Marking variable as addressable from within SSA pass

[Bonzini <bonzini at gnu dot org>]

Hi,

I am trying to implement vector operation lowering as an SSA pass.  The 
pass is similar to tree-complex; I work on tree-ssa, slightly modified to
use bsi's also at -O0 similar to what is done in the tree-profiling branch,
but this is ok (it bootstraps).

So far I made it work as a non-SSA pass which I run just before
expanding, but I would like to run it as well just after loop
optimization, so that dom can clean up the code it generates.

The pass takes, for example,

  V4QI T_1;
  V4QI T_2;
  V4QI T_3;
  T_3 = T_1 & T_2;

and converts it into

  V4QI T_1;
  V4QI T_2;
  V4QI T_3;
  unsigned int *T_4;
  unsigned int *T_5;
  unsigned int *T_6;
  unsigned int T_7;
  unsigned int T_8;
  T_4 = (unsigned int *) &T_1;  
  T_5 = (unsigned int *) &T_2;  
  T_6 = (unsigned int *) &T_3;  
  T_7 = *T_4;
  T_8 = *T_5;
  T_9 = T_4 & T_5;
  *T_6 = T_9;

I do tweak the alias sets of the unsigned int *Ã that I generate.  All
this mess should hopefully be cleaned up by dom -- indeed even CSE and
ADDRESSOF manage to clean most of it.

I am setting the TREE_ADDRESSABLE bit of T_1, T_2 and T_3 but it is not
enough.  During variable renaming, stmt_ann returns an error_mark and
then everything goes haywire until I get an ICE near note_addressable.
Is there anything more I should do to mark these variables as
addressable?

Thank you,

Paolo