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Finish off taking SPRs out of register file

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With this, the register file now contains 64 entries, for 32 GPRs and
32 FPRs, rather than the 128 it had previously.  Several things get
simplified - decode1 no longer has to work out the ispr{1,2,o} values,
decode_input_reg_{a,b,c} no longer have the t = SPR case, etc.

Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
This commit is contained in:
Paul Mackerras 2022-02-19 19:03:49 +11:00
parent 337b104250
commit fdb3ef6874
8 changed files with 37 additions and 107 deletions
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45
common.vhdl
View File

@ -86,30 +86,19 @@ package common is
-- GPR indices in the register file (GPR only)
subtype gpr_index_t is std_ulogic_vector(4 downto 0);
-- Extended GPR index (can hold an SPR or a FPR)
subtype gspr_index_t is std_ulogic_vector(6 downto 0);
-- Extended GPR index (can hold a GPR or a FPR)
subtype gspr_index_t is std_ulogic_vector(5 downto 0);
-- FPR indices
subtype fpr_index_t is std_ulogic_vector(4 downto 0);
-- Some SPRs are stored in the register file, they use the magic
-- GPR numbers above 31.
-- FPRs are stored in the register file, using GSPR
-- numbers from 32 to 63.
--
-- The function fast_spr_num() returns the corresponding fast
-- pseudo-GPR number for a given SPR number. The result MSB
-- indicates if this is indeed a fast SPR. If clear, then
-- the SPR is not stored in the GPR file.
--
-- FPRs are also stored in the register file, using GSPR
-- numbers from 64 to 95.
--
function fast_spr_num(spr: spr_num_t) return gspr_index_t;
-- Indices conversion functions
function gspr_to_gpr(i: gspr_index_t) return gpr_index_t;
function gpr_to_gspr(i: gpr_index_t) return gspr_index_t;
function gpr_or_spr_to_gspr(g: gpr_index_t; s: gspr_index_t) return gspr_index_t;
function is_fast_spr(s: gspr_index_t) return std_ulogic;
function fpr_to_gspr(f: fpr_index_t) return gspr_index_t;
-- The XER is split: the common bits (CA, OV, SO, OV32 and CA32) are
@ -271,9 +260,6 @@ package common is
stop_mark : std_ulogic;
nia: std_ulogic_vector(63 downto 0);
insn: std_ulogic_vector(31 downto 0);
ispr1: gspr_index_t; -- (G)SPR used for branch condition (CTR) or mfspr
ispr2: gspr_index_t; -- (G)SPR used for branch target (CTR, LR, TAR)
ispro: gspr_index_t; -- (G)SPR written with LR or CTR
decode: decode_rom_t;
br_pred: std_ulogic; -- Branch was predicted to be taken
big_endian: std_ulogic;
@ -282,7 +268,6 @@ package common is
end record;
constant Decode1ToDecode2Init : Decode1ToDecode2Type :=
(valid => '0', stop_mark => '0', nia => (others => '0'), insn => (others => '0'),
ispr1 => (others => '0'), ispr2 => (others => '0'), ispro => (others => '0'),
decode => decode_rom_init, br_pred => '0', big_endian => '0',
spr_info => spr_id_init, ram_spr => ram_spr_info_init);
@ -783,10 +768,6 @@ package body common is
begin
return to_integer(unsigned(insn(15 downto 11) & insn(20 downto 16)));
end;
function fast_spr_num(spr: spr_num_t) return gspr_index_t is
begin
return "0000000";
end;
function gspr_to_gpr(i: gspr_index_t) return gpr_index_t is
begin
@ -795,26 +776,12 @@ package body common is
function gpr_to_gspr(i: gpr_index_t) return gspr_index_t is
begin
return "00" & i;
end;
function gpr_or_spr_to_gspr(g: gpr_index_t; s: gspr_index_t) return gspr_index_t is
begin
if s(5) = '1' then
return s;
else
return gpr_to_gspr(g);
end if;
end;
function is_fast_spr(s: gspr_index_t) return std_ulogic is
begin
return s(5);
return "0" & i;
end;
function fpr_to_gspr(f: fpr_index_t) return gspr_index_t is
begin
return "10" & f;
return "1" & f;
end;
function tag_match(tag1 : instr_tag_t; tag2 : instr_tag_t) return boolean is

