Ping.
Teresa
On Thu, Nov 15, 2012 at 12:10 PM, Teresa Johnson <tejohn...@google.com> wrote:
> Revised patch that fixes failures encountered when enabling
> -freorder-blocks-and-partition, including the failure reported in PR 53743.
>
> This includes new verification code to ensure no cold blocks dominate hot
> blocks contributed by Steven Bosscher.
>
> I attempted to make the handling of partition updates through the optimization
> passes much more consistent, removing a number of partial fixes in the code
> stream in the process. The code to fixup partitions (including the
> BB_PARTITION
> assignement, region crossing jump notes, and switch text section notes) is
> now handled in a few centralized locations. For example, inside
> rtl_redirect_edge_and_branch and force_nonfallthru_and_redirect, so that
> callers
> don't need to attempt the fixup themselves.
>
> For optimization passes that make adjustments to the cfg while in cfg layout
> mode that are not easy to fix up incrementally, the new routine
> fixup_partitions handles the cleanup globally. This does require calculation
> of the dominance relation, however, as far as I can tell the routines which
> now invoke this global fixup (try_optimize_cfg and commit_edge_insertions)
> are invoked typically once (or a small number of times in the case of
> try_optimize_cfg) per optimization pass. Additionally, I compared the
> -ftime-report output for some large fdo compilations and saw only minimal
> increases in the dominance computation times, which were only a tiny percent
> of the overall compile time.
>
> Additionally, I added a flag to the rtl_data structure to indicate whether
> any partitioning was actually performed, so that optimizations which were
> conservatively disabled whenever the flag_reorder_blocks_and_partition
> is enabled (e.g. try_crossjump_to_edge, part of connect_traces) can be less
> conservative for functions where no partitions were formed (e.g. they are
> completely hot).
>
> Bootstrapped and tested on x86_64-unknown-linux-gnu. Also tested with
> SPEC2006 int
> benchmarks and internal google benchmarks using profile feedback and
> -freorder-blocks-and-partition to get more coverage. Ok for trunk?
>
> Thanks,
> Teresa
>
> 2012-11-14 Teresa Johnson <tejohn...@google.com>
> Steven Bosscher <ste...@gcc.gnu.org>
>
> * cfghooks.h (cfg_layout_finalize): New parameter.
> * modulo-sched.c (rest_of_handle_sms): New cfg_layout_finalize
> parameter.
> * ifcvt.c (find_if_case_1): Replace BB_COPY_PARTITION with assert
> as this is now done by redirect_edge_and_branch_force.
> * function.c (thread_prologue_and_epilogue_insns): Insert new bb after
> barriers, new cfg_layout_finalize parameter, and don't store exit
> predecessor BB until after it is potentially split.
> * function.h (struct rtl_data): New flag has_bb_partition.
> * hw-doloop.c (reorder_loops): New cfg_layout_finalize parameter.
> * cfgcleanup.c (try_crossjump_to_edge): Only skip optimization if
> any blocks in function actually partitioned.
> (try_optimize_cfg): If cfg changed, invoke fixup_partitions to clean
> up partitioning.
> * bb-reorder.c (connect_traces): Only look for partitions and skip
> block copying if any blocks in function actually partitioned.
> (emit_barrier_after_bb): Handle insertion in non-cfglayout mode.
> (find_rarely_executed_basic_blocks_and_crossing_edges): Ensure
> that no cold blocks dominate a hot block.
> (fix_up_fall_thru_edges): Replace BB_COPY_PARTITION with assert
> as this is now done by force_nonfallthru_and_redirect.
> (add_reg_crossing_jump_notes): Handle the fact that some jumps may
> already be marked with region crossing note.
> (reorder_basic_blocks): Only need to verify partitions if any
> blocks in function actually partitioned.
> (insert_section_boundary_note): Only need to insert note if any
> blocks in function actually partitioned.
> (rest_of_handle_reorder_blocks): New cfg_layout_finalize
> parameter, and remove call to insert_section_boundary_note as this
> is now called via cfg_layout_finalize/fixup_reorder_chain.
> (duplicate_computed_gotos): New cfg_layout_finalize
> parameter.
> (partition_hot_cold_basic_blocks): Set flag indicating function
> has bb partitions.
> * bb-reorder.h: Declare insert_section_boundary_note and
> emit_barrier_after_bb, which are no longer static.
> * basic-block.h: Declare new function fixup_partitions.
> * cfgrtl.c (try_redirect_by_replacing_jump): Remove unnecessary
> check for region crossing note.
> (fixup_partition_crossing): New function.
> (fixup_bb_partition): Ditto.
> (rtl_redirect_edge_and_branch): Fixup partition boundaries.
> (force_nonfallthru_and_redirect): Fixup partition boundaries,
> remove old code that tried to do this. Emit barrier correctly
> when we are in cfglayout mode.
> (rtl_split_edge): Correctly fixup partition boundaries.
> (commit_one_edge_insertion): Remove old code that tried to
> fixup region crossing edge since this is now handled in
> split_block, and set up insertion point correctly since
> block may now end in a jump.
> (commit_edge_insertions): Invoke fixup_partitions to sanitize
> partition
> boundaries after optimizations that modify cfg and before trying to
> verify the flow info.
> (fixup_partitions): New function.
> (rtl_verify_flow_info_1): Add verification that no cold bbs dominate
> hot bbs.
> (record_effective_endpoints): Remove region-crossing notes and set
> flag
> indicating that they need to be reinserted on exit from cfglayout
> mode.
> (outof_cfg_layout_mode): New cfg_layout_finalize parameter.
> (fixup_reorder_chain): Call insert_section_boundary_note if necessary.
> Remove old code that attempted to fixup region crossing note as
> this is now handled in force_nonfallthru_and_redirect.
