[Bug tree-optimization/84503] [7/8 Regression] store-merging miscompilation on powerpc64 with -O3 since r241789

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84503

--- Comment #6 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Author: jakub
Date: Thu Feb 22 08:28:42 2018
New Revision: 257891

URL: https://gcc.gnu.org/viewcvs?rev=257891&root=gcc&view=rev
Log:
        PR tree-optimization/84503
        * gimple-ssa-store-merging.c (merged_store_group::merge_into): Compute
        width as info->bitpos + info->bitsize - start.
        (merged_store_group::merge_overlapping): Simplify width computation.
        (check_no_overlap): New function.
        (imm_store_chain_info::try_coalesce_bswap): Compute expected
        start + width and last_order of the group, fail if check_no_overlap
        fails.
        (imm_store_chain_info::coalesce_immediate_stores): Don't merge info
        to group if check_no_overlap fails.

        * gcc.dg/pr84503-1.c: New test.
        * gcc.dg/pr84503-2.c: New test.

Added:
    trunk/gcc/testsuite/gcc.dg/pr84503-1.c
    trunk/gcc/testsuite/gcc.dg/pr84503-2.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/gimple-ssa-store-merging.c
    trunk/gcc/testsuite/ChangeLog