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Fix plru_tb to use the new plrufn and take out the old plru.vhdl

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This reworks (and simplifies) plru_tb to use the new plrufn module
instead of the old (and now unused) plru module.

The latter is now removed completely.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This commit is contained in:
Benjamin Herrenschmidt 2022-10-23 15:24:11 +11:00
parent 4e32dcff80
commit 6068b635ae
4 changed files with 59 additions and 158 deletions
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2
Makefile
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@ -68,7 +68,7 @@ all: $(all)
$(shell scripts/make_version.sh git.vhdl) $(shell scripts/make_version.sh git.vhdl)
core_files = decode_types.vhdl common.vhdl wishbone_types.vhdl fetch1.vhdl \ core_files = decode_types.vhdl common.vhdl wishbone_types.vhdl fetch1.vhdl \
utils.vhdl plru.vhdl plrufn.vhdl cache_ram.vhdl icache.vhdl \ utils.vhdl plrufn.vhdl cache_ram.vhdl icache.vhdl \
predecode.vhdl decode1.vhdl helpers.vhdl insn_helpers.vhdl \ predecode.vhdl decode1.vhdl helpers.vhdl insn_helpers.vhdl \
control.vhdl decode2.vhdl register_file.vhdl \ control.vhdl decode2.vhdl register_file.vhdl \
cr_file.vhdl crhelpers.vhdl ppc_fx_insns.vhdl rotator.vhdl \ cr_file.vhdl crhelpers.vhdl ppc_fx_insns.vhdl rotator.vhdl \

1
microwatt.core
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@ -33,7 +33,6 @@ filesets:
- insn_helpers.vhdl - insn_helpers.vhdl
- core.vhdl - core.vhdl
- icache.vhdl - icache.vhdl
- plru.vhdl
- plrufn.vhdl - plrufn.vhdl
- cache_ram.vhdl - cache_ram.vhdl
- core_debug.vhdl - core_debug.vhdl

86
plru.vhdl
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@ -1,86 +0,0 @@
library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;
use ieee.math_real.all;
entity plru is
generic (
BITS : positive := 2
)
;
port (
clk : in std_ulogic;
rst : in std_ulogic;
acc : in std_ulogic_vector(BITS-1 downto 0);
acc_en : in std_ulogic;
lru : out std_ulogic_vector(BITS-1 downto 0)
);
end entity plru;
architecture rtl of plru is
-- Each level of the tree (from leaf to root) has half the number of nodes
-- of the previous level. So for a 2^N bits LRU, we have a level of N/2 bits
-- one of N/4 bits etc.. down to 1. This gives us 2^N-1 nodes. Ie, 2 bits
-- LRU has 3 nodes (2 + 1), 4 bits LRU has 15 nodes (8 + 4 + 2 + 1) etc...
constant count : positive := 2 ** BITS - 1;
subtype node_t is integer range 0 to count - 1;
type tree_t is array(node_t) of std_ulogic;
signal tree: tree_t;
begin
-- XXX Check if we can turn that into a little ROM instead that
-- takes the tree bit vector and returns the LRU. See if it's better
-- in term of FPGA resource usage...
get_lru: process(tree)
variable node : node_t;
variable abit : std_ulogic;
begin
node := 0;
for i in 0 to BITS-1 loop
-- report "GET: i:" & integer'image(i) & " node:" & integer'image(node) & " val:" & std_ulogic'image(tree(node));
abit := tree(node);
lru(BITS-1-i) <= abit;
if i /= BITS-1 then
node := node * 2;
if abit = '1' then
node := node + 2;
else
node := node + 1;
end if;
end if;
end loop;
end process;
update_lru: process(clk)
variable node : node_t;
variable abit : std_ulogic;
begin
if rising_edge(clk) then
if rst = '1' then
tree <= (others => '0');
elsif acc_en = '1' then
node := 0;
for i in 0 to BITS-1 loop
abit := acc(BITS-1-i);
tree(node) <= not abit;
-- report "UPD: i:" & integer'image(i) & " node:" & integer'image(node) & " val" & std_ulogic'image(not abit);
if i /= BITS-1 then
node := node * 2;
if abit = '1' then
node := node + 2;
else
node := node + 1;
end if;
end if;
end loop;
end if;
end if;
-- if falling_edge(clk) then
-- if acc_en = '1' then
-- report "UPD: tree:" & to_string(tree);
-- end if;
-- end if;
end process;
end;

