Move jump threading before reload
r266734 has introduced a new instance of jump threading pass in order to take advantage of opportunities that combine opens up. It was perceived back then that it was beneficial to delay it after reload, since that might produce even more such opportunities. Unfortunately jump threading interferes with hot/cold partitioning. In the code from PR92007, it converts the following +-------------------------- 2/HOT ------------------------+ | | v v 3/HOT --> 5/HOT --> 8/HOT --> 11/COLD --> 6/HOT --EH--> 16/HOT | ^ | | +-------------------------------+ into the following: +---------------------- 2/HOT ------------------+ | | v v 3/HOT --> 8/HOT --> 11/COLD --> 6/COLD --EH--> 16/HOT This makes hot bb 6 dominated by cold bb 11, and because of this fixup_partitions makes bb 6 cold as well, which in turn makes EH edge 6->16 a crossing one. Not only can't we have crossing EH edges, we are also not allowed to introduce new crossing edges after reload in general, since it might require extra registers on some targets. Therefore, move the jump threading pass between combine and hot/cold partitioning. Building SPEC 2006 and SPEC 2017 with the old and the new code indicates that: * When doing jump threading right after reload, 3889 edges are threaded. * When doing jump threading right after combine, 3918 edges are threaded. This means this change will not introduce performance regressions. gcc/ChangeLog: 2019-10-28 Ilya Leoshkevich <iii@linux.ibm.com> PR rtl-optimization/92007 * cfgcleanup.c (thread_jump): Add an assertion that we don't call it after reload if hot/cold partitioning has been done. (class pass_postreload_jump): Rename to pass_jump_after_combine. (make_pass_postreload_jump): Rename to make_pass_jump_after_combine. * passes.def(pass_postreload_jump): Move before reload, rename to pass_jump_after_combine. * tree-pass.h (make_pass_postreload_jump): Rename to make_pass_jump_after_combine. gcc/testsuite/ChangeLog: 2019-10-28 Ilya Leoshkevich <iii@linux.ibm.com> PR rtl-optimization/92007 * g++.dg/opt/pr92007.C: New test (from Arseny Solokha). From-SVN: r277507
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@ -1,3 +1,17 @@
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2019-10-28 Ilya Leoshkevich <iii@linux.ibm.com>
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PR rtl-optimization/92007
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* cfgcleanup.c (thread_jump): Add an assertion that we don't
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call it after reload if hot/cold partitioning has been done.
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(class pass_postreload_jump): Rename to
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pass_jump_after_combine.
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(make_pass_postreload_jump): Rename to
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make_pass_jump_after_combine.
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* passes.def(pass_postreload_jump): Move before reload, rename
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to pass_jump_after_combine.
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* tree-pass.h (make_pass_postreload_jump): Rename to
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make_pass_jump_after_combine.
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2019-10-25 Jan Hubicka <hubicka@ucw.cz>
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PR ipa/92242
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@ -259,6 +259,10 @@ thread_jump (edge e, basic_block b)
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bool failed = false;
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reg_set_iterator rsi;
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/* Jump threading may cause fixup_partitions to introduce new crossing edges,
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which is not allowed after reload. */
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gcc_checking_assert (!reload_completed || !crtl->has_bb_partition);
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if (b->flags & BB_NONTHREADABLE_BLOCK)
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return NULL;
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@ -3280,10 +3284,10 @@ make_pass_jump (gcc::context *ctxt)
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namespace {
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const pass_data pass_data_postreload_jump =
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const pass_data pass_data_jump_after_combine =
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{
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RTL_PASS, /* type */
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"postreload_jump", /* name */
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"jump_after_combine", /* name */
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OPTGROUP_NONE, /* optinfo_flags */
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TV_JUMP, /* tv_id */
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0, /* properties_required */
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@ -3293,20 +3297,20 @@ const pass_data pass_data_postreload_jump =
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0, /* todo_flags_finish */
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};
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class pass_postreload_jump : public rtl_opt_pass
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class pass_jump_after_combine : public rtl_opt_pass
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{
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public:
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pass_postreload_jump (gcc::context *ctxt)
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: rtl_opt_pass (pass_data_postreload_jump, ctxt)
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pass_jump_after_combine (gcc::context *ctxt)
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: rtl_opt_pass (pass_data_jump_after_combine, ctxt)
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{}
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/* opt_pass methods: */
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virtual unsigned int execute (function *);
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}; // class pass_postreload_jump
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}; // class pass_jump_after_combine
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unsigned int
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pass_postreload_jump::execute (function *)
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pass_jump_after_combine::execute (function *)
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{
