[X86][AMX] Add description of x86_amx to LangRef.

Differential Revision: https://reviews.llvm.org/D100032

docs/BitCodeFormat.rst

@@ -1322,6 +1322,13 @@ operand fields are
 * *paramty*: Zero or more type indices representing the parameter types of the
   function
 
+TYPE_CODE_X86_AMX Record
+^^^^^^^^^^^^^^^^^^^^^^^^
+
+``[X86_AMX]``
+
+The ``X86_AMX`` record (code 24) adds an ``x86_amx`` type to the type table.
+
 .. _CONSTANTS_BLOCK:
 
 CONSTANTS_BLOCK Contents

docs/LangRef.rst

@@ -3242,6 +3242,24 @@ The binary format of half, float, double, and fp128 correspond to the
 IEEE-754-2008 specifications for binary16, binary32, binary64, and binary128
 respectively.
 
+X86_amx Type
+""""""""""""
+
+:Overview:
+
+The x86_amx type represents a value held in an AMX tile register on an x86
+machine. The operations allowed on it are quite limited. Only few intrinsics
+are allowed: stride load and store, zero and dot product. No instruction is
+allowed for this type. There are no arguments, arrays, pointers, vectors
+or constants of this type.
+
+:Syntax:
+
+::
+
+      x86_amx
+
+
 X86_mmx Type
 """"""""""""
 
@@ -3636,7 +3654,7 @@ represented by ``0xH`` followed by 4 hexadecimal digits. The bfloat 16-bit
 format is represented by ``0xR`` followed by 4 hexadecimal digits. All
 hexadecimal formats are big-endian (sign bit at the left).
 
-There are no constants of type x86_mmx.
+There are no constants of type x86_mmx and x86_amx.
 
 .. _complexconstants: