[clang] aligned attribute doc (PR #195278)

[Kartik Ohlan via cfe-commits]

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@@ -10000,3 +9983,40 @@ different languages to coexist on the same call stack while each interpreting
 exceptions according to their own rules.
   }];
 }
+
+def AlignedDocs : Documentation {
+  let Category = DocCatDecl;
+  let Heading = "aligned";
+  let Content = [{
+The ``aligned`` attribute specifies a minimum alignment (in bytes) for a 
+variable, structure field, or type definition. The attribute takes an 
+optional integer constant expression that must evaluate to a power of two.
+
+.. code-block:: c++
+
+  struct __attribute__((aligned(8))) S { 
+    short f[3]; 
+  };
+
+If the alignment factor is omitted, the compiler defaults to the largest 
+alignment supported by the target machine for any data type. 
+
+Applying this attribute to a structure or union changes the type's layout 
+properties. To ensure that array indexing and pointer arithmetic remain 
+consistent, the compiler automatically increases the structure's total size 
+(via tail padding) to a multiple of the alignment value. For example, a 
+struct with a natural size of 6 bytes marked ``aligned(8)`` will be 
+padded to 8 bytes.
+
+The attribute is additive and can only increase alignment; it cannot decrease 
+alignment below the type's natural requirement. To force a smaller 
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Ko496-glitch wrote:

got it thanks, i added this, please let me know it looks good

https://github.com/llvm/llvm-project/pull/195278