GCC Middle and Back End API Reference
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#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "backend.h"
#include "rtl.h"
#include "tree.h"
#include "gimple.h"
#include "cfghooks.h"
#include "cfganal.h"
#include "cfgloop.h"
#include "gimple-iterator.h"
#include "gimplify-me.h"
#include "tree-ssa-loop-manip.h"
#include "dumpfile.h"
#include "sreal.h"
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edge | mfb_kj_edge |
Given LOOP structure with filled header and latch, find the body of the corresponding loop and add it to loops tree. Insert the LOOP as a son of outer.
References add_bb_to_loop(), cfun, flow_loop_tree_node_add(), flow_loop_tree_node_remove(), FOR_EACH_EDGE, free(), get_loop_body_with_size(), loop::header, i, basic_block_def::loop_father, loop_outer(), n_basic_blocks_for_fn, loop::num_nodes, place_new_loop(), remove_bb_from_loops(), and rescan_loop_exit().
Referenced by create_empty_loop_on_edge(), expand_oacc_for(), expand_omp_atomic_pipeline(), expand_omp_for_generic(), expand_omp_for_ordered_loops(), expand_omp_for_static_chunk(), expand_omp_for_static_nochunk(), expand_omp_simd(), expand_omp_taskloop_for_inner(), form_subloop(), loop_version(), simd_clone_adjust(), and tree_optimize_tail_calls_1().
Check whether LOOP's body can be duplicated.
References can_copy_bbs_p(), free(), get_loop_body(), and loop::num_nodes.
Referenced by can_unroll_loop_p(), decide_unrolling(), and parallelize_loops().
Duplicate loop bounds and other information we store about the loop into its duplicate.
References loop::any_estimate, loop::any_likely_upper_bound, loop::any_upper_bound, loop::can_be_parallel, loop::constraints, loop::dont_vectorize, loop::estimate_state, loop::finite_p, loop::force_vectorize, gcc_checking_assert, loop::in_oacc_kernels_region, loop::nb_iterations_estimate, loop::nb_iterations_likely_upper_bound, loop::nb_iterations_upper_bound, loop::owned_clique, loop::safelen, loop::simdlen, loop::unroll, and loop::warned_aggressive_loop_optimizations.
Referenced by copy_loops(), duplicate_loop(), and loop_version().
Loop manipulation code for GNU compiler. Copyright (C) 2002-2024 Free Software Foundation, Inc. This file is part of GCC. GCC is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3, or (at your option) any later version. GCC is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with GCC; see the file COPYING3. If not see <http://www.gnu.org/licenses/>.
Copies structure of subloops of N loops, stored in array COPIED_LOOPS, into TARGET loop, placing newly created loops into loop tree adding them to TARGETs sibling list at the end in order.
References duplicate_loop(), duplicate_subloops(), gcc_assert, i, loop::inner, and loop::next.
Referenced by duplicate_loop_body_to_header_edge().
Creates an if region as shown above. CONDITION is used to create the test for the if. | | ------------- ------------- | | pred_bb | | pred_bb | | ------------- ------------- | | | | | | ENTRY_EDGE | | ENTRY_EDGE V | | ====> ------------- | | | cond_bb | | | | CONDITION | | | ------------- | V / \ | ------------- e_false / \ e_true | | succ_bb | V V | ------------- ----------- ----------- | | false_bb | | true_bb | | ----------- ----------- | \ / | \ / | V V | ------------- | | join_bb | | ------------- | | exit_edge (result) | V | ----------- | | succ_bb | | ----------- |
References CDI_DOMINATORS, force_gimple_operand_gsi(), gimple_build_cond_from_tree(), gsi_insert_after(), gsi_last_bb(), GSI_NEW_STMT, make_edge(), NULL, NULL_TREE, set_immediate_dominator(), single_pred_p(), single_succ_edge(), and split_edge().
