Add check for causality

checks/rvfi_causal_check.py

@@ -0,0 +1,81 @@
+from nmigen import *
+from nmigen.hdl.ast import *
+
+class rvfi_causal_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)
+        found_non_causal = Signal(1, reset=0)
+
+        with m.If(self.reset):
+            m.d.sync += found_non_causal.eq(0)
+        with m.Else():
+            with m.If(self.check):
+                m.d.comb += Assume(register_index != 0)
+                m.d.comb += Assume(self.rvfi_valid)
+                m.d.comb += Assume(register_index == self.rvfi_rd_addr)
+                m.d.comb += Assume(insn_order == self.rvfi_order)
+                m.d.comb += Assert(~found_non_causal)
+            with m.Else():
+                with m.If(self.rvfi_valid & (self.rvfi_order > insn_order) & \
+                    ((register_index == self.rvfi_rs1_addr) | \
+                    (register_index == self.rvfi_rs2_addr))):
+                    m.d.sync += found_non_causal.eq(1)
+
+        return m