10
decode1.vhdl
View File

@ -177,7 +177,7 @@ architecture behaviour of decode1 is
-- addpcis
2#001# => (ALU, NONE, OP_ADD, CIA, CONST_DXHI4, NONE, RT, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', NONE, '0', '0', NONE),
-- bclr, bcctr, bctar
2#100# => (ALU, NONE, OP_BCREG, NONE, NONE, NONE, SPR, '1', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', NONE, '1', '0', NONE),
2#100# => (ALU, NONE, OP_BCREG, NONE, NONE, NONE, NONE, '1', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', NONE, '1', '0', NONE),
-- isync
2#111# => (ALU, NONE, OP_ISYNC, NONE, NONE, NONE, NONE, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', NONE, '0', '0', NONE),
-- rfid
@ -329,7 +329,7 @@ architecture behaviour of decode1 is
2#1001000000# => (ALU, NONE, OP_MCRXRX, NONE, NONE, NONE, NONE, '0', '1', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', NONE, '0', '0', NONE), -- mcrxrx
2#0000010011# => (ALU, NONE, OP_MFCR, NONE, NONE, NONE, RT, '1', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', NONE, '0', '0', NONE), -- mfcr/mfocrf
2#0001010011# => (ALU, NONE, OP_MFMSR, NONE, NONE, NONE, RT, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', NONE, '0', '1', NONE), -- mfmsr
2#0101010011# => (ALU, NONE, OP_MFSPR, SPR, NONE, RS, RT, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', NONE, '0', '0', NONE), -- mfspr
2#0101010011# => (ALU, NONE, OP_MFSPR, NONE, NONE, RS, RT, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', NONE, '0', '0', NONE), -- mfspr
2#0100001001# => (DVU, NONE, OP_MOD, RA, RB, NONE, RT, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', NONE, '0', '0', NONE), -- modud
2#0100001011# => (DVU, NONE, OP_MOD, RA, RB, NONE, RT, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '1', '0', NONE, '0', '0', NONE), -- moduw
2#1100001001# => (DVU, NONE, OP_MOD, RA, RB, NONE, RT, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '1', NONE, '0', '0', NONE), -- modsd
@ -337,7 +337,7 @@ architecture behaviour of decode1 is
2#0010010000# => (ALU, NONE, OP_MTCRF, NONE, NONE, RS, NONE, '0', '1', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', NONE, '0', '0', NONE), -- mtcrf/mtocrf
2#0010010010# => (ALU, NONE, OP_MTMSRD, NONE, NONE, RS, NONE, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '1', '0', NONE, '0', '0', NONE), -- mtmsr
2#0010110010# => (ALU, NONE, OP_MTMSRD, NONE, NONE, RS, NONE, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', NONE, '0', '0', NONE), -- mtmsrd # ignore top bits and d
2#0111010011# => (ALU, NONE, OP_MTSPR, NONE, NONE, RS, SPR, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', NONE, '0', '0', NONE), -- mtspr
2#0111010011# => (ALU, NONE, OP_MTSPR, NONE, NONE, RS, NONE, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', NONE, '0', '0', NONE), -- mtspr
2#0001001001# => (ALU, NONE, OP_MUL_H64, RA, RB, NONE, RT, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '1', RC, '0', '0', NONE), -- mulhd
2#0000001001# => (ALU, NONE, OP_MUL_H64, RA, RB, NONE, RT, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '0', '0', RC, '0', '0', NONE), -- mulhdu
2#0001001011# => (ALU, NONE, OP_MUL_H32, RA, RB, NONE, RT, '0', '0', '0', '0', ZERO, '0', NONE, '0', '0', '0', '0', '1', '1', RC, '0', '0', NONE), -- mulhw
@ -670,10 +670,6 @@ begin
-- major opcode 31, lots of things
v.decode := decode_op_31_array(to_integer(unsigned(f_in.insn(10 downto 1))));
-- Work out ispr1/ispro independent of v.decode since they seem to be critical path
v.ispr1 := fast_spr_num(sprn);
v.ispro := fast_spr_num(sprn);
if std_match(f_in.insn(10 downto 1), "01-1010011") then
-- mfspr or mtspr
-- Make mtspr to slow SPRs single issue

