commit eb50384ee0cdeeefa61ae89bdbb2875500b7ce60 Author: Robin Dapp Date: Wed Nov 27 13:53:40 2019 +0100 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. diff --git a/gcc/ifcvt.c b/gcc/ifcvt.c index 6ae883cbdd4..f7765e60548 100644 --- a/gcc/ifcvt.c +++ b/gcc/ifcvt.c @@ -772,7 +772,7 @@ 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 **); @@ -1711,7 +1711,8 @@ 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; @@ -1743,23 +1744,30 @@ 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 019bbb62882..25eecf29ed8 100644 --- a/gcc/optabs.c +++ b/gcc/optabs.c @@ -52,6 +52,9 @@ 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); +rtx emit_conditional_move (rtx, rtx, rtx, rtx, rtx, machine_mode); + /* Debug facility for use in GDB. */ void debug_optab_libfuncs (void); @@ -4875,6 +4878,7 @@ 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) @@ -4925,18 +4929,10 @@ emit_conditional_move (rtx target, enum rtx_code code, rtx op0, rtx op1, OPTAB_WIDEN, &comparison, &cmpmode); if (comparison) { - 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; - } + rtx res = emit_conditional_move (target, comparison, + op2, op3, mode); + if (res != NULL_RTX) + return res; } delete_insns_since (last); restore_pending_stack_adjust (&save); @@ -4959,6 +4955,73 @@ emit_conditional_move (rtx target, enum rtx_code code, rtx op0, rtx op1, } } +/* Helper function that, in addition to COMPARISON, also tries + the reversed REV_COMPARISON with swapped OP2 and OP3. As opposed + to when we pass the specific constituents of a comparison, no + additional insns are emitted for it. It might still be necessary + to emit more than one insn for the final conditional move, though. */ + +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) +{ + 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)) + { + if (!target) + target = gen_reg_rtx (mode); + + emit_move_insn (target, op3); + return target; + } + + if (mode == VOIDmode) + mode = GET_MODE (op2); + + icode = direct_optab_handler (movcc_optab, mode); + + if (icode == CODE_FOR_nothing) + return NULL_RTX; + + if (!target) + target = gen_reg_rtx (mode); + + 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; + } + + return NULL_RTX; +} + /* Emit a conditional negate or bitwise complement using the negcc or notcc optabs if available. Return NULL_RTX if such operations 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,