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[Ada] Defer processing of unknown CTW/E conditions to the back end

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2019-08-14  Bob Duff  <duff@adacore.com>

gcc/ada/

	* sem_prag.adb (Process_Compile_Time_Warning_Or_Error): Defer
	processing to the back end in all cases where the pragma's
	condition is not known at compile time during the front end
	(except in generics), as opposed to detecting 'Size attributes
	and the like. This ensures that we take advantage of whatever
	can be compile-time known after running the back end, as opposed
	to having the front end guess what the back end can do.  Remove
	a little duplicated code at the call site.
	* gnat1drv.adb (Post_Compilation_Validation_Checks): Unlock the
	Elists while in Validate_Compile_Time_Warning_Errors, because it
	does analysis and name resolution, which sometimes involves
	adding Elists.

From-SVN: r274466
This commit is contained in:
Bob Duff 2019-08-14 09:52:20 +00:00 committed by Pierre-Marie de Rodat
parent 4b96d3861e
commit 2d1439c7ad
3 changed files with 31 additions and 63 deletions

15
gcc/ada/ChangeLog

@ -1,3 +1,18 @@
2019-08-14 Bob Duff <duff@adacore.com>
* sem_prag.adb (Process_Compile_Time_Warning_Or_Error): Defer
processing to the back end in all cases where the pragma's
condition is not known at compile time during the front end
(except in generics), as opposed to detecting 'Size attributes
and the like. This ensures that we take advantage of whatever
can be compile-time known after running the back end, as opposed
to having the front end guess what the back end can do. Remove
a little duplicated code at the call site.
* gnat1drv.adb (Post_Compilation_Validation_Checks): Unlock the
Elists while in Validate_Compile_Time_Warning_Errors, because it
does analysis and name resolution, which sometimes involves
adding Elists.
2019-08-14 Eric Botcazou <ebotcazou@adacore.com>
* einfo.ads (Is_Called): Document new usage on E_Package

2
gcc/ada/gnat1drv.adb

@ -1022,9 +1022,11 @@ procedure Gnat1drv is
Atree.Unlock;
Nlists.Unlock;
Elists.Unlock;
Sem.Unlock;
Sem_Prag.Validate_Compile_Time_Warning_Errors;
Sem.Lock;
Elists.Lock;
Nlists.Lock;
Atree.Lock;

77
gcc/ada/sem_prag.adb

@ -7598,46 +7598,7 @@ package body Sem_Prag is
-------------------------------------------
procedure Process_Compile_Time_Warning_Or_Error is
Validation_Needed : Boolean := False;
function Check_Node (N : Node_Id) return Traverse_Result;
-- Tree visitor that checks if N is an attribute reference that can
-- be statically computed by the back end. Validation_Needed is set
-- to True if found.
----------------
-- Check_Node --
----------------
function Check_Node (N : Node_Id) return Traverse_Result is
begin
if Nkind (N) = N_Attribute_Reference
and then Is_Entity_Name (Prefix (N))
and then not Is_Generic_Unit (Scope (Entity (Prefix (N))))
then
declare
Attr_Id : constant Attribute_Id :=
Get_Attribute_Id (Attribute_Name (N));
begin
if Attr_Id = Attribute_Alignment
or else Attr_Id = Attribute_Size
then
Validation_Needed := True;
end if;
end;
end if;
return OK;
end Check_Node;
procedure Check_Expression is new Traverse_Proc (Check_Node);
-- Local variables
Arg1x : constant Node_Id := Get_Pragma_Arg (Arg1);
-- Start of processing for Process_Compile_Time_Warning_Or_Error
begin
-- In GNATprove mode, pragmas Compile_Time_Error and
-- Compile_Time_Warning are ignored, as the analyzer may not have the
@ -7655,20 +7616,18 @@ package body Sem_Prag is
Check_Arg_Is_OK_Static_Expression (Arg2, Standard_String);
Analyze_And_Resolve (Arg1x, Standard_Boolean);
-- If the condition is known at compile time (now), process it now.
-- Otherwise, register the expression for validation after the back
-- end has been called, because it might be known at compile time
-- then. For example, if the expression is "Record_Type'Size /= 32"
-- it might be known after the back end has determined the size of
-- Record_Type. We do not defer processing if we're inside a generic
-- unit, because we will have more information in the instances.
if Compile_Time_Known_Value (Arg1x) then
Process_Compile_Time_Warning_Or_Error (N, Sloc (Arg1));
-- Register the expression for its validation after the back end has
-- been called if it has occurrences of attributes Size or Alignment
-- (because they may be statically computed by the back end and hence
-- the whole expression needs to be reevaluated).
else
Check_Expression (Arg1x);
if Validation_Needed then
Validate_Compile_Time_Warning_Error (N);
end if;
elsif not Inside_A_Generic then
Validate_Compile_Time_Warning_Error (N);
end if;
end Process_Compile_Time_Warning_Or_Error;
@ -14449,25 +14408,17 @@ package body Sem_Prag is
-- Processing for this pragma is shared with Psect_Object
------------------------
-- Compile_Time_Error --
------------------------
----------------------------------------------
-- Compile_Time_Error, Compile_Time_Warning --
----------------------------------------------
-- pragma Compile_Time_Error
-- (boolean_EXPRESSION, static_string_EXPRESSION);
when Pragma_Compile_Time_Error =>
GNAT_Pragma;
Process_Compile_Time_Warning_Or_Error;
--------------------------
-- Compile_Time_Warning --
--------------------------
-- pragma Compile_Time_Warning
-- (boolean_EXPRESSION, static_string_EXPRESSION);
when Pragma_Compile_Time_Warning =>
when Pragma_Compile_Time_Error | Pragma_Compile_Time_Warning =>
GNAT_Pragma;
Process_Compile_Time_Warning_Or_Error;