[Bug tree-optimization/68128] A huge regression in Parboil v2.5 OpenMP CUTCP test (2.5 times lower performance)

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68128

--- Comment #8 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Author: jakub
Date: Thu Nov 26 10:18:50 2015
New Revision: 230932

URL: https://gcc.gnu.org/viewcvs?rev=230932&root=gcc&view=rev
Log:
        PR tree-optimization/68128
        * tree.h (OMP_CLAUSE_SHARED_READONLY): Define.
        * gimplify.c: Include gimple-walk.h.
        (enum gimplify_omp_var_data): Add GOVD_WRITTEN.
        (omp_notice_variable): Set flags to n->value if n already
        exists in target region, but we need to jump to do_outer.
        (omp_shared_to_firstprivate_optimizable_decl_p,
        omp_mark_stores, omp_find_stores_op, omp_find_stores_stmt): New
        functions.
        (gimplify_adjust_omp_clauses_1): Set OMP_CLAUSE_SHARED_READONLY
        on OMP_CLAUSE_SHARED if it is a scalar non-addressable that is
        not modified in the body.  Call omp_mark_stores for outer
        contexts on OMP_CLAUSE_SHARED clauses if they could be written
        in the body or on OMP_CLAUSE_LASTPRIVATE.
        (gimplify_adjust_omp_clauses): Add body argument, call
        omp_find_stores_{stmt,op} on the body through walk_gimple_seq.
        Set OMP_CLAUSE_SHARED_READONLY
        on OMP_CLAUSE_SHARED if it is a scalar non-addressable that is
        not modified in the body.  Call omp_mark_stores for outer
        contexts on OMP_CLAUSE_SHARED clauses if they could be written
        in the body or on OMP_CLAUSE_LASTPRIVATE or on OMP_CLAUSE_LINEAR
        without OMP_CLAUSE_LINEAR_NO_COPYOUT or on OMP_CLAUSE_REDUCTION.
        (gimplify_oacc_cache, gimplify_omp_parallel, gimplify_omp_task,
        gimplify_omp_for, gimplify_omp_workshare, gimplify_omp_target_update,
        gimplify_expr): Adjust gimplify_adjust_omp_clauses callers.
        * tree-nested.c (convert_nonlocal_omp_clauses,
        convert_local_omp_clauses): Clear OMP_CLAUSE_SHARED_READONLY on
        non-local vars or local vars referenced from nested routines.
        * omp-low.c (scan_sharing_clauses): For OMP_CLAUSE_SHARED_READONLY
        attempt to optimize it into OMP_CLAUSE_FIRSTPRIVATE.  Even for
        TREE_READONLY, don't call use_pointer_for_field with non-NULL
        second argument until we are sure we are keeping OMP_CLAUSE_SHARED.

        * gcc.dg/gomp/pr68128-1.c: New test.
        * gcc.dg/gomp/pr68128-2.c: New test.

Added:
    trunk/gcc/testsuite/gcc.dg/gomp/pr68128-1.c
    trunk/gcc/testsuite/gcc.dg/gomp/pr68128-2.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/gimplify.c
    trunk/gcc/omp-low.c
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/tree-nested.c
    trunk/gcc/tree.h