From dc448c953074a70cd04c4344c8b6ebc5a30f8c3a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Adri=C3=A0=20Armejach?=
 <66964292+aarmejach@users.noreply.github.com>
Date: Fri, 17 Jan 2025 23:45:43 +0100
Subject: [PATCH] mem-ruby: set RubySystem pointer during TBE alloc (#1930)
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Currently the RubySystem pointer is set when set_tbe is performed, which
effectively clears the NetDest objects from the TBE (if any). This is
fine if the TBE has been just allocated before set_tbe is called (no
NetDest info in the TBE). However, the CHI protocol has an action
(RestoreFromHazard) that performs a set_tbe over a TBE that had already
been set, i.e., it already has valid NetDest data.

This patch sets the RubySystem pointer when the TBE is allocated, which
is more natural and follows the style already adopted in the
PerfectCacheMemory class (#1864).

Co-authored-by: Adrià Armejach <adria.armejach@bsc.es>
---
 src/mem/ruby/structures/TBETable.hh   | 19 +++++++++++++++++--
 src/mem/slicc/symbols/StateMachine.py | 13 ++++++-------
 2 files changed, 23 insertions(+), 9 deletions(-)

diff --git a/src/mem/ruby/structures/TBETable.hh b/src/mem/ruby/structures/TBETable.hh
index 72770ce42f..8c93c7dc09 100644
--- a/src/mem/ruby/structures/TBETable.hh
+++ b/src/mem/ruby/structures/TBETable.hh
@@ -45,6 +45,7 @@
 #include <unordered_map>
 
 #include "mem/ruby/common/Address.hh"
+#include "mem/ruby/system/RubySystem.hh"
 
 namespace gem5
 {
@@ -70,7 +71,7 @@ class TBETable
         return (m_number_of_TBEs - m_map.size()) >= n;
     }
 
-    void setBlockSize(const int block_size) { m_block_size = block_size; }
+    void setRubySystem(RubySystem* rs);
 
     ENTRY *getNullEntry();
     ENTRY *lookup(Addr address);
@@ -89,6 +90,10 @@ class TBETable
   private:
     int m_number_of_TBEs = 0;
     int m_block_size = 0;
+    RubySystem* m_ruby_system = nullptr;
+
+    static constexpr bool entryRequiresRubySystem =
+        std::is_member_function_pointer_v<decltype(&ENTRY::setRubySystem)>;
 };
 
 template<class ENTRY>
@@ -100,6 +105,14 @@ operator<<(std::ostream& out, const TBETable<ENTRY>& obj)
     return out;
 }
 
+template<class ENTRY>
+inline
+void TBETable<ENTRY>::setRubySystem(RubySystem* rs)
+{
+    m_ruby_system = rs;
+    m_block_size = rs->getBlockSizeBytes();
+}
+
 template<class ENTRY>
 inline bool
 TBETable<ENTRY>::isPresent(Addr address) const
@@ -116,7 +129,9 @@ TBETable<ENTRY>::allocate(Addr address)
     assert(!isPresent(address));
     assert(m_map.size() < m_number_of_TBEs);
     assert(m_block_size > 0);
-    m_map.emplace(address, ENTRY(m_block_size));
+    ENTRY new_entry = ENTRY(m_block_size);
+    new_entry.setRubySystem(m_ruby_system);
+    m_map.emplace(address, new_entry);
 }
 
 template<class ENTRY>
diff --git a/src/mem/slicc/symbols/StateMachine.py b/src/mem/slicc/symbols/StateMachine.py
index c1052086bf..d7b94c24b1 100644
--- a/src/mem/slicc/symbols/StateMachine.py
+++ b/src/mem/slicc/symbols/StateMachine.py
@@ -831,13 +831,13 @@ $c_ident::init()
                         comment = f"Type {vtype.ident} default"
                         code('*$vid = ${{vtype["default"]}}; // $comment')
 
-                    # For objects that require knowing the cache line size,
+                    # For objects that require a pointer to RubySystem,
                     # set the value here.
-                    if vtype.c_ident in ("TBETable"):
-                        block_size_func = "m_ruby_system->getBlockSizeBytes()"
-                        code(f"(*{vid}).setBlockSize({block_size_func});")
-
-                    if vtype.c_ident in ("NetDest", "PerfectCacheMemory"):
+                    if vtype.c_ident in (
+                        "NetDest",
+                        "PerfectCacheMemory",
+                        "TBETable",
+                    ):
                         code(f"(*{vid}).setRubySystem(m_ruby_system);")
 
         for param in self.config_parameters:
@@ -1271,7 +1271,6 @@ void
 $c_ident::set_tbe(${{self.TBEType.c_ident}}*& m_tbe_ptr, ${{self.TBEType.c_ident}}* m_new_tbe)
 {
   m_tbe_ptr = m_new_tbe;
-  m_tbe_ptr->setRubySystem(m_ruby_system);
 }
 
 void