am 31675153: Merge branch \'upstream\' into merge_2

* commit '31675153bd2d7617db8cb6aeb58054934c7b9f73': (542 commits)
  MaximumSpanningTree::EdgeWeightCompare: Make this comparator actually be a strict weak ordering, and don't pass possibly-null pointers to dyn_cast.
  Fix misaligned access in MachO object file reader: despite containing an int64_t, Symbol64TableEntry is actually only stored with 4-byte alignment within the file.
  Fix unaligned memory accesses when performing relocations in X86 JIT. There's no cost to using memcpy here: the fixed code is optimized by LLVM to perfect machine code.
  Don't pass a null pointer to cast<> in its unit tests.
  Don't bind a reference to a dereferenced null pointer (for return value of WeakVH::operator*).
  [ms-inline asm] Do not report a Parser error when matching inline assembly.
  Ignore the documentation-suggested location for compile_commands.json
  The presence of the empty file "foo" unfortunately does not improve LLVM in any way.
  Remove unnecessary cast that was also unnecessarily casting away constness.
  Provide a portability macro for __builtin_trap.
  Fix macros arguments with an underscore, dot or dollar in them. This is based on a patch by Andy/PaX. I added the support for dot and dollar.
  [ms-inline asm] Expose the ErrorInfo from the MatchInstructionImpl.  In general, this is the index of the operand that failed to match.
  Formatting.  No functional change.
  Make the wording in of the "expected identifier" error in the .macro directive consistent with the other "expected identifier" errors. Extracted from the Andy/PaX patch. I added the test.
  Pacify PVS-Studio by changing the type rather than doing a cast, a tweak suggested by David Blaikie.
  Add support for the --param ssp-buffer-size= driver option. PR9673
  Use typedefs. Fix indentation. Extracted from the Andy/PaX patch.
  Remove unused variable. Extracted from the Andy/PaX patch.
  Fix typo. Extracted from the Andy/PaX patch.
  MCJIT: Tidy up the constructor.
  ...

1 files changed, 14 insertions, 13 deletions

diff --git a/include/llvm/Support/AlignOf.h b/include/llvm/Support/AlignOf.h
index 85607c8..cf71251 100644
--- a/include/llvm/Support/AlignOf.h
+++ b/include/llvm/Support/AlignOf.h
@@ -107,8 +107,8 @@ LLVM_ALIGNEDCHARARRAY_TEMPLATE_ALIGNMENT(8192);
 // Any larger and MSVC complains.
 #undef LLVM_ALIGNEDCHARARRAY_TEMPLATE_ALIGNMENT
 
-/// \brief This class template exposes a typedef for type containing a suitable
-/// aligned character array to hold elements of any of up to four types.
+/// \brief This union template exposes a suitably aligned and sized character
+/// array member which can hold elements of any of up to four types.
 ///
 /// These types may be arrays, structs, or any other types. The goal is to
 /// produce a union type containing a character array which, when used, forms
@@ -116,7 +116,8 @@ LLVM_ALIGNEDCHARARRAY_TEMPLATE_ALIGNMENT(8192);
 /// than four types can be added at the cost of more boiler plate.
 template <typename T1,
           typename T2 = char, typename T3 = char, typename T4 = char>
-class AlignedCharArray {
+union AlignedCharArrayUnion {
+private:
   class AlignerImpl {
     T1 t1; T2 t2; T3 t3; T4 t4;
 
@@ -127,6 +128,12 @@ class AlignedCharArray {
   };
 
 public:
+  /// \brief The character array buffer for use by clients.
+  ///
+  /// No other member of this union should be referenced. The exist purely to
+  /// constrain the layout of this character array.
+  char buffer[sizeof(SizerImpl)];
+
   // Sadly, Clang and GCC both fail to align a character array properly even
   // with an explicit alignment attribute. To work around this, we union
   // the character array that will actually be used with a struct that contains
@@ -134,16 +141,10 @@ public:
   // and GCC will properly register the alignment of a struct containing an
   // aligned member, and this alignment should carry over to the character
   // array in the union.
-  union union_type {
-    // This is the only member of the union which should be used by clients:
-    char buffer[sizeof(SizerImpl)];
-
-    // This member of the union only exists to force the alignment.
-    struct {
-      typename llvm::AlignedCharArrayImpl<AlignOf<AlignerImpl>::Alignment>::type
-        nonce_inner_member;
-    } nonce_member;
-  };
+  struct {
+    typename llvm::AlignedCharArrayImpl<AlignOf<AlignerImpl>::Alignment>::type
+      nonce_inner_member;
+  } nonce_member;
 };
 
 } // end namespace llvm