From 0526fa57290941c8b7febd138ab4c637b83f3d05 Mon Sep 17 00:00:00 2001 From: Robin Dapp Date: Wed, 27 Nov 2019 13:53:40 +0100 Subject: [PATCH v2 4/7] ifcvt/optabs: Allow using a CC comparison for emit_conditional_move. Currently we only ever call emit_conditional_move with the comparison (as well as its comparands) we got from the jump. Thus, backends are going to emit a CC comparison for every conditional move that is being generated instead of re-using the existing CC. This, combined with emitting temporaries for each conditional move, causes sky-high costs for conditional moves. This patch allows to re-use a CC so the costing situation is improved a bit. --- gcc/ifcvt.c | 40 ++++++++----- gcc/optabs.c | 164 ++++++++++++++++++++++++++++++++++----------------- gcc/optabs.h | 1 + 3 files changed, 135 insertions(+), 70 deletions(-) diff --git a/gcc/ifcvt.c b/gcc/ifcvt.c index 91b54dbea9c..7ce60d0af8d 100644 --- a/gcc/ifcvt.c +++ b/gcc/ifcvt.c @@ -771,7 +771,7 @@ static int noce_try_addcc (struct noce_if_info *); static int noce_try_store_flag_constants (struct noce_if_info *); static int noce_try_store_flag_mask (struct noce_if_info *); static rtx noce_emit_cmove (struct noce_if_info *, rtx, enum rtx_code, rtx, - rtx, rtx, rtx); + rtx, rtx, rtx, rtx = NULL, rtx = NULL); static int noce_try_cmove (struct noce_if_info *); static int noce_try_cmove_arith (struct noce_if_info *); static rtx noce_get_alt_condition (struct noce_if_info *, rtx, rtx_insn **); @@ -1710,7 +1710,8 @@ noce_try_store_flag_mask (struct noce_if_info *if_info) static rtx noce_emit_cmove (struct noce_if_info *if_info, rtx x, enum rtx_code code, - rtx cmp_a, rtx cmp_b, rtx vfalse, rtx vtrue) + rtx cmp_a, rtx cmp_b, rtx vfalse, rtx vtrue, rtx cc_cmp, + rtx rev_cc_cmp) { rtx target ATTRIBUTE_UNUSED; int unsignedp ATTRIBUTE_UNUSED; @@ -1742,23 +1743,30 @@ noce_emit_cmove (struct noce_if_info *if_info, rtx x, enum rtx_code code, end_sequence (); } - /* Don't even try if the comparison operands are weird - except that the target supports cbranchcc4. */ - if (! general_operand (cmp_a, GET_MODE (cmp_a)) - || ! general_operand (cmp_b, GET_MODE (cmp_b))) - { - if (!have_cbranchcc4 - || GET_MODE_CLASS (GET_MODE (cmp_a)) != MODE_CC - || cmp_b != const0_rtx) - return NULL_RTX; - } - unsignedp = (code == LTU || code == GEU || code == LEU || code == GTU); - target = emit_conditional_move (x, code, cmp_a, cmp_b, VOIDmode, - vtrue, vfalse, GET_MODE (x), - unsignedp); + if (cc_cmp != NULL_RTX && rev_cc_cmp != NULL_RTX) + target = emit_conditional_move (x, cc_cmp, rev_cc_cmp, + vtrue, vfalse, GET_MODE (x)); + else + { + /* Don't even try if the comparison operands are weird + except that the target supports cbranchcc4. */ + if (! general_operand (cmp_a, GET_MODE (cmp_a)) + || ! general_operand (cmp_b, GET_MODE (cmp_b))) + { + if (!have_cbranchcc4 + || GET_MODE_CLASS (GET_MODE (cmp_a)) != MODE_CC + || cmp_b != const0_rtx) + return NULL_RTX; + } + + target = emit_conditional_move (x, code, cmp_a, cmp_b, VOIDmode, + vtrue, vfalse, GET_MODE (x), + unsignedp); + } + if (target) return target; diff --git a/gcc/optabs.c b/gcc/optabs.c index 62a6bdb4c59..7410f23e0ad 100644 --- a/gcc/optabs.c +++ b/gcc/optabs.c @@ -52,6 +52,8 @@ static void prepare_float_lib_cmp (rtx, rtx, enum rtx_code, rtx *, static rtx expand_unop_direct (machine_mode, optab, rtx, rtx, int); static void