On Thu, Apr 17, 2014 at 2:21 PM, Martin Jambor <mjam...@suse.cz> wrote:
> On Wed, Apr 16, 2014 at 11:22:28AM +0200, Richard Biener wrote:
>> On Tue, 15 Apr 2014, Martin Jambor wrote:
>>
>> > Hi,
>> >
>> > back in January in
>> > http://gcc.gnu.org/ml/gcc-patches/2014-01/msg00848.html Eric pointed
>> > out a testcase where the problem was SRA not scalarizing an aggregate
>> > because it was involved in a throwing statement. The reason is that
>> > SRA is likely to need to append new statements after each one where a
>> > replaced aggregate is present, but throwing statements must end their
>> > BBs. This patch comes up with a fix for most such situations by
>> > adding these new statements onto a single successor non-EH edge, if
>> > there is one and only one such edge.
>> >
>> > I have bootstrapped and tested a very similar version on x86_64-linux,
>> > bootstrap and testing of this exact one is currently underway. OK for
>> > trunk? Eric, if and once this gets in, can you please add the
>> > testcase from your original post to the suite?
>> >
>> > Thanks,
>> >
>> > Martin
>> >
>> >
>> > 2014-04-15 Martin Jambor <mjam...@suse.cz>
>> >
>> > * tree-sra.c (single_non_eh_succ): New function.
>> > (disqualify_ops_if_throwing_stmt): Renamed to
>> > disqualify_if_bad_bb_terminating_stmt. Allow throwing statements
>> > having one non-EH successor BB.
>> > (gsi_for_eh_followups): New function.
>> > (sra_modify_expr): If stmt ends bb, use single non-EH successor to
>> > generate loads into replacements.
>> > (sra_modify_assign): Likewise and and also use the simple path for
>> > such statements.
>> > (sra_modify_function_body): Iterate safely over BBs.
>> >
>
> ...
>
>> > @@ -2734,6 +2758,19 @@ get_access_for_expr (tree expr)
>> > return get_var_base_offset_size_access (base, offset, max_size);
>> > }
>> >
>> > +/* Split the single non-EH successor edge from BB (there must be exactly
>> > one)
>> > + and return a gimple iterator to the new block. */
>> > +
>> > +static gimple_stmt_iterator
>> > +gsi_for_eh_followups (basic_block bb)
>> > +{
>> > + edge e = single_non_eh_succ (bb);
>> > + gcc_assert (e);
>> > +
>> > + basic_block new_bb = split_edge (e);
>> > + return gsi_start_bb (new_bb);
>> > +}
>> > +
>> > /* Replace the expression EXPR with a scalar replacement if there is one
>> > and
>> > generate other statements to do type conversion or subtree copying if
>> > necessary. GSI is used to place newly created statements, WRITE is
>> > true if
>> > @@ -2763,6 +2800,13 @@ sra_modify_expr (tree *expr, gimple_stmt_iterator
>> > *gsi, bool write)
>> > type = TREE_TYPE (*expr);
>> >
>> > loc = gimple_location (gsi_stmt (*gsi));
>> > + gimple_stmt_iterator alt_gsi = gsi_none ();
>> > + if (write && stmt_ends_bb_p (gsi_stmt (*gsi)))
>> > + {
>> > + alt_gsi = gsi_for_eh_followups (gsi_bb (*gsi));
>> > + gsi = &alt_gsi;
>>
>> I think you should try to either use gsi_insert_on_edge_immediate
>> (yeah, bad we can't build a gsi_for_edge_insert ()) or add
>> a gsi_for_edge_insert () building on gimple_find_edge_insert_loc
>> (note the before/after flag that returns - gsi_insert_* variants
>> that take a flag specifying after/before would come handy here).
>> You could also add a flag to gimple_find_edge_insert_loc whether
>> it always should be possible to use gsi_insert_after and split
>> the block in some more cases (or split it if both after and
>> before inserts should be valid, but that would not split in
>> the very rare case of an empty successor only).
>>
>> Basically usually you can avoid splitting the edge.
>
> The following patch adds gsi_start_edge for that purpose and uses it
> together with gsi_commit_edge_inserts from within SRA.
>
> I did not make it an inline static function in the header like the
> other gsi initializing functions because that would make
> gimple-iterator.h depend on tree-cfg.h and with our current flat
> includes that triggered changes of includes in half a gazillion
> unrelated c files (I have that patch too because I was apparently too
> lazy to think before the third coffee yesterday but I do not think it
> is worth it).
>
> Bootstrapped and tested on x86_64-linux, this time it also includes
> Eric's testcase. OK for trunk?
Ok.
Thanks,
Richard.
> Thanks,
>
> Martin
>
>
> 2014-04-16 Martin Jambor <mjam...@suse.cz>
>
> * gimple-iterator.c (gsi_start_edge): New function.