class loop * create_empty_loop_on_edge | ( | edge | entry_edge, |
tree | initial_value, | ||
tree | stride, | ||
tree | upper_bound, | ||
tree | iv, | ||
tree * | iv_before, | ||
tree * | iv_after, | ||
class loop * | outer ) |
create_empty_loop_on_edge | | - pred_bb - ------ pred_bb ------ | | | | iv0 = initial_value | | -----|----- ---------|----------- | | ______ | entry_edge | | entry_edge / | | | | ====> | -V---V- loop_header ------------- | V | | iv_before = phi (iv0, iv_after) | | - succ_bb - | ---|----------------------------- | | | | | | ----------- | ---V--- loop_body --------------- | | | iv_after = iv_before + stride | | | | if (iv_before < upper_bound) | | | ---|--------------\-------------- | | | \ exit_e | | V \ | | - loop_latch - V- succ_bb - | | | | | | | | /------------- ----------- | \ ___ / Creates an empty loop as shown above, the IV_BEFORE is the SSA_NAME that is used before the increment of IV. IV_BEFORE should be used for adding code to the body that uses the IV. OUTER is the outer loop in which the new loop should be inserted. Both INITIAL_VALUE and UPPER_BOUND expressions are gimplified and inserted on the loop entry edge. This implies that this function should be used only when the UPPER_BOUND expression is a loop invariant.
References add_loop(), alloc_loop(), CDI_DOMINATORS, create_iv(), profile_probability::even(), force_gimple_operand(), force_gimple_operand_gsi(), gcc_assert, gimple_build_cond(), gimple_cond_lhs(), gimple_cond_set_lhs(), gsi_commit_edge_inserts(), gsi_insert_after(), gsi_insert_seq_on_edge(), gsi_last_bb(), GSI_NEW_STMT, loop::header, loop::latch, loop_preheader_edge(), make_edge(), NULL, NULL_TREE, redirect_edge_succ_nodup(), scale_loop_frequencies(), set_immediate_dominator(), single_exit(), single_pred_edge(), single_succ(), single_succ_edge(), split_block_after_labels(), split_edge(), and update_dominators_in_loop().
basic_block create_preheader | ( | class loop * | loop, |
int | flags ) |
Creates a pre-header for a LOOP. Returns newly created block. Unless CP_SIMPLE_PREHEADERS is set in FLAGS, we only force LOOP to have single entry; otherwise we also force preheader block to have only one successor. When CP_FALLTHRU_PREHEADERS is set in FLAGS, we force the preheader block to be a fallthru predecessor to the loop header and to have only predecessors from outside of the loop. The function also updates dominators.
References BB_END, cfun, CP_FALLTHRU_PREHEADERS, CP_SIMPLE_PREHEADERS, dump_file, EDGE_COMPLEX, EDGE_PRED, ENTRY_BLOCK_PTR_FOR_FN, basic_block_def::flags, FOR_EACH_EDGE, gcc_assert, has_preds_from_loop(), loop::header, JUMP_P, loop::latch, loop_latch_edge(), make_forwarder_block(), mfb_keep_just(), mfb_kj_edge, move_block_after(), NULL, loop::num, basic_block_def::preds, single_succ_edge(), single_succ_p(), and split_edge().
Referenced by create_preheaders(), generate_loops_for_partition(), and fwd_jt_path_registry::thread_through_loop_header().
void create_preheaders | ( | int | flags | ) |
Create preheaders for each loop; for meaning of FLAGS see create_preheader.
References cfun, create_preheader(), current_loops, LOOPS_HAVE_PREHEADERS, and loops_state_set().
Referenced by apply_loop_flags(), and tree_estimate_probability().
Copies copy of LOOP as subloop of TARGET loop, placing newly created loop into loops structure. If AFTER is non-null the new loop is added at AFTER->next, otherwise in front of TARGETs sibling list.
References alloc_loop(), cfun, copy_loop_info(), flow_loop_tree_node_add(), place_new_loop(), and set_loop_copy().
