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@ -31,6 +31,21 @@ architecture behaviour of decode1 is
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signal r, rin : Decode1ToDecode2Type;
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signal s : Decode1ToDecode2Type;
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constant illegal_inst : decode_rom_t :=
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(NONE, OP_ILLEGAL, NONE, NONE, NONE, NONE, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', NONE, '0', '0');
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type reg_internal_t is record
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override : std_ulogic;
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override_decode: decode_rom_t;
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override_unit: std_ulogic;
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force_single: std_ulogic;
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end record;
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constant reg_internal_t_init : reg_internal_t :=
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(override => '0', override_decode => illegal_inst, override_unit => '0', force_single => '0');
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signal ri, ri_in : reg_internal_t;
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signal si : reg_internal_t;
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subtype major_opcode_t is unsigned(5 downto 0);
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type major_rom_array_t is array(0 to 63) of decode_rom_t;
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type minor_valid_array_t is array(0 to 1023) of std_ulogic;
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@ -41,9 +56,6 @@ architecture behaviour of decode1 is
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type op_31_subop_array_t is array(0 to 1023) of decode_rom_t;
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type minor_rom_array_2_t is array(0 to 3) of decode_rom_t;
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constant illegal_inst : decode_rom_t :=
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(ALU, OP_ILLEGAL, NONE, NONE, NONE, NONE, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', RC, '0', '1');
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constant major_decode_rom_array : major_rom_array_t := (
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-- unit internal in1 in2 in3 out CR CR inv inv cry cry ldst BR sgn upd rsrv 32b sgn rc lk sgl
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-- op in out A out in out len ext pipe
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@ -107,25 +119,21 @@ architecture behaviour of decode1 is
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-- indexed by bits 10..1 of instruction word
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constant decode_op_19_valid : minor_valid_array_t := (
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-- addpcis, 5 upper bits are part of constant
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2#0000000010# => '1', 2#0000100010# => '1', 2#0001000010# => '1', 2#0001100010# => '1', 2#0010000010# => '1', 2#0010100010# => '1', 2#0011000010# => '1', 2#0011100010# => '1',
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2#0100000010# => '1', 2#0100100010# => '1', 2#0101000010# => '1', 2#0101100010# => '1', 2#0110000010# => '1', 2#0110100010# => '1', 2#0111000010# => '1', 2#0111100010# => '1',
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2#1000000010# => '1', 2#1000100010# => '1', 2#1001000010# => '1', 2#1001100010# => '1', 2#1010000010# => '1', 2#1010100010# => '1', 2#1011000010# => '1', 2#1011100010# => '1',
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2#1100000010# => '1', 2#1100100010# => '1', 2#1101000010# => '1', 2#1101100010# => '1', 2#1110000010# => '1', 2#1110100010# => '1', 2#1111000010# => '1', 2#1111100010# => '1',
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2#0001000000# to 2#0001011111# => '1', -- addpcis, 5 upper bits are part of constant
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2#1000010000# => '1', -- bcctr
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2#0000010000# => '1', -- bclr
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2#1000110000# => '1', -- bctar
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2#0100000001# => '1', -- crand
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2#0010000001# => '1', -- crandc
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2#0100100001# => '1', -- creqv
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2#0011100001# => '1', -- crnand
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2#1000000000# => '1', -- bclr
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2#1000010001# => '1', -- bctar
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2#0000101000# => '1', -- crand
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2#0000100100# => '1', -- crandc
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2#0000101001# => '1', -- creqv
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2#0000100111# => '1', -- crnand
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2#0000100001# => '1', -- crnor
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2#0111000001# => '1', -- cror
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2#0110100001# => '1', -- crorc
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2#0011000001# => '1', -- crxor
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2#0010010110# => '1', -- isync
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2#0000101110# => '1', -- cror
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2#0000101101# => '1', -- crorc
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2#0000100110# => '1', -- crxor
