Remove execute2 stage

Since the condition setting got moved to writeback, execute2 does
nothing aside from wasting a cycle.  This removes it.

Signed-off-by: Paul Mackerras <paulus@ozlabs.org>

Makefile

@@ -17,7 +17,7 @@ common.o: decode_types.o
 control.o: gpr_hazard.o cr_hazard.o
 sim_jtag.o: sim_jtag_socket.o
 core_tb.o: common.o wishbone_types.o core.o soc.o sim_jtag.o
-core.o: common.o wishbone_types.o fetch1.o fetch2.o icache.o decode1.o decode2.o register_file.o cr_file.o execute1.o execute2.o loadstore1.o loadstore2.o multiply.o writeback.o core_debug.o divider.o
+core.o: common.o wishbone_types.o fetch1.o fetch2.o icache.o decode1.o decode2.o register_file.o cr_file.o execute1.o loadstore1.o loadstore2.o multiply.o writeback.o core_debug.o divider.o
 core_debug.o: common.o
 countzero.o:
 countzero_tb.o: common.o glibc_random.o countzero.o
@@ -27,7 +27,6 @@ decode1.o: common.o decode_types.o
 decode2.o: decode_types.o common.o helpers.o insn_helpers.o control.o
 decode_types.o:
 execute1.o: decode_types.o common.o helpers.o crhelpers.o insn_helpers.o ppc_fx_insns.o rotator.o logical.o countzero.o
-execute2.o: common.o
 fetch1.o: common.o
 fetch2.o: common.o wishbone_types.o
 glibc_random_helpers.o:

common.vhdl

@@ -164,21 +164,7 @@ package common is
 	end record;
 	constant Loadstore2ToWritebackInit : Loadstore2ToWritebackType := (valid => '0', write_enable => '0', sign_extend => '0', byte_reverse => '0', second_word => '0', others => (others => '0'));
 
-	type Execute1ToExecute2Type is record
+	type Execute1ToWritebackType is record
-		valid: std_ulogic;
-		write_enable : std_ulogic;
-		write_reg: std_ulogic_vector(4 downto 0);
-		write_data: std_ulogic_vector(63 downto 0);
-		write_len : std_ulogic_vector(3 downto 0);
-		write_cr_enable : std_ulogic;
-		write_cr_mask : std_ulogic_vector(7 downto 0);
-		write_cr_data : std_ulogic_vector(31 downto 0);
-		rc : std_ulogic;
-                sign_extend: std_ulogic;
-	end record;
-	constant Execute1ToExecute2Init : Execute1ToExecute2Type := (valid => '0', write_enable => '0', write_cr_enable => '0', rc => '0', sign_extend => '0',  others => (others => '0'));
-
-	type Execute2ToWritebackType is record
 		valid: std_ulogic;
 		rc : std_ulogic;
 		write_enable : std_ulogic;
@@ -190,7 +176,7 @@ package common is
 		write_cr_data : std_ulogic_vector(31 downto 0);
                 sign_extend: std_ulogic;
 	end record;
-	constant Execute2ToWritebackInit : Execute2ToWritebackType := (valid => '0', rc => '0', write_enable => '0', write_cr_enable => '0', sign_extend => '0', others => (others => '0'));
+	constant Execute1ToWritebackInit : Execute1ToWritebackType := (valid => '0', rc => '0', write_enable => '0', write_cr_enable => '0', sign_extend => '0', others => (others => '0'));
 
 	type MultiplyToWritebackType is record
 		valid: std_ulogic;

core.vhdl

@@ -54,8 +54,7 @@ architecture behave of core is
     signal writeback_to_cr_file: WritebackToCrFileType;
 
     -- execute signals
-    signal execute1_to_execute2: Execute1ToExecute2Type;
+    signal execute1_to_writeback: Execute1ToWritebackType;
-    signal execute2_to_writeback: Execute2ToWritebackType;
     signal execute1_to_fetch1: Execute1ToFetch1Type;
 