> (duplicate_insn_chain): Don't duplicate switch section notes.
> (cfg_layout_finalize): Pass new parameter to fixup_reorder_chain.
> (rtl_can_remove_branch_p): Remove unnecessary check for region
> crossing
> note.
>
> Index: cfghooks.h
> ===================================================================
> --- cfghooks.h (revision 193376)
> +++ cfghooks.h (working copy)
> @@ -204,7 +204,7 @@ extern void copy_bbs (basic_block *, unsigned, bas
> void account_profile_record (struct profile_record *, int);
>
> extern void cfg_layout_initialize (unsigned int);
> -extern void cfg_layout_finalize (void);
> +extern void cfg_layout_finalize (bool);
>
> /* Hooks containers. */
> extern struct cfg_hooks gimple_cfg_hooks;
> @@ -218,4 +218,3 @@ extern void cfg_layout_rtl_register_cfg_hooks (voi
> extern void gimple_register_cfg_hooks (void);
> extern struct cfg_hooks get_cfg_hooks (void);
> extern void set_cfg_hooks (struct cfg_hooks);
> -
> Index: modulo-sched.c
> ===================================================================
> --- modulo-sched.c (revision 193376)
> +++ modulo-sched.c (working copy)
> @@ -3354,7 +3354,7 @@ rest_of_handle_sms (void)
> if (bb->next_bb != EXIT_BLOCK_PTR)
> bb->aux = bb->next_bb;
> free_dominance_info (CDI_DOMINATORS);
> - cfg_layout_finalize ();
> + cfg_layout_finalize (false);
> #endif /* INSN_SCHEDULING */
> return 0;
> }
> Index: ifcvt.c
> ===================================================================
> --- ifcvt.c (revision 193376)
> +++ ifcvt.c (working copy)
> @@ -3900,10 +3900,9 @@ find_if_case_1 (basic_block test_bb, edge then_edg
> if (new_bb)
> {
> df_bb_replace (then_bb_index, new_bb);
> - /* Since the fallthru edge was redirected from test_bb to new_bb,
> - we need to ensure that new_bb is in the same partition as
> - test bb (you can not fall through across section boundaries). */
> - BB_COPY_PARTITION (new_bb, test_bb);
> + /* This should have been done above via force_nonfallthru_and_redirect
> + (possibly called from redirect_edge_and_branch_force). */
> + gcc_assert (BB_PARTITION (new_bb) == BB_PARTITION (test_bb));
> }
>
> num_true_changes++;
> Index: function.c
> ===================================================================
> --- function.c (revision 193376)
> +++ function.c (working copy)
> @@ -6249,8 +6249,10 @@ thread_prologue_and_epilogue_insns (void)
> break;
> if (e)
> {
> - copy_bb = create_basic_block (NEXT_INSN (BB_END (e->src)),
> - NULL_RTX, e->src);
> + /* Make sure we insert after any barriers. */
> + rtx end = get_last_bb_insn (e->src);
> + copy_bb = create_basic_block (NEXT_INSN (end),
> + NULL_RTX, e->src);
> BB_COPY_PARTITION (copy_bb, e->src);
> }
> else
> @@ -6475,7 +6477,7 @@ thread_prologue_and_epilogue_insns (void)
> if (cur_bb->index >= NUM_FIXED_BLOCKS
> && cur_bb->next_bb->index >= NUM_FIXED_BLOCKS)
> cur_bb->aux = cur_bb->next_bb;
> - cfg_layout_finalize ();
> + cfg_layout_finalize (false);
> }
>
> epilogue_done:
> @@ -6517,7 +6519,7 @@ epilogue_done:
> basic_block simple_return_block_cold = NULL;
> edge pending_edge_hot = NULL;
> edge pending_edge_cold = NULL;
> - basic_block exit_pred = EXIT_BLOCK_PTR->prev_bb;
> + basic_block exit_pred;
> int i;
>
> gcc_assert (entry_edge != orig_entry_edge);
> @@ -6545,6 +6547,12 @@ epilogue_done:
> else
> pending_edge_cold = e;
> }
> +
> + /* Save a pointer to the exit's predecessor BB for use in
> + inserting new BBs at the end of the function. Do this
> + after the call to split_block above which may split
> + the original exit pred. */
> + exit_pred = EXIT_BLOCK_PTR->prev_bb;
>
> FOR_EACH_VEC_ELT (edge, unconverted_simple_returns, i, e)
> {
> Index: function.h
> ===================================================================
> --- function.h (revision 193376)
> +++ function.h (working copy)
> @@ -459,6 +459,11 @@ struct GTY(()) rtl_data {
> sched2) and is useful only if the port defines LEAF_REGISTERS. */
> bool uses_only_leaf_regs;
>
> + /* Nonzero if the function being compiled has undergone hot/cold
> partitioning
> + (under flag_reorder_blocks_and_partition) and has at least one cold
> + block. */
> + bool has_bb_partition;
> +
> /* Like regs_ever_live, but 1 if a reg is set or clobbered from an
> asm. Unlike regs_ever_live, elements of this array corresponding
> to eliminable regs (like the frame pointer) are set if an asm
> Index: hw-doloop.c
> ===================================================================
> --- hw-doloop.c (revision 193376)
> +++ hw-doloop.c (working copy)
> @@ -547,7 +547,7 @@ reorder_loops (hwloop_info loops)
> else
> bb->aux = NULL;
> }
> - cfg_layout_finalize ();
> + cfg_layout_finalize (false);
> clear_aux_for_blocks ();
> df_analyze ();
> }
