, for testability.
+  template <typename... Ty>
+  using FixedSizeStorage = TrailingObjects::FixedSizeStorage<Ty...>;
+
   using TrailingObjects::totalSizeToAlloc;
   using TrailingObjects::additionalSizeToAlloc;
   using TrailingObjects::getTrailingObjects;
@@ -94,6 +97,9 @@ public:
   }
 
   // Pull some protected members in as public, for testability.
+  template <typename... Ty>
+  using FixedSizeStorage = TrailingObjects::FixedSizeStorage<Ty...>;
+
   using TrailingObjects::totalSizeToAlloc;
   using TrailingObjects::additionalSizeToAlloc;
   using TrailingObjects::getTrailingObjects;
@@ -106,7 +112,20 @@ TEST(TrailingObjects, OneArg) {
   EXPECT_EQ(Class1::additionalSizeToAlloc<short>(1), sizeof(short));
   EXPECT_EQ(Class1::additionalSizeToAlloc<short>(3), sizeof(short) * 3);
 
+  EXPECT_EQ(
+      llvm::alignOf<Class1>(),
+      llvm::alignOf<Class1::FixedSizeStorage<short>::with_counts<1>::type>());
+  EXPECT_EQ(sizeof(Class1::FixedSizeStorage<short>::with_counts<1>::type),
+            llvm::alignTo(Class1::totalSizeToAlloc<short>(1),
+                          llvm::alignOf<Class1>()));
   EXPECT_EQ(Class1::totalSizeToAlloc<short>(1), sizeof(Class1) + sizeof(short));
+
+  EXPECT_EQ(
+      llvm::alignOf<Class1>(),
+      llvm::alignOf<Class1::FixedSizeStorage<short>::with_counts<3>::type>());
+  EXPECT_EQ(sizeof(Class1::FixedSizeStorage<short>::with_counts<3>::type),
+            llvm::alignTo(Class1::totalSizeToAlloc<short>(3),
+                          llvm::alignOf<Class1>()));
   EXPECT_EQ(Class1::totalSizeToAlloc<short>(3),
             sizeof(Class1) + sizeof(short) * 3);
 
@@ -131,6 +150,14 @@ TEST(TrailingObjects, TwoArg) {
   EXPECT_EQ((Class2::additionalSizeToAlloc<double, short>(3, 1)),
             sizeof(double) * 3 + sizeof(short));
 
+  EXPECT_EQ(
+      llvm::alignOf<Class2>(),
+      (llvm::alignOf<
+          Class2::FixedSizeStorage<double, short>::with_counts<1, 1>::type>()));
+  EXPECT_EQ(
+      sizeof(Class2::FixedSizeStorage<double, short>::with_counts<1, 1>::type),
+      llvm::alignTo(Class2::totalSizeToAlloc<double, short>(1, 1),
+                    llvm::alignOf<Class2>()));
   EXPECT_EQ((Class2::totalSizeToAlloc<double, short>(1, 1)),
             sizeof(Class2) + sizeof(double) + sizeof(short));
 
@@ -165,6 +192,16 @@ TEST(TrailingObjects, ThreeArg) {
   EXPECT_EQ((Class3::additionalSizeToAlloc<double, short, bool>(1, 1, 3)),
             sizeof(double) + sizeof(short) + 3 * sizeof(bool));
   EXPECT_EQ(sizeof(Class3), llvm::alignTo(1, llvm::alignOf<double>()));
+
+  EXPECT_EQ(llvm::alignOf<Class3>(),
+            (llvm::alignOf<Class3::FixedSizeStorage<
+                 double, short, bool>::with_counts<1, 1, 3>::type>()));
+  EXPECT_EQ(
+      sizeof(Class3::FixedSizeStorage<double, short,
+                                      bool>::with_counts<1, 1, 3>::type),
+      llvm::alignTo(Class3::totalSizeToAlloc<double, short, bool>(1, 1, 3),
+                    llvm::alignOf<Class3>()));
+
   std::unique_ptr<char[]> P(new char[1000]);
   Class3 *C = reinterpret_cast<Class3 *>(P.get());
   EXPECT_EQ(C->getTrailingObjects<double>(), reinterpret_cast<double *>(C + 1));
@@ -186,6 +223,16 @@ TEST(TrailingObjects, Realignment) {
   EXPECT_EQ((Class4::additionalSizeToAlloc<char, long>(1, 1)),
             llvm::alignTo(sizeof(long) + 1, llvm::alignOf<long>()));
   EXPECT_EQ(sizeof(Class4), llvm::alignTo(1, llvm::alignOf<long>()));
+
+  EXPECT_EQ(
+      llvm::alignOf<Class4>(),
+      (llvm::alignOf<
+          Class4::FixedSizeStorage<char, long>::with_counts<1, 1>::type>()));
+  EXPECT_EQ(
+      sizeof(Class4::FixedSizeStorage<char, long>::with_counts<1, 1>::type),
+      llvm::alignTo(Class4::totalSizeToAlloc<char, long>(1, 1),
+                    llvm::alignOf<Class4>()));
+
   std::unique_ptr<char[]> P(new char[1000]);
   Class4 *C = reinterpret_cast<Class4 *>(P.get());
   EXPECT_EQ(C->getTrailingObjects<char>(), reinterpret_cast<char *>(C + 1));