48
decode2.vhdl
View File

@ -82,21 +82,11 @@ architecture behaviour of decode2 is
constant decode_output_reg_init : decode_output_reg_t := ('0', (others => '0'));
function decode_input_reg_a (t : input_reg_a_t; insn_in : std_ulogic_vector(31 downto 0);
ispr : gspr_index_t;
instr_addr : std_ulogic_vector(63 downto 0))
return decode_input_reg_t is
begin
if t = RA or (t = RA_OR_ZERO and insn_ra(insn_in) /= "00000") then
return ('1', gpr_to_gspr(insn_ra(insn_in)), (others => '0'));
elsif t = SPR then
-- ISPR must be either a valid fast SPR number or all 0 for a slow SPR.
-- If it's all 0, we don't treat it as a dependency as slow SPRs
-- operations are single issue.
--
assert is_fast_spr(ispr) = '1' or ispr = "0000000"
report "Decode A says SPR but ISPR is invalid:" &
to_hstring(ispr) severity failure;
return (is_fast_spr(ispr), ispr, (others => '0'));
elsif t = CIA then
return ('0', (others => '0'), instr_addr);
elsif HAS_FPU and t = FRA then
@ -106,8 +96,8 @@ architecture behaviour of decode2 is
end if;
end;
function decode_input_reg_b (t : input_reg_b_t; insn_in : std_ulogic_vector(31 downto 0);
ispr : gspr_index_t) return decode_input_reg_t is
function decode_input_reg_b (t : input_reg_b_t; insn_in : std_ulogic_vector(31 downto 0))
return decode_input_reg_t is
variable ret : decode_input_reg_t;
begin
case t is
@ -143,14 +133,6 @@ architecture behaviour of decode2 is
ret := ('0', (others => '0'), x"00000000000000" & "00" & insn_in(1) & insn_in(15 downto 11));
when CONST_SH32 =>
ret := ('0', (others => '0'), x"00000000000000" & "000" & insn_in(15 downto 11));
when SPR =>
-- ISPR must be either a valid fast SPR number or all 0 for a slow SPR.
-- If it's all 0, we don't treat it as a dependency as slow SPRs
-- operations are single issue.
assert is_fast_spr(ispr) = '1' or ispr = "0000000"
report "Decode B says SPR but ISPR is invalid:" &
to_hstring(ispr) severity failure;
ret := (is_fast_spr(ispr), ispr, (others => '0'));
when NONE =>
ret := ('0', (others => '0'), (others => '0'));
end case;
@ -183,8 +165,8 @@ architecture behaviour of decode2 is
end case;
end;
function decode_output_reg (t : output_reg_a_t; insn_in : std_ulogic_vector(31 downto 0);
ispr : gspr_index_t) return decode_output_reg_t is
function decode_output_reg (t : output_reg_a_t; insn_in : std_ulogic_vector(31 downto 0))
return decode_output_reg_t is
begin
case t is
when RT =>
@ -195,18 +177,10 @@ architecture behaviour of decode2 is
if HAS_FPU then
return ('1', fpr_to_gspr(insn_frt(insn_in)));
else
return ('0', "0000000");
return ('0', "000000");
end if;
when SPR =>
-- ISPR must be either a valid fast SPR number or all 0 for a slow SPR.
-- If it's all 0, we don't treat it as a dependency as slow SPRs
-- operations are single issue.
assert is_fast_spr(ispr) = '1' or ispr = "0000000"
report "Decode B says SPR but ISPR is invalid:" &
to_hstring(ispr) severity failure;
return (is_fast_spr(ispr), ispr);
when NONE =>
return ('0', "0000000");
return ('0', "000000");
end case;
end;
@ -386,10 +360,10 @@ begin
decoded_reg_c <= decode_input_reg_init;
decoded_reg_o <= decode_output_reg_init;
if d_in.valid = '1' then
decoded_reg_a <= decode_input_reg_a (d_in.decode.input_reg_a, d_in.insn, d_in.ispr1, d_in.nia);
decoded_reg_b <= decode_input_reg_b (d_in.decode.input_reg_b, d_in.insn, d_in.ispr2);
decoded_reg_a <= decode_input_reg_a (d_in.decode.input_reg_a, d_in.insn, d_in.nia);
decoded_reg_b <= decode_input_reg_b (d_in.decode.input_reg_b, d_in.insn);
decoded_reg_c <= decode_input_reg_c (d_in.decode.input_reg_c, d_in.insn);
decoded_reg_o <= decode_output_reg (d_in.decode.output_reg_a, d_in.insn, d_in.ispro);
decoded_reg_o <= decode_output_reg (d_in.decode.output_reg_a, d_in.insn);
end if;
r_out.read1_enable <= decoded_reg_a.reg_valid;
@ -565,9 +539,7 @@ begin
v.e.result_sel := result_select(op);
v.e.sub_select := subresult_select(op);
if op = OP_MFSPR then
if is_fast_spr(d_in.ispr1) = '1' then
v.e.result_sel := "000"; -- adder_result, effectively a_in
elsif d_in.ram_spr.valid = '1' then
if d_in.ram_spr.valid = '1' then
v.e.result_sel := "101"; -- ramspr_result
elsif d_in.spr_info.valid = '0' then
-- Privileged mfspr to invalid/unimplemented SPR numbers