     -- load store signals
@@ -204,17 +203,10 @@ begin
             flush_out => flush,
             e_in => decode2_to_execute1,
             f_out => execute1_to_fetch1,
-            e_out => execute1_to_execute2,
+            e_out => execute1_to_writeback,
             terminate_out => terminate
             );
 
-    execute2_0: entity work.execute2
-        port map (
-            clk => clk,
-            e_in => execute1_to_execute2,
-            e_out => execute2_to_writeback
-            );
-
     loadstore1_0: entity work.loadstore1
         port map (
             clk => clk,
@@ -249,7 +241,7 @@ begin
     writeback_0: entity work.writeback
         port map (
             clk => clk,
-            e_in => execute2_to_writeback,
+            e_in => execute1_to_writeback,
             l_in => loadstore2_to_writeback,
             m_in => multiply_to_writeback,
             d_in => divider_to_writeback,

execute1.vhdl

@@ -25,7 +25,7 @@ entity execute1 is
 		-- asynchronous
 		f_out : out Execute1ToFetch1Type;
 
-		e_out : out Execute1ToExecute2Type;
+		e_out : out Execute1ToWritebackType;
 
 		terminate_out : out std_ulogic
 	);
@@ -34,7 +34,7 @@ end entity execute1;
 architecture behaviour of execute1 is
 	type reg_type is record
 		--f : Execute1ToFetch1Type;
-		e : Execute1ToExecute2Type;
+		e : Execute1ToWritebackType;
 	end record;
 
 	signal r, rin : reg_type;
@@ -124,7 +124,7 @@ begin
 		newcrf := (others => '0');
 
 		v := r;
-		v.e := Execute1ToExecute2Init;
+		v.e := Execute1ToWritebackInit;
 		--v.f := Execute1ToFetch1TypeInit;
 
 		ctrl_tmp <= ctrl;

execute2.vhdl

@@ -1,52 +0,0 @@
-library ieee;
-use ieee.std_logic_1164.all;
-use ieee.numeric_std.all;
-
-library work;
-use work.common.all;
-
--- 2 cycle ALU
--- We handle rc form instructions here
-
-entity execute2 is
-    port (
-        clk   : in std_ulogic;
-
-        e_in  : in Execute1ToExecute2Type;
-        e_out : out Execute2ToWritebackType
-        );
-end execute2;
-
-architecture behave of execute2 is
-    signal r, rin : Execute2ToWritebackType;
-begin
-    execute2_0: process(clk)
-    begin
-        if rising_edge(clk) then
-            r <= rin;
-        end if;
-    end process;
-
-    execute2_1: process(all)
-        variable v : Execute2ToWritebackType;
-    begin
-        v := rin;
-
-        v.valid := e_in.valid;
-        v.write_enable := e_in.write_enable;
-        v.write_reg := e_in.write_reg;
-        v.write_data := e_in.write_data;
-        v.write_cr_enable := e_in.write_cr_enable;
-        v.write_cr_mask := e_in.write_cr_mask;
-        v.write_cr_data := e_in.write_cr_data;
-        v.rc := e_in.rc;
-        v.write_len := e_in.write_len;
-        v.sign_extend := e_in.sign_extend;
-
-        -- Update registers
-        rin <= v;
-
-        -- Update outputs
-        e_out <= r;
-    end process;
-end;

microwatt.core

@@ -24,7 +24,6 @@ filesets:
       - cr_hazard.vhdl
       - control.vhdl
       - execute1.vhdl
-      - execute2.vhdl
       - loadstore1.vhdl
       - loadstore2.vhdl
       - multiply.vhdl

writeback.vhdl

@@ -10,7 +10,7 @@ entity writeback is
     port (
         clk          : in std_ulogic;
 
-        e_in         : in Execute2ToWritebackType;
+        e_in         : in Execute1ToWritebackType;
         l_in         : in Loadstore2ToWritebackType;
         m_in         : in MultiplyToWritebackType;
         d_in         : in DividerToWritebackType;