[Sema] PR26444 fix crash when alignment value is >= 2**16

[hintonda]

Summary

Sema allows max values up to 2**28, use unsigned instead of unsiged
short to hold values that large.

[hintonda]

Added comment
Added comment to test file.

[majnemer]

LGTM

[hintonda]

Thanks David. Btw, could you commit it for me? I don't have commit access.

[hintonda]

I don't have commit access, so could someone commit for me. Thanks...

[majnemer]

I committed this a few days ago in rL262466. Closing this differential.

[hintonda]

Great, thanks David.

lib/CodeGen/CGValue.h

 /// An aggregate value slot.
 class AggValueSlot {
   /// The address.
   llvm::Value *Addr;
 
   // Qualifiers
   Qualifiers Quals;
 
-  unsigned short Alignment;
+  unsigned Alignment;
 
   /// DestructedFlag - This is set to true if some external code is
   /// responsible for setting up a destructor for the slot.  Otherwise
   /// the code which constructs it should push the appropriate cleanup.
   bool DestructedFlag : 1;
 
   /// ObjCGCFlag - This is set to true if writing to the memory in the
   /// slot might require calling an appropriate Objective-C GC

test/Sema/attr-aligned.c

 // RUN: %clang_cc1 -triple i386-apple-darwin9 -fsyntax-only -verify %s
 
 int x __attribute__((aligned(3))); // expected-error {{requested alignment is not a power of 2}}
 int y __attribute__((aligned(1 << 29))); // expected-error {{requested alignment must be 268435456 bytes or smaller}}
 
+// PR26444
+int y __attribute__((aligned(1 << 28)));
+
 // PR3254
 short g0[3] __attribute__((aligned));
 short g0_chk[__alignof__(g0) == 16 ? 1 : -1]; 
 
 // <rdar://problem/6840045>
 typedef char ueber_aligned_char __attribute__((aligned(8)));
 
 struct struct_with_ueber_char {