util: support --bp-type=DecoupledBPUWithBTB in xiangshan.py

OpenXiangShan · Feb 28, 2025 · 7ee27fe · 7ee27fe
1 parent 1d1c79d
commit 7ee27fe
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Showing 3 changed files with 15 additions and 3 deletions.
diff --git a/configs/example/xiangshan.py b/configs/example/xiangshan.py
@@ -113,15 +113,25 @@ def build_test_system(np, args):
         args.enable_loop_buffer = True
 
     for i in range(np):
-        if args.bp_type is None or args.bp_type == 'DecoupledBPUWithFTB':
+        if args.bp_type is None or args.bp_type == 'DecoupledBPUWithFTB' or args.bp_type == 'DecoupledBPUWithBTB':
             enable_bp_db = len(args.enable_bp_db) > 1
             if enable_bp_db:
                 bp_db_switches = args.enable_bp_db[1] + ['basic']
                 print("BP db switches:", bp_db_switches)
             else:
                 bp_db_switches = []
-
-            test_sys.cpu[i].branchPred = DecoupledBPUWithFTB(
+            # for DecoupledBPUWithBTB, loop predictor and jump ahead predictor are not supported
+            if args.bp_type == 'DecoupledBPUWithBTB':
+                if args.enable_loop_predictor or args.enable_loop_buffer:
+                    print("loop predictor and loop buffer not supported for DecoupledBPUWithBTB")
+                    args.enable_loop_predictor = False
+                    args.enable_loop_buffer = False
+                if args.enable_jump_ahead_predictor:
+                    print("jump ahead predictor not supported for DecoupledBPUWithBTB")
+                    args.enable_jump_ahead_predictor = False
+
+            BPClass = ObjectList.bp_list.get(args.bp_type)
+            test_sys.cpu[i].branchPred = BPClass(
                                             bpDBSwitches=bp_db_switches,
                                             enableLoopBuffer=args.enable_loop_buffer,
                                             enableLoopPredictor=args.enable_loop_predictor,

diff --git a/src/cpu/pred/BranchPredictor.py b/src/cpu/pred/BranchPredictor.py
@@ -999,6 +999,7 @@ class BTBTAGE(TimedBaseBTBPredictor):
     cxx_class = 'gem5::branch_prediction::btb_pred::BTBTAGE'
     cxx_header = "cpu/pred/btb/btb_tage.hh"
 
+    enableSC = Param.Bool(False, "Enable SC or not")    # TODO: BTBTAGE doesn't support SC
     numPredictors = Param.Unsigned(4, "Number of TAGE predictors")
     tableSizes = VectorParam.Unsigned([4096]*4, "the ITTAGE T0~Tn length")
     TTagBitSizes = VectorParam.Unsigned([8]*4, "the T0~Tn entry's tag bit size")

diff --git a/src/cpu/pred/btb/btb_tage.cc b/src/cpu/pred/btb/btb_tage.cc
@@ -26,6 +26,7 @@ tablePcShifts(p.TTagPcShifts),
 histLengths(p.histLengths),
 maxHistLen(p.maxHistLen),
 numTablesToAlloc(p.numTablesToAlloc),
+enableSC(p.enableSC),
 tageStats(this, p.numPredictors)
 {
     DPRINTF(TAGE, "BTBTAGE constructor\n");