[Bug regression/69838] New: [regression] Lra deletes EH_REGION

["vogt at linux dot vnet.ibm.com" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69838

            Bug ID: 69838
           Summary: [regression] Lra deletes EH_REGION
           Product: gcc
           Version: 6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: regression
          Assignee: unassigned at gcc dot gnu.org
          Reporter: vogt at linux dot vnet.ibm.com
  Target Milestone: ---
              Host: s390x
            Target: s390x

Created attachment 37704
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=37704&action=edit
Ira dump (ok)

It looks like Lra does not handle EH_REGION notes correctly.  There is at least
one Gnat testcase where Lra wrongly deletes all exception handling code
(gcc/testsuite/gnat.dg/null_pointer_deref1.adb):

-- snip --
procedure Null_Pointer_Deref1 is 
   type Int_Ptr is access all Integer; 

   function Ident return Int_Ptr is 
   begin 
     return null; 
   end; 

   Data : Int_Ptr := Ident; 
begin 
   Data.all := 1; 
exception 
   when Constraint_Error | Storage_Error => null; 
end; 
-- snip --

The exception handling code vanishes in the reload pass (see attached rtl
dumps).  As a consequence, the exception is not caugt by the function and the
program terminates with an error.  With -mno-lra the test case works fine, and
the code in reload1.c seems to have special treatment for EH_REGION notes that
is missing in ira.c.