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cleanup_cfg (flag_thread_jumps ? CLEANUP_THREADING : 0);
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return 0;
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@ -3315,9 +3319,9 @@ pass_postreload_jump::execute (function *)
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} // anon namespace
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rtl_opt_pass *
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make_pass_postreload_jump (gcc::context *ctxt)
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make_pass_jump_after_combine (gcc::context *ctxt)
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{
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return new pass_postreload_jump (ctxt);
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return new pass_jump_after_combine (ctxt);
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}
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namespace {
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@ -439,6 +439,7 @@ along with GCC; see the file COPYING3. If not see
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NEXT_PASS (pass_ud_rtl_dce);
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NEXT_PASS (pass_combine);
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NEXT_PASS (pass_if_after_combine);
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NEXT_PASS (pass_jump_after_combine);
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NEXT_PASS (pass_partition_blocks);
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NEXT_PASS (pass_outof_cfg_layout_mode);
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NEXT_PASS (pass_split_all_insns);
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@ -455,7 +456,6 @@ along with GCC; see the file COPYING3. If not see
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NEXT_PASS (pass_reload);
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NEXT_PASS (pass_postreload);
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PUSH_INSERT_PASSES_WITHIN (pass_postreload)
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NEXT_PASS (pass_postreload_jump);
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NEXT_PASS (pass_postreload_cse);
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NEXT_PASS (pass_gcse2);
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NEXT_PASS (pass_split_after_reload);
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@ -1,3 +1,8 @@
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2019-10-28 Ilya Leoshkevich <iii@linux.ibm.com>
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PR rtl-optimization/92007
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* g++.dg/opt/pr92007.C: New test (from Arseny Solokha).
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2019-10-28 Tobias Burnus <tobias@codesourcery.com>
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PR fortran/91863
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@ -0,0 +1,32 @@
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// PR rtl-optimization/92007
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// { dg-do compile }
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// { dg-options "-O2 -fno-tree-dominator-opts -fno-tree-forwprop --param max-cse-insns=0 -Wno-return-type -std=gnu++98 -freorder-blocks-and-partition" }
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void
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sb (int *);
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class d4 {
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public:
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~d4();
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void gb ();
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int op () { return no; }
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int wl () { return tf; }
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bool ee () try { gb (); } catch (...) { return false; }
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bool b1 () { return (tf == no) ? false : ee (); }
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private:
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int no, tf;
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};
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void
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hs (int *v9)
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{
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d4 p6;
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p6.gb ();
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if (p6.op () > p6.wl ())
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{
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p6.b1 ();
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sb (v9);
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}
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}
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@ -564,6 +564,7 @@ extern rtl_opt_pass *make_pass_stack_ptr_mod (gcc::context *ctxt);
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extern rtl_opt_pass *make_pass_initialize_regs (gcc::context *ctxt);
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extern rtl_opt_pass *make_pass_combine (gcc::context *ctxt);
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extern rtl_opt_pass *make_pass_if_after_combine (gcc::context *ctxt);
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extern rtl_opt_pass *make_pass_jump_after_combine (gcc::context *ctxt);
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extern rtl_opt_pass *make_pass_ree (gcc::context *ctxt);
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extern rtl_opt_pass *make_pass_partition_blocks (gcc::context *ctxt);
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extern rtl_opt_pass *make_pass_match_asm_constraints (gcc::context *ctxt);
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@ -581,7 +582,6 @@ extern rtl_opt_pass *make_pass_clean_state (gcc::context *ctxt);
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extern rtl_opt_pass *make_pass_branch_prob (gcc::context *ctxt);
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extern rtl_opt_pass *make_pass_value_profile_transformations (gcc::context
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*ctxt);
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extern rtl_opt_pass *make_pass_postreload_jump (gcc::context *ctxt);
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extern rtl_opt_pass *make_pass_postreload_cse (gcc::context *ctxt);
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extern rtl_opt_pass *make_pass_gcse2 (gcc::context *ctxt);
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extern rtl_opt_pass *make_pass_split_after_reload (gcc::context *ctxt);
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