From b6f72ce7c911ccafea5941ff7f4dc64a8406c179 Mon Sep 17 00:00:00 2001
From: Donald Sebastian Leung <dl@m-labs.hk>
Date: Wed, 29 Jul 2020 16:47:36 +0800
Subject: [PATCH] Add rvfi_reg_check

---
 checks/rvfi_reg_check.py | 84 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 84 insertions(+)
 create mode 100644 checks/rvfi_reg_check.py

diff --git a/checks/rvfi_reg_check.py b/checks/rvfi_reg_check.py
new file mode 100644
index 0000000..5347be8
--- /dev/null
+++ b/checks/rvfi_reg_check.py
@@ -0,0 +1,84 @@
+from nmigen import *
+from nmigen.hdl.ast import *
+
+class rvfi_reg_check(Elaboratable):
+    def __init__(self, RISCV_FORMAL_ILEN=32, RISCV_FORMAL_XLEN=32):
+        self.RISCV_FORMAL_ILEN = RISCV_FORMAL_ILEN
+        self.RISCV_FORMAL_XLEN = RISCV_FORMAL_XLEN
+        self.reset = Signal(1)
+        self.check = Signal(1)
+        self.rvfi_valid = Signal(1)
+        self.rvfi_order = Signal(64)
+        self.rvfi_insn = Signal(self.RISCV_FORMAL_ILEN)
+        self.rvfi_trap = Signal(1)
+        self.rvfi_halt = Signal(1)
+        self.rvfi_intr = Signal(1)
+        self.rvfi_mode = Signal(2)
+        self.rvfi_ixl = Signal(2)
+        self.rvfi_rs1_addr = Signal(5)
+        self.rvfi_rs2_addr = Signal(5)
+        self.rvfi_rs1_rdata = Signal(self.RISCV_FORMAL_XLEN)
+        self.rvfi_rs2_rdata = Signal(self.RISCV_FORMAL_XLEN)
+        self.rvfi_rd_addr = Signal(5)
+        self.rvfi_rd_wdata = Signal(self.RISCV_FORMAL_XLEN)
+        self.rvfi_pc_rdata = Signal(self.RISCV_FORMAL_XLEN)
+        self.rvfi_pc_wdata = Signal(self.RISCV_FORMAL_XLEN)
+        self.rvfi_mem_addr = Signal(self.RISCV_FORMAL_XLEN)
+        self.rvfi_mem_rmask = Signal(int(self.RISCV_FORMAL_XLEN // 8))
+        self.rvfi_mem_wmask = Signal(int(self.RISCV_FORMAL_XLEN // 8))
+        self.rvfi_mem_rdata = Signal(self.RISCV_FORMAL_XLEN)
+        self.rvfi_mem_wdata = Signal(self.RISCV_FORMAL_XLEN)
+    def ports(self):
+        input_ports = [
+            self.reset,
+            self.check,
+            self.rvfi_valid,
+            self.rvfi_order,
+            self.rvfi_insn,
+            self.rvfi_trap,
+            self.rvfi_halt,
+            self.rvfi_intr,
+            self.rvfi_mode,
+            self.rvfi_ixl,
+            self.rvfi_rs1_addr,
+            self.rvfi_rs2_addr,
+            self.rvfi_rs1_rdata,
+            self.rvfi_rs2_rdata,
+            self.rvfi_rd_addr,
+            self.rvfi_rd_wdata,
+            self.rvfi_pc_rdata,
+            self.rvfi_pc_wdata,
+            self.rvfi_mem_addr,
+            self.rvfi_mem_rmask,
+            self.rvfi_mem_wmask,
+            self.rvfi_mem_rdata,
+            self.rvfi_mem_wdata
+        ]
+        output_ports = []
+        return input_ports + output_ports
+    def elaborate(self, platform):
+        m = Module()
+
+        insn_order = AnyConst(64)
+        register_index = AnyConst(5)
+        register_shadow = Signal(self.RISCV_FORMAL_XLEN, reset=0)
+        register_written = Signal(1, reset=0)
+
+        with m.If(self.reset):
+            m.d.sync += register_shadow.eq(0)
+            m.d.sync += register_written.eq(0)
+        with m.Else():
+            with m.If(self.check):
+                m.d.comb += Assume(self.rvfi_valid)
+                m.d.comb += Assume(insn_order == self.rvfi_order)
+
+                with m.If(register_written & (register_index == self.rvfi_rs1_addr)):
+                    m.d.comb += Assert(register_shadow == self.rvfi_rs1_rdata)
+                with m.If(register_written & (register_index == self.rvfi_rs2_addr)):
+                    m.d.comb += Assert(register_shadow == self.rvfi_rs2_rdata)
+            with m.Else():
+                with m.If(self.rvfi_valid & (self.rvfi_order < insn_order) & (register_index == self.rvfi_rd_addr)):
+                    m.d.sync += register_shadow.eq(self.rvfi_rd_wdata)
+                    m.d.sync += register_written.eq(1)
+        
+        return m