diff options
Diffstat (limited to 'gcc/ada/exp_util.adb')
| -rw-r--r-- | gcc/ada/exp_util.adb | 83 |
1 files changed, 54 insertions, 29 deletions
diff --git a/gcc/ada/exp_util.adb b/gcc/ada/exp_util.adb index 6eb4243..acd1073 100644 --- a/gcc/ada/exp_util.adb +++ b/gcc/ada/exp_util.adb @@ -4238,9 +4238,9 @@ package body Exp_Util is -- When a function call appears in Object.Operation format, the -- original representation has two possible forms depending on the -- availability of actual parameters: - -- - -- Obj.Func_Call -- N_Selected_Component - -- Obj.Func_Call (Param) -- N_Indexed_Component + + -- Obj.Func_Call N_Selected_Component + -- Obj.Func_Call (Param) N_Indexed_Component else if Nkind (Expr) = N_Indexed_Component then @@ -4557,15 +4557,6 @@ package body Exp_Util is -- Start of processing for Is_Aliased begin - -- Aliasing in expression with actions does not matter because the - -- scope of the transient object is always limited by the scope of - -- the EWA. Such objects are always hooked and always finalized at - -- the end of the EWA's scope. - - if Nkind (Rel_Node) = N_Expression_With_Actions then - return False; - end if; - Stmt := First_Stmt; while Present (Stmt) loop if Nkind (Stmt) = N_Object_Declaration then @@ -5295,18 +5286,34 @@ package body Exp_Util is function Is_Volatile_Reference (N : Node_Id) return Boolean is begin - if Nkind (N) in N_Has_Etype - and then Present (Etype (N)) - and then Treat_As_Volatile (Etype (N)) - then + -- Only source references are to be treated as volatile, internally + -- generated stuff cannot have volatile external effects. + + if not Comes_From_Source (N) then + return False; + + -- Never true for reference to a type + + elsif Is_Entity_Name (N) and then Is_Type (Entity (N)) then + return False; + + -- True if object reference with volatile type + + elsif Is_Volatile_Object (N) then return True; + -- True if reference to volatile entity + elsif Is_Entity_Name (N) then return Treat_As_Volatile (Entity (N)); + -- True for slice of volatile array + elsif Nkind (N) = N_Slice then return Is_Volatile_Reference (Prefix (N)); + -- True if volatile component + elsif Nkind_In (N, N_Indexed_Component, N_Selected_Component) then if (Is_Entity_Name (Prefix (N)) and then Has_Volatile_Components (Entity (Prefix (N)))) @@ -5318,6 +5325,8 @@ package body Exp_Util is return Is_Volatile_Reference (Prefix (N)); end if; + -- Otherwise false + else return False; end if; @@ -6844,9 +6853,7 @@ package body Exp_Util is -- (this happens because routines Duplicate_Subexpr_XX implicitly invoke -- Remove_Side_Effects). - if No (Exp_Type) - or else Ekind (Exp_Type) = E_Access_Attribute_Type - then + if No (Exp_Type) or else Ekind (Exp_Type) = E_Access_Attribute_Type then return; -- No action needed for side-effect free expressions @@ -6913,9 +6920,12 @@ package body Exp_Util is Insert_Action (Exp, E); -- If the expression has the form v.all then we can just capture the - -- pointer, and then do an explicit dereference on the result. + -- pointer, and then do an explicit dereference on the result, but + -- this is not right if this is a volatile reference. - elsif Nkind (Exp) = N_Explicit_Dereference then + elsif Nkind (Exp) = N_Explicit_Dereference + and then not Is_Volatile_Reference (Exp) + then Def_Id := Make_Temporary (Loc, 'R', Exp); Res := Make_Explicit_Dereference (Loc, New_Occurrence_Of (Def_Id, Loc)); @@ -6987,17 +6997,21 @@ package body Exp_Util is -- This is needed for correctness in the case of a volatile object of -- a non-volatile type because the Make_Reference call of the "default" -- approach would generate an illegal access value (an access value - -- cannot designate such an object - see Analyze_Reference). We skip - -- using this scheme if we have an object of a volatile type and we do - -- not have Name_Req set true (see comments for Side_Effect_Free). - - -- In Ada 2012 a qualified expression is an object, but for purposes of - -- removing side effects it still need to be transformed into a separate - -- declaration, particularly if the expression is an aggregate. + -- cannot designate such an object - see Analyze_Reference). elsif Is_Object_Reference (Exp) and then Nkind (Exp) /= N_Function_Call + + -- In Ada 2012 a qualified expression is an object, but for purposes + -- of removing side effects it still need to be transformed into a + -- separate declaration, particularly in the case of an aggregate. + and then Nkind (Exp) /= N_Qualified_Expression + + -- We skip using this scheme if we have an object of a volatile + -- type and we do not have Name_Req set true (see comments for + -- Side_Effect_Free). + and then (Name_Req or else not Treat_As_Volatile (Exp_Type)) then Def_Id := Make_Temporary (Loc, 'R', Exp); @@ -8030,6 +8044,12 @@ package body Exp_Util is -- Start of processing for Side_Effect_Free begin + -- If volatile reference, always consider it to have side effects + + if Is_Volatile_Reference (N) then + return False; + end if; + -- Note on checks that could raise Constraint_Error. Strictly, if we -- take advantage of 11.6, these checks do not count as side effects. -- However, we would prefer to consider that they are side effects, @@ -8043,12 +8063,17 @@ package body Exp_Util is if Is_Entity_Name (N) then + -- A type reference is always side effect free + + if Is_Type (Entity (N)) then + return True; + -- Variables are considered to be a side effect if Variable_Ref -- is set or if we have a volatile reference and Name_Req is off. -- If Name_Req is True then we can't help returning a name which -- effectively allows multiple references in any case. - if Is_Variable (N, Use_Original_Node => False) then + elsif Is_Variable (N, Use_Original_Node => False) then return not Variable_Ref and then (not Is_Volatile_Reference (N) or else Name_Req); |