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2#1011000100# => '1', -- isync
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2#0000000000# => '1', -- mcrf
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2#0000010010# => '1', -- rfid
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2#1001000000# => '1', -- rfid
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others => '0'
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);
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@ -193,10 +201,10 @@ architecture behaviour of decode1 is
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2#1000111010# => (ALU, OP_CNTZ, NONE, NONE, RS, RA, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', RC, '0', '0'), -- cnttzd
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2#1000011010# => (ALU, OP_CNTZ, NONE, NONE, RS, RA, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '1', '0', RC, '0', '0'), -- cnttzw
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2#1011110011# => (ALU, OP_DARN, NONE, NONE, NONE, RT, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', NONE, '0', '0'), -- darn
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2#0001010110# => (ALU, OP_NOP, NONE, NONE, NONE, NONE, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', NONE, '0', '1'), -- dcbf
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2#0000110110# => (ALU, OP_NOP, NONE, NONE, NONE, NONE, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', NONE, '0', '1'), -- dcbst
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2#0100010110# => (ALU, OP_NOP, NONE, NONE, NONE, NONE, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', NONE, '0', '1'), -- dcbt
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2#0011110110# => (ALU, OP_NOP, NONE, NONE, NONE, NONE, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', NONE, '0', '1'), -- dcbtst
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2#0001010110# => (ALU, OP_DCBF, NONE, NONE, NONE, NONE, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', NONE, '0', '1'), -- dcbf
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2#0000110110# => (ALU, OP_DCBST, NONE, NONE, NONE, NONE, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', NONE, '0', '1'), -- dcbst
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2#0100010110# => (ALU, OP_DCBT, NONE, NONE, NONE, NONE, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', NONE, '0', '1'), -- dcbt
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2#0011110110# => (ALU, OP_DCBTST, NONE, NONE, NONE, NONE, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', NONE, '0', '1'), -- dcbtst
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2#1111110110# => (LDST, OP_DCBZ, RA_OR_ZERO, RB, NONE, NONE, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', NONE, '0', '0'), -- dcbz
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2#0110001001# => (ALU, OP_DIVE, RA, RB, NONE, RT, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', RC, '0', '0'), -- divdeu
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2#1110001001# => (ALU, OP_DIVE, RA, RB, NONE, RT, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', RC, '0', '0'), -- divdeuo
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@ -222,7 +230,7 @@ architecture behaviour of decode1 is
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2#1101111010# => (ALU, OP_EXTSWSLI, NONE, CONST_SH, RS, RA, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', RC, '0', '0'), -- extswsli
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2#1101111011# => (ALU, OP_EXTSWSLI, NONE, CONST_SH, RS, RA, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', RC, '0', '0'), -- extswsli
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2#1111010110# => (ALU, OP_ICBI, NONE, NONE, NONE, NONE, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', NONE, '0', '1'), -- icbi
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2#0000010110# => (ALU, OP_NOP, NONE, NONE, NONE, NONE, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', NONE, '0', '1'), -- icbt
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2#0000010110# => (ALU, OP_ICBT, NONE, NONE, NONE, NONE, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', NONE, '0', '1'), -- icbt
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2#0000001111# => (ALU, OP_ISEL, RA_OR_ZERO, RB, NONE, RT, '1', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', NONE, '0', '1'), -- isel
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2#0000101111# => (ALU, OP_ISEL, RA_OR_ZERO, RB, NONE, RT, '1', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', NONE, '0', '0'), -- isel
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2#0001001111# => (ALU, OP_ISEL, RA_OR_ZERO, RB, NONE, RT, '1', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', NONE, '0', '0'), -- isel
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@ -401,19 +409,24 @@ begin
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if rst = '1' then
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r <= Decode1ToDecode2Init;
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s <= Decode1ToDecode2Init;
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ri <= reg_internal_t_init;
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si <= reg_internal_t_init;
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elsif flush_in = '1' then
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r.valid <= '0';
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s.valid <= '0';
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elsif s.valid = '1' then
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if stall_in = '0' then
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r <= s;
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ri <= si;