emit_libcall_block_1 (rtx_insn *, rtx, rtx, rtx, bool); +static rtx emit_conditional_move (rtx, rtx, rtx, rtx, machine_mode); + /* Debug facility for use in GDB. */ void debug_optab_libfuncs (void); @@ -4747,7 +4749,6 @@ emit_conditional_move (rtx target, enum rtx_code code, rtx op0, rtx op1, machine_mode mode, int unsignedp) { rtx comparison; - rtx_insn *last; enum insn_code icode; enum rtx_code reversed; @@ -4774,6 +4775,7 @@ emit_conditional_move (rtx target, enum rtx_code code, rtx op0, rtx op1, /* get_condition will prefer to generate LT and GT even if the old comparison was against zero, so undo that canonicalization here since comparisons against zero are cheaper. */ + if (code == LT && op1 == const1_rtx) code = LE, op1 = const0_rtx; else if (code == GT && op1 == constm1_rtx) @@ -4782,17 +4784,30 @@ emit_conditional_move (rtx target, enum rtx_code code, rtx op0, rtx op1, if (cmode == VOIDmode) cmode = GET_MODE (op0); - enum rtx_code orig_code = code; + /* If the first condition operand is constant and the second is not, swap + them. In that case we also need to reverse the comparison. + If both are non-constant It is possible that the conditional move + will not expand with operands in this order, e.g. when we are about to + create a min/max expression and the operands do not match the condition. + In that case we also need the reversed condition code and comparison. */ + + rtx rev_comparison = NULL_RTX; bool swapped = false; - if (swap_commutative_operands_p (op2, op3) - && ((reversed = reversed_comparison_code_parts (code, op0, op1, NULL)) - != UNKNOWN)) + + code = unsignedp ? unsigned_condition (code) : code; + comparison = simplify_gen_relational (code, VOIDmode, cmode, op0, op1); + + if ((reversed = reversed_comparison_code_parts (code, op0, op1, NULL)) + != UNKNOWN) { - std::swap (op2, op3); - code = reversed; - swapped = true; + reversed = unsignedp ? unsigned_condition (reversed) : reversed; + rev_comparison = simplify_gen_relational (reversed, VOIDmode, cmode, + op0, op1); } + if (swap_commutative_operands_p (op2, op3) && reversed != UNKNOWN) + swapped = true; + if (mode == VOIDmode) mode = GET_MODE (op2); @@ -4804,58 +4819,99 @@ emit_conditional_move (rtx target, enum rtx_code code, rtx op0, rtx op1, if (!target) target = gen_reg_rtx (mode); - for (int pass = 0; ; pass++) + if (comparison && COMPARISON_P (comparison)) + prepare_cmp_insn (XEXP (comparison, 0), XEXP (comparison, 1), + GET_CODE (comparison), NULL_RTX, + unsignedp, OPTAB_WIDEN, &comparison, &cmode); + else + return NULL_RTX; + + if (rev_comparison && COMPARISON_P (rev_comparison)) + prepare_cmp_insn (XEXP (rev_comparison, 0), XEXP (rev_comparison, 1), + GET_CODE (rev_comparison), NULL_RTX, + unsignedp, OPTAB_WIDEN, &rev_comparison, &cmode); + + if (!swapped) + return emit_conditional_move (target, comparison, rev_comparison, + op2, op3, mode); + else + return emit_conditional_move (target, rev_comparison, comparison, + op3, op2, mode); +} + +/* Helper function for emitting a conditional move. Given a COMPARISON + and a reversed REV_COMPARISON it will try to expand a conditional move + with COMPARISON first and try with REV_COMPARISON if that fails. */ + +rtx +emit_conditional_move (rtx target, rtx comparison, rtx rev_comparison, + rtx op2, rtx op3, machine_mode mode) +{ + + rtx res = emit_conditional_move (target, comparison, op2, op3, mode); + + if (res != NULL_RTX) + return res; + + return emit_conditional_move (target, rev_comparison, op3, op2, mode); +} + +/* Helper for emitting a conditional move. */ + +static rtx +emit_conditional_move (rtx target, rtx comparison, + rtx op2, rtx op3, machine_mode mode) +{ + rtx_insn *last; + enum insn_code icode; + + if (comparison == NULL_RTX || !COMPARISON_P (comparison)) + return NULL_RTX; + + /* If the two source operands are identical, that's just a move. */ + if (rtx_equal_p (op2, op3)) { - code = unsignedp ? unsigned_condition (code) : code; - comparison = simplify_gen_relational (code, VOIDmode, cmode, op0, op1); + if (!target) + target = gen_reg_rtx (mode); - /* We can get const0_rtx or const_true_rtx in some circumstances. Just - punt and let the caller figure out how best to deal with this - situation. */ - if (COMPARISON_P (comparison)) - { - saved_pending_stack_adjust save; - save_pending_stack_adjust (&save); - last = get_last_insn (); - do_pending_stack_adjust (); - machine_mode cmpmode = cmode; - prepare_cmp_insn (XEXP (comparison, 0), XEXP (comparison, 1), - GET_CODE (comparison), NULL_RTX, unsignedp, - OPTAB_WIDEN, &comparison, &cmpmode); - if (comparison) - { - class expand_operand ops[4]; + emit_move_insn (target, op3); + return target; + } - create_output_operand (&ops[0], target, mode); - create_fixed_operand (&ops[1], comparison); - create_input_operand (&ops[2], op2, mode); - create_input_operand (&ops[3], op3, mode); - if (maybe_expand_insn (icode, 4, ops)) - { - if (ops[0].value != target) - convert_move (target, ops[0].value, false); - return target; - } - } - delete_insns_since (last); - restore_pending_stack_adjust (&save); - } + if (mode == VOIDmode) + mode = GET_MODE (op2); - if (pass == 1) - return NULL_RTX; + icode = direct_optab_handler (movcc_optab, mode); - /* If the preferred op2/op3 order is not usable, retry with other - operand order, perhaps it will expand successfully. */ - if (swapped) - code = orig_code; - else if ((reversed = reversed_comparison_code_parts (orig_code, op0, op1, - NULL)) - != UNKNOWN) - code = reversed; - else - return NULL_RTX; - std::swap (op2, op3); + if (icode == CODE_FOR_nothing) + return NULL_RTX; + + if (!target) + target = gen_reg_rtx (mode); + + saved_pending_stack_adjust save; + save_pending_stack_adjust (&save); + last = get_last_insn (); + do_pending_stack_adjust (); + + class expand_operand ops[4]; + + create_output_operand (&ops[0], target, mode); + create_fixed_operand (&ops[1], comparison); + create_input_operand (&ops[2], op2, mode); + create_input_operand (&ops[3], op3, mode); + + if (maybe_expand_insn (icode, 4, ops)) + { + if (ops[0].value != target) + convert_move (target, ops[0].value, false); + return target; } + + delete_insns_since (last); + restore_pending_stack_adjust (&save); + + return NULL_RTX; } diff --git a/gcc/optabs.h b/gcc/optabs.h index 3bbceff92d9..f853b93f37f 100644 --- a/gcc/optabs.h +++ b/gcc/optabs.h @@ -281,6 +281,7 @@ extern void emit_indirect_jump (rtx); /* Emit a conditional move operation. */ rtx emit_conditional_move (rtx, enum rtx_code, rtx, rtx, machine_mode, rtx, rtx, machine_mode, int); +rtx emit_conditional_move (rtx, rtx, rtx, rtx, rtx, machine_mode); /* Emit a conditional negate or bitwise complement operation. */ rtx emit_conditional_neg_or_complement (rtx, rtx_code, machine_mode, rtx, -- 2.31.1