> Index: cfgcleanup.c
> ===================================================================
> --- cfgcleanup.c (revision 193376)
> +++ cfgcleanup.c (working copy)
> @@ -1824,7 +1824,7 @@ try_crossjump_to_edge (int mode, edge e1, edge e2,
> partition boundaries). See the comments at the top of
> bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
>
> - if (flag_reorder_blocks_and_partition && reload_completed)
> + if (crtl->has_bb_partition && reload_completed)
> return false;
>
> /* Search backward through forwarder blocks. We don't need to worry
> @@ -2767,10 +2767,21 @@ try_optimize_cfg (int mode)
> df_analyze ();
> }
>
> + if (changed)
> + {
> + /* Edge forwarding in particular can cause hot blocks
> previously
> + reached by both hot and cold blocks to become dominated only
> + by cold blocks. This will cause the verification below to
> fail,
> + and lead to now cold code in the hot section. This is not
> easy
> + to detect and fix during edge forwarding, and in some cases
> + is only visible after newly unreachable blocks are deleted,
> + which will be done in fixup_partitions. */
> + fixup_partitions ();
> +
> #ifdef ENABLE_CHECKING
> - if (changed)
> - verify_flow_info ();
> + verify_flow_info ();
> #endif
> + }
>
> changed_overall |= changed;
> first_pass = false;
> Index: bb-reorder.c
> ===================================================================
> --- bb-reorder.c (revision 193376)
> +++ bb-reorder.c (working copy)
> @@ -1054,7 +1054,7 @@ connect_traces (int n_traces, struct trace *traces
> current_partition = BB_PARTITION (traces[0].first);
> two_passes = false;
>
> - if (flag_reorder_blocks_and_partition)
> + if (crtl->has_bb_partition)
> for (i = 0; i < n_traces && !two_passes; i++)
> if (BB_PARTITION (traces[0].first)
> != BB_PARTITION (traces[i].first))
> @@ -1263,7 +1263,7 @@ connect_traces (int n_traces, struct trace *traces
> }
> }
>
> - if (flag_reorder_blocks_and_partition)
> + if (crtl->has_bb_partition)
> try_copy = false;
>
> /* Copy tiny blocks always; copy larger blocks only when the
> @@ -1381,13 +1381,14 @@ get_uncond_jump_length (void)
> return length;
> }
>
> -/* Emit a barrier into the footer of BB. */
> +/* Emit a barrier after BB, into the footer if we are in CFGLAYOUT mode. */
>
> -static void
> +void
> emit_barrier_after_bb (basic_block bb)
> {
> rtx barrier = emit_barrier_after (BB_END (bb));
> - BB_FOOTER (bb) = unlink_insn_chain (barrier, barrier);
> + if (current_ir_type () == IR_RTL_CFGLAYOUT)
> + BB_FOOTER (bb) = unlink_insn_chain (barrier, barrier);
> }
>
> /* The landing pad OLD_LP, in block OLD_BB, has edges from both partitions.
> @@ -1463,18 +1464,109 @@ find_rarely_executed_basic_blocks_and_crossing_edg
> {
> VEC(edge, heap) *crossing_edges = NULL;
> basic_block bb;
> - edge e;
> - edge_iterator ei;
> + edge e, e2;
> + edge_iterator ei, ei2;
> + unsigned int cold_bb_count = 0;
> + VEC (basic_block, heap) *bbs_in_hot_partition = NULL;
> + VEC (basic_block, heap) *bbs_newly_hot = NULL;
>
> /* Mark which partition (hot/cold) each basic block belongs in. */
> FOR_EACH_BB (bb)
> {
> if (probably_never_executed_bb_p (cfun, bb))
> - BB_SET_PARTITION (bb, BB_COLD_PARTITION);
> + {
> + BB_SET_PARTITION (bb, BB_COLD_PARTITION);
> + cold_bb_count++;
> + }
> else
> - BB_SET_PARTITION (bb, BB_HOT_PARTITION);
> + {
> + BB_SET_PARTITION (bb, BB_HOT_PARTITION);
> + VEC_safe_push (basic_block, heap, bbs_in_hot_partition, bb);
> + }
> }
>
> + /* Ensure that no cold bbs dominate hot bbs. This could happen as a result
> of
> + several different possibilities. One is that there are edge weight
> insanities
> + due to optimization phases that do not properly update basic block
> profile
> + counts. The second is that the entry of the function may not be hot,
> because
> + it is entered fewer times than the number of profile training runs, but
> there
> + is a loop inside the function that causes blocks within the function to
> be
> + above the threshold for hotness. */
> + if (cold_bb_count)
> + {
> + bool dom_calculated_here = !dom_info_available_p (CDI_DOMINATORS);
> +
> + if (dom_calculated_here)
> + calculate_dominance_info (CDI_DOMINATORS);
> +
> + /* Keep examining hot bbs until we have either checked them all, or
> + re-marked all cold bbs hot. */
> + while (! VEC_empty (basic_block, bbs_in_hot_partition)
> + && cold_bb_count)
> + {
> + basic_block dom_bb;
> +
> + bb = VEC_pop (basic_block, bbs_in_hot_partition);
> + dom_bb = get_immediate_dominator (CDI_DOMINATORS, bb);
> +
> + /* If bb's immediate dominator is also hot then it is ok. */
> + if (BB_PARTITION (dom_bb) != BB_COLD_PARTITION)
> + continue;
> +
> + /* We have a hot bb with an immediate dominator that is cold.
