Allow the Lock_Free aspect of a protected type to be True (but only by
explicit specification) if Ceiling_Locking locking policy has been specified.
Clarify that the Lock_Free aspect takes precedence over the Ceiling_Locking
policy in that case.
Tested on x86_64-pc-linux-gnu, committed on trunk
gcc/ada/
* sem_ch9.adb
(Satisfies_Lock_Free_Requirements): If Ceiling_Locking locking
policy has been specified, then either return False (if Lock_Free
was not explicitly specified) or generate a warning that ceiling
locking will not be implemented for this protected unit (if
Lock_Free was explicitly specified). Generate an error message (in
addition to returning False) if an explicit Lock_Free aspect
specification is rejected because atomic primitives are not
supported on the given target.
* doc/gnat_rm/implementation_defined_pragmas.rst: Clarify that the
Lock_Free aspect for a protected unit takes precedence over the
Ceiling_Locking locking policy in the case where both apply.
* gnat_rm.texi: Regenerate.diff --git a/gcc/ada/doc/gnat_rm/implementation_defined_pragmas.rst b/gcc/ada/doc/gnat_rm/implementation_defined_pragmas.rst
--- a/gcc/ada/doc/gnat_rm/implementation_defined_pragmas.rst
+++ b/gcc/ada/doc/gnat_rm/implementation_defined_pragmas.rst
@@ -3752,7 +3752,12 @@ In addition, each protected subprogram body must satisfy:
* May not dereferenced access values
* Function calls and attribute references must be static
-
+If the Lock_Free aspect is specified to be True for a protected unit
+and the Ceiling_Locking locking policy is in effect, then the run-time
+actions associated with the Ceiling_Locking locking policy (described in
+Ada RM D.3) are not performed when a protected operation of the protected
+unit is executed.
+
Pragma Loop_Invariant
=====================
diff --git a/gcc/ada/gnat_rm.texi b/gcc/ada/gnat_rm.texi
--- a/gcc/ada/gnat_rm.texi
+++ b/gcc/ada/gnat_rm.texi
@@ -19,7 +19,7 @@
@copying
@quotation
-GNAT Reference Manual , Aug 25, 2022
+GNAT Reference Manual , Sep 09, 2022
AdaCore
@@ -5273,6 +5273,12 @@ May not dereferenced access values
Function calls and attribute references must be static
@end itemize
+If the Lock_Free aspect is specified to be True for a protected unit
+and the Ceiling_Locking locking policy is in effect, then the run-time
+actions associated with the Ceiling_Locking locking policy (described in
+Ada RM D.3) are not performed when a protected operation of the protected
+unit is executed.
+
@node Pragma Loop_Invariant,Pragma Loop_Optimize,Pragma Lock_Free,Implementation Defined Pragmas
@anchor{gnat_rm/implementation_defined_pragmas pragma-loop-invariant}@anchor{95}
@section Pragma Loop_Invariant
diff --git a/gcc/ada/sem_ch9.adb b/gcc/ada/sem_ch9.adb
--- a/gcc/ada/sem_ch9.adb
+++ b/gcc/ada/sem_ch9.adb
@@ -651,9 +651,34 @@ package body Sem_Ch9 is
begin
if not Support_Atomic_Primitives_On_Target then
+ if Lock_Free_Given then
+ Error_Msg_N
+ ("Lock_Free aspect requires target support for "
+ & "atomic primitives", N);
+ end if;
return False;
end if;
+ -- Deal with case where Ceiling_Locking locking policy is
+ -- in effect.
+
+ if Locking_Policy = 'C' then
+ if Lock_Free_Given then
+ -- Explicit Lock_Free aspect spec overrides
+ -- Ceiling_Locking so we generate a warning.
+
+ Error_Msg_N
+ ("Lock_Free aspect specification overrides "
+ & "Ceiling_Locking locking policy??", N);
+ else
+ -- If Ceiling_Locking locking policy is in effect, then
+ -- Lock_Free can be explicitly specified but it is
+ -- never the default.
+
+ return False;
+ end if;
+ end if;
+
-- Get the number of errors detected by the compiler so far
if Lock_Free_Given then
