diff options
Diffstat (limited to 'gcc/ada/sem_ch5.adb')
-rw-r--r-- | gcc/ada/sem_ch5.adb | 86 |
1 files changed, 65 insertions, 21 deletions
diff --git a/gcc/ada/sem_ch5.adb b/gcc/ada/sem_ch5.adb index f38c213..b2a3661 100644 --- a/gcc/ada/sem_ch5.adb +++ b/gcc/ada/sem_ch5.adb @@ -4425,7 +4425,7 @@ package body Sem_Ch5 is if not (Present (Current_Subprogram) and then Ekind (Current_Subprogram) = E_Function - and then (Nkind (Original_Node (N)) = N_Raise_Statement + and then (Nkind (N) in N_Raise_Statement or else (Nkind (N) = N_Procedure_Call_Statement and then Is_Entity_Name (Name (N)) @@ -4444,39 +4444,59 @@ package body Sem_Ch5 is -- unreachable code, since it is useless and we don't want -- to generate junk warnings. - -- We skip this step if we are not in code generation mode - -- or CodePeer mode. + -- We skip this step if we are not in code generation mode. -- This is the one case where we remove dead code in the -- semantics as opposed to the expander, and we do not want -- to remove code if we are not in code generation mode, since -- this messes up the tree or loses useful information for - -- CodePeer. + -- analysis tools such as CodePeer. -- Note that one might react by moving the whole circuit to -- exp_ch5, but then we lose the warning in -gnatc mode. - if Operating_Mode = Generate_Code - and then not CodePeer_Mode - then + if Operating_Mode = Generate_Code then loop - Nxt := Next (N); - - -- Quit deleting when we have nothing more to delete - -- or if we hit a label (since someone could transfer - -- control to a label, so we should not delete it). + declare + Del : constant Node_Id := Next (N); + -- Node to be possibly deleted + begin + -- Quit deleting when we have nothing more to delete + -- or if we hit a label (since someone could transfer + -- control to a label, so we should not delete it). - exit when No (Nxt) or else Nkind (Nxt) = N_Label; + exit when No (Del) or else Nkind (Del) = N_Label; - -- Statement/declaration is to be deleted + -- Statement/declaration is to be deleted - Analyze (Nxt); - Remove (Nxt); - Kill_Dead_Code (Nxt); + Analyze (Del); + Kill_Dead_Code (Del); + Remove (Del); + end; end loop; + + -- If this is a function, we add "raise Program_Error;", + -- because otherwise, we will get incorrect warnings about + -- falling off the end of the function. + + declare + Subp : constant Entity_Id := Current_Subprogram; + begin + if Present (Subp) and then Ekind (Subp) = E_Function then + Insert_After_And_Analyze (N, + Make_Raise_Program_Error (Sloc (Error_Node), + Reason => PE_Missing_Return)); + end if; + end; + end if; - Error_Msg_N ("??unreachable code!", Error_Node); + -- Suppress the warning in instances, because a statement can + -- be unreachable in some instances but not others. + + if not In_Instance then + Error_Msg_N ("??unreachable code!", Error_Node); + end if; end if; -- If the unconditional transfer of control instruction is the @@ -4535,9 +4555,33 @@ package body Sem_Ch5 is end if; -- This was one of the cases we are looking for (i.e. the parent - -- construct was IF, CASE or block) so decrement count. - - Unblocked_Exit_Count := Unblocked_Exit_Count - 1; + -- construct was IF, CASE or block). In most cases, we simply + -- decrement the count. However, if the parent is something like: + -- + -- if cond then + -- raise ...; -- or some other jump + -- end if; + -- + -- where cond is an expression that is known-true at compile time, + -- we can treat that as just the jump -- i.e. anything following + -- the if statement is unreachable. We don't do this for simple + -- cases like "if True" or "if Debug_Flag", because that causes + -- too many warnings. + + if Nkind (P) = N_If_Statement + and then Present (Then_Statements (P)) + and then No (Elsif_Parts (P)) + and then No (Else_Statements (P)) + and then Is_OK_Static_Expression (Condition (P)) + and then Is_True (Expr_Value (Condition (P))) + and then not Is_Trivial_Boolean (Condition (P)) + and then not Is_Static_Constant_Name (Condition (P)) + then + pragma Assert (Unblocked_Exit_Count = 2); + Unblocked_Exit_Count := 0; + else + Unblocked_Exit_Count := Unblocked_Exit_Count - 1; + end if; end if; end if; end Check_Unreachable_Code; |