[Ada] Document requirements for Pragma Lock_Free

2019-08-20  Arnaud Charlet  <charlet@adacore.com>

gcc/ada/

	* doc/gnat_rm/implementation_defined_pragmas.rst: Document
	requirements for Pragma Lock_Free.
	* gnat_rm.texi: Regenerate.

From-SVN: r274717

gcc/ada/ChangeLog

+2019-08-20  Arnaud Charlet  <charlet@adacore.com>
+
+	* doc/gnat_rm/implementation_defined_pragmas.rst: Document
+	requirements for Pragma Lock_Free.
+	* gnat_rm.texi: Regenerate.
+
 2019-08-20  Philippe Gil  <gil@adacore.com>
 
 	* bindgen.adb (Gen_Main): Set gnat_argc/gnat_argv to argc/argv

gcc/ada/doc/gnat_rm/implementation_defined_pragmas.rst

@@ -3649,6 +3649,24 @@ the implementation of protected operations must be implemented without locks.
 Compilation fails if the compiler cannot generate lock-free code for the
 operations.
 
+The current conditions required to support this pragma are:
+
+* Protected type declarations may not contain entries
+* Protected subprogram declarations may not have nonelementary parameters
+
+In addition, each protected subprogram body must satisfy:
+
+* May reference only one protected component
+* May not reference nonconstant entities outside the protected subprogram
+  scope.
+* May not contain address representation items, allocators, or quantified
+  expressions.
+* May not contain delay, goto, loop, or procedure-call statements.
+* May not contain exported and imported entities
+* May not dereferenced access values
+* Function calls and attribute references must be static
+
+
 Pragma Loop_Invariant
 =====================
 

gcc/ada/gnat_rm.texi

@@ -5115,6 +5115,47 @@ the implementation of protected operations must be implemented without locks.
 Compilation fails if the compiler cannot generate lock-free code for the
 operations.
 
+The current conditions required to support this pragma are:
+
+
+@itemize *
+
+@item 
+Protected type declarations may not contain entries
+
+@item 
+Protected subprogram declarations may not have nonelementary parameters
+@end itemize
+
+In addition, each protected subprogram body must satisfy:
+
+
+@itemize *
+
+@item 
+May reference only one protected component
+
+@item 
+May not reference nonconstant entities outside the protected subprogram
+scope.
+
+@item 
+May not contain address representation items, allocators, or quantified
+expressions.
+
+@item 
+May not contain delay, goto, loop, or procedure-call statements.
+
+@item 
+May not contain exported and imported entities
+
+@item 
+May not dereferenced access values
+
+@item 
+Function calls and attribute references must be static
+@end itemize
+
 @node Pragma Loop_Invariant,Pragma Loop_Optimize,Pragma Lock_Free,Implementation Defined Pragmas
 @anchor{gnat_rm/implementation_defined_pragmas pragma-loop-invariant}@anchor{98}
 @section Pragma Loop_Invariant