Referenced by copy_loops_to(), duplicate_subloops(), gimple_duplicate_sese_tail(), and slpeel_tree_duplicate_loop_to_edge_cfg().
bool duplicate_loop_body_to_header_edge | ( | class loop * | loop, |
edge | e, | ||
unsigned int | ndupl, | ||
sbitmap | wont_exit, | ||
edge | orig, | ||
vec< edge > * | to_remove, | ||
int | flags ) |
Duplicates body of LOOP to given edge E NDUPL times. Takes care of updating loop structure and dominators (order of inner subloops is retained). E's destination must be LOOP header for this to work, i.e. it must be entry or latch edge of this loop; these are unique, as the loops must have preheaders for this function to work correctly (in case E is latch, the function unrolls the loop, if E is entry edge, it peels the loop). Store edges created by copying ORIG edge from copies corresponding to set bits in WONT_EXIT bitmap (bit 0 corresponds to original LOOP body, the other copies are numbered in order given by control flow through them) into TO_REMOVE array. Returns false if duplication is impossible.
References profile_probability::always(), profile_count::apply_probability(), profile_count::apply_scale(), profile_probability::apply_scale(), basic_block_def::aux, loop::aux, BITMAP_ALLOC, bitmap_bit_p, BITMAP_FREE, bitmap_set_bit, can_copy_bbs_p(), CDI_DOMINATORS, copy_bbs(), copy_loops_to(), DLTHE_FLAG_COMPLETTE_PEEL, DLTHE_FLAG_FLAT_PROFILE, DLTHE_FLAG_UPDATE_FREQ, DLTHE_RECORD_COPY_NUMBER, dominated_by_p(), EXECUTE_IF_SET_IN_BITMAP, loop::exits, basic_block_def::flags, flow_bb_inside_loop_p(), FOR_EACH_EDGE, FOR_EACH_VEC_ELT, force_edge_cold(), free(), gcc_assert, get_dominated_by(), get_loop_body_in_dom_order(), get_loop_exit_edges(), header, loop::header, i, loop::inner, loop::latch, basic_block_def::loop_father, loop_latch_edge(), nearest_common_dominator(), loop::next, profile_count::nonzero_p(), NULL, loop::num_nodes, profile_count::probability_in(), redirect_edge_and_branch_force(), scale_bbs_frequencies(), scale_bbs_frequencies_profile_count(), set_immediate_dominator(), set_loop_copy(), basic_block_def::succs, and profile_count::zero().
Referenced by gimple_duplicate_loop_body_to_header_edge(), unroll_loop_constant_iterations(), unroll_loop_runtime_iterations(), and unroll_loop_stupid().
Copies structure of subloops of LOOP into TARGET loop, placing newly created loops into loop tree at the end of TARGETs sibling list in the original order.
References duplicate_loop(), duplicate_subloops(), gcc_assert, loop::inner, and loop::next.
Referenced by copy_loops_to(), duplicate_subloops(), gimple_duplicate_sese_tail(), and slpeel_tree_duplicate_loop_to_edge_cfg().
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Find path -- i.e. the basic blocks dominated by edge E and put them into array BBS, that will be allocated large enough to contain them. E->dest must have exactly one predecessor for this to work (it is easy to achieve and we do not put it here because we do not want to alter anything by this function). The number of basic blocks in the path is returned.
References cfun, dfs_enumerate_from(), EDGE_COUNT, gcc_assert, n_basic_blocks_for_fn, and rpe_enum_p().
Referenced by remove_path().
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Fix placement of basic block BB inside loop hierarchy -- Let L be a loop to that BB belongs. Then every successor of BB must either 1) belong to some superloop of loop L, or 2) be a header of loop K such that K->outer is superloop of L Returns true if we had to move BB into other loop to enforce this condition, false if the placement of BB was already correct (provided that placements of its successors are correct).
References add_bb_to_loop(), cfun, current_loops, EXIT_BLOCK_PTR_FOR_FN, flow_loop_nested_p(), FOR_EACH_EDGE, basic_block_def::loop_father, loop_outer(), remove_bb_from_loops(), and basic_block_def::succs.
Referenced by fix_bb_placements().
