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Merge pull request #65 from antonblanchard/loadstore-opt

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A small loadstore optimisation, and some reformatting
pull/67/head
Anton Blanchard 5 years ago committed by GitHub
parent 4df05e0598 687051ecbb
commit c5d327cebf
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GPG Key ID: 4AEE18F83AFDEB23
2 changed files with 185 additions and 182 deletions
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76
loadstore1.vhdl
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@ -10,55 +10,55 @@ use work.helpers.all;
-- We calculate the address in the first cycle

entity loadstore1 is
port (
clk : in std_ulogic;
port (
clk : in std_ulogic;

l_in : in Decode2ToLoadstore1Type;
l_in : in Decode2ToLoadstore1Type;

l_out : out Loadstore1ToLoadstore2Type
);
l_out : out Loadstore1ToLoadstore2Type
);
end loadstore1;

architecture behave of loadstore1 is
signal r, rin : Loadstore1ToLoadstore2Type;
signal lsu_sum : std_ulogic_vector(63 downto 0);
signal r, rin : Loadstore1ToLoadstore2Type;
signal lsu_sum : std_ulogic_vector(63 downto 0);
begin
-- Calculate the address in the first cycle
lsu_sum <= std_ulogic_vector(unsigned(l_in.addr1) + unsigned(l_in.addr2)) when l_in.valid = '1' else (others => '0');
-- Calculate the address in the first cycle
lsu_sum <= std_ulogic_vector(unsigned(l_in.addr1) + unsigned(l_in.addr2)) when l_in.valid = '1' else (others => '0');

loadstore1_0: process(clk)
begin
if rising_edge(clk) then
r <= rin;
end if;
end process;
loadstore1_0: process(clk)
begin
if rising_edge(clk) then
r <= rin;
end if;
end process;

loadstore1_1: process(all)
variable v : Loadstore1ToLoadstore2Type;
begin
v := r;
loadstore1_1: process(all)
variable v : Loadstore1ToLoadstore2Type;
begin
v := r;

v.valid := l_in.valid;
v.load := l_in.load;
v.data := l_in.data;
v.write_reg := l_in.write_reg;
v.length := l_in.length;
v.byte_reverse := l_in.byte_reverse;
v.sign_extend := l_in.sign_extend;
v.update := l_in.update;
v.update_reg := l_in.update_reg;
v.valid := l_in.valid;
v.load := l_in.load;
v.data := l_in.data;
v.write_reg := l_in.write_reg;
v.length := l_in.length;
v.byte_reverse := l_in.byte_reverse;
v.sign_extend := l_in.sign_extend;
v.update := l_in.update;
v.update_reg := l_in.update_reg;

-- byte reverse stores in the first cycle
if v.load = '0' and l_in.byte_reverse = '1' then
v.data := byte_reverse(l_in.data, to_integer(unsigned(l_in.length)));
end if;
-- byte reverse stores in the first cycle
if v.load = '0' and l_in.byte_reverse = '1' then
v.data := byte_reverse(l_in.data, to_integer(unsigned(l_in.length)));
end if;

v.addr := lsu_sum;
v.addr := lsu_sum;

-- Update registers
rin <= v;
-- Update registers
rin <= v;

-- Update outputs
l_out <= r;
end process;
-- Update outputs
l_out <= r;
end process;
end;

291
loadstore2.vhdl
Unescape Escape View File

@ -11,154 +11,157 @@ use work.wishbone_types.all;
-- In this cycle we read or write any data and do sign extension and update if required.

entity loadstore2 is
port (
clk : in std_ulogic;
port (
clk : in std_ulogic;

l_in : in Loadstore1ToLoadstore2Type;
w_out : out Loadstore2ToWritebackType;
l_in : in Loadstore1ToLoadstore2Type;
w_out : out Loadstore2ToWritebackType;

m_in : in wishbone_slave_out;
m_out : out wishbone_master_out
);
m_in : in wishbone_slave_out;
m_out : out wishbone_master_out
);
end loadstore2;

architecture behave of loadstore2 is
signal l_saved : Loadstore1ToLoadstore2Type;
signal w_tmp : Loadstore2ToWritebackType;
signal m_tmp : wishbone_master_out;

type state_t is (IDLE, WAITING_FOR_READ_ACK, WAITING_FOR_WRITE_ACK);
signal state : state_t := IDLE;