6
decode_types.vhdl
View File

@ -22,11 +22,11 @@ package decode_types is
OP_BCD, OP_ADDG6S,
OP_FETCH_FAILED
);
type input_reg_a_t is (NONE, RA, RA_OR_ZERO, SPR, CIA, FRA);
type input_reg_a_t is (NONE, RA, RA_OR_ZERO, CIA, FRA);
type input_reg_b_t is (NONE, RB, CONST_UI, CONST_SI, CONST_SI_HI, CONST_UI_HI, CONST_LI, CONST_BD,
CONST_DXHI4, CONST_DS, CONST_DQ, CONST_M1, CONST_SH, CONST_SH32, SPR, FRB);
CONST_DXHI4, CONST_DS, CONST_DQ, CONST_M1, CONST_SH, CONST_SH32, FRB);
type input_reg_c_t is (NONE, RS, RCR, FRC, FRS);
type output_reg_a_t is (NONE, RT, RA, SPR, FRT);
type output_reg_a_t is (NONE, RT, RA, FRT);
type rc_t is (NONE, ONE, RC);
type carry_in_t is (ZERO, CA, OV, ONE);

5
execute1.vhdl
View File

@ -1135,7 +1135,7 @@ begin
when OP_DARN =>
when OP_MFMSR =>
when OP_MFSPR =>
if is_fast_spr(e_in.read_reg1) = '1' or e_in.spr_is_ram = '1' then
if e_in.spr_is_ram = '1' then
if e_in.valid = '1' then
report "MFSPR to SPR " & integer'image(decode_spr_num(e_in.insn)) &
"=" & to_hstring(alu_result);
@ -1216,8 +1216,7 @@ begin
when others =>
end case;
end if;
if e_in.spr_select.valid = '0' and is_fast_spr(e_in.write_reg) = '0' and
e_in.spr_is_ram = '0' then
if e_in.spr_select.valid = '0' and e_in.spr_is_ram = '0' then
-- mtspr to unimplemented SPRs should be a nop in
-- supervisor mode and a program interrupt for user mode
if ex1.msr(MSR_PR) = '1' then

