library ieee; use ieee.std_logic_1164.all; use ieee.numeric_std.all; library work; use work.decode_types.all; use work.common.all; use work.helpers.all; use work.crhelpers.all; use work.insn_helpers.all; use work.ppc_fx_insns.all; entity execute1 is generic ( EX1_BYPASS : boolean := true ); port ( clk : in std_ulogic; rst : in std_ulogic; -- asynchronous flush_out : out std_ulogic; stall_out : out std_ulogic; e_in : in Decode2ToExecute1Type; -- asynchronous l_out : out Execute1ToLoadstore1Type; f_out : out Execute1ToFetch1Type; e_out : out Execute1ToWritebackType; icache_inval : out std_ulogic; terminate_out : out std_ulogic ); end entity execute1; architecture behaviour of execute1 is type reg_type is record e : Execute1ToWritebackType; lr_update : std_ulogic; next_lr : std_ulogic_vector(63 downto 0); mul_in_progress : std_ulogic; div_in_progress : std_ulogic; ldst_in_progress : std_ulogic; cntz_in_progress : std_ulogic; slow_op_dest : gpr_index_t; slow_op_rc : std_ulogic; slow_op_oe : std_ulogic; slow_op_xerc : xer_common_t; end record; signal r, rin : reg_type; signal a_in, b_in, c_in : std_ulogic_vector(63 downto 0); signal ctrl: ctrl_t := (others => (others => '0')); signal ctrl_tmp: ctrl_t := (others => (others => '0')); signal right_shift, rot_clear_left, rot_clear_right: std_ulogic; signal rotator_result: std_ulogic_vector(63 downto 0); signal rotator_carry: std_ulogic; signal logical_result: std_ulogic_vector(63 downto 0); signal countzero_result: std_ulogic_vector(63 downto 0); signal popcnt_result: std_ulogic_vector(63 downto 0); signal parity_result: std_ulogic_vector(63 downto 0); -- multiply signals signal x_to_multiply: Execute1ToMultiplyType; signal multiply_to_x: MultiplyToExecute1Type; -- divider signals signal x_to_divider: Execute1ToDividerType; signal divider_to_x: DividerToExecute1Type; procedure set_carry(e: inout Execute1ToWritebackType; carry32 : in std_ulogic; carry : in std_ulogic) is begin e.xerc.ca32 := carry32; e.xerc.ca := carry; e.write_xerc_enable := '1'; end; procedure set_ov(e: inout Execute1ToWritebackType; ov : in std_ulogic; ov32 : in std_ulogic) is begin e.xerc.ov32 := ov32; e.xerc.ov := ov; if ov = '1' then e.xerc.so := '1'; end if; e.write_xerc_enable := '1'; end; function calc_ov(msb_a : std_ulogic; msb_b: std_ulogic; ca: std_ulogic; msb_r: std_ulogic) return std_ulogic is begin return (ca xor msb_r) and not (msb_a xor msb_b); end; function decode_input_carry(ic : carry_in_t; xerc : xer_common_t) return std_ulogic is begin case ic is when ZERO => return '0'; when CA => return xerc.ca; when ONE => return '1'; end case; end; begin rotator_0: entity work.rotator port map ( rs => c_in, ra => a_in, shift => b_in(6 downto 0), insn => e_in.insn, is_32bit => e_in.is_32bit, right_shift => right_shift, arith => e_in.is_signed, clear_left => rot_clear_left, clear_right => rot_clear_right, result => rotator_result, carry_out => rotator_carry ); logical_0: entity work.logical port map ( rs => c_in, rb => b_in, op => e_in.insn_type, invert_in => e_in.invert_a, invert_out => e_in.invert_out, result => logical_result, datalen => e_in.data_len, popcnt => popcnt_result, parity => parity_result ); countzero_0: entity work.zero_counter port map ( clk => clk, rs => c_in, count_right => e_in.insn(10), is_32bit => e_in.is_32bit, result => countzero_result ); multiply_0: entity work.multiply port map ( clk => clk, m_in => x_to_multiply, m_out => multiply_to_x ); divider_0: entity work.divider port map ( clk => clk, rst => rst, d_in => x_to_divider, d_out => divider_to_x ); a_in <= r.e.write_data when EX1_BYPASS and e_in.bypass_data1 = '1' else e_in.read_data1; b_in <= r.e.write_data when EX1_BYPASS and e_in.bypass_data2 = '1' else e_in.read_data2; c_in <= r.e.write_data when EX1_BYPASS and e_in.bypass_data3 = '1' else e_in.read_data3; execute1_0: process(clk) begin if rising_edge(clk) then r <= rin; ctrl <= ctrl_tmp; assert not (r.lr_update = '1' and e_in.valid = '1') report "LR update collision with valid in EX1" severity failure; if r.lr_update = '1' then report "LR update to " & to_hstring(r.next_lr); end if; end if; end process; execute1_1: process(all) variable v : reg_type; variable a_inv : std_ulogic_vector(63 downto 0); variable result : std_ulogic_vector(63 downto 0); variable newcrf : std_ulogic_vector(3 downto 0); variable result_with_carry : std_ulogic_vector(64 downto 0); variable result_en : std_ulogic; variable crnum : crnum_t; variable crbit : integer range 0 to 31; variable scrnum : crnum_t; variable lo, hi : integer; variable sh, mb, me : std_ulogic_vector(5 downto 0); variable sh32, mb32, me32 : std_ulogic_vector(4 downto 0); variable bo, bi : std_ulogic_vector(4 downto 0); variable bf, bfa : std_ulogic_vector(2 downto 0); variable cr_op : std_ulogic_vector(9 downto 0); variable cr_operands : std_ulogic_vector(1 downto 0); variable bt, ba, bb : std_ulogic_vector(4 downto 0); variable btnum, banum, bbnum : integer range 0 to 31; variable crresult : std_ulogic; variable l : std_ulogic; variable next_nia : std_ulogic_vector(63 downto 0); variable carry_32, carry_64 : std_ulogic; variable sign1, sign2 : std_ulogic; variable abs1, abs2 : signed(63 downto 0); variable overflow : std_ulogic; variable negative : std_ulogic; variable zerohi, zerolo : std_ulogic; variable msb_a, msb_b : std_ulogic; variable a_lt : std_ulogic; variable lv : Execute1ToLoadstore1Type; begin result := (others => '0'); result_with_carry := (others => '0'); result_en := '0'; newcrf := (others => '0'); v := r; v.e := Execute1ToWritebackInit; -- XER forwarding. To avoid having to track XER hazards, we -- use the previously latched value. -- -- If the XER was modified by a multiply or a divide, those are -- single issue, we'll get the up to date value from decode2 from -- the register file. -- -- If it was modified by an instruction older than the previous -- one in EX1, it will have also hit writeback and will be up -- to date in decode2. -- -- That leaves us with the case where it was updated by the previous -- instruction in EX1. In that case, we can forward it back here. -- -- This will break if we allow pipelining of multiply and divide, -- but ideally, those should go via EX1 anyway and run as a state -- machine from here. -- -- One additional hazard to beware of is an XER:SO modifying instruction -- in EX1 followed immediately by a store conditional. Due to our -- writeback latency, the store will go down the LSU with the previous -- XER value, thus the stcx. will set CR0:SO using an obsolete SO value. -- -- We will need to handle that if we ever make stcx. not single issue -- -- We always pass a valid XER value downto writeback even when -- we aren't updating it, in order for XER:SO -> CR0:SO transfer -- to work for RC instructions. -- if r.e.write_xerc_enable = '1' then v.e.xerc := r.e.xerc; else v.e.xerc := e_in.xerc; end