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

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

Differential Revision: http://reviews.llvm.org/D17248

Patch by Don Hinton!

llvm-svn: 262466

clang/lib/CodeGen/CGValue.h

@@ -445,7 +445,7 @@ class AggValueSlot {
   // 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

clang/test/Sema/attr-aligned.c

@@ -3,6 +3,9 @@
 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];