2
loadstore1.vhdl
View File

@ -97,7 +97,7 @@ architecture behave of loadstore1 is
mode_32bit => '0', addr => (others => '0'),
byte_sel => x"00", second_bytes => x"00",
store_data => (others => '0'), instr_tag => instr_tag_init,
write_reg => 7x"00", length => x"0",
write_reg => 6x"00", length => x"0",
elt_length => x"0", byte_reverse => '0', brev_mask => "000",
sign_extend => '0', update => '0',
xerc => xerc_init, reserve => '0',

2
logical.vhdl
View File

@ -167,7 +167,7 @@ begin
end if;
tmp(7 downto 0) := rs(7 downto 0);
when others =>
-- e.g. OP_MTSPR
-- e.g. OP_MFSPR
tmp := rs;
end case;

26
register_file.vhdl
View File

@ -34,7 +34,7 @@ entity register_file is
end entity register_file;
architecture behaviour of register_file is
type regfile is array(0 to 127) of std_ulogic_vector(63 downto 0);
type regfile is array(0 to 63) of std_ulogic_vector(63 downto 0);
signal registers : regfile := (others => (others => '0'));
signal rd_port_b : std_ulogic_vector(63 downto 0);
signal dbg_data : std_ulogic_vector(63 downto 0);
@ -47,15 +47,11 @@ begin
if rising_edge(clk) then
if w_in.write_enable = '1' then
w_addr := w_in.write_reg;
if HAS_FPU and w_addr(6) = '1' then
if HAS_FPU and w_addr(5) = '1' then
report "Writing FPR " & to_hstring(w_addr(4 downto 0)) & " " & to_hstring(w_in.write_data);
else
w_addr(6) := '0';
if w_addr(5) = '0' then
report "Writing GPR " & to_hstring(w_addr) & " " & to_hstring(w_in.write_data);
else
report "Writing GSPR " & to_hstring(w_addr) & " " & to_hstring(w_in.write_data);
end if;
w_addr(5) := '0';
report "Writing GPR " & to_hstring(w_addr) & " " & to_hstring(w_in.write_data);
end if;
assert not(is_x(w_in.write_data)) and not(is_x(w_in.write_reg)) severity failure;
registers(to_integer(unsigned(w_addr))) <= w_in.write_data;
@ -73,11 +69,11 @@ begin
c_addr := d_in.read3_reg;
w_addr := w_in.write_reg;
if not HAS_FPU then
-- Make it obvious that we only want 64 GSPRs for a no-FPU implementation
a_addr(6) := '0';
b_addr(6) := '0';
c_addr(6) := '0';
w_addr(6) := '0';
-- Make it obvious that we only want 32 GSPRs for a no-FPU implementation
a_addr(5) := '0';
b_addr(5) := '0';
c_addr(5) := '0';
w_addr(5) := '0';
end if;
if d_in.read1_enable = '1' then
report "Reading GPR " & to_hstring(a_addr) & " " & to_hstring(registers(to_integer(unsigned(a_addr))));
@ -93,7 +89,7 @@ begin
if d_in.read2_enable = '0' and dbg_gpr_req = '1' and dbg_ack = '0' then
b_addr := dbg_gpr_addr;
if not HAS_FPU then
b_addr(6) := '0';
b_addr(5) := '0';
end if;
end if;
rd_port_b <= registers(to_integer(unsigned(b_addr)));
@ -150,7 +146,7 @@ begin
if rising_edge(clk) then
log_data <= w_in.write_data &
w_in.write_enable &
w_in.write_reg;
'0' & w_in.write_reg;
end if;
end process;
log_out <= log_data;