This patch avoids an unnecessary exception propagation in the compiler when
handling the "delay" construct. This should avoid the crashes/hangs observed
in PR 80590 on g-exptty.adb among others.
Note that the proper fix for this PR is to do a full bootstrap of GCC, since
the issue is that GNAT switched from SJLJ to ZCX exception handling from
GCC 7 to GCC 8, causing these inconsistencies that can only be resolved via
a full bootstrap, or by using the newly built compiler to build new compilers.
Tested on x86_64-pc-linux-gnu
Verified manually that no exception propagation occurs in gnat1 with this
patch when compiling g-exptty.adb, g-locfil.adb, s-gloloc.adb and g-socthi.adb.
Tom, if you could confirm that you are unblocked and can move forward on
reenabling Ada on your builds, that'd be great, let me know.
Committed on branches 8, 9 and trunk.
2019-06-17 Arnaud Charlet <char...@adacore.com>
PR ada/80590
* exp_ch9.adb (Expand_N_Delay_Relative_Statement): Swap the two
conditions to avoid a unnecessary exception propagation in the default
case.
--
Index: exp_ch9.adb
===================================================================
--- exp_ch9.adb (revision 272370)
+++ exp_ch9.adb (working copy)
@@ -8258,18 +8258,17 @@
Proc : Entity_Id;
begin
- -- Try to use System.Relative_Delays.Delay_For only if available. This
- -- is the implementation used on restricted platforms when Ada.Calendar
- -- is not available.
+ -- Try to use Ada.Calendar.Delays.Delay_For if available.
- if RTE_Available (RO_RD_Delay_For) then
- Proc := RTE (RO_RD_Delay_For);
+ if RTE_Available (RO_CA_Delay_For) then
+ Proc := RTE (RO_CA_Delay_For);
- -- Otherwise, use Ada.Calendar.Delays.Delay_For and emit an error
- -- message if not available.
+ -- Otherwise, use System.Relative_Delays.Delay_For and emit an error
+ -- message if not available. This is the implementation used on
+ -- restricted platforms when Ada.Calendar is not available.
else
- Proc := RTE (RO_CA_Delay_For);
+ Proc := RTE (RO_RD_Delay_For);
end if;
Rewrite (N,
