[Bug tree-optimization/78821] GCC7: Copying whole 32 bits structure field by field not optimised into copying whole 32 bits at once

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78821

--- Comment #16 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Author: jakub
Date: Mon Nov 20 10:10:23 2017
New Revision: 254948

URL: https://gcc.gnu.org/viewcvs?rev=254948&root=gcc&view=rev
Log:
        PR tree-optimization/78821
        * gimple-ssa-store-merging.c (find_bswap_or_nop_load): Give up
        if base is TARGET_MEM_REF.  If base is not MEM_REF, set base_addr
        to the address of the base rather than the base itself.
        (find_bswap_or_nop_1): Just use pointer comparison for vuse check.
        (find_bswap_or_nop_finalize): New function.
        (find_bswap_or_nop): Use it.
        (bswap_replace): Return a tree rather than bool, change first
        argument from gimple * to gimple_stmt_iterator, allow inserting
        into an empty sequence, allow ins_stmt to be NULL - then emit
        all stmts into gsi.  Fix up MEM_REF address gimplification.
        (pass_optimize_bswap::execute): Adjust bswap_replace caller.
        (struct store_immediate_info): Add N and INS_STMT non-static
        data members.
        (store_immediate_info::store_immediate_info): Initialize them
        from newly added ctor args.
        (merged_store_group::apply_stores): Formatting fixes.  Sort by
        bitpos at the end.
        (stmts_may_clobber_ref_p): For stores call also
        refs_anti_dependent_p.
        (gather_bswap_load_refs): New function.
        (imm_store_chain_info::try_coalesce_bswap): New method.
        (imm_store_chain_info::coalesce_immediate_stores): Use it.
        (split_group): Handle LROTATE_EXPR and NOP_EXPR rhs_code specially.
        (imm_store_chain_info::output_merged_store): Fail if number of
        new estimated stmts is bigger or equal than old.  Handle LROTATE_EXPR
        and NOP_EXPR rhs_code.
        (pass_store_merging::process_store): Compute n and ins_stmt, if
        ins_stmt is non-NULL and the store rhs is otherwise invalid, use
        LROTATE_EXPR rhs_code.  Pass n and ins_stmt to store_immediate_info
        ctor.
        (pass_store_merging::execute): Calculate dominators.

        * gcc.dg/store_merging_16.c: New test.

Added:
    trunk/gcc/testsuite/gcc.dg/store_merging_16.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/gimple-ssa-store-merging.c
    trunk/gcc/testsuite/ChangeLog