[gem5-dev] Change in gem5/gem5[develop]: mem-ruby: TBE table supports multiple entries

[Gerrit]

Tiago Mück has uploaded this change for review. (  
https://gem5-review.googlesource.com/c/public/gem5/+/31261 )

Change subject: mem-ruby: TBE table supports multiple entries
......................................................................

mem-ruby: TBE table supports multiple entries

allocateNext allows a new TBE to be allocated for the same address
before deallocating the current one. New entries are visible and
returned by lookup after the previous one is deallocated.

Change-Id: Ia97b1b328e1fa23b300b38402bdf381ee48b6ec7
Signed-off-by: Tiago Mück <tiago.m...@arm.com>
---
M src/mem/ruby/structures/TBETable.hh
1 file changed, 27 insertions(+), 10 deletions(-)



diff --git a/src/mem/ruby/structures/TBETable.hh  
b/src/mem/ruby/structures/TBETable.hh
index b4a723b..1505743 100644
--- a/src/mem/ruby/structures/TBETable.hh
+++ b/src/mem/ruby/structures/TBETable.hh
@@ -42,6 +42,7 @@
 #define __MEM_RUBY_STRUCTURES_TBETABLE_HH__

 #include <iostream>
+#include <queue>
 #include <unordered_map>

 #include "mem/ruby/common/Address.hh"
@@ -51,17 +52,18 @@
 {
   public:
     TBETable(int number_of_TBEs)
-        : m_number_of_TBEs(number_of_TBEs)
+        : m_size(0), m_number_of_TBEs(number_of_TBEs)
     {
     }

     bool isPresent(Addr address) const;
+    ENTRY* allocateNext(Addr address);
     void allocate(Addr address);
     void deallocate(Addr address);
     bool
     areNSlotsAvailable(int n, Tick current_time) const
     {
-        return (m_number_of_TBEs - m_map.size()) >= n;
+        return (m_number_of_TBEs - m_size) >= n;
     }

     ENTRY *getNullEntry();
@@ -76,7 +78,8 @@
     TBETable& operator=(const TBETable& obj);

     // Data Members (m_prefix)
-    std::unordered_map<Addr, ENTRY> m_map;
+    int m_size;
+    std::unordered_map<Addr, std::queue<ENTRY>> m_map;

   private:
     int m_number_of_TBEs;
@@ -96,8 +99,8 @@
 TBETable<ENTRY>::isPresent(Addr address) const
 {
     assert(address == makeLineAddress(address));
-    assert(m_map.size() <= m_number_of_TBEs);
-    return !!m_map.count(address);
+    assert(m_size <= m_number_of_TBEs);
+    return m_map.count(address) > 0;
 }

 template<class ENTRY>
@@ -105,8 +108,17 @@
 TBETable<ENTRY>::allocate(Addr address)
 {
     assert(!isPresent(address));
-    assert(m_map.size() < m_number_of_TBEs);
-    m_map[address] = ENTRY();
+    allocateNext(address);
+}
+
+template<class ENTRY>
+inline ENTRY*
+TBETable<ENTRY>::allocateNext(Addr address)
+{
+    assert(m_size < m_number_of_TBEs);
+    m_map[address].emplace();
+    ++m_size;
+    return &(m_map[address].back());
 }

 template<class ENTRY>
@@ -114,8 +126,12 @@
 TBETable<ENTRY>::deallocate(Addr address)
 {
     assert(isPresent(address));
-    assert(m_map.size() > 0);
-    m_map.erase(address);
+    assert(m_size > 0);
+    auto iter = m_map.find(address);
+    iter->second.pop();
+    if (iter->second.empty())
+      m_map.erase(iter);
+    --m_size;
 }

 template<class ENTRY>
@@ -130,7 +146,8 @@
 inline ENTRY*
 TBETable<ENTRY>::lookup(Addr address)
 {
-  if (m_map.find(address) != m_map.end()) return  
&(m_map.find(address)->second);
+  if (m_map.find(address) != m_map.end())
+    return &(m_map.find(address)->second.front());
   return NULL;
 }


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Gerrit-Project: public/gem5
Gerrit-Branch: develop
Gerrit-Change-Id: Ia97b1b328e1fa23b300b38402bdf381ee48b6ec7
Gerrit-Change-Number: 31261
Gerrit-PatchSet: 1
Gerrit-Owner: Tiago Mück <tiago.m...@arm.com>
Gerrit-MessageType: newchange
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