diff options
Diffstat (limited to 'gcc/ada/libgnat/a-conhel.adb')
| -rw-r--r-- | gcc/ada/libgnat/a-conhel.adb | 38 |
1 files changed, 27 insertions, 11 deletions
diff --git a/gcc/ada/libgnat/a-conhel.adb b/gcc/ada/libgnat/a-conhel.adb index 1a30b53..316c866 100644 --- a/gcc/ada/libgnat/a-conhel.adb +++ b/gcc/ada/libgnat/a-conhel.adb @@ -6,7 +6,7 @@ -- -- -- B o d y -- -- -- --- Copyright (C) 2015-2020, Free Software Foundation, Inc. -- +-- Copyright (C) 2015-2021, Free Software Foundation, Inc. -- -- -- -- GNAT is free software; you can redistribute it and/or modify it under -- -- terms of the GNU General Public License as published by the Free Soft- -- @@ -27,6 +27,13 @@ package body Ada.Containers.Helpers is + Max_Count : constant := 2**31 - 1; + -- Used in assertions below, to make sure the counts don't wrap around. + -- This can help detect bugs in which Adjust and Finalize calls are + -- improperly generated. An extra Decrement could otherwise cause + -- wraparound from 0 to 2**32-1. The highest count seen so far is + -- around 25, so this should be plenty. + package body Generic_Implementation is use type SAC.Atomic_Unsigned; @@ -50,6 +57,7 @@ package body Ada.Containers.Helpers is begin if T_Check then SAC.Increment (T_Counts.Busy); + pragma Assert (T_Counts.Busy <= Max_Count); end if; end Busy; @@ -112,7 +120,9 @@ package body Ada.Containers.Helpers is begin if T_Check then SAC.Increment (T_Counts.Lock); + pragma Assert (T_Counts.Lock <= Max_Count); SAC.Increment (T_Counts.Busy); + pragma Assert (T_Counts.Busy <= Max_Count); end if; end Lock; @@ -122,17 +132,20 @@ package body Ada.Containers.Helpers is procedure TC_Check (T_Counts : Tamper_Counts) is begin - if T_Check and then T_Counts.Busy > 0 then - raise Program_Error with - "attempt to tamper with cursors"; + if T_Check then + if T_Counts.Busy > 0 then + raise Program_Error with + "attempt to tamper with cursors"; + end if; + + -- The lock status (which monitors "element tampering") always + -- implies that the busy status (which monitors "cursor + -- tampering") is set too; this is a representation invariant. + -- Thus if the busy count is zero, then the lock count + -- must also be zero. + + pragma Assert (T_Counts.Lock = 0); end if; - - -- The lock status (which monitors "element tampering") always - -- implies that the busy status (which monitors "cursor tampering") - -- is set too; this is a representation invariant. Thus if the busy - -- bit is not set, then the lock bit must not be set either. - - pragma Assert (T_Counts.Lock = 0); end TC_Check; -------------- @@ -155,6 +168,7 @@ package body Ada.Containers.Helpers is begin if T_Check then SAC.Decrement (T_Counts.Busy); + pragma Assert (T_Counts.Busy <= Max_Count); end if; end Unbusy; @@ -166,7 +180,9 @@ package body Ada.Containers.Helpers is begin if T_Check then SAC.Decrement (T_Counts.Lock); + pragma Assert (T_Counts.Lock <= Max_Count); SAC.Decrement (T_Counts.Busy); + pragma Assert (T_Counts.Busy <= Max_Count); end if; end Unlock; |