126
plru_tb.vhdl
View File

@ -3,6 +3,7 @@ context vunit_lib.vunit_context;
library ieee; library ieee;
use ieee.std_logic_1164.all; use ieee.std_logic_1164.all;
use ieee.numeric_std.all;
library work; library work;
use work.common.all; use work.common.all;
@ -17,22 +18,25 @@ architecture behave of plru_tb is
signal rst : std_ulogic; signal rst : std_ulogic;
constant clk_period : time := 10 ns; constant clk_period : time := 10 ns;
constant plru_bits : integer := 3;
signal acc_en : std_ulogic; subtype plru_val_t is std_ulogic_vector(plru_bits - 1 downto 0);
signal acc : std_ulogic_vector(2 downto 0); subtype plru_tree_t is std_ulogic_vector(2 ** plru_bits - 2 downto 0);
signal lru : std_ulogic_vector(2 downto 0); signal do_update : std_ulogic := '0';
signal acc : plru_val_t;
signal lru : plru_val_t;
signal state : plru_tree_t;
signal state_upd : plru_tree_t;
begin begin
plru0: entity work.plru plrufn0: entity work.plrufn
generic map( generic map(
BITS => 3 BITS => plru_bits
) )
port map( port map(
clk => clk,
rst => rst,
acc => acc, acc => acc,
acc_en => acc_en, tree_in => state,
tree_out => state_upd,
lru => lru lru => lru
); );
@ -52,7 +56,26 @@ begin
wait; wait;
end process; end process;
stim: process plru_process: process(clk)
begin
if rising_edge(clk) then
if rst = '1' then
state <= (others => '0');
elsif do_update = '1' then
state <= state_upd;
end if;
end if;
end process;
stim_process: process
procedure test_access(acc_val: integer; expected: integer) is
begin
acc <= std_ulogic_vector(to_unsigned(acc_val, acc'length));
do_update <= '1';
wait for clk_period;
info("accessed " & integer'image(acc_val) & " LRU=" & to_hstring(lru));
check_equal(lru, expected, result("LRU ACC=" & integer'image(acc_val)));
end procedure;
begin begin
test_runner_setup(runner, runner_cfg); test_runner_setup(runner, runner_cfg);
@ -61,66 +84,31 @@ begin
info("reset state:" & to_hstring(lru)); info("reset state:" & to_hstring(lru));
check_equal(lru, 0, result("LRU ")); check_equal(lru, 0, result("LRU "));
info("accessing 1:"); test_access(1, 4);
acc <= "001"; test_access(2, 4);
acc_en <= '1'; test_access(7, 0);
wait for clk_period; test_access(4, 0);
info("lru:" & to_hstring(lru)); test_access(3, 6);
check_equal(lru, 4, result("LRU")); test_access(5, 0);
test_access(3, 6);
test_access(5, 0);
test_access(6, 0);
test_access(0, 4);
test_access(1, 4);
test_access(2, 4);
test_access(3, 4);
test_access(4, 0);
test_access(5, 0);
test_access(6, 0);
test_access(7, 0);
test_access(6, 0);
test_access(5, 0);
test_access(4, 0);
test_access(3, 7);
test_access(2, 7);
test_access(1, 7);
test_access(0, 7);
info("accessing 2:");
acc <= "010";
wait for clk_period;
info("lru:" & to_hstring(lru));
check_equal(lru, 4, result("LRU"));
info("accessing 7:");
acc <= "111";
wait for clk_period;
info("lru:" & to_hstring(lru));
check_equal(lru, 0, result("LRU"));
info("accessing 4:");
acc <= "100";
wait for clk_period;
info("lru:" & to_hstring(lru));
check_equal(lru, 0, result("LRU"));
info("accessing 3:");
acc <= "011";
wait for clk_period;
info("lru:" & to_hstring(lru));
check_equal(lru, 6, result("LRU"));
info("accessing 5:");
acc <= "101";
wait for clk_period;
info("lru:" & to_hstring(lru));
check_equal(lru, 0, result("LRU"));
info("accessing 3:");
acc <= "011";
wait for clk_period;
info("lru:" & to_hstring(lru));
check_equal(lru, 6, result("LRU"));
info("accessing 5:");
acc <= "101";
wait for clk_period;
info("lru:" & to_hstring(lru));
check_equal(lru, 0, result("LRU"));
info("accessing 6:");
acc <= "110";
wait for clk_period;
info("lru:" & to_hstring(lru));
check_equal(lru, 0, result("LRU"));
info("accessing 0:");
acc <= "000";
wait for clk_period;
info("lru:" & to_hstring(lru));
check_equal(lru, 4, result("LRU"));
wait for clk_period; wait for clk_period;
wait for clk_period; wait for clk_period;