> + The dominator needs to be re-marked to hot. */
> + BB_SET_PARTITION (dom_bb, BB_HOT_PARTITION);
> + cold_bb_count--;
> +
> + /* Now we need to examine newly-hot dom_bb to see if it is also
> + dominated by a cold bb. */
> + VEC_safe_push (basic_block, heap, bbs_in_hot_partition, dom_bb);
> +
> + /* We should also adjust any cold blocks that the newly-hot bb
> + feeds and see if it makes sense to re-mark those as hot as
> + well. */
> + VEC_safe_push (basic_block, heap, bbs_newly_hot, dom_bb);
> + while (! VEC_empty (basic_block, bbs_newly_hot))
> + {
> + basic_block new_hot_bb = VEC_pop (basic_block, bbs_newly_hot);
> + /* Examine all successors of this newly-hot bb to see if they
> + are cold and should be re-marked as hot. */
> + FOR_EACH_EDGE (e, ei, new_hot_bb->succs)
> + {
> + bool any_cold_preds = false;
> + basic_block succ = e->dest;
> + if (BB_PARTITION (succ) != BB_COLD_PARTITION)
> + continue;
> + /* Does this block have any cold predecessors now? */
> + FOR_EACH_EDGE (e2, ei2, succ->preds)
> + {
> + if (BB_PARTITION (e2->src) == BB_COLD_PARTITION)
> + {
> + any_cold_preds = true;
> + break;
> + }
> + }
> + if (any_cold_preds)
> + continue;
> +
> + /* Here we have a successor of newly-hot bb that is cold
> + but no longer has any cold precessessors. Since the
> original
> + assignment of our newly-hot bb was incorrect, this
> successor's
> + assignment as cold is also suspect. Go ahead and
> re-mark it
> + as hot now too. Better heuristics may be in order here.
> */
> + BB_SET_PARTITION (succ, BB_HOT_PARTITION);
> + cold_bb_count--;
> + VEC_safe_push (basic_block, heap, bbs_in_hot_partition,
> succ);
> + /* Examine this successor as a newly-hot bb. */
> + VEC_safe_push (basic_block, heap, bbs_newly_hot, succ);
> + }
> + }
> + }
> +
> + if (dom_calculated_here)
> + free_dominance_info (CDI_DOMINATORS);
> + }
> +
> /* The format of .gcc_except_table does not allow landing pads to
> be in a different partition as the throw. Fix this by either
> moving or duplicating the landing pads. */
> @@ -1766,10 +1858,10 @@ fix_up_fall_thru_edges (void)
> new_bb->aux = cur_bb->aux;
> cur_bb->aux = new_bb;
>
> - /* Make sure new fall-through bb is in same
> - partition as bb it's falling through from. */
> + /* This is done by force_nonfallthru_and_redirect. */
> + gcc_assert (BB_PARTITION (new_bb)
> + == BB_PARTITION (cur_bb));
>
> - BB_COPY_PARTITION (new_bb, cur_bb);
> single_succ_edge (new_bb)->flags |= EDGE_CROSSING;
> }
> else
> @@ -2067,7 +2159,10 @@ add_reg_crossing_jump_notes (void)
> FOR_EACH_BB (bb)
> FOR_EACH_EDGE (e, ei, bb->succs)
> if ((e->flags & EDGE_CROSSING)
> - && JUMP_P (BB_END (e->src)))
> + && JUMP_P (BB_END (e->src))
> + /* Some notes were added during fix_up_fall_thru_edges, via
> + force_nonfallthru_and_redirect. */
> + && !find_reg_note (BB_END (e->src), REG_CROSSING_JUMP, NULL_RTX))
> add_reg_note (BB_END (e->src), REG_CROSSING_JUMP, NULL_RTX);
> }
>
> @@ -2160,7 +2255,7 @@ reorder_basic_blocks (void)
> dump_flow_info (dump_file, dump_flags);
> }
>
> - if (flag_reorder_blocks_and_partition)
> + if (crtl->has_bb_partition)
> verify_hot_cold_block_grouping ();
> }
>
> @@ -2172,14 +2267,14 @@ reorder_basic_blocks (void)
> encountering this note will make the compiler switch between the
> hot and cold text sections. */
>
> -static void
> +void
> insert_section_boundary_note (void)
> {
> basic_block bb;
> rtx new_note;
> int first_partition = 0;
>
> - if (!flag_reorder_blocks_and_partition)
> + if (!crtl->has_bb_partition)
> return;
>
> FOR_EACH_BB (bb)
> @@ -2222,10 +2317,8 @@ rest_of_handle_reorder_blocks (void)
> FOR_EACH_BB (bb)
> if (bb->next_bb != EXIT_BLOCK_PTR)
> bb->aux = bb->next_bb;
> - cfg_layout_finalize ();
> + cfg_layout_finalize (true);
>
> - /* Add NOTE_INSN_SWITCH_TEXT_SECTIONS notes. */
> - insert_section_boundary_note ();
> return 0;
> }
>
> @@ -2366,7 +2459,7 @@ duplicate_computed_gotos (void)
> }
>
> done:
> - cfg_layout_finalize ();
> + cfg_layout_finalize (false);
>
> BITMAP_FREE (candidates);
> return 0;
> @@ -2511,6 +2604,8 @@ partition_hot_cold_basic_blocks (void)
> if (crossing_edges == NULL)
> return 0;
>
> + crtl->has_bb_partition = true;
> +
> /* Make sure the source of any crossing edge ends in a jump and the
> destination of any crossing edge has a label. */
> add_labels_and_missing_jumps (crossing_edges);
> Index: bb-reorder.h
> ===================================================================
> --- bb-reorder.h (revision 193376)
