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Only stall IF fsms when absolutely necessary

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This should take care of our synthesis issues (hopefully)
This commit is contained in:
Andreas Traber 2015-09-09 14:28:07 +02:00
parent 847b652ce5
commit 463e74cf05
2 changed files with 14 additions and 5 deletions
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5
controller.sv
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@ -1036,7 +1036,7 @@ module controller
pc_mux_sel_o = `PC_JUMP;
if (~stall_id_o)
ctrl_fsm_ns = BRANCH_DELAY;
ctrl_fsm_ns = DECODE;
end
// handle hwloops
@ -1076,7 +1076,6 @@ module controller
// assume branch instruction is in EX
if (jump_in_ex_i == `BRANCH_COND && ~branch_decision_i) begin
// not taken
pc_mux_sel_o = `PC_INCR;
// if we want to debug, flush the pipeline
// the current_pc_if will take the value of the next instruction to
@ -1103,7 +1102,7 @@ module controller
ctrl_fsm_ns = DBG_FLUSH_EX;
end else begin
if (~stall_id_o)
ctrl_fsm_ns = BRANCH_DELAY;
ctrl_fsm_ns = DECODE;
end
end
end

14
if_stage.sv
View file

@ -97,7 +97,7 @@ module if_stage
logic unaligned_jump;
// instr_core_interface
logic branch_req;
logic branch_req, branch_req_Q;
logic [31:0] fetch_addr_n;
logic fetch_valid;
@ -212,8 +212,15 @@ module if_stage
begin
if (rst_n == 1'b0) begin
offset_fsm_cs <= IDLE;
branch_req_Q <= 1'b0;
end else begin
offset_fsm_cs <= offset_fsm_ns;
if (stall_if_i)
branch_req_Q <= branch_req | branch_req_Q;
else
branch_req_Q <= 1'b0;
end
end
@ -296,9 +303,10 @@ module if_stage
// take care of jumps and branches
if(~stall_id_i) begin
if (branch_req_Q == 1'b0) begin
if (jump_in_ex_i == `BRANCH_COND) begin
if (branch_decision_i) begin
valid_o = 1'b0;
// branch taken
branch_req = 1'b1;
if (unaligned_jump)
@ -310,6 +318,8 @@ module if_stage
end else if (jump_in_id_i == `BRANCH_JAL || jump_in_id_i == `BRANCH_JALR
|| dbg_set_npc_i
|| hwloop_jump_i) begin
valid_o = 1'b0;
// switch to new PC from ID stage
branch_req = 1'b1;
if (unaligned_jump)