From 2b1e0de9de881b39dc5bd3d9f3dda04ff7e8f173 Mon Sep 17 00:00:00 2001
From: Graham Edgecombe <gpe@grahamedgecombe.com>
Date: Tue, 26 Dec 2017 16:46:01 +0000
Subject: [PATCH] Propagate mem_fence signal through the pipeline

---
 rv32.sv         | 2 ++
 rv32_decode.sv  | 3 +++
 rv32_execute.sv | 3 +++
 3 files changed, 8 insertions(+)

diff --git a/rv32.sv b/rv32.sv
index 9314a84..41b74f8 100644
--- a/rv32.sv
+++ b/rv32.sv
@@ -60,6 +60,7 @@ module rv32 (
     logic decode_mem_write;
     logic [1:0] decode_mem_width;
     logic decode_mem_zero_extend;
+    logic decode_mem_fence;
     logic [1:0] decode_branch_op;
     logic decode_branch_pc_src;
     logic [4:0] decode_rd;
@@ -76,6 +77,7 @@ module rv32 (
     logic execute_mem_write;
     logic [1:0] execute_mem_width;
     logic execute_mem_zero_extend;
+    logic execute_mem_fence;
     logic [1:0] execute_branch_op;
     logic [4:0] execute_rd;
     logic execute_rd_write;
diff --git a/rv32_decode.sv b/rv32_decode.sv
index 6562cc2..adc439c 100644
--- a/rv32_decode.sv
+++ b/rv32_decode.sv
@@ -41,6 +41,7 @@ module rv32_decode (
     output logic mem_write_out,
     output logic [1:0] mem_width_out,
     output logic mem_zero_extend_out,
+    output logic mem_fence_out,
     output logic [1:0] branch_op_out,
     output logic branch_pc_src_out,
     output logic [4:0] rd_out,
@@ -122,6 +123,7 @@ module rv32_decode (
             mem_write_out <= 0;
             mem_width_out <= 2'bx;
             mem_zero_extend_out <= 1'bx;
+            mem_fence_out <= 0;
             branch_op_out <= `RV32_BRANCH_OP_NEVER;
             branch_pc_src_out <= 1'bx;
             rd_out <= rd;
@@ -478,6 +480,7 @@ module rv32_decode (
                 end
                 `RV32_INSTR_FENCE_I: begin
                     valid_out <= 1;
+                    mem_fence_out <= 1;
                 end
                 `RV32_INSTR_ECALL: begin
                     valid_out <= 1;
diff --git a/rv32_execute.sv b/rv32_execute.sv
index 342a31a..293e87e 100644
--- a/rv32_execute.sv
+++ b/rv32_execute.sv
@@ -22,6 +22,7 @@ module rv32_execute (
     input mem_write_in,
     input [1:0] mem_width_in,
     input mem_zero_extend_in,
+    input mem_fence_in,
     input [1:0] branch_op_in,
     input branch_pc_src_in,
     input [4:0] rd_in,
@@ -45,6 +46,7 @@ module rv32_execute (
     output logic mem_write_out,
     output logic [1:0] mem_width_out,
     output logic mem_zero_extend_out,
+    output logic mem_fence_out,
     output logic [1:0] branch_op_out,
     output logic [4:0] rd_out,
     output logic rd_write_out,
@@ -113,6 +115,7 @@ module rv32_execute (
             mem_write_out <= mem_write_in;
             mem_width_out <= mem_width_in;
             mem_zero_extend_out <= mem_zero_extend_in;
+            mem_fence_out <= mem_fence_in;
             branch_op_out <= branch_op_in;
             rd_out <= rd_in;
             rd_write_out <= rd_write_in;