> +++ bb-reorder.h (working copy)
> @@ -36,4 +36,8 @@ extern struct target_bb_reorder *this_target_bb_re
>
> extern int get_uncond_jump_length (void);
>
> +extern void insert_section_boundary_note (void);
> +
> +extern void emit_barrier_after_bb (basic_block bb);
> +
> #endif
> Index: basic-block.h
> ===================================================================
> --- basic-block.h (revision 193376)
> +++ basic-block.h (working copy)
> @@ -806,6 +806,7 @@ extern basic_block force_nonfallthru_and_redirect
> extern bool contains_no_active_insn_p (const_basic_block);
> extern bool forwarder_block_p (const_basic_block);
> extern bool can_fallthru (basic_block, basic_block);
> +extern void fixup_partitions (void);
>
> /* In cfgbuild.c. */
> extern void find_many_sub_basic_blocks (sbitmap);
> Index: cfgrtl.c
> ===================================================================
> --- cfgrtl.c (revision 193376)
> +++ cfgrtl.c (working copy)
> @@ -46,6 +46,7 @@ along with GCC; see the file COPYING3. If not see
> #include "tree.h"
> #include "hard-reg-set.h"
> #include "basic-block.h"
> +#include "bb-reorder.h"
> #include "regs.h"
> #include "flags.h"
> #include "function.h"
> @@ -67,11 +68,12 @@ along with GCC; see the file COPYING3. If not see
> Only applicable if the CFG is in cfglayout mode. */
> static GTY(()) rtx cfg_layout_function_footer;
> static GTY(()) rtx cfg_layout_function_header;
> +static bool had_sec_boundary_notes;
>
> static rtx skip_insns_after_block (basic_block);
> static void record_effective_endpoints (void);
> static rtx label_for_bb (basic_block);
> -static void fixup_reorder_chain (void);
> +static void fixup_reorder_chain (bool finalize_reorder_blocks);
>
> void verify_insn_chain (void);
> static void fixup_fallthru_exit_predecessor (void);
> @@ -976,8 +978,7 @@ try_redirect_by_replacing_jump (edge e, basic_bloc
> partition boundaries). See the comments at the top of
> bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
>
> - if (find_reg_note (insn, REG_CROSSING_JUMP, NULL_RTX)
> - || BB_PARTITION (src) != BB_PARTITION (target))
> + if (BB_PARTITION (src) != BB_PARTITION (target))
> return NULL;
>
> /* We can replace or remove a complex jump only when we have exactly
> @@ -1286,6 +1287,71 @@ redirect_branch_edge (edge e, basic_block target)
> return e;
> }
>
> +/* Called when edge E has been redirected to a new destination,
> + in order to update the region crossing flag on the edge and
> + jump. */
> +
> +static void
> +fixup_partition_crossing (edge e, basic_block target)
> +{
> + rtx note;
> +
> + gcc_assert (e->dest == target);
> +
> + if (e->src == ENTRY_BLOCK_PTR || target == EXIT_BLOCK_PTR)
> + return;
> + /* If we redirected an existing edge, it may already be marked
> + crossing, even though the new src is missing a reg crossing note.
> + But make sure reg crossing note doesn't already exist before
> + inserting. */
> + if (BB_PARTITION (e->src) != BB_PARTITION (target))
> + {
> + e->flags |= EDGE_CROSSING;
> + note = find_reg_note (BB_END (e->src), REG_CROSSING_JUMP, NULL_RTX);
> + if (JUMP_P (BB_END (e->src))
> + && !note)
> + add_reg_note (BB_END (e->src), REG_CROSSING_JUMP, NULL_RTX);
> + }
> + else if (BB_PARTITION (e->src) == BB_PARTITION (target))
> + {
> + e->flags &= ~EDGE_CROSSING;
> + /* Remove the region crossing note from jump at end of
> + e->src if it exists. */
> + note = find_reg_note (BB_END (e->src), REG_CROSSING_JUMP, NULL_RTX);
> + if (note)
> + remove_note (BB_END (e->src), note);
> + }
> +}
> +
> +/* Called when block BB has been reassigned to a different partition,
> + to ensure that the region crossing attributes are updated. */
> +
> +static void
> +fixup_bb_partition (basic_block bb)
> +{
> + edge e;
> + edge_iterator ei;
> +
> + /* Now need to make bb's pred edges non-region crossing. */
> + FOR_EACH_EDGE (e, ei, bb->preds)
> + {
> + fixup_partition_crossing (e, e->dest);
> + }
> +
> + /* Possibly need to make bb's successor edges region crossing,
> + or remove stale region crossing. */
> + FOR_EACH_EDGE (e, ei, bb->succs)
> + {
> + if ((e->flags & EDGE_FALLTHRU)
> + && BB_PARTITION (bb) != BB_PARTITION (e->dest)
> + && e->dest != EXIT_BLOCK_PTR)
> + /* force_nonfallthru_and_redirect calls fixup_partition_crossing. */
> + force_nonfallthru (e);
> + else
> + fixup_partition_crossing (e, e->dest);
> + }
> +}
> +
> /* Attempt to change code to redirect edge E to TARGET. Don't do that on
> expense of adding new instructions or reordering basic blocks.
