From: Luke Kenneth Casson Leighton <lkcl@lkcl.net>
Date: Tue, 2 May 2023 17:44:12 +0000 (+0100)
Subject: start on cycle-accurate model of inorder core
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=c7825f315360293049acecd13675aab5f8fd0772;p=openpower-isa.git

start on cycle-accurate model of inorder core
---

diff --git a/src/openpower/cyclemodel/inorder.py b/src/openpower/cyclemodel/inorder.py
new file mode 100644
index 00000000..42176990
--- /dev/null
+++ b/src/openpower/cyclemodel/inorder.py
@@ -0,0 +1,37 @@
+#!/usr/bin/env python3
+# An In-order cycle-accurate model of a Power ISA 3.0 hardware implementation
+
+class RegisterWrite(set):
+    def expect_write(self, regs): self.update(regs)
+    def write_expected(self, regs): len(self.intersection(regs)) != 0
+    def retire_write(self, regs): self.difference_update(regs)
+
+class Execute:
+    def __init__(self, cpu):
+        self.stages = []
+        self.cpu = cpu
+
+    def add_stage(self, cycles_away, stage):
+        while cycles_away > len(self.stages):
+            self.stages.append([])
+        self.stages[cycles_away].append(stage)
+
+    def add_instruction(self, insn, writeregs):
+        self.add_stage(2, {'insn': insn, 'writes': writeregs})
+
+    def tick(self):
+        self.stages.pop(0)
+
+    def process_instructions(self):
+        stall = False                 # stalls if not all writes possible
+        instructions = self.stages[0] # get list of instructions
+        to_write = set()              # need to know total writes
+        for instruction in instructions:
+            to_write.update(instruction['writes'])
+        # see if all writes can be done, otherwise stall
+        writes_possible = self.cpu.all_writes_possible(to_write):
+        if writes_possible != to_write:
+            stall = True
+        # retire the writes that are possible in this cycle (regfile writes)
+        self.cpu.regs.retire_write(to_write)
+        return stall