[MachineSink] Reduce the number of unnecessary invalidations of StoreInstrCache (NFC) (#68676)

momchil-velikov · web-flow · commit 2ceabf6bdc64 · 2023-10-12T10:06:19.000+01:00
Don't invalidate the cache when erasing instructions which cannot ever
appear in the cache.
diff --git a/llvm/lib/CodeGen/MachineSink.cpp b/llvm/lib/CodeGen/MachineSink.cpp
@@ -539,9 +539,10 @@ bool MachineSinking::PerformSinkAndFold(MachineInstr &MI,
       New = TII->emitLdStWithAddr(*SinkDst, MaybeAM);
     }
     LLVM_DEBUG(dbgs() << "yielding"; New->dump());
+    // Clear the StoreInstrCache, since we may invalidate it by erasing.
+    if (SinkDst->mayStore() && !SinkDst->hasOrderedMemoryRef())
+      StoreInstrCache.clear();
     SinkDst->eraseFromParent();
-    // Clear the StoreInstrCache, since we may have invalidated it by erasing.
-    StoreInstrCache.clear();
   }
 
   // Collect operands that need to be cleaned up because the registers no longer

Original file line number	Diff line number	Diff line change
`@@ -539,9 +539,10 @@ bool MachineSinking::PerformSinkAndFold(MachineInstr &MI,`
`539`	`539`	`New = TII->emitLdStWithAddr(*SinkDst, MaybeAM);`
`540`	`540`	`}`
`541`	`541`	`LLVM_DEBUG(dbgs() << "yielding"; New->dump());`
	`542`	`+ // Clear the StoreInstrCache, since we may invalidate it by erasing.`
	`543`	`+ if (SinkDst->mayStore() && !SinkDst->hasOrderedMemoryRef())`
	`544`	`+ StoreInstrCache.clear();`
`542`	`545`	`SinkDst->eraseFromParent();`
`543`		`- // Clear the StoreInstrCache, since we may have invalidated it by erasing.`
`544`		`- StoreInstrCache.clear();`
`545`	`546`	`}`
`546`	`547`
`547`	`548`	`// Collect operands that need to be cleaned up because the registers no longer`