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Fix placements of basic blocks inside loop hierarchy stored in loops; i.e. enforce condition stated in description of fix_bb_placement. We start from basic block FROM that had some of its successors removed, so that his placement no longer has to be correct, and iteratively fix placement of its predecessors that may change if placement of FROM changed. Also fix placement of subloops of FROM->loop_father, that might also be altered due to this change; the condition for them is similar, except that instead of successors we consider edges coming out of the loops. If the changes may invalidate the information about irreducible regions, IRRED_INVALIDATED is set to true. If LOOP_CLOSED_SSA_INVLIDATED is non-zero then all basic blocks with changed loop_father are collected there.
References bitmap_bit_p, bitmap_clear(), bitmap_clear_bit(), bitmap_set_bit, cfun, current_loops, find_common_loop(), fix_bb_placement(), fix_loop_placement(), flow_loop_nested_p(), FOR_EACH_EDGE, free(), get_loop_body(), loop::header, i, basic_block_def::index, last_basic_block_for_fn, basic_block_def::loop_father, loop_outer(), loop::num_nodes, basic_block_def::preds, queue, and basic_block_def::succs.
Referenced by fix_loop_placements(), remove_path(), and unloop().
Fix placement of LOOP inside loop tree, i.e. find the innermost superloop of LOOP to that leads at least one exit edge of LOOP, and set it as the immediate superloop of LOOP. Return true if the immediate superloop of LOOP changed. IRRED_INVALIDATED is set to true if a change in the loop structures might invalidate the information about irreducible regions.
References current_loops, loop::exits, find_common_loop(), flow_loop_nested_p(), flow_loop_tree_node_add(), flow_loop_tree_node_remove(), FOR_EACH_VEC_ELT, get_loop_exit_edges(), i, loop_outer(), loop::num_nodes, and rescan_loop_exit().
Referenced by fix_bb_placements(), and fix_loop_placements().
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Fix placement of superloops of LOOP inside loop tree, i.e. ensure that condition stated in description of fix_loop_placement holds for them. It is used in case when we removed some edges coming out of LOOP, which may cause the right placement of LOOP inside loop tree to change. IRRED_INVALIDATED is set to true if a change in the loop structures might invalidate the information about irreducible regions.
References fix_bb_placements(), fix_loop_placement(), loop_outer(), and loop_preheader_edge().
Referenced by remove_path().
void force_single_succ_latches | ( | void | ) |
Forces all loop latches to have only single successor.
References cfun, find_edge(), gcc_checking_assert, loop::header, loop::latch, LOOPS_HAVE_SIMPLE_LATCHES, loops_state_set(), NULL, single_succ_p(), and split_edge().
Referenced by apply_loop_flags().
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True when a candidate preheader BLOCK has predecessors from LOOP.
References FOR_EACH_EDGE, and basic_block_def::preds.
Referenced by create_preheader().
Return exit that suitable for update when loop iterations changed.
References loop::exits, get_loop_exit_edges(), single_exit(), and single_likely_exit().
Referenced by scale_loop_profile(), and update_loop_exit_probability_scale_dom_bbs().
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Redirects edge E to basic block DEST.
References redirect_edge_and_branch_force().
Referenced by loop_version().
class loop * loop_version | ( | class loop * | loop, |
void * | cond_expr, | ||
basic_block * | condition_bb, | ||
profile_probability | then_prob, | ||
profile_probability | else_prob, | ||
profile_probability | then_scale, | ||
profile_probability | else_scale, | ||
bool | place_after ) |
Main entry point for Loop Versioning transformation. This transformation given a condition and a loop, creates -if (condition) { loop_copy1 } else { loop_copy2 }, where loop_copy1 is the loop transformed in one way, and loop_copy2 is the loop transformed in another way (or unchanged). COND_EXPR may be a run time test for things that were not resolved by static analysis (overlapping ranges (anti-aliasing), alignment, etc.). If non-NULL, CONDITION_BB is set to the basic block containing the condition. THEN_PROB is the probability of the then edge of the if. THEN_SCALE is the ratio by that the frequencies in the original loop should be scaled. ELSE_SCALE is the ratio by that the frequencies in the new loop should be scaled. If PLACE_AFTER is true, we place the new loop after LOOP in the instruction stream, otherwise it is placed before LOOP.
