[Bug debug/51377] New: ICE when generating debug info for targets with multiple pointer sizes

[Bug debug/51377] New: ICE when generating debug info for targets with multiple pointer sizes

[nickc at redhat dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51377

             Bug #: 51377
           Summary: ICE when generating debug info for targets with
                    multiple pointer sizes
    Classification: Unclassified
           Product: gcc
           Version: 4.7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: debug
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: nickc@redhat.com


Created attachment 25966
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=25966
Source for test case

This is a follow up to a problem first reported here:

http://gcc.gnu.org/ml/gcc/2011-11/msg00397.html

[Bug debug/51377] ICE when generating debug info for targets with multiple pointer sizes

[nickc at redhat dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51377

--- Comment #1 from Nick Clifton <nickc at redhat dot com> 2011-12-01 10:44:57 UTC ---
Created attachment 25967
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=25967
Test for mixed pointer modes in the assertion.

[Bug debug/51377] ICE when generating debug info for targets with multiple pointer sizes

[nickc at redhat dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51377

--- Comment #2 from Nick Clifton <nickc at redhat dot com> 2011-12-01 10:54:35 UTC ---
[Darn - hit return too early].

When compiling for a target that supports multiple pointer sizes (eg s390)
generating debug information can trigger an ICE in the compiler:

  % s390-gcc -c -g -O2 -m64 fred.i
  fred.i: In function 'bar':
  fred.i:37:1: internal compiler error: in expand_debug_locations, at
cfgexpand.c:3687

The insn looks like this:

  (debug_insn 6 5 7 2 (var_location:SI temp$union_field$ptr_field (scratch))
fred.i:31 -1 (nil))

but the debug expression associated with it looks like this:

  (debug_expr:DI D#1)

The problem, I believe, is in the assertion at line 3687, not the debug
expression itself.  The expression has been created by converting the gimple
for the right hand side of the assignment on line 31 of fred.i:

   & arg_1(D)->bytes

into tree form.  This conversion chooses DImode since that is the default
pointer mode on this particular target.  The fact that this expression is then
cast to an SImode pointer is irrelevant - the expression itself is a DImode
pointer expression.

I have uploaded a proposed patch for this problem, based on an original patch
created by DJ, but tweaked a little bit by me.  It extends the assetion in
expand_debug_locations() to allow for the fact that pointer expressions might
use multiple modes.

Cheers
  Nick