>
> @@ -1302,16 +1368,18 @@ rtl_redirect_edge_and_branch (edge e, basic_block
> {
> edge ret;
> basic_block src = e->src;
> + basic_block dest = e->dest;
>
> if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
> return NULL;
>
> - if (e->dest == target)
> + if (dest == target)
> return e;
>
> if ((ret = try_redirect_by_replacing_jump (e, target, false)) != NULL)
> {
> df_set_bb_dirty (src);
> + fixup_partition_crossing (ret, target);
> return ret;
> }
>
> @@ -1320,6 +1388,7 @@ rtl_redirect_edge_and_branch (edge e, basic_block
> return NULL;
>
> df_set_bb_dirty (src);
> + fixup_partition_crossing (ret, target);
> return ret;
> }
>
> @@ -1454,18 +1523,16 @@ force_nonfallthru_and_redirect (edge e, basic_bloc
> /* Make sure new block ends up in correct hot/cold section. */
>
> BB_COPY_PARTITION (jump_block, e->src);
> - if (flag_reorder_blocks_and_partition
> - && targetm_common.have_named_sections
> - && JUMP_P (BB_END (jump_block))
> - && !any_condjump_p (BB_END (jump_block))
> - && (EDGE_SUCC (jump_block, 0)->flags & EDGE_CROSSING))
> - add_reg_note (BB_END (jump_block), REG_CROSSING_JUMP, NULL_RTX);
>
> /* Wire edge in. */
> new_edge = make_edge (e->src, jump_block, EDGE_FALLTHRU);
> new_edge->probability = probability;
> new_edge->count = count;
>
> + /* If e->src was previously region crossing, it no longer is
> + and the reg crossing note should be removed. */
> + fixup_partition_crossing (new_edge, jump_block);
> +
> /* Redirect old edge. */
> redirect_edge_pred (e, jump_block);
> e->probability = REG_BR_PROB_BASE;
> @@ -1521,13 +1588,16 @@ force_nonfallthru_and_redirect (edge e, basic_bloc
> LABEL_NUSES (label)++;
> }
>
> - emit_barrier_after (BB_END (jump_block));
> + /* We might be in cfg layout mode, and if so, the following routine will
> + insert the barrier correctly. */
> + emit_barrier_after_bb (jump_block);
> redirect_edge_succ_nodup (e, target);
>
> if (abnormal_edge_flags)
> make_edge (src, target, abnormal_edge_flags);
>
> df_mark_solutions_dirty ();
> + fixup_partition_crossing (e, target);
> return new_bb;
> }
>
> @@ -1626,7 +1696,7 @@ rtl_move_block_after (basic_block bb ATTRIBUTE_UNU
> static basic_block
> rtl_split_edge (edge edge_in)
> {
> - basic_block bb;
> + basic_block bb, new_bb;
> rtx before;
>
> /* Abnormal edges cannot be split. */
> @@ -1659,12 +1729,26 @@ rtl_split_edge (edge edge_in)
> else
> {
> bb = create_basic_block (before, NULL, edge_in->dest->prev_bb);
> - /* ??? Why not edge_in->dest->prev_bb here? */
> - BB_COPY_PARTITION (bb, edge_in->dest);
> + if (edge_in->src == ENTRY_BLOCK_PTR)
> + BB_COPY_PARTITION (bb, edge_in->dest);
> + else
> + /* Put the split bb into the src partition, to avoid creating
> + a situation where a cold bb dominates a hot bb, in the case
> + where src is cold and dest is hot. The src will dominate
> + the new bb (whereas it might not have dominated dest). */
> + BB_COPY_PARTITION (bb, edge_in->src);
> }
>
> make_single_succ_edge (bb, edge_in->dest, EDGE_FALLTHRU);
>
> + /* Can't allow a region crossing edge to be fallthrough. */
> + if (BB_PARTITION (bb) != BB_PARTITION (edge_in->dest)
> + && edge_in->dest != EXIT_BLOCK_PTR)
> + {
> + new_bb = force_nonfallthru (single_succ_edge (bb));
> + gcc_assert (!new_bb);
> + }
> +
> /* For non-fallthru edges, we must adjust the predecessor's
> jump instruction to target our new block. */
> if ((edge_in->flags & EDGE_FALLTHRU) == 0)
> @@ -1777,17 +1861,13 @@ commit_one_edge_insertion (edge e)
> else
> {
> bb = split_edge (e);
> - after = BB_END (bb);
>
> - if (flag_reorder_blocks_and_partition
> - && targetm_common.have_named_sections
> - && e->src != ENTRY_BLOCK_PTR
> - && BB_PARTITION (e->src) == BB_COLD_PARTITION
> - && !(e->flags & EDGE_CROSSING)
> - && JUMP_P (after)
> - && !any_condjump_p (after)
> - && (single_succ_edge (bb)->flags & EDGE_CROSSING))
> - add_reg_note (after, REG_CROSSING_JUMP, NULL_RTX);
> + /* If e crossed a partition boundary, we needed to make bb end in
> + a region-crossing jump, even though it was originally fallthru. */
> + if (JUMP_P (BB_END (bb)))
> + before = BB_END (bb);
> + else
> + after = BB_END (bb);
> }
>
> /* Now that we've found the spot, do the insertion. */
> @@ -1827,6 +1907,14 @@ commit_edge_insertions (void)
> {
> basic_block bb;
>
> + /* Optimization passes that invoke this routine can cause hot blocks
> + previously reached by both hot and cold blocks to become dominated only
> + by cold blocks. This will cause the verification below to fail,
> + and lead to now cold code in the hot section. In some cases this
> + may only be visible after newly unreachable blocks are deleted,
> + which will be done by fixup_partitions. */
> + fixup_partitions ();
> +
> #ifdef ENABLE_CHECKING
> verify_flow_info ();
> #endif
> @@ -2028,7 +2116,75 @@ get_last_bb_insn (basic_block bb)
>
> return end;
> }
> -
> +
> +/* Perform cleanup on the hot/cold bb partitioning after optimization
> + passes that modify the cfg. */
> +
> +void
> +fixup_partitions (void)
> +{
> + basic_block bb;
> +
> + if (!crtl->has_bb_partition)
> + return;
> +
> + /* Delete any blocks that became unreachable and weren't
> + already cleaned up, for example during edge forwarding
> + and convert_jumps_to_returns. This will expose more
> + opportunities for fixing the partition boundaries here.
> + Also, the calculation of the dominance graph during verification
> + will assert if there are unreachable nodes. */
> + delete_unreachable_blocks ();
> +
> + /* If there are partitions, do a sanity check on them: A basic block in
> + a cold partition cannot dominate a basic block in a hot partition.
