[Bug rtl-optimization/84071] [7/8 regression] wrong elimination of zero-extension after sign-extended load

[ebotcazou at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84071

--- Comment #13 from Eric Botcazou <ebotcazou at gcc dot gnu.org> ---
Author: ebotcazou
Date: Wed Jan 31 10:08:08 2018
New Revision: 257226

URL: https://gcc.gnu.org/viewcvs?rev=257226&root=gcc&view=rev
Log:
        PR rtl-optimization/84071
        * combine.c (record_dead_and_set_regs_1): Record the source unmodified
        for a paradoxical SUBREG on a WORD_REGISTER_OPERATIONS target.

Added:
    branches/gcc-7-branch/gcc/testsuite/gcc.c-torture/execute/20180131-1.c
      - copied unchanged from r257224,
trunk/gcc/testsuite/gcc.c-torture/execute/20180131-1.c
Modified:
    branches/gcc-7-branch/gcc/ChangeLog
    branches/gcc-7-branch/gcc/combine.c
    branches/gcc-7-branch/gcc/testsuite/ChangeLog