[Bug rtl-optimization/70687] Undefined shift in change_zero_ext in combine.c

[rsandifo at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70687

--- Comment #4 from rsandifo at gcc dot gnu.org <rsandifo at gcc dot gnu.org> ---
Author: rsandifo
Date: Tue May  3 10:29:55 2016
New Revision: 235811

URL: https://gcc.gnu.org/viewcvs?rev=235811&root=gcc&view=rev
Log:
PR 70687: Use wide_int in combine.c:change_zero_ext

PR 70687 reports a case where combine.c mishandles integer modes
wider than unsigned HOST_WIDE_INT.  I don't have a testcase since
the PR is just pointing out the hole.

Also, I think a ZERO_EXTEND of a vector mode could in principle satisfy
the subreg condition but wouldn't be equivalent to an AND.  E.g.:

      (zero_extend:V4DI (subreg:V4SI (reg:V4DI R) 0))

Tested on x86_64-linux-gnu.

gcc/
        PR rtl-optimization/70687
        * combine.c (change_zero_ext): Check for scalar modes.  Use wide_int
        instead of unsigned HOST_WIDE_INT.

Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/combine.c