[ARC] Add documentation naked, ilink and firq

gcc/
xxxx-xx-xx  Claudiu Zissulescu  <claziss@synopsys.com>

	* doc/extend.texi (ARC Function Attributes): Update info.

From-SVN: r272237

gcc/ChangeLog

+2019-06-13  Claudiu Zissulescu  <claziss@synopsys.com>
+
+	* doc/extend.texi (ARC Function Attributes): Update info.
+
 2019-06-13  Feng Xue  <fxue@os.amperecomputing.com>
 
 	PR tree-optimization/89713

gcc/doc/extend.texi

@@ -4140,7 +4140,8 @@ void f () __attribute__ ((interrupt ("ilink1")));
 @end smallexample
 
 Permissible values for this parameter are: @w{@code{ilink1}} and
-@w{@code{ilink2}}.
+@w{@code{ilink2}} for ARCv1 architecture, and @w{@code{ilink}} and
+@w{@code{firq}} for ARCv2 architecture.
 
 @item long_call
 @itemx medium_call
@@ -4183,6 +4184,17 @@ This attribute allows one to mark secure-code functions that are
 callable from normal mode.  The location of the secure call function
 into the @code{sjli} table needs to be passed as argument.
 
+@item naked
+@cindex @code{naked} function attribute, ARC
+This attribute allows the compiler to construct the requisite function
+declaration, while allowing the body of the function to be assembly
+code.  The specified function will not have prologue/epilogue
+sequences generated by the compiler.  Only basic @code{asm} statements
+can safely be included in naked functions (@pxref{Basic Asm}).  While
+using extended @code{asm} or a mixture of basic @code{asm} and C code
+may appear to work, they cannot be depended upon to work reliably and
+are not supported.
+
 @end table
 
 @node ARM Function Attributes