> + Fixup any that now violate this requirement, as a result of edge
> + forwarding and unreachable block deletion. */
> + VEC (basic_block, heap) *bbs_in_cold_partition = NULL;
> + VEC (basic_block, heap) *bbs_to_fix = NULL;
> + FOR_EACH_BB (bb)
> + if ((BB_PARTITION (bb) == BB_COLD_PARTITION))
> + VEC_safe_push (basic_block, heap, bbs_in_cold_partition, bb);
> + if (! VEC_empty (basic_block, bbs_in_cold_partition))
> + {
> + bool dom_calculated_here = !dom_info_available_p (CDI_DOMINATORS);
> + basic_block son;
> +
> + if (dom_calculated_here)
> + calculate_dominance_info (CDI_DOMINATORS);
> +
> + while (! VEC_empty (basic_block, bbs_in_cold_partition))
> + {
> + bb = VEC_pop (basic_block, bbs_in_cold_partition);
> + /* If bb is not yet cold (because it was added below as
> + a block dominated by a cold bb) then mark it cold here. */
> + if ((BB_PARTITION (bb) != BB_COLD_PARTITION))
> + {
> + BB_SET_PARTITION (bb, BB_COLD_PARTITION);
> + VEC_safe_push (basic_block, heap, bbs_to_fix, bb);
> + }
> + /* Any blocks dominated by a block in the cold section
> + must also be cold. */
> + for (son = first_dom_son (CDI_DOMINATORS, bb);
> + son;
> + son = next_dom_son (CDI_DOMINATORS, son))
> + VEC_safe_push (basic_block, heap, bbs_in_cold_partition, son);
> + }
> +
> + if (dom_calculated_here)
> + free_dominance_info (CDI_DOMINATORS);
> + }
> +
> + /* Do the partition fixup after all necessary blocks have been converted to
> + cold, so that we only update the region crossings the minimum number of
> + places, which can require forcing edges to be non fallthru. */
> + while (! VEC_empty (basic_block, bbs_to_fix))
> + {
> + bb = VEC_pop (basic_block, bbs_to_fix);
> + fixup_bb_partition (bb);
> + }
> +}
> +
> /* Verify the CFG and RTL consistency common for both underlying RTL and
> cfglayout RTL.
>
> @@ -2052,6 +2208,7 @@ rtl_verify_flow_info_1 (void)
> rtx x;
> int err = 0;
> basic_block bb;
> + bool have_partitions = false;
>
> /* Check the general integrity of the basic blocks. */
> FOR_EACH_BB_REVERSE (bb)
> @@ -2169,6 +2326,8 @@ rtl_verify_flow_info_1 (void)
>
> if (e->flags & EDGE_ABNORMAL)
> n_abnormal++;
> +
> + have_partitions |= is_crossing;
> }
>
> if (n_eh && !find_reg_note (BB_END (bb), REG_EH_REGION, NULL_RTX))
> @@ -2293,6 +2452,40 @@ rtl_verify_flow_info_1 (void)
> }
> }
>
> + /* If there are partitions, do a sanity check on them: A basic block in
> + a cold partition cannot dominate a basic block in a hot partition. */
> + VEC (basic_block, heap) *bbs_in_cold_partition = NULL;
> + if (have_partitions && !err)
> + FOR_EACH_BB (bb)
> + if ((BB_PARTITION (bb) == BB_COLD_PARTITION))
> + VEC_safe_push (basic_block, heap, bbs_in_cold_partition, bb);
> + if (! VEC_empty (basic_block, bbs_in_cold_partition))
> + {
> + bool dom_calculated_here = !dom_info_available_p (CDI_DOMINATORS);
> + basic_block son;
> +
> + if (dom_calculated_here)
> + calculate_dominance_info (CDI_DOMINATORS);
> +
> + while (! VEC_empty (basic_block, bbs_in_cold_partition))
> + {
> + bb = VEC_pop (basic_block, bbs_in_cold_partition);
> + if ((BB_PARTITION (bb) != BB_COLD_PARTITION))
> + {
> + error ("non-cold basic block %d dominated "
> + "by a block in the cold partition", bb->index);
> + err = 1;
> + }
> + for (son = first_dom_son (CDI_DOMINATORS, bb);
> + son;
> + son = next_dom_son (CDI_DOMINATORS, son))
> + VEC_safe_push (basic_block, heap, bbs_in_cold_partition, son);
> + }
> +
> + if (dom_calculated_here)
> + free_dominance_info (CDI_DOMINATORS);
> + }
> +
> /* Clean up. */
> return err;
> }
> @@ -2965,14 +3158,41 @@ record_effective_endpoints (void)
> else
> cfg_layout_function_header = NULL_RTX;
>
> + had_sec_boundary_notes = false;
> +
> next_insn = get_insns ();
> FOR_EACH_BB (bb)
> {
> rtx end;
>
> if (PREV_INSN (BB_HEAD (bb)) && next_insn != BB_HEAD (bb))
> - BB_HEADER (bb) = unlink_insn_chain (next_insn,
> - PREV_INSN (BB_HEAD (bb)));
> + {
> + /* Rather than try to keep section boundary notes incrementally
> + up-to-date through cfg layout optimizations, simply remove them
> + and flag that they should be re-inserted when exiting
> + cfg layout mode. */
> + rtx check_insn = next_insn;
> + while (check_insn)
> + {
> + if (NOTE_P (check_insn)
> + && NOTE_KIND (check_insn) ==
> NOTE_INSN_SWITCH_TEXT_SECTIONS)
> + {
> + had_sec_boundary_notes |= true;
> + /* Remove note from chain. Grab new next_insn first. */
> + if (next_insn == check_insn)
> + next_insn = NEXT_INSN (check_insn);
> + /* Delete note. */
> + delete_insn (check_insn);
> + /* There will only be one. */
