From 7931588467940a809b72d24c6dfc1419b0f2110f Mon Sep 17 00:00:00 2001
From: Alban Gruin <alban.gruin@irit.fr>
Date: Thu, 18 Mar 2021 13:30:25 +0100
Subject: [PATCH] scoreboard: scan the scoreboard for memory operations
Signed-off-by: Alban Gruin <alban.gruin@irit.fr>
---
src/ariane.sv | 9 +++++++++
src/issue_stage.sv | 5 ++++-
src/scoreboard.sv | 43 ++++++++++++++++++++++++++++++-------------
src/verifier.sv | 3 +++
4 files changed, 46 insertions(+), 14 deletions(-)
diff --git a/src/ariane.sv b/src/ariane.sv
index 4463e622..9e4216ef 100644
--- a/src/ariane.sv
+++ b/src/ariane.sv
@@ -94,6 +94,11 @@ module ariane import ariane_pkg::*; #(
// --------------
logic has_mem_access_id_verif;
+ // --------------
+ // ISSUE -> verifier
+ // --------------
+ logic has_mem_access_is_verif;
+
// --------------
// ISSUE <-> EX
// --------------
@@ -362,6 +367,7 @@ module ariane import ariane_pkg::*; #(
.we_fpr_i ( we_fpr_commit_id ),
.commit_instr_o ( commit_instr_id_commit ),
.commit_ack_i ( commit_ack ),
+ .has_mem_access_o ( has_mem_access_is_verif ),
.*
);
@@ -635,6 +641,9 @@ module ariane import ariane_pkg::*; #(
// ID
.id_has_mem_access_i (has_mem_access_id_verif),
+ // IS
+ .is_has_mem_access_i (has_mem_access_is_verif),
+
// CO
.commit_instr_i (commit_instr_id_commit),
.commit_ack_i (commit_ack)
diff --git a/src/issue_stage.sv b/src/issue_stage.sv
index 2258eb69..54c41221 100644
--- a/src/issue_stage.sv
+++ b/src/issue_stage.sv
@@ -70,7 +70,10 @@ module issue_stage import ariane_pkg::*; #(
input logic [NR_COMMIT_PORTS-1:0] we_fpr_i,
output scoreboard_entry_t [NR_COMMIT_PORTS-1:0] commit_instr_o,
- input logic [NR_COMMIT_PORTS-1:0] commit_ack_i
+ input logic [NR_COMMIT_PORTS-1:0] commit_ack_i,
+
+ // to verifier
+ output has_mem_access_o
);
// ---------------------------------------------------
// Scoreboard (SB) <-> Issue and Read Operands (IRO)
diff --git a/src/scoreboard.sv b/src/scoreboard.sv
index c48d44c9..a20b0ef1 100644
--- a/src/scoreboard.sv
+++ b/src/scoreboard.sv
@@ -60,7 +60,10 @@ module scoreboard #(
input logic [NR_WB_PORTS-1:0][ariane_pkg::TRANS_ID_BITS-1:0] trans_id_i, // transaction ID at which to write the result back
input logic [NR_WB_PORTS-1:0][riscv::XLEN-1:0] wbdata_i, // write data in
input ariane_pkg::exception_t [NR_WB_PORTS-1:0] ex_i, // exception from a functional unit (e.g.: ld/st exception)
- input logic [NR_WB_PORTS-1:0] wt_valid_i // data in is valid
+ input logic [NR_WB_PORTS-1:0] wt_valid_i, // data in is valid
+
+ // to verifier
+ output logic has_mem_access_o
);
localparam int unsigned BITS_ENTRIES = $clog2(NR_ENTRIES);
@@ -77,6 +80,8 @@ module scoreboard #(
logic [NR_COMMIT_PORTS-1:0][BITS_ENTRIES-1:0] commit_pointer_n, commit_pointer_q;
logic [$clog2(NR_COMMIT_PORTS):0] num_commit;
+ logic [NR_ENTRIES-1:0] has_mem_access_n, has_mem_access_q;
+
// the issue queue is full don't issue any new instructions
// works since aligned to power of 2
assign issue_full = &issue_cnt_q;
@@ -91,6 +96,9 @@ module scoreboard #(
end
end