function length_to_sel(length : in std_logic_vector(3 downto 0)) return std_ulogic_vector is
begin
case length is
when "0001" =>
return "00000001";
when "0010" =>
return "00000011";
when "0100" =>
return "00001111";
when "1000" =>
return "11111111";
when others =>
return "00000000";
end case;
end function length_to_sel;

function wishbone_data_shift(address : in std_ulogic_vector(63 downto 0)) return natural is
begin
return to_integer(unsigned(address(2 downto 0))) * 8;
end function wishbone_data_shift;

function wishbone_data_sel(size : in std_logic_vector(3 downto 0); address : in std_logic_vector(63 downto 0)) return std_ulogic_vector is
begin
return std_ulogic_vector(shift_left(unsigned(length_to_sel(size)), to_integer(unsigned(address(2 downto 0)))));
end function wishbone_data_sel;
signal l_saved : Loadstore1ToLoadstore2Type;
signal w_tmp : Loadstore2ToWritebackType;
signal m_tmp : wishbone_master_out;

type state_t is (IDLE, WAITING_FOR_READ_ACK, WAITING_FOR_WRITE_ACK);
signal state : state_t := IDLE;

function length_to_sel(length : in std_logic_vector(3 downto 0)) return std_ulogic_vector is
begin
case length is
when "0001" =>
return "00000001";
when "0010" =>
return "00000011";
when "0100" =>
return "00001111";
when "1000" =>
return "11111111";
when others =>
return "00000000";
end case;
end function length_to_sel;

function wishbone_data_shift(address : in std_ulogic_vector(63 downto 0)) return natural is
begin
return to_integer(unsigned(address(2 downto 0))) * 8;
end function wishbone_data_shift;

function wishbone_data_sel(size : in std_logic_vector(3 downto 0); address : in std_logic_vector(63 downto 0)) return std_ulogic_vector is
begin
return std_ulogic_vector(shift_left(unsigned(length_to_sel(size)), to_integer(unsigned(address(2 downto 0)))));
end function wishbone_data_sel;
begin
w_out <= w_tmp;
m_out <= m_tmp;

loadstore2_0: process(clk)
variable tmp : std_ulogic_vector(63 downto 0);
variable data : std_ulogic_vector(63 downto 0);
begin
if rising_edge(clk) then
tmp := (others => '0');
data := (others => '0');

w_tmp <= Loadstore2ToWritebackInit;

l_saved <= l_saved;

case_0: case state is
when IDLE =>
if l_in.valid = '1' then
m_tmp <= wishbone_master_out_init;

m_tmp.sel <= wishbone_data_sel(l_in.length, l_in.addr);
m_tmp.adr <= l_in.addr(63 downto 3) & "000";
m_tmp.cyc <= '1';
m_tmp.stb <= '1';

l_saved <= l_in;

if l_in.load = '1' then
m_tmp.we <= '0';

-- Load with update instructions write two GPR destinations.
-- We don't want the expense of two write ports, so make it
-- single in the pipeline and write back the update GPR now
-- and the load once we get the data back. We'll have to
-- revisit this when loads can take exceptions.
if l_in.update = '1' then
w_tmp.write_enable <= '1';
w_tmp.write_reg <= l_in.update_reg;
w_tmp.write_data <= l_in.addr;
end if;

state <= WAITING_FOR_READ_ACK;
else
m_tmp.we <= '1';

data := l_in.data;
m_tmp.dat <= std_logic_vector(shift_left(unsigned(data), wishbone_data_shift(l_in.addr)));

assert l_in.sign_extend = '0' report "sign extension doesn't make sense for stores" severity failure;

state <= WAITING_FOR_WRITE_ACK;
end if;
end if;

when WAITING_FOR_READ_ACK =>
if m_in.ack = '1' then
tmp := std_logic_vector(shift_right(unsigned(m_in.dat), wishbone_data_shift(l_saved.addr)));
case to_integer(unsigned(l_saved.length)) is
when 0 =>
when 1 =>
data(7 downto 0) := tmp(7 downto 0);
when 2 =>
data(15 downto 0) := tmp(15 downto 0);
when 4 =>
data(31 downto 0) := tmp(31 downto 0);
when 8 =>
data(63 downto 0) := tmp(63 downto 0);
when others =>
assert false report "invalid length" severity failure;
end case;

if l_saved.sign_extend = '1' then
data := sign_extend(data, to_integer(unsigned(l_saved.length)));
end if;

if l_saved.byte_reverse = '1' then
data := byte_reverse(data, to_integer(unsigned(l_saved.length)));
end if;

w_tmp.write_data <= data;