> + break;
> + }
> + check_insn = NEXT_INSN (check_insn);
> + }
> + /* If we still have header instructions left after above loop. */
> + if (next_insn != BB_HEAD (bb))
> + BB_HEADER (bb) = unlink_insn_chain (next_insn,
> + PREV_INSN (BB_HEAD (bb)));
> + }
> end = skip_insns_after_block (bb);
> if (NEXT_INSN (BB_END (bb)) && BB_END (bb) != end)
> BB_FOOTER (bb) = unlink_insn_chain (NEXT_INSN (BB_END (bb)), end);
> @@ -3000,7 +3220,7 @@ outof_cfg_layout_mode (void)
> if (bb->next_bb != EXIT_BLOCK_PTR)
> bb->aux = bb->next_bb;
>
> - cfg_layout_finalize ();
> + cfg_layout_finalize (false);
>
> return 0;
> }
> @@ -3120,10 +3340,13 @@ relink_block_chain (bool stay_in_cfglayout_mode)
> }
>
>
> -/* Given a reorder chain, rearrange the code to match. */
> +/* Given a reorder chain, rearrange the code to match. If
> + this is called when we will FINALIZE_REORDER_BLOCKS, or when
> + section boundary notes were removed on entry to cfg layout
> + mode, insert section boundary notes here. */
>
> static void
> -fixup_reorder_chain (void)
> +fixup_reorder_chain (bool finalize_reorder_blocks)
> {
> basic_block bb;
> rtx insn = NULL;
> @@ -3150,7 +3373,7 @@ static void
> PREV_INSN (BB_HEADER (bb)) = insn;
> insn = BB_HEADER (bb);
> while (NEXT_INSN (insn))
> - insn = NEXT_INSN (insn);
> + insn = NEXT_INSN (insn);
> }
> if (insn)
> NEXT_INSN (insn) = BB_HEAD (bb);
> @@ -3175,6 +3398,11 @@ static void
> insn = NEXT_INSN (insn);
>
> set_last_insn (insn);
> +
> + /* Add NOTE_INSN_SWITCH_TEXT_SECTIONS notes. */
> + if (had_sec_boundary_notes || finalize_reorder_blocks)
> + insert_section_boundary_note ();
> +
> #ifdef ENABLE_CHECKING
> verify_insn_chain ();
> #endif
> @@ -3187,7 +3415,7 @@ static void
> edge e_fall, e_taken, e;
> rtx bb_end_insn;
> rtx ret_label = NULL_RTX;
> - basic_block nb, src_bb;
> + basic_block nb;
> edge_iterator ei;
>
> if (EDGE_COUNT (bb->succs) == 0)
> @@ -3322,7 +3550,6 @@ static void
> /* We got here if we need to add a new jump insn.
> Note force_nonfallthru can delete E_FALL and thus we have to
> save E_FALL->src prior to the call to force_nonfallthru. */
> - src_bb = e_fall->src;
> nb = force_nonfallthru_and_redirect (e_fall, e_fall->dest, ret_label);
> if (nb)
> {
> @@ -3330,17 +3557,6 @@ static void
> bb->aux = nb;
> /* Don't process this new block. */
> bb = nb;
> -
> - /* Make sure new bb is tagged for correct section (same as
> - fall-thru source, since you cannot fall-thru across
> - section boundaries). */
> - BB_COPY_PARTITION (src_bb, single_pred (bb));
> - if (flag_reorder_blocks_and_partition
> - && targetm_common.have_named_sections
> - && JUMP_P (BB_END (bb))
> - && !any_condjump_p (BB_END (bb))
> - && (EDGE_SUCC (bb, 0)->flags & EDGE_CROSSING))
> - add_reg_note (BB_END (bb), REG_CROSSING_JUMP, NULL_RTX);
> }
> }
>
> @@ -3644,10 +3860,11 @@ duplicate_insn_chain (rtx from, rtx to)
> case NOTE_INSN_FUNCTION_BEG:
> /* There is always just single entry to function. */
> case NOTE_INSN_BASIC_BLOCK:
> + /* We should only switch text sections once. */
> + case NOTE_INSN_SWITCH_TEXT_SECTIONS:
> break;
>
> case NOTE_INSN_EPILOGUE_BEG:
> - case NOTE_INSN_SWITCH_TEXT_SECTIONS:
> emit_note_copy (insn);
> break;
>
> @@ -3759,10 +3976,13 @@ break_superblocks (void)
> }
>
> /* Finalize the changes: reorder insn list according to the sequence
> specified
> - by aux pointers, enter compensation code, rebuild scope forest. */
> + by aux pointers, enter compensation code, rebuild scope forest. If
> + this is called when we will FINALIZE_REORDER_BLOCKS, indicate that
> + to fixup_reorder_chain so that it can insert the proper switch text
> + section notes. */
>
> void
> -cfg_layout_finalize (void)
> +cfg_layout_finalize (bool finalize_reorder_blocks)
> {
> #ifdef ENABLE_CHECKING
> verify_flow_info ();
> @@ -3775,7 +3995,7 @@ void
> #endif
> )
> fixup_fallthru_exit_predecessor ();
> - fixup_reorder_chain ();
> + fixup_reorder_chain (finalize_reorder_blocks);
>
> rebuild_jump_labels (get_insns ());
> delete_dead_jumptables ();
> @@ -4454,8 +4674,7 @@ rtl_can_remove_branch_p (const_edge e)
> if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
> return false;
>
> - if (find_reg_note (insn, REG_CROSSING_JUMP, NULL_RTX)
> - || BB_PARTITION (src) != BB_PARTITION (target))
> + if (BB_PARTITION (src) != BB_PARTITION (target))
> return false;
>
> if (!onlyjump_p (insn)
>
> --
> This patch is available for review at http://codereview.appspot.com/6823047
--
Teresa Johnson | Software Engineer | tejohn...@google.com | 408-460-2413
