This removes RTL loop unswitching (see last years discussion about compile-time issues of that pass). RTL loop unswitching is enabled together with GIMPLE loop unswitching at -O3 and by -floop-unswitch. It's clearly the wrong place to do high-level loop transforms these days, and the cost of maintainance doesn't outweight the questionable benefit.
Thus the following patch removes it. Bootstrap / regtest pending on x86_64-unknown-linux-gnu (I hope for testsuite fallout). Any objections? Thanks, Richard. 2014-04-15 Richard Biener <rguent...@suse.de> * Makefile.in (OBJS): Remove loop-unswitch.o. * loop-unswitch.c: Delete. * tree-pass.h (make_pass_rtl_unswitch): Remove. * passes.def (pass_rtl_unswitch): Likewise. * loop-init.c (gate_rtl_unswitch): Likewise. (rtl_unswitch): Likewise. (pass_data_rtl_unswitch): Likewise. (pass_rtl_unswitch): Likewise. (make_pass_rtl_unswitch): Likewise. * rtl.h (reversed_condition): Likewise. (compare_and_jump_seq): Likewise. * loop-iv.c (reversed_condition): Move here from loop-unswitch.c and make static. * loop-unroll.c (compare_and_jump_seq): Likewise. Index: gcc/Makefile.in =================================================================== --- gcc/Makefile.in (revision 209410) +++ gcc/Makefile.in (working copy) @@ -1294,7 +1294,6 @@ OBJS = \ loop-invariant.o \ loop-iv.o \ loop-unroll.o \ - loop-unswitch.o \ lower-subreg.o \ lra.o \ lra-assigns.o \ Index: gcc/tree-pass.h =================================================================== --- gcc/tree-pass.h (revision 209410) +++ gcc/tree-pass.h (working copy) @@ -512,7 +512,6 @@ extern rtl_opt_pass *make_pass_outof_cfg extern rtl_opt_pass *make_pass_loop2 (gcc::context *ctxt); extern rtl_opt_pass *make_pass_rtl_loop_init (gcc::context *ctxt); extern rtl_opt_pass *make_pass_rtl_move_loop_invariants (gcc::context *ctxt); -extern rtl_opt_pass *make_pass_rtl_unswitch (gcc::context *ctxt); extern rtl_opt_pass *make_pass_rtl_unroll_and_peel_loops (gcc::context *ctxt); extern rtl_opt_pass *make_pass_rtl_doloop (gcc::context *ctxt); extern rtl_opt_pass *make_pass_rtl_loop_done (gcc::context *ctxt); Index: gcc/passes.def =================================================================== --- gcc/passes.def (revision 209410) +++ gcc/passes.def (working copy) @@ -341,7 +341,6 @@ along with GCC; see the file COPYING3. PUSH_INSERT_PASSES_WITHIN (pass_loop2) NEXT_PASS (pass_rtl_loop_init); NEXT_PASS (pass_rtl_move_loop_invariants); - NEXT_PASS (pass_rtl_unswitch); NEXT_PASS (pass_rtl_unroll_and_peel_loops); NEXT_PASS (pass_rtl_doloop); NEXT_PASS (pass_rtl_loop_done); Index: gcc/loop-init.c =================================================================== --- gcc/loop-init.c (revision 209410) +++ gcc/loop-init.c (working copy) @@ -518,61 +518,7 @@ make_pass_rtl_move_loop_invariants (gcc: } -/* Loop unswitching for RTL. */ -static bool -gate_rtl_unswitch (void) -{ - return flag_unswitch_loops; -} - -static unsigned int -rtl_unswitch (void) -{ - if (number_of_loops (cfun) > 1) - unswitch_loops (); - return 0; -} - -namespace { - -const pass_data pass_data_rtl_unswitch = -{ - RTL_PASS, /* type */ - "loop2_unswitch", /* name */ - OPTGROUP_LOOP, /* optinfo_flags */ - true, /* has_gate */ - true, /* has_execute */ - TV_LOOP_UNSWITCH, /* tv_id */ - 0, /* properties_required */ - 0, /* properties_provided */ - 0, /* properties_destroyed */ - 0, /* todo_flags_start */ - TODO_verify_rtl_sharing, /* todo_flags_finish */ -}; - -class pass_rtl_unswitch : public rtl_opt_pass -{ -public: - pass_rtl_unswitch (gcc::context *ctxt) - : rtl_opt_pass (pass_data_rtl_unswitch, ctxt) - {} - - /* opt_pass methods: */ - bool gate () { return gate_rtl_unswitch (); } - unsigned int execute () { return rtl_unswitch (); } - -}; // class pass_rtl_unswitch - -} // anon namespace - -rtl_opt_pass * -make_pass_rtl_unswitch (gcc::context *ctxt) -{ - return new pass_rtl_unswitch (ctxt); -} - - -/* Loop unswitching for RTL. */ +/* Loop unrolling and peeling for RTL. */ static bool gate_rtl_unroll_and_peel_loops (void) { Index: gcc/loop-iv.c =================================================================== --- gcc/loop-iv.c (revision 209410) +++ gcc/loop-iv.c (working copy) @@ -1732,6 +1732,21 @@ canon_condition (rtx cond) return cond; } +/* Reverses CONDition; returns NULL if we cannot. */ + +static rtx +reversed_condition (rtx cond) +{ + enum rtx_code reversed; + reversed = reversed_comparison_code (cond, NULL); + if (reversed == UNKNOWN) + return NULL_RTX; + else + return gen_rtx_fmt_ee (reversed, + GET_MODE (cond), XEXP (cond, 0), + XEXP (cond, 1)); +} + /* Tries to use the fact that COND holds to simplify EXPR. ALTERED is the set of altered regs. */ Index: gcc/loop-unroll.c =================================================================== --- gcc/loop-unroll.c (revision 209410) +++ gcc/loop-unroll.c (working copy) @@ -1060,6 +1060,59 @@ split_edge_and_insert (edge e, rtx insns return bb; } +/* Prepare a sequence comparing OP0 with OP1 using COMP and jumping to LABEL if + true, with probability PROB. If CINSN is not NULL, it is the insn to copy + in order to create a jump. */ + +static rtx +compare_and_jump_seq (rtx op0, rtx op1, enum rtx_code comp, rtx label, int prob, + rtx cinsn) +{ + rtx seq, jump, cond; + enum machine_mode mode; + + mode = GET_MODE (op0); + if (mode == VOIDmode) + mode = GET_MODE (op1); + + start_sequence (); + if (GET_MODE_CLASS (mode) == MODE_CC) + { + /* A hack -- there seems to be no easy generic way how to make a + conditional jump from a ccmode comparison. */ + gcc_assert (cinsn); + cond = XEXP (SET_SRC (pc_set (cinsn)), 0); + gcc_assert (GET_CODE (cond) == comp); + gcc_assert (rtx_equal_p (op0, XEXP (cond, 0))); + gcc_assert (rtx_equal_p (op1, XEXP (cond, 1))); + emit_jump_insn (copy_insn (PATTERN (cinsn))); + jump = get_last_insn (); + gcc_assert (JUMP_P (jump)); + JUMP_LABEL (jump) = JUMP_LABEL (cinsn); + LABEL_NUSES (JUMP_LABEL (jump))++; + redirect_jump (jump, label, 0); + } + else + { + gcc_assert (!cinsn); + + op0 = force_operand (op0, NULL_RTX); + op1 = force_operand (op1, NULL_RTX); + do_compare_rtx_and_jump (op0, op1, comp, 0, + mode, NULL_RTX, NULL_RTX, label, -1); + jump = get_last_insn (); + gcc_assert (JUMP_P (jump)); + JUMP_LABEL (jump) = label; + LABEL_NUSES (label)++; + } + add_int_reg_note (jump, REG_BR_PROB, prob); + + seq = get_insns (); + end_sequence (); + + return seq; +} + /* Unroll LOOP for which we are able to count number of iterations in runtime LOOP->LPT_DECISION.TIMES times. The transformation does this (with some extra care for case n < 0): Index: gcc/rtl.h =================================================================== --- gcc/rtl.h (revision 209410) +++ gcc/rtl.h (working copy) @@ -2743,10 +2743,6 @@ extern unsigned int variable_tracking_ma extern void get_mode_bounds (enum machine_mode, int, enum machine_mode, rtx *, rtx *); -/* In loop-unswitch.c */ -extern rtx reversed_condition (rtx); -extern rtx compare_and_jump_seq (rtx, rtx, enum rtx_code, rtx, int, rtx); - /* In loop-iv.c */ extern rtx canon_condition (rtx); extern void simplify_using_condition (rtx, rtx *, bitmap);