+ // check instructions in the scoreboard for memory operations
+ assign has_mem_access_o = (|has_mem_access_q);
+
// an instruction is ready for issue if we have place in the issue FIFO and it the decoder says it is valid
always_comb begin
issue_instr_o = decoded_instr_i;
@@ -106,8 +114,9 @@ module scoreboard #(
// keep track of all issued instructions
always_comb begin : issue_fifo
// default assignment
- mem_n = mem_q;
- issue_en = 1'b0;
+ mem_n = mem_q;
+ issue_en = 1'b0;
+ has_mem_access_n = has_mem_access_q;
// if we got a acknowledge from the issue stage, put this scoreboard entry in the queue
if (decoded_instr_valid_i && decoded_instr_ack_o && !flush_unissued_instr_i) begin
@@ -118,6 +127,7 @@ module scoreboard #(
ariane_pkg::is_rd_fpr(decoded_instr_i.op), // whether rd goes to the fpr
decoded_instr_i // decoded instruction record
};
+ has_mem_access_n[issue_pointer_q] = decoded_instr_i.fu inside {ariane_pkg::LOAD, ariane_pkg::STORE};
end
// ------------
@@ -146,6 +156,9 @@ module scoreboard #(
// write the fflags back from the FPU (exception valid is never set), leave tval intact
else if (mem_q[trans_id_i[i]].sbe.fu inside {ariane_pkg::FPU, ariane_pkg::FPU_VEC})
mem_n[trans_id_i[i]].sbe.ex.cause = ex_i[i].cause;
+
+ if (mem_n[trans_id_i[i]].sbe.fu != ariane_pkg::STORE)
+ has_mem_access_n[trans_id_i[i]] = 1'b0;
end
end
@@ -156,8 +169,9 @@ module scoreboard #(
for (logic [BITS_ENTRIES-1:0] i = 0; i < NR_COMMIT_PORTS; i++) begin
if (commit_ack_i[i]) begin
// this instruction is no longer in issue e.g.: it is considered finished
- mem_n[commit_pointer_q[i]].issued = 1'b0;
- mem_n[commit_pointer_q[i]].sbe.valid = 1'b0;
+ mem_n[commit_pointer_q[i]].issued = 1'b0;
+ mem_n[commit_pointer_q[i]].sbe.valid = 1'b0;
+ has_mem_access_n[commit_pointer_q[i]] = 1'b0;
end
end
@@ -170,6 +184,7 @@ module scoreboard #(
mem_n[i].issued = 1'b0;
mem_n[i].sbe.valid = 1'b0;
mem_n[i].sbe.ex.valid = 1'b0;
+ has_mem_access_n[i] = 1'b0;
end
end
end
@@ -353,15 +368,17 @@ module scoreboard #(
// sequential process
always_ff @(posedge clk_i or negedge rst_ni) begin : regs
if(!rst_ni) begin
- mem_q <= '{default: 0};
- issue_cnt_q <= '0;
- commit_pointer_q <= '0;
- issue_pointer_q <= '0;
+ mem_q <= '{default: 0};
+ issue_cnt_q <= '0;
+ commit_pointer_q <= '0;
+ issue_pointer_q <= '0;
+ has_mem_access_q <= '0;
end else begin
- issue_cnt_q <= issue_cnt_n;
- issue_pointer_q <= issue_pointer_n;
- mem_q <= mem_n;
- commit_pointer_q <= commit_pointer_n;
+ issue_cnt_q <= issue_cnt_n;
+ issue_pointer_q <= issue_pointer_n;
+ mem_q <= mem_n;
+ commit_pointer_q <= commit_pointer_n;
+ has_mem_access_q <= has_mem_access_n;
end
end
diff --git a/src/verifier.sv b/src/verifier.sv
index cc4278b8..5ff2707d 100644
--- a/src/verifier.sv
+++ b/src/verifier.sv
@@ -12,6 +12,9 @@ module verifier #(
// ID
input logic id_has_mem_access_i,
+ // IS
+ input logic is_has_mem_access_i,
+
// CO
input ariane_pkg::scoreboard_entry_t [NR_COMMIT_PORTS-1:0] commit_instr_i,
input logic [NR_COMMIT_PORTS-1:0] commit_ack_i
--
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