if; v.lr_update := '0'; v.mul_in_progress := '0'; v.div_in_progress := '0'; v.cntz_in_progress := '0'; v.ldst_in_progress := '0'; -- signals to multiply unit x_to_multiply <= Execute1ToMultiplyInit; x_to_multiply.insn_type <= e_in.insn_type; x_to_multiply.is_32bit <= e_in.is_32bit; if e_in.is_32bit = '1' then if e_in.is_signed = '1' then x_to_multiply.data1 <= (others => a_in(31)); x_to_multiply.data1(31 downto 0) <= a_in(31 downto 0); x_to_multiply.data2 <= (others => b_in(31)); x_to_multiply.data2(31 downto 0) <= b_in(31 downto 0); else x_to_multiply.data1 <= '0' & x"00000000" & a_in(31 downto 0); x_to_multiply.data2 <= '0' & x"00000000" & b_in(31 downto 0); end if; else if e_in.is_signed = '1' then x_to_multiply.data1 <= a_in(63) & a_in; x_to_multiply.data2 <= b_in(63) & b_in; else x_to_multiply.data1 <= '0' & a_in; x_to_multiply.data2 <= '0' & b_in; end if; end if; -- signals to divide unit sign1 := '0'; sign2 := '0'; if e_in.is_signed = '1' then if e_in.is_32bit = '1' then sign1 := a_in(31); sign2 := b_in(31); else sign1 := a_in(63); sign2 := b_in(63); end if; end if; -- take absolute values if sign1 = '0' then abs1 := signed(a_in); else abs1 := - signed(a_in); end if; if sign2 = '0' then abs2 := signed(b_in); else abs2 := - signed(b_in); end if; x_to_divider <= Execute1ToDividerInit; x_to_divider.is_signed <= e_in.is_signed; x_to_divider.is_32bit <= e_in.is_32bit; if e_in.insn_type = OP_MOD then x_to_divider.is_modulus <= '1'; end if; x_to_divider.neg_result <= sign1 xor (sign2 and not x_to_divider.is_modulus); if e_in.is_32bit = '0' then -- 64-bit forms if e_in.insn_type = OP_DIVE then x_to_divider.is_extended <= '1'; end if; x_to_divider.dividend <= std_ulogic_vector(abs1); x_to_divider.divisor <= std_ulogic_vector(abs2); else -- 32-bit forms x_to_divider.is_extended <= '0'; if e_in.insn_type = OP_DIVE then -- extended forms x_to_divider.dividend <= std_ulogic_vector(abs1(31 downto 0)) & x"00000000"; else x_to_divider.dividend <= x"00000000" & std_ulogic_vector(abs1(31 downto 0)); end if; x_to_divider.divisor <= x"00000000" & std_ulogic_vector(abs2(31 downto 0)); end if; ctrl_tmp <= ctrl; -- FIXME: run at 512MHz not core freq ctrl_tmp.tb <= std_ulogic_vector(unsigned(ctrl.tb) + 1); terminate_out <= '0'; icache_inval <= '0'; stall_out <= '0'; f_out <= Execute1ToFetch1TypeInit; -- Next insn adder used in a couple of places next_nia := std_ulogic_vector(unsigned(e_in.nia) + 4); -- rotator control signals right_shift <= '1' when e_in.insn_type = OP_SHR else '0'; rot_clear_left <= '1' when e_in.insn_type = OP_RLC or e_in.insn_type = OP_RLCL else '0'; rot_clear_right <= '1' when e_in.insn_type = OP_RLC or e_in.insn_type = OP_RLCR else '0'; if e_in.valid = '1' then v.e.valid := '1'; v.e.write_reg := e_in.write_reg; v.slow_op_dest := gspr_to_gpr(e_in.write_reg); v.slow_op_rc := e_in.rc; v.slow_op_oe := e_in.oe; v.slow_op_xerc := v.e.xerc; case_0: case e_in.insn_type is when OP_ILLEGAL => terminate_out <= '1'; report "illegal"; when OP_NOP => -- Do nothing when OP_ADD | OP_CMP => if e_in.invert_a = '0' then a_inv := a_in; else a_inv := not a_in; end if; result_with_carry := ppc_adde(a_inv, b_in, decode_input_carry(e_in.input_carry, v.e.xerc)); result := result_with_carry(63 downto 0); carry_32 := result(32) xor a_inv(32) xor b_in(32); carry_64 := result_with_carry(64); if e_in.insn_type = OP_ADD then if e_in.output_carry = '1' then set_carry(v.e, carry_32, carry_64); end