[Bug rtl-optimization/78547] [7 Regression] ICE: in loc_cmp, at var-tracking.c:3417 with -Os -g -mstringop-strategy=libcall -freorder-blocks-algorithm=simple

["jgreenhalgh at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78547

James Greenhalgh <jgreenhalgh at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |hjl at gcc dot gnu.org,
                   |                            |ienkovich at gcc dot gnu.org

--- Comment #2 from James Greenhalgh <jgreenhalgh at gcc dot gnu.org> ---
I'd be surprised if r238594 was the root cause, but it may have exposed
something latent. This revision changed the cost model for if conversion,
effectively disabling it in this testcase. You can emulate turning off
if-conversion for the testcase with -fno-if-conversion on the command line.
Adding that, you can continue the bisect further back until r237647 which looks
more probable given the testcase body.

I'm now compiling with:

  -Os -g -mstringop-strategy=libcall -freorder-blocks-algorithm=simple
-fdump-rtl-all-all -fno-if-conversion


Author: hjl <hjl@138bc75d-0d04-0410-961f-82ee72b054a4>
Date:   Tue Jun 21 14:24:31 2016 +0000

    Convert V1TImode register to TImode in debug insn

    TImode register referenced in debug insn can be converted to V1TImode
    by scalar to vector optimization.  After converting a TImode register
    to V1TImode, we need to check all debug insns on its use chain to
    convert the V1TImode register to SUBREG TImode.

    gcc/

    2016-06-21  H.J. Lu  <hongjiu.lu@intel.com>
            Ilya Enkovich  <ilya.enkovich@intel.com>

        PR target/71549
        * config/i386/i386.c (timode_scalar_chain::fix_debug_reg_uses):
        New member function to convert V1TImode register to SUBREG
        TImode in debug insn.
        (timode_scalar_chain::convert_insn): Call fix_debug_reg_uses
        after changing register mode to V1TImode.

    gcc/testsuite/

    2016-06-21  H.J. Lu  <hongjiu.lu@intel.com>

        PR target/71549
        * gcc.target/i386/pr71549.c: New test.


    git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@237647