From fdb61389099cee41b86c25c3d1ddb660b509e5fa Mon Sep 17 00:00:00 2001
From: Julian Blake Kongslie
Date: Sat, 19 Nov 2022 16:29:27 -0800
Subject: Pipelined microarchitecture, which even almost works!

Includes such horrors as the "unstore" operation for undoing
autoincremented addresses on instructions subsequently found to be
bogus.
---
 uarch/core.h | 74 ++++++++++++++++++++++++++++++++++++++++++++++++------------
 1 file changed, 60 insertions(+), 14 deletions(-)

(limited to 'uarch/core.h')

diff --git a/uarch/core.h b/uarch/core.h
index a6772f3..b53a205 100644
--- a/uarch/core.h
+++ b/uarch/core.h
@@ -13,6 +13,12 @@
 
 struct core;
 
+struct restart {
+    infra::transaction tr;
+    unsigned int new_pc;
+    bool interrupt;
+};
+
 struct fetch_bundle {
     infra::transaction tr;
     unsigned int gen;
@@ -20,10 +26,12 @@ struct fetch_bundle {
     memory::line data;
 };
 
-struct fetch_restart {
+struct inst_bundle {
     infra::transaction tr;
-    unsigned int new_gen;
-    unsigned int new_pc;
+    unsigned int gen;
+    unsigned int pc;
+    std::uint64_t icount;
+    instruction_context inst;
 };
 
 struct fetch_stage : public infra::sim {
@@ -31,8 +39,8 @@ struct fetch_stage : public infra::sim {
 
     memory::inline_cache<8, 2> cache;
 
-    unsigned int gen = 0;
     unsigned int pc;
+
     bool didrestart = false;
     bool outstandingfill = false;
 
@@ -44,20 +52,38 @@ struct fetch_stage : public infra::sim {
 struct decode_stage : public infra::sim {
     core &c;
 
+    bool interrupt = false;
+
+    unsigned int pc;
+    std::uint64_t icount;
+
+    decode_stage(core &c);
+
+    void clock();
+};
+
+struct indir_stage : public infra::sim {
+    core &c;
+
     unsigned int gen = 0;
 
-    bool interrupt = false;
+    indir_stage(core &c);
+
+    void clock();
+};
+
+struct exec_stage : public infra::sim {
+    core &c;
+
+    unsigned int gen = 0;
 
     unsigned int acc;
     unsigned int link;
     unsigned int mq;
     unsigned int pc;
     std::array<uint_fast32_t, NUM_CTLREGS> ctlregs;
-    std::uint64_t icount;
-    instruction_context inst;
-    bool outstandingfill = false;
 
-    decode_stage(core &c);
+    exec_stage(core &c);
 
     void clock();
 };
@@ -66,30 +92,50 @@ struct core {
     iomodel &system;
     funcchecker checker;
 
-    memory::dram mem{12};
+    std::optional<restart> restarto;
+    unsigned int gen = 0;
+
+    std::uint64_t icount;
+
+    memory::dram mem{0};
     infra::port<memory::dram::command> mem_commandp;
 
-    infra::priority_arbiter<memory::dram::command, 2> mem_command_arb;
+    infra::priority_arbiter<memory::dram::command, 5> mem_command_arb;
 
     infra::port<memory::dram::command> fetch_mem_commandp;
     infra::port<memory::dram::response> fetch_mem_responsep;
     infra::port<fetch_bundle> fetch_bundlep;
-    std::optional<fetch_restart> fetch_restarto;
 
     infra::port<memory::dram::command> decode_mem_commandp;
     infra::port<memory::dram::response> decode_mem_responsep;
+    infra::port<inst_bundle> decode_to_exec_instp;
+
+    infra::port<inst_bundle> indir_instp;
+    infra::port<memory::dram::command> indir_mem_load_commandp;
+    infra::port<memory::dram::command> indir_mem_store_commandp;
+    infra::port<memory::dram::response> indir_mem_responsep;
+    infra::port<inst_bundle> indir_to_exec_instp;
+
+    infra::port<memory::dram::command> exec_mem_commandp;
+    infra::port<memory::dram::response> exec_mem_responsep;
 
     // Construction order is execution order within a cycle, so this list should be back-to-front (for zero-cycle restarts)
+    exec_stage exec{*this};
+    indir_stage indir{*this};
     decode_stage decode{*this};
     fetch_stage fetch{*this};
 
     core(iomodel &model)
         : system(model)
         , checker(model)
+        , icount(checker.icount)
     {
         mem.commandp = &mem_commandp;
         mem_command_arb.outp = &mem_commandp;
-        mem_command_arb.peerp[0] = &decode_mem_commandp;
-        mem_command_arb.peerp[1] = &fetch_mem_commandp;
+        mem_command_arb.peerp[0] = &exec_mem_commandp;
+        mem_command_arb.peerp[1] = &indir_mem_store_commandp;
+        mem_command_arb.peerp[2] = &indir_mem_load_commandp;
+        mem_command_arb.peerp[3] = &decode_mem_commandp;
+        mem_command_arb.peerp[4] = &fetch_mem_commandp;
     }
 };
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