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minor optimizations

This commit is contained in:
Clifford Wolf 2015-06-07 20:08:04 +02:00
parent 8e3e0bfba0
commit 60867e10a9
1 changed files with 7 additions and 5 deletions
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12
picorv32.v
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@ -176,6 +176,7 @@ module picorv32 #(
reg is_sltiu_bltu_sltu; reg is_sltiu_bltu_sltu;
reg is_beq_bne_blt_bge_bltu_bgeu; reg is_beq_bne_blt_bge_bltu_bgeu;
reg is_lbu_lhu_lw; reg is_lbu_lhu_lw;
reg is_compare;
always @(posedge clk) begin always @(posedge clk) begin
is_lui_auipc_jal <= |{instr_lui, instr_auipc, instr_jal}; is_lui_auipc_jal <= |{instr_lui, instr_auipc, instr_jal};
@ -189,6 +190,7 @@ module picorv32 #(
is_sltiu_bltu_sltu <= |{instr_sltiu, instr_bltu, instr_sltu}; is_sltiu_bltu_sltu <= |{instr_sltiu, instr_bltu, instr_sltu};
is_beq_bne_blt_bge_bltu_bgeu <= |{instr_beq, instr_bne, instr_blt, instr_bge, instr_bltu, instr_bgeu}; is_beq_bne_blt_bge_bltu_bgeu <= |{instr_beq, instr_bne, instr_blt, instr_bge, instr_bltu, instr_bgeu};
is_lbu_lhu_lw <= |{instr_lbu, instr_lhu, instr_lw}; is_lbu_lhu_lw <= |{instr_lbu, instr_lhu, instr_lw};
is_compare <= |{instr_beq, instr_bne, instr_bge, instr_bgeu, is_slti_blt_slt, is_sltiu_bltu_sltu};
end end
assign instr_trap = !{instr_lui, instr_auipc, instr_jal, instr_jalr, assign instr_trap = !{instr_lui, instr_auipc, instr_jal, instr_jalr,
@ -388,7 +390,7 @@ module picorv32 #(
alu_out = reg_op1 + reg_op2; alu_out = reg_op1 + reg_op2;
instr_sub: instr_sub:
alu_out = reg_op1 - reg_op2; alu_out = reg_op1 - reg_op2;
|{instr_beq, instr_bne, instr_bge, instr_bgeu, is_slti_blt_slt, is_sltiu_bltu_sltu}: is_compare:
alu_out = alu_out_0; alu_out = alu_out_0;
instr_xori || instr_xor: instr_xori || instr_xor:
alu_out = reg_op1 ^ reg_op2; alu_out = reg_op1 ^ reg_op2;
@ -548,14 +550,14 @@ module picorv32 #(
end end
end end
cpu_state_exec: begin cpu_state_exec: begin
latched_store <= alu_out_0;
latched_branch <= alu_out_0;
reg_out <= reg_pc + decoded_imm; reg_out <= reg_pc + decoded_imm;
if (is_beq_bne_blt_bge_bltu_bgeu) begin if (is_beq_bne_blt_bge_bltu_bgeu) begin
latched_rd <= 0; latched_rd <= 0;
if (mem_done) if (mem_done)
cpu_state <= cpu_state_fetch; cpu_state <= cpu_state_fetch;
if (alu_out_0) begin if (alu_out_0) begin
latched_store <= 1;
latched_branch <= 1;
decoder_trigger <= 0; decoder_trigger <= 0;
set_mem_do_rinst = 1; set_mem_do_rinst = 1;
end end
@ -567,10 +569,10 @@ module picorv32 #(
end end
end end
cpu_state_shift: begin cpu_state_shift: begin
latched_store <= 1;
if (reg_sh == 0) begin if (reg_sh == 0) begin
reg_out <= reg_op1; reg_out <= reg_op1;
mem_do_rinst <= mem_do_prefetch; mem_do_rinst <= mem_do_prefetch;
latched_store <= 1;
cpu_state <= cpu_state_fetch; cpu_state <= cpu_state_fetch;
end else if (reg_sh >= 4) begin end else if (reg_sh >= 4) begin
(* parallel_case, full_case *) (* parallel_case, full_case *)
@ -609,6 +611,7 @@ module picorv32 #(
end end
end end
cpu_state_ldmem: begin cpu_state_ldmem: begin
latched_store <= 1;
if (!mem_do_prefetch || mem_done) begin if (!mem_do_prefetch || mem_done) begin
if (!mem_do_rdata) begin if (!mem_do_rdata) begin
(* parallel_case, full_case *) (* parallel_case, full_case *)
@ -617,7 +620,6 @@ module picorv32 #(
instr_lh || instr_lhu: mem_wordsize <= 1; instr_lh || instr_lhu: mem_wordsize <= 1;
instr_lw: mem_wordsize <= 0; instr_lw: mem_wordsize <= 0;
endcase endcase
latched_store <= 1;
latched_is_lu <= is_lbu_lhu_lw; latched_is_lu <= is_lbu_lhu_lw;
latched_is_lh <= instr_lh; latched_is_lh <= instr_lh;
latched_is_lb <= instr_lb; latched_is_lb <= instr_lb;