[Bug rtl-optimization/64682] [5 Regression] wrong code at -O2 and -O3 on x86_64-linux-gnu

[segher at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64682

--- Comment #13 from Segher Boessenkool <segher at gcc dot gnu.org> ---
Author: segher
Date: Thu Nov  9 10:23:30 2017
New Revision: 254565

URL: https://gcc.gnu.org/viewcvs?rev=254565&root=gcc&view=rev
Log:
        Backport from mainline
        2017-11-01  Segher Boessenkool  <segher@kernel.crashing.org>

        PR rtl-optimization/64682
        PR rtl-optimization/69567
        PR rtl-optimization/69737
        PR rtl-optimization/82683
        * combine.c (distribute_notes) <REG_DEAD>: If the new I2 sets the same
        register mentioned in the note, drop the note, unless it came from I3,
        in which case it should go to I3 again.

Modified:
    branches/gcc-6-branch/gcc/ChangeLog
    branches/gcc-6-branch/gcc/combine.c