References add_bb_to_loop(), add_loop(), alloc_loop(), cfg_hook_duplicate_loop_body_to_header_edge(), copy_loop_info(), basic_block_def::flags, free(), get_bb_copy(), get_loop_body_in_dom_order(), loop::header, i, loop::latch, basic_block_def::loop_father, loop_outer(), loop_preheader_edge(), loop_redirect_edge(), lv_adjust_loop_entry_edge(), lv_flush_pending_stmts(), move_block_after(), NULL, loop::num_nodes, remove_bb_from_loops(), scale_loop_frequencies(), set_loop_copy(), single_pred_edge(), single_succ_edge(), split_edge(), and update_dominators_in_loop().
Referenced by do_split_loop_on_cond(), gen_parallel_loop(), split_loop(), tree_transform_and_unroll_loop(), tree_unswitch_loop(), vect_loop_versioning(), version_loop_by_alias_check(), and version_loop_for_if_conversion().
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This function is called from loop_version. It splits the entry edge of the loop we want to version, adds the versioning condition, and adjust the edges to the two versions of the loop appropriately. e is an incoming edge. Returns the basic block containing the condition. --- edge e ---- > [second_head] Split it and insert new conditional expression and adjust edges. --- edge e ---> [cond expr] ---> [first_head] | +---------> [second_head] THEN_PROB is the probability of then branch of the condition. ELSE_PROB is the probability of else branch. Note that they may be both REG_BR_PROB_BASE when condition is IFN_LOOP_VECTORIZED or IFN_LOOP_DIST_ALIAS.
References CDI_DOMINATORS, current_ir_type(), gcc_assert, IR_GIMPLE, lv_add_condition_to_bb(), lv_adjust_loop_header_phi(), make_edge(), NULL, set_immediate_dominator(), single_succ_edge(), and split_edge().
Referenced by loop_version().
References mfb_kj_edge.
Referenced by create_preheader(), and fwd_jt_path_registry::thread_through_loop_header().
Creates place for a new LOOP in loops structure of FN.
References loops_for_fn(), loop::num, number_of_loops(), and vec_safe_push().
Referenced by add_loop(), copy_loops(), duplicate_loop(), and input_cfg().
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Remove basic blocks BBS. NBBS is the number of the basic blocks.
References delete_basic_block(), and i.
Referenced by remove_path().
Removes path beginning at edge E, i.e. remove basic blocks dominated by E and update loop structures and dominators. Return true if we were able to remove the path, false otherwise (and nothing is affected then).
References bitmap_bit_p, bitmap_clear(), bitmap_set_bit, can_remove_branch_p(), cancel_loop_tree(), CDI_DOMINATORS, cfun, dominated_by_p(), EXIT_BLOCK_PTR_FOR_FN, find_path(), first_dom_son(), fix_bb_placements(), fix_loop_placements(), FOR_EACH_EDGE, free(), get_immediate_dominator(), i, basic_block_def::index, iterate_fix_dominators(), last_basic_block_for_fn, loop::latch, basic_block_def::loop_father, loop_outer(), LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS, loops_state_satisfies_p(), mark_irreducible_loops(), n_basic_blocks_for_fn, next_dom_son(), remove_bbs(), remove_branch(), single_pred_edge(), single_pred_p(), split_edge(), and unloop().
Referenced by tree_transform_and_unroll_loop(), unloop_loops(), unroll_loop_constant_iterations(), and unroll_loop_runtime_iterations().
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Checks whether basic block BB is dominated by DATA.
References CDI_DOMINATORS, and dominated_by_p().
Referenced by find_path().
void scale_dominated_blocks_in_loop | ( | class loop * | loop, |
basic_block | bb, | ||
profile_count | num, | ||
profile_count | den ) |
Scales the frequencies of all basic blocks in LOOP that are strictly dominated by BB by NUM/DEN.
References profile_count::apply_scale(), CDI_DOMINATORS, basic_block_def::count, first_dom_son(), flow_bb_inside_loop_p(), next_dom_son(), profile_count::nonzero_p(), loop::num, worklist, and profile_count::zero().
Referenced by tree_transform_and_unroll_loop(), and update_loop_exit_probability_scale_dom_bbs().
void scale_loop_frequencies | ( | class loop * | loop, |
profile_probability | p ) |
Scale profile of loop by P.
