cpu-o3: replace oldest BTB entry based on branch execution

Cao Jiaming · Cao Jiaming · commit 24dee3d361f9 · 2025-12-24T10:52:19.000+08:00
Change-Id: I49a0b5eda44fe0f5355f7177250ae83dc5b61e03
diff --git a/src/cpu/pred/btb/mbtb.cc b/src/cpu/pred/btb/mbtb.cc
@@ -555,7 +555,9 @@ MBTB::updateBTBEntry(const BTBEntry& entry, const FetchStream &stream)
         return;
     } else {
         // Not found anywhere, replace oldest in SRAM set
-        replaceOldestInSRAMSet(sram_id, btb_idx, target_mru[btb_idx], ticked_entry);
+        if (stream.exeTaken && stream.exeBranchInfo.pc == ticked_entry.pc) {
+            replaceOldestInSRAMSet(sram_id, btb_idx, target_mru[btb_idx], ticked_entry);
+        }
     }
 }
 

Original file line number	Diff line number	Diff line change
`@@ -555,7 +555,9 @@ MBTB::updateBTBEntry(const BTBEntry& entry, const FetchStream &stream)`
`555`	`555`	`return;`
`556`	`556`	`} else {`
`557`	`557`	`// Not found anywhere, replace oldest in SRAM set`
`558`		`- replaceOldestInSRAMSet(sram_id, btb_idx, target_mru[btb_idx], ticked_entry);`
	`558`	`+ if (stream.exeTaken && stream.exeBranchInfo.pc == ticked_entry.pc) {`
	`559`	`+ replaceOldestInSRAMSet(sram_id, btb_idx, target_mru[btb_idx], ticked_entry);`
	`560`	`+ }`
`559`	`561`	`}`
`560`	`562`	`}`
`561`	`563`