if; if e_in.oe = '1' then set_ov(v.e, calc_ov(a_inv(63), b_in(63), carry_64, result_with_carry(63)), calc_ov(a_inv(31), b_in(31), carry_32, result_with_carry(31))); end if; result_en := '1'; else -- CMP and CMPL instructions -- Note, we have done RB - RA, not RA - RB bf := insn_bf(e_in.insn); l := insn_l(e_in.insn); v.e.write_cr_enable := '1'; crnum := to_integer(unsigned(bf)); v.e.write_cr_mask := num_to_fxm(crnum); zerolo := not (or (a_in(31 downto 0) xor b_in(31 downto 0))); zerohi := not (or (a_in(63 downto 32) xor b_in(63 downto 32))); if zerolo = '1' and (l = '0' or zerohi = '1') then -- values are equal newcrf := "001" & v.e.xerc.so; else if l = '1' then -- 64-bit comparison msb_a := a_in(63); msb_b := b_in(63); else -- 32-bit comparison msb_a := a_in(31); msb_b := b_in(31); end if; if msb_a /= msb_b then -- Subtraction might overflow, but -- comparison is clear from MSB difference. -- for signed, 0 is greater; for unsigned, 1 is greater a_lt := msb_a xnor e_in.is_signed; else -- Subtraction cannot overflow since MSBs are equal. -- carry = 1 indicates RA is smaller (signed or unsigned) a_lt := (not l and carry_32) or (l and carry_64); end if; newcrf := a_lt & not a_lt & '0' & v.e.xerc.so; end if; for i in 0 to 7 loop lo := i*4; hi := lo + 3; v.e.write_cr_data(hi downto lo) := newcrf; end loop; end if; when OP_AND | OP_OR | OP_XOR => result := logical_result; result_en := '1'; when OP_B => f_out.redirect <= '1'; if (insn_aa(e_in.insn)) then f_out.redirect_nia <= std_ulogic_vector(signed(b_in)); else f_out.redirect_nia <= std_ulogic_vector(signed(e_in.nia) + signed(b_in)); end if; when OP_BC => -- read_data1 is CTR bo := insn_bo(e_in.insn); bi := insn_bi(e_in.insn); if bo(4-2) = '0' then result := std_ulogic_vector(unsigned(a_in) - 1); result_en := '1'; v.e.write_reg := fast_spr_num(SPR_CTR); end if; if ppc_bc_taken(bo, bi, e_in.cr, a_in) = 1 then f_out.redirect <= '1'; if (insn_aa(e_in.insn)) then f_out.redirect_nia <= std_ulogic_vector(signed(b_in)); else f_out.redirect_nia <= std_ulogic_vector(signed(e_in.nia) + signed(b_in)); end if; end if; when OP_BCREG => -- read_data1 is CTR -- read_data2 is target register (CTR, LR or TAR) bo := insn_bo(e_in.insn); bi := insn_bi(e_in.insn); if bo(4-2) = '0' and e_in.insn(10) = '0' then result := std_ulogic_vector(unsigned(a_in) - 1); result_en := '1'; v.e.write_reg := fast_spr_num(SPR_CTR); end if; if ppc_bc_taken(bo, bi, e_in.cr, a_in) = 1 then f_out.redirect <= '1'; f_out.redirect_nia <= b_in(63 downto 2) & "00"; end if; when OP_CMPB => result := ppc_cmpb(c_in, b_in); result_en := '1'; when OP_CNTZ => v.e.valid := '0'; v.cntz_in_progress := '1'; stall_out <= '1'; when OP_EXTS => -- note data_len is a 1-hot encoding negative := (e_in.data_len(0) and c_in(7)) or (e_in.data_len(1) and c_in(15)) or (e_in.data_len(2) and c_in(31)); result := (others => negative); if e_in.data_len(2) = '1' then result(31 downto 16) := c_in(31 downto 16); end if; if e_in.data_len(2) = '1' or e_in.data_len(1) = '1' then result(15 downto 8) := c_in(15 downto 8); end if; result(7 downto 0) := c_in(7 downto 0); result_en := '1'; when OP_ISEL => crbit := to_integer(unsigned(insn_bc(e_in.insn))); if e_in.cr(31-crbit) = '1' then result := a_in; else result := b_in; end if; result_en := '1'; when OP_MCRF => cr_op := insn_cr(e_in.insn); report "CR OP " & to_hstring(cr_op); if cr_op(0) = '0' then -- MCRF bf := insn_bf(e_in.insn); bfa := insn_bfa(e_in.insn); v.e.write_cr_enable := '1'; crnum := to_integer(unsigned(bf)); scrnum := to_integer(unsigned(bfa)); v.e.write_cr_mask := num_to_fxm(crnum); for i in 0 to 7 loop lo := (7-i)*4; hi := lo + 3; if i = scrnum then newcrf := e_in.cr(hi downto lo); end if; end loop; for i in 0 to 7 loop lo := i*4; hi := lo + 3; v.e.write_cr_data(hi downto lo) := newcrf; end loop; else v.e.write_cr_enable := '1'; bt := insn_bt(e_in.insn); ba := insn_ba(e_in.insn); bb := insn_bb(e_in.insn); btnum := 31 - to_integer(unsigned(bt)); banum := 31 - to_integer(unsigned(ba)); bbnum := 31 - to_integer(unsigned(bb)); -- Bits 5-8 of cr_op give the truth table of the requested -- logical operation cr_operands := e_in.cr(banum) & e_in.cr(bbnum); crresult := cr_op(5 + to_integer(unsigned(cr_operands))); v.e.write_cr_mask := num_to_fxm((31-btnum) / 4); for i in 0 to 31 loop if i = btnum then v.e.write_cr_data(i) := crresult; else v.e.write_cr_data(i) := e_in.cr(i); end if; end loop; end if; when OP_MFSPR => if is_fast_spr(e_in.read_reg1) then result := a_in; if decode_spr_num(e_in.insn) = SPR_XER then -- bits 0:31 and 35:43 are treated as reserved and return 0s when read using mfxer result(63 downto 32) := (others => '0'); result(63-32) := v.e.xerc.so; result(63-33) := v.e.xerc.ov; result(63-34) := v.e.xerc.ca; result(63-35 downto 63-43) := "000000000"; result(63-44) := v.e.xerc.ov32; result(63-45) := v.e.xerc.ca32; end if; else case decode_spr_num(e_in.insn) is when SPR_TB => result := ctrl.tb; when others => result := (others => '0'); end case; end if; result_en := '1'; when OP_MFCR => if e_in.insn(20) = '0' then -- mfcr result := x"00000000" & e_in.cr; else -- mfocrf crnum := fxm_to_num(insn_fxm(e_in.insn)); result := (others => '0'); for i in 0 to 7 loop lo := (7-i)*4; hi := lo + 3; if crnum = i then result(hi downto lo) := e_in.cr(hi downto lo); end if; end loop; end if; result_en := '1'; when OP_MTCRF => v.e.write_cr_enable := '1'; if e_in.insn(20) = '0' then -- mtcrf v.e.write_cr_mask := insn_fxm(e_in.insn); else -- mtocrf: We require one hot priority encoding here crnum := fxm_to_num(insn_fxm(e_in.insn)); v.e.write_cr_mask := num_to_fxm(crnum); end if; v.e.write_cr_data := c_in(31 downto 0); when OP_MTSPR => report "MTSPR to SPR " & integer'image(decode_spr_num(e_in.insn)) & "=" & to_hstring(c_in); if is_fast_spr(e_in.write_reg) then result := c_in; result_en := '1'; if decode_spr_num(e_in.insn) = SPR_XER then v.e.xerc.so := c_in(63-32); v.e.xerc.ov := c_in(63-33); v.e.xerc.ca := c_in(63-34); v.e.xerc.ov32 := c_in(63-44); v.e.xerc.ca32 := c_in(63-45); v.e.write_xerc_enable := '1'; end if; else -- TODO: Implement slow SPRs -- case decode_spr_num(e_in.insn) is -- when others => -- end case; end if; when OP_POPCNT => result := popcnt_result; result_en := '1'; when OP_PRTY => result := parity_result; result_en := '1'; when OP_RLC | OP_RLCL | OP_RLCR | OP_SHL | OP_SHR => result := rotator_result; if e_in.output_carry = '1' then set_carry(v.e, rotator_carry, rotator_carry); end if; result_en := '1'; when OP_SIM_CONFIG => -- bit 0 was used to select the microwatt console, which -- we no longer support. result := x"0000000000000000"; result_en := '1'; when OP_TDI => -- Keep our test cases happy for now, ignore trap instructions report "OP_TDI FIXME"; when OP_ISYNC => f_out.redirect <= '1'; f_out.redirect_nia <= next_nia; when OP_ICBI => icache_inval <= '1'; when OP_MUL_L64 | OP_MUL_H64 | OP_MUL_H32 => v.e.valid := '0'; v.mul_in_progress := '1'; stall_out <= '1'; x_to_multiply.valid <= '1'; when OP_DIV | OP_DIVE | OP_MOD => v.e.valid := '0'; v.div_in_progress := '1'; stall_out <= '1'; x_to_divider.valid <= '1'; when OP_LOAD | OP_STORE => -- loadstore/dcache has its own port to writeback v.e.valid := '0'; stall_out <= '1'; v.ldst_in_progress := '1'; when others => terminate_out <= '1'; report "illegal"; end case; v.e.rc := e_in.rc and e_in.valid; -- Update LR on the next cycle after a branch link -- -- WARNING: The LR update isn't tracked by our hazard tracker. This -- will work (well I hope) because it only happens on branches -- which will flush all decoded instructions. By the time -- fetch catches up, we'll have the new LR. This will -- *not* work properly however if we have a branch predictor, -- in which case the solution would probably be to keep a -- local cache of the updated LR in execute1 (flushed on -- exceptions) that is used instead of the value from -- decode when its content is valid. if e_in.lr = '1' then v.lr_update := '1'; v.next_lr := next_nia; v.e.valid := '0'; report "Delayed LR update to " & to_hstring(next_nia); stall_out <= '1'; end if; elsif r.lr_update = '1' then result_en := '1'; result := r.next_lr; v.e.write_reg := fast_spr_num(SPR_LR); v.e.valid := '1'; elsif r.cntz_in_progress = '1' then -- cnt[lt]z always takes two cycles result := countzero_result; result_en := '1'; v.e.write_reg := gpr_to_gspr(v.slow_op_dest); v.e.rc := v.slow_op_rc; v.e.xerc := v.slow_op_xerc; v.e.valid := '1'; elsif r.ldst_in_progress = '1' then -- assert stall for 2 cycles on load/store, then -- the stall output from dcache takes over stall_out <= '1'; elsif r.mul_in_progress = '1' or r.div_in_progress = '1' then if (r.mul_in_progress = '1' and multiply_to_x.valid = '1') or (r.div_in_progress = '1' and divider_to_x.valid = '1') then if r.mul_in_progress = '1' then result := multiply_to_x.write_reg_data; overflow := multiply_to_x.overflow; else result := divider_to_x.write_reg_data; overflow := divider_to_x.overflow; end if; result_en := '1'; v.e.write_reg := gpr_to_gspr(v.slow_op_dest); v.e.rc := v.slow_op_rc; v.e.xerc := v.slow_op_xerc; v.e.write_xerc_enable := v.slow_op_oe; -- We must test oe because the RC update code in writeback -- will use the xerc value to set CR0:SO so we must not clobber -- xerc if OE wasn't set. if v.slow_op_oe = '1' then v.e.xerc.ov := overflow; v.e.xerc.ov32 := overflow; v.e.xerc.so := v.slow_op_xerc.so or overflow; end if; v.e.valid := '1'; else stall_out <= '1'; v.mul_in_progress := r.mul_in_progress; v.div_in_progress := r.div_in_progress; end if; end if; v.e.write_data := result; v.e.write_enable := result_en; -- Outputs to loadstore1 (async) lv := Execute1ToLoadstore1Init; if e_in.valid = '1' and (e_in.insn_type = OP_LOAD or e_in.insn_type = OP_STORE) then lv.valid := '1'; end if; if e_in.insn_type = OP_LOAD then lv.load := '1'; end if; lv.addr1 := a_in; lv.addr2 := b_in; lv.data := c_in; lv.write_reg := gspr_to_gpr(e_in.write_reg); lv.length := e_in.data_len; lv.byte_reverse := e_in.byte_reverse; lv.sign_extend := e_in.sign_extend; lv.update := e_in.update; lv.update_reg := gspr_to_gpr(e_in.read_reg1); lv.xerc := v.e.xerc; lv.reserve := e_in.reserve; lv.rc := e_in.rc; -- Update registers rin <= v; -- update outputs --f_out <= r.f; l_out <= lv; e_out <= r.e; flush_out <= f_out.redirect; end process; end architecture behaviour;