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s.valid <= '0';
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end if;
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else
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s <= rin;
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si <= ri_in;
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s.valid <= rin.valid and r.valid and stall_in;
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if r.valid = '0' or stall_in = '0' then
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r <= rin;
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ri <= ri_in;
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end if;
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end if;
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end if;
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@ -422,6 +435,7 @@ begin
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decode1_1: process(all)
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variable v : Decode1ToDecode2Type;
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variable vi : reg_internal_t;
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variable f : Decode1ToFetch1Type;
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variable majorop : major_opcode_t;
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variable minor4op : std_ulogic_vector(10 downto 0);
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@ -432,37 +446,30 @@ begin
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variable br_offset : signed(23 downto 0);
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begin
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v := Decode1ToDecode2Init;
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vi := reg_internal_t_init;
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v.valid := f_in.valid;
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v.nia := f_in.nia;
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v.insn := f_in.insn;
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v.stop_mark := f_in.stop_mark;
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v.ispr1 := (others => '0');
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v.ispr2 := (others => '0');
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if f_in.valid = '1' then
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report "Decode insn " & to_hstring(f_in.insn) & " at " & to_hstring(f_in.nia);
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end if;
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br_offset := (others => '0');
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majorop := unsigned(f_in.insn(31 downto 26));
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if f_in.fetch_failed = '1' then
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v.valid := '1';
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-- Only send down a single OP_FETCH_FAILED
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if r.decode.insn_type = OP_FETCH_FAILED then
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v.valid := '0';
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end if;
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v.decode := fetch_fail_inst;
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v.decode := major_decode_rom_array(to_integer(majorop));
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elsif majorop = "000100" then
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case to_integer(unsigned(majorop)) is
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when 4 =>
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-- major opcode 4, mostly VMX/VSX stuff but also some integer ops (madd*)
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minor4op := f_in.insn(5 downto 0) & f_in.insn(10 downto 6);
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if decode_op_4_valid(to_integer(unsigned(minor4op))) = '1' then
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vi.override := not decode_op_4_valid(to_integer(unsigned(minor4op)));
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v.decode := decode_op_4_array(to_integer(unsigned(f_in.insn(5 downto 0))));
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else
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v.decode := illegal_inst;
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end if;
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elsif majorop = "011111" then
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when 31 =>
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-- major opcode 31, lots of things
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v.decode := decode_op_31_array(to_integer(unsigned(f_in.insn(10 downto 1))));
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@ -474,32 +481,35 @@ begin
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-- mfspr or mtspr
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-- Make slow SPRs single issue
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if is_fast_spr(v.ispr1) = '0' then
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v.decode.sgl_pipe := '1';
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vi.force_single := '1';
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-- send MMU-related SPRs to loadstore1
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case sprn is
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when SPR_DAR | SPR_DSISR | SPR_PID | SPR_PRTBL =>
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v.decode.unit := LDST;
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vi.override_decode.unit := LDST;
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vi.override_unit := '1';
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when others =>
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end case;
