[Bug target/54457] [x32] Fail to combine 64bit index + constant

[ubizjak at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54457

Uros Bizjak <ubizjak at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
   Last reconfirmed|                            |2012-09-24
         AssignedTo|unassigned at gcc dot       |ubizjak at gmail dot com
                   |gnu.org                     |
     Ever Confirmed|0                           |1

--- Comment #2 from Uros Bizjak <ubizjak at gmail dot com> 2012-09-24 22:48:37 UTC ---
Created attachment 28261
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=28261
Proposed patch

Patch that enhances combine_simplify_rtx to generate canonical binop sequences
that simplify_plus_minus can recognize and further optimize.

Bootstrapped and regression tested on x86_64-pc-linux-gnu.

Patched gcc generates expected code for the above testcase:

foo:
        movzbl  array+1(%edi), %eax
        ret