> * gimple-iterator.h (gsi_start_edge): Declare.
> * tree-sra.c (single_non_eh_succ): New function.
> (disqualify_ops_if_throwing_stmt): Renamed to
> disqualify_if_bad_bb_terminating_stmt. Allow throwing statements
> having one non-EH successor BB.
> (sra_modify_expr): If stmt ends bb, use single non-EH successor to
> generate loads into replacements.
> (sra_modify_assign): Likewise and and also use the simple path for
> such statements.
> (sra_modify_function_body): Commit statements on edges.
>
> testsuite/
> * gnat.dg/opt34.adb: New.
> * gnat.dg/opt34_pkg.ads: Likewise.
>
> diff --git a/gcc/gimple-iterator.c b/gcc/gimple-iterator.c
> index 1cfeb73..8a1ec53 100644
> --- a/gcc/gimple-iterator.c
> +++ b/gcc/gimple-iterator.c
> @@ -689,6 +689,15 @@ gsi_insert_seq_on_edge (edge e, gimple_seq seq)
> gimple_seq_add_seq (&PENDING_STMT (e), seq);
> }
>
> +/* Return a new iterator pointing to the first statement in sequence of
> + statements on edge E. Such statements need to be subsequently moved into
> a
> + basic block by calling gsi_commit_edge_inserts. */
> +
> +gimple_stmt_iterator
> +gsi_start_edge (edge e)
> +{
> + return gsi_start (PENDING_STMT (e));
> +}
>
> /* Insert the statement pointed-to by GSI into edge E. Every attempt
> is made to place the statement in an existing basic block, but
> diff --git a/gcc/gimple-iterator.h b/gcc/gimple-iterator.h
> index c35dc81..909d58b 100644
> --- a/gcc/gimple-iterator.h
> +++ b/gcc/gimple-iterator.h
> @@ -123,6 +123,8 @@ gsi_start_bb (basic_block bb)
> return i;
> }
>
> +gimple_stmt_iterator gsi_start_edge (edge e);
> +
> /* Return a new iterator initially pointing to GIMPLE_SEQ's last statement.
> */
>
> static inline gimple_stmt_iterator
> diff --git a/gcc/testsuite/gnat.dg/opt34.adb b/gcc/testsuite/gnat.dg/opt34.adb
> new file mode 100644
> index 0000000..a5d0ab6
> --- /dev/null
> +++ b/gcc/testsuite/gnat.dg/opt34.adb
> @@ -0,0 +1,29 @@
> +-- { dg-do compile }
> +-- { dg-options "-O -fdump-tree-esra" }
> +
> +with Opt34_Pkg; use Opt34_Pkg;
> +
> +procedure Opt34 is
> +
> + function Local_Fun (Arg : T_Private) return T_Private is
> + Result : T_Private;
> + begin
> +
> + case Get_Integer (Arg) is
> + when 1 =>
> + Result := Get_Private (100);
> + when 2 =>
> + Result := T_Private_Zero;
> + when others =>
> + null;
> + end case;
> +
> + return Result;
> + end Local_Fun;
> +
> +begin
> + Assert (Get_Integer (Local_Fun (Get_Private (1))) = 100);
> +end;
> +
> +-- { dg-final { scan-tree-dump "Created a replacement for result" "esra" } }
> +-- { dg-final { cleanup-tree-dump "esra" } }
> diff --git a/gcc/testsuite/gnat.dg/opt34_pkg.ads
> b/gcc/testsuite/gnat.dg/opt34_pkg.ads
> new file mode 100644
> index 0000000..83ecb49
> --- /dev/null
> +++ b/gcc/testsuite/gnat.dg/opt34_pkg.ads
> @@ -0,0 +1,14 @@
> +package Opt34_Pkg is
> +
> + type T_Private is record
> + I : Integer := 0;
> + end record;
> +
> + T_Private_Zero : constant T_Private := (I => 0);
> +
> + function Get_Private (I : Integer) return T_Private;
> + function Get_Integer (X : T_Private) return Integer;
> +
> + procedure Assert (Cond : Boolean);
> +
> +end Opt34_Pkg;
> diff --git a/gcc/tree-sra.c b/gcc/tree-sra.c
> index ffef13d..73e681d 100644
> --- a/gcc/tree-sra.c
> +++ b/gcc/tree-sra.c
> @@ -1142,17 +1142,41 @@ build_access_from_expr (tree expr, gimple stmt, bool
> write)
> return false;
> }
>
> -/* Disqualify LHS and RHS for scalarization if STMT must end its basic block
> in
> - modes in which it matters, return true iff they have been disqualified.