References free(), get_loop_body(), loop::num_nodes, and scale_bbs_frequencies().
Referenced by create_empty_loop_on_edge(), loop_version(), scale_loop_profile(), vect_loop_versioning(), and vect_transform_loop().
void scale_loop_profile | ( | class loop * | loop, |
profile_probability | p, | ||
gcov_type | iteration_bound ) |
Scale profile in LOOP by P. If ITERATION_BOUND is not -1, scale even further if loop is predicted to iterate too many times. Before caling this function, preheader block profile should be already scaled to final count. This is necessary because loop iterations are determined by comparing header edge count to latch ege count and thus they need to be scaled synchronously.
References profile_probability::always(), basic_block_def::count, profile_probability::dump(), dump_file, dump_flags, expected_loop_iterations_by_profile(), loop::header, loop_count_in(), loop_exit_for_scaling(), loop::num, scale_loop_frequencies(), TDF_DETAILS, sreal::to_double(), profile_count::uninitialized(), and update_loop_exit_probability_scale_dom_bbs().
Referenced by scale_profile_for_vect_loop(), tree_transform_and_unroll_loop(), try_unroll_loop_completely(), and vect_do_peeling().
Remove the latch edge of a LOOP and update loops to indicate that the LOOP was removed. After this function, original loop latch will have no successor, which caller is expected to fix somehow. If this may cause the information about irreducible regions to become invalid, IRRED_INVALIDATED is set to true. LOOP_CLOSED_SSA_INVALIDATED, if non-NULL, is a bitmap where we store basic blocks that had non-trivial update on their loop_father.
References add_bb_to_loop(), delete_loop(), fix_bb_placements(), flow_loop_tree_node_add(), flow_loop_tree_node_remove(), free(), get_loop_body(), i, loop::inner, loop::latch, loop_outer(), loop_preheader_edge(), loop::num_nodes, remove_bb_from_loops(), remove_edge(), and single_succ_edge().
Referenced by remove_path(), and unloop_loops().
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Recompute dominance information for basic blocks outside LOOP.
References bitmap_bit_p, bitmap_clear(), bitmap_set_bit, CDI_DOMINATORS, cfun, first_dom_son(), free(), get_loop_body(), i, basic_block_def::index, iterate_fix_dominators(), last_basic_block_for_fn, next_dom_son(), loop::num_nodes, and vNULL.
Referenced by create_empty_loop_on_edge(), and loop_version().
edge update_loop_exit_probability_scale_dom_bbs | ( | class loop * | loop, |
edge | exit_edge, | ||
profile_count | desired_count ) |
Assume that loop's entry count and profile up to a given EXIT_EDGE is consistent. Update exit probability so loop exists with PROFILE_COUNT and rescale profile of basic blocks inside loop dominated by EXIT_EDGE->src. This is useful after number of iteraitons of loop has changed. If EXIT_EDGE is NULL, the function will try to identify suitable exit. If DESIRED_COUNT is NULL, loop entry count will be used. In consistent profile usually loop exists as many times as it is entred. Return updated exit if successfull and NULL otherwise.
References cfun, basic_block_def::count, profile_count::differs_from_p(), profile_count::dump(), dump_file, dump_flags, FOR_EACH_EDGE, profile_count::initialized_p(), just_once_each_iteration_p(), loop::latch, loop_count_in(), loop_exit_edge_p(), loop_exit_for_scaling(), NULL, loop::num, profile_count::probability_in(), scale_dominated_blocks_in_loop(), set_edge_probability_and_rescale_others(), single_pred_p(), and TDF_DETAILS.
Referenced by scale_loop_profile(), split_loop(), tree_transform_and_unroll_loop(), and unroll_loop_constant_iterations().
edge mfb_kj_edge |
A callback for make_forwarder block, to redirect all edges except for MFB_KJ_EDGE to the entry part. E is the edge for that we should decide whether to redirect it.
Referenced by create_preheader(), mfb_keep_just(), and fwd_jt_path_registry::thread_through_loop_header().