cpu-o3: update tick handling in MBTB entry

Cao Jiaming · Cao Jiaming · commit ff995689cdad · 2025-12-24T10:18:14.000+08:00
Change-Id: If352e96f0a50c922a32f6ad41dc871cbc92a14f3
diff --git a/src/cpu/pred/btb/mbtb.cc b/src/cpu/pred/btb/mbtb.cc
@@ -540,9 +540,10 @@ MBTB::updateBTBEntry(const BTBEntry& entry, const FetchStream &stream)
     }
 
     auto entry_to_write = buildUpdatedEntry(entry, existing_ptr, stream, btb_tag);
-    auto ticked_entry = TickedBTBEntry(entry_to_write, it->tick);
-    if (stream.exeBranchInfo.pc == ticked_entry.pc && stream.exeTaken) {
-        ticked_entry.tick = curTick();
+    auto ticked_entry = TickedBTBEntry(entry_to_write, curTick());
+    if (stream.exeBranchInfo.pc != ticked_entry.pc) {
+        // do not update tick if this entry is not for the executed branch
+        ticked_entry.tick = it->tick;
     }
 
     if (found) {

Original file line number	Diff line number	Diff line change
`@@ -540,9 +540,10 @@ MBTB::updateBTBEntry(const BTBEntry& entry, const FetchStream &stream)`
`540`	`540`	`}`
`541`	`541`
`542`	`542`	`auto entry_to_write = buildUpdatedEntry(entry, existing_ptr, stream, btb_tag);`
`543`		`- auto ticked_entry = TickedBTBEntry(entry_to_write, it->tick);`
`544`		`- if (stream.exeBranchInfo.pc == ticked_entry.pc && stream.exeTaken) {`
`545`		`- ticked_entry.tick = curTick();`
	`543`	`+ auto ticked_entry = TickedBTBEntry(entry_to_write, curTick());`
	`544`	`+ if (stream.exeBranchInfo.pc != ticked_entry.pc) {`
	`545`	`+ // do not update tick if this entry is not for the executed branch`
	`546`	`+ ticked_entry.tick = it->tick;`
`546`	`547`	`}`
`547`	`548`
`548`	`549`	`if (found) {`