-- write data to register file
w_tmp.valid <= '1';
w_tmp.write_enable <= '1';
w_tmp.write_reg <= l_saved.write_reg;

m_tmp <= wishbone_master_out_init;
state <= IDLE;
end if;

when WAITING_FOR_WRITE_ACK =>
if m_in.ack = '1' then
w_tmp.valid <= '1';
if l_saved.update = '1' then
w_tmp.write_enable <= '1';
w_tmp.write_reg <= l_saved.update_reg;
w_tmp.write_data <= l_saved.addr;
end if;

m_tmp <= wishbone_master_out_init;
state <= IDLE;
end if;
end case;
end if;
end process;
w_out <= w_tmp;
m_out <= m_tmp;

loadstore2_0: process(clk)
variable tmp : std_ulogic_vector(63 downto 0);
variable data : std_ulogic_vector(63 downto 0);
variable sign_extend_byte_reverse : std_ulogic_vector(1 downto 0);
begin
if rising_edge(clk) then
tmp := (others => '0');
data := (others => '0');

w_tmp <= Loadstore2ToWritebackInit;

l_saved <= l_saved;

case_0: case state is
when IDLE =>
if l_in.valid = '1' then
m_tmp <= wishbone_master_out_init;

m_tmp.sel <= wishbone_data_sel(l_in.length, l_in.addr);
m_tmp.adr <= l_in.addr(63 downto 3) & "000";
m_tmp.cyc <= '1';
m_tmp.stb <= '1';

l_saved <= l_in;

if l_in.load = '1' then
m_tmp.we <= '0';

-- Load with update instructions write two GPR destinations.
-- We don't want the expense of two write ports, so make it
-- single in the pipeline and write back the update GPR now
-- and the load once we get the data back. We'll have to
-- revisit this when loads can take exceptions.
if l_in.update = '1' then
w_tmp.write_enable <= '1';
w_tmp.write_reg <= l_in.update_reg;
w_tmp.write_data <= l_in.addr;
end if;

state <= WAITING_FOR_READ_ACK;
else
m_tmp.we <= '1';

data := l_in.data;
m_tmp.dat <= std_logic_vector(shift_left(unsigned(data), wishbone_data_shift(l_in.addr)));

assert l_in.sign_extend = '0' report "sign extension doesn't make sense for stores" severity failure;

state <= WAITING_FOR_WRITE_ACK;
end if;
end if;

when WAITING_FOR_READ_ACK =>
if m_in.ack = '1' then
tmp := std_logic_vector(shift_right(unsigned(m_in.dat), wishbone_data_shift(l_saved.addr)));
case to_integer(unsigned(l_saved.length)) is
when 0 =>
when 1 =>
data(7 downto 0) := tmp(7 downto 0);
when 2 =>
data(15 downto 0) := tmp(15 downto 0);
when 4 =>
data(31 downto 0) := tmp(31 downto 0);
when 8 =>
data(63 downto 0) := tmp(63 downto 0);
when others =>
assert false report "invalid length" severity failure;
end case;

sign_extend_byte_reverse := l_saved.sign_extend & l_saved.byte_reverse;

case sign_extend_byte_reverse is
when "10" =>
data := sign_extend(data, to_integer(unsigned(l_saved.length)));
when "01" =>
data := byte_reverse(data, to_integer(unsigned(l_saved.length)));
when others =>
end case;

w_tmp.write_data <= data;

-- write data to register file
w_tmp.valid <= '1';
w_tmp.write_enable <= '1';
w_tmp.write_reg <= l_saved.write_reg;

m_tmp <= wishbone_master_out_init;
state <= IDLE;
end if;

when WAITING_FOR_WRITE_ACK =>
if m_in.ack = '1' then
w_tmp.valid <= '1';
if l_saved.update = '1' then
w_tmp.write_enable <= '1';
w_tmp.write_reg <= l_saved.update_reg;
w_tmp.write_data <= l_saved.addr;
end if;

m_tmp <= wishbone_master_out_init;
state <= IDLE;
end if;
end case;
end if;
end process;
end;

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