fix: enable BTB ckpt

feat: add BTB json ckpt (back)

Because of the modification brought by TAGE to the BTB,
it was necessary to work it out again.

components/BranchPredictor/BTB.cpp

@@ -96,6 +96,40 @@ BTB::update(BranchFeedback const& aFeedback)
     return update(aFeedback.thePC, aFeedback.theActualType, aFeedback.theActualTarget);
 }
 
+json
+BTB::saveState() const {
+
+    json checkpoint;
+
+    for(size_t i = 0; i < theBTBSets; i++){
+
+      checkpoint.emplace_back(json::array());
+
+      auto block = theBTB[i].blocks.begin();
+      auto end = theBTB[i].blocks.end();
+
+      size_t j = 0;
+      for (; block != end; block++, j++) {
+        uint8_t type = 15;
+        switch(block->theBranchType){
+          case kNonBranch: type = 0; break;
+          case kConditional: type = 1; break;
+          case kUnconditional: type = 2; break;
+          case kCall: type = 3; break;
+          case kIndirectReg: type = 4; break;
+          case kIndirectCall: type = 5; break;
+          case kReturn: type = 6; break;
+          default:
+            //DBG_Assert(false, (<< "Don't know how to save type " << block->theBranchType));
+            break;
+        }
+        checkpoint[i][j] = {{"PC", (uint64_t)block->thePC}, {"target", (uint64_t)block->theTarget}, {"type", (uint8_t)type}};
+      }
+    }
+
+    return checkpoint;
+
+}
 // void
 // BTB::loadState(json checkpoint)
 //{

components/BranchPredictor/BTB.hpp

@@ -3,9 +3,11 @@
 
 #include "BTBSet.hpp"
 #include "core/types.hpp"
+#include "core/checkpoint/json.hpp"
 
 #include <vector>
 
+using json = nlohmann::json;
 using namespace Flexus::SharedTypes;
 
 class BTB
@@ -35,6 +37,8 @@ class BTB
     // Update or add a new entry to the BTB
     bool update(VirtualMemoryAddress aPC, eBranchType aType, VirtualMemoryAddress aTarget);
     bool update(BranchFeedback const& aFeedback);
+
+    json saveState() const;
 };
 
 #endif

components/BranchPredictor/BTBSet.hpp

@@ -13,12 +13,12 @@
  */
 class BTBSet
 {
-  private:
+  public:
     std::vector<BTBEntry> blocks; // Array of blocks make up a set
+  private:
     std::vector<uint32_t> replacementQueue;
-
     void updateReplacementQueue(uint32_t index); // [MADHUR] Right now, it is LRU
-
+    //
   public:
     BTBSet();
 

components/BranchPredictor/BranchPredictor.cpp

@@ -166,8 +166,8 @@ void BranchPredictor::saveState(std::string const& aDirName) {
 
     json checkpoint;
 
-    // checkpoint["BTB"] = theBTB.saveState();
-    checkpoint["TAGE"] = theTage.saveState();
+    checkpoint["btb"] = theBTB.saveState();
+    checkpoint["tage"] = theTage.saveState();
 
     ofs << std::setw(4) << checkpoint << std::endl;
     ofs.close();