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end if;
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end if;
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elsif majorop = "010000" then
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when 16 =>
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-- CTR may be needed as input to bc
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v.decode := major_decode_rom_array(to_integer(majorop));
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if f_in.insn(23) = '0' then
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v.ispr1 := fast_spr_num(SPR_CTR);
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end if;
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-- Predict backward branches as taken, forward as untaken
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|
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v.br_pred := f_in.insn(15);
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br_offset := resize(signed(f_in.insn(15 downto 2)), 24);
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elsif majorop = "010011" then
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if decode_op_19_valid(to_integer(unsigned(f_in.insn(10 downto 1)))) = '0' then
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|
|
report "op 19 illegal subcode";
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|
|
v.decode := illegal_inst;
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else
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when 18 =>
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-- Unconditional branches are always taken
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|
|
v.br_pred := '1';
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br_offset := signed(f_in.insn(25 downto 2));
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when 19 =>
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|
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vi.override := not decode_op_19_valid(to_integer(unsigned(f_in.insn(5 downto 1) & f_in.insn(10 downto 6))));
|
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|
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op_19_bits := f_in.insn(5) & f_in.insn(3) & f_in.insn(2);
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|
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v.decode := decode_op_19_array(to_integer(unsigned(op_19_bits)));
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|
|
|
report "op 19 sub " & to_hstring(op_19_bits);
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|
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end if;
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|
|
-- Work out ispr1/ispr2 independent of v.decode since they seem to be critical path
|
|
|
|
|
if f_in.insn(2) = '0' then
|
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|
|
@ -523,36 +533,39 @@ begin
|
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|
|
v.ispr2 := fast_spr_num(SPR_SRR0);
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end if;
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|
elsif majorop = "011110" then
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when 30 =>
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|
v.decode := decode_op_30_array(to_integer(unsigned(f_in.insn(4 downto 1))));
|
|
|
|
|
|
|
|
|
|
elsif majorop = "111010" then
|
|
|
|
|
when 48 =>
|
|
|
|
|
-- ori, special-case the standard NOP
|
|
|
|
|
if std_match(f_in.insn, "01100000000000000000000000000000") then
|
|
|
|
|
report "PPC_nop";
|
|
|
|
|
vi.override := '1';
|
|
|
|
|
vi.override_decode := nop_instr;
|
|
|
|
|
end if;
|
|
|
|
|
|
|
|
|
|
when 58 =>
|
|
|
|
|
v.decode := decode_op_58_array(to_integer(unsigned(f_in.insn(1 downto 0))));
|
|
|
|
|
|
|
|
|
|
elsif majorop = "111110" then
|
|
|
|
|
when 62 =>
|
|
|
|
|
v.decode := decode_op_62_array(to_integer(unsigned(f_in.insn(1 downto 0))));
|
|
|
|
|
|
|
|
|
|
elsif std_match(f_in.insn, "01100000000000000000000000000000") then
|
|
|
|
|
report "PPC_nop";
|
|
|
|
|
v.decode := nop_instr;
|
|
|
|
|
when others =>
|
|
|
|
|
end case;
|
|
|
|
|
|
|
|
|
|
else
|
|
|
|
|
v.decode := major_decode_rom_array(to_integer(majorop));
|
|
|
|
|
if f_in.fetch_failed = '1' then
|
|
|
|
|
v.valid := '1';
|
|
|
|
|
vi.override := '1';
|
|
|
|
|
vi.override_decode := fetch_fail_inst;
|
|
|
|
|
-- Only send down a single OP_FETCH_FAILED
|
|
|
|
|
if ri.override = '1' and ri.override_decode.insn_type = OP_FETCH_FAILED then
|
|
|
|
|
v.valid := '0';
|
|
|
|
|
end if;
|
|
|
|
|
end if;
|
|
|
|
|
|
|
|
|
|
-- Branch predictor
|
|
|
|
|
-- Note bclr, bcctr and bctar are predicted not taken as we have no
|
|
|
|
|
-- count cache or link stack.
|
|
|
|
|
br_offset := (others => '0');
|
|
|
|
|
if majorop = 18 then
|
|
|
|
|
-- Unconditional branches are always taken
|
|
|
|
|
v.br_pred := '1';
|
|
|
|
|
br_offset := signed(f_in.insn(25 downto 2));
|
|
|
|
|
elsif majorop = 16 then
|
|
|
|
|
-- Predict backward branches as taken, forward as untaken
|
|
|
|
|
v.br_pred := f_in.insn(15);
|
|
|
|
|
br_offset := resize(signed(f_in.insn(15 downto 2)), 24);
|
|
|
|
|
end if;
|
|
|
|
|
br_nia := f_in.nia(63 downto 2);
|
|
|
|
|
if f_in.insn(1) = '1' then
|
|
|
|
|
br_nia := (others => '0');
|
|
|
|
@ -563,9 +576,18 @@ begin
|
|
|
|
|
|
|
|
|
|
-- Update registers
|
|
|
|
|
rin <= v;
|
|
|
|
|
ri_in <= vi;
|
|
|
|
|
|
|
|
|
|
-- Update outputs
|
|
|
|
|
d_out <= r;
|
|
|
|
|
if ri.override = '1' then
|
|
|
|
|
d_out.decode <= ri.override_decode;
|
|
|
|
|
elsif ri.override_unit = '1' then
|
|
|
|
|
d_out.decode.unit <= ri.override_decode.unit;
|
|
|
|
|
end if;
|
|
|
|
|
if ri.force_single = '1' then
|
|
|
|
|
d_out.decode.sgl_pipe <= '1';
|
|
|
|
|
end if;
|
|
|
|
|
f_out <= f;
|
|
|
|
|
flush_out <= f.redirect;
|
|
|
|
|
end process;
|
|
|
|
|