> RHS
> - may be NULL, in that case ignore it. If we scalarize an aggregate in
> - intra-SRA we may need to add statements after each statement. This is not
> - possible if a statement unconditionally has to end the basic block. */
> +/* Return the single non-EH successor edge of BB or NULL if there is none or
> + more than one. */
> +
> +static edge
> +single_non_eh_succ (basic_block bb)
> +{
> + edge e, res = NULL;
> + edge_iterator ei;
> +
> + FOR_EACH_EDGE (e, ei, bb->succs)
> + if (!(e->flags & EDGE_EH))
> + {
> + if (res)
> + return NULL;
> + res = e;
> + }
> +
> + return res;
> +}
> +
> +/* Disqualify LHS and RHS for scalarization if STMT has to terminate its BB
> and
> + there is no alternative spot where to put statements SRA might need to
> + generate after it. The spot we are looking for is an edge leading to a
> + single non-EH successor, if it exists and is indeed single. RHS may be
> + NULL, in that case ignore it. */
> +
> static bool
> -disqualify_ops_if_throwing_stmt (gimple stmt, tree lhs, tree rhs)
> +disqualify_if_bad_bb_terminating_stmt (gimple stmt, tree lhs, tree rhs)
> {
> if ((sra_mode == SRA_MODE_EARLY_INTRA || sra_mode == SRA_MODE_INTRA)
> - && (stmt_can_throw_internal (stmt) || stmt_ends_bb_p (stmt)))
> + && stmt_ends_bb_p (stmt))
> {
> + if (single_non_eh_succ (gimple_bb (stmt)))
> + return false;
> +
> disqualify_base_of_expr (lhs, "LHS of a throwing stmt.");
> if (rhs)
> disqualify_base_of_expr (rhs, "RHS of a throwing stmt.");
> @@ -1180,7 +1204,7 @@ build_accesses_from_assign (gimple stmt)
> lhs = gimple_assign_lhs (stmt);
> rhs = gimple_assign_rhs1 (stmt);
>
> - if (disqualify_ops_if_throwing_stmt (stmt, lhs, rhs))
> + if (disqualify_if_bad_bb_terminating_stmt (stmt, lhs, rhs))
> return false;
>
> racc = build_access_from_expr_1 (rhs, stmt, false);
> @@ -1319,7 +1343,7 @@ scan_function (void)
> }
>
> t = gimple_call_lhs (stmt);
> - if (t && !disqualify_ops_if_throwing_stmt (stmt, t, NULL))
> + if (t && !disqualify_if_bad_bb_terminating_stmt (stmt, t, NULL))
> ret |= build_access_from_expr (t, stmt, true);
> break;
>
> @@ -2763,6 +2787,13 @@ sra_modify_expr (tree *expr, gimple_stmt_iterator
> *gsi, bool write)
> type = TREE_TYPE (*expr);
>
> loc = gimple_location (gsi_stmt (*gsi));
> + gimple_stmt_iterator alt_gsi = gsi_none ();
> + if (write && stmt_ends_bb_p (gsi_stmt (*gsi)))
> + {
> + alt_gsi = gsi_start_edge (single_non_eh_succ (gsi_bb (*gsi)));
> + gsi = &alt_gsi;
> + }
> +
> if (access->grp_to_be_replaced)
> {
> tree repl = get_access_replacement (access);
> @@ -3226,14 +3257,23 @@ sra_modify_assign (gimple *stmt, gimple_stmt_iterator
> *gsi)
> if (modify_this_stmt
> || gimple_has_volatile_ops (*stmt)
> || contains_vce_or_bfcref_p (rhs)
> - || contains_vce_or_bfcref_p (lhs))
> + || contains_vce_or_bfcref_p (lhs)
> + || stmt_ends_bb_p (*stmt))
> {
> if (access_has_children_p (racc))
> generate_subtree_copies (racc->first_child, racc->base, 0, 0, 0,
> gsi, false, false, loc);
> if (access_has_children_p (lacc))
> - generate_subtree_copies (lacc->first_child, lacc->base, 0, 0, 0,
> - gsi, true, true, loc);
> + {
> + gimple_stmt_iterator alt_gsi = gsi_none ();
> + if (stmt_ends_bb_p (*stmt))
> + {
> + alt_gsi = gsi_start_edge (single_non_eh_succ (gsi_bb (*gsi)));
> + gsi = &alt_gsi;
> + }
> + generate_subtree_copies (lacc->first_child, lacc->base, 0, 0, 0,
> + gsi, true, true, loc);
> + }
> sra_stats.separate_lhs_rhs_handling++;
>
> /* This gimplification must be done after generate_subtree_copies,
> @@ -3397,6 +3437,7 @@ sra_modify_function_body (void)
> }
> }
>
> + gsi_commit_edge_inserts ();
> return cfg_changed;
> }
>
