[Mlir-commits] [mlir] [mlir] Optimize `isOpTriviallyDead` greedy rewriter checks for deeply nested IR (PR #231423)

[Ivan Butygin]

================
@@ -66,49 +99,93 @@ static bool wouldOpBeTriviallyDeadImpl(Operation *rootOp) {
       }
     }
 
-    // If the op has memory effects, try to characterize them to see if the op
-    // is trivially dead here.
-    if (auto effectInterface = dyn_cast<MemoryEffectOpInterface>(op)) {
-      // Check to see if this op either has no effects, or only allocates/reads
-      // memory.
-      SmallVector<MemoryEffects::EffectInstance, 1> effects;
-      effectInterface.getEffects(effects);
+    if (!hasOnlyDeadEffects(op, hasRecursiveEffects))
+      return false;
+  }
 
-      // Gather all results of this op that are allocated.
-      SmallPtrSet<Value, 4> allocResults;
-      for (const MemoryEffects::EffectInstance &it : effects)
-        if (isa<MemoryEffects::Allocate>(it.getEffect()) && it.getValue() &&
-            it.getValue().getDefiningOp() == op)
-          allocResults.insert(it.getValue());
-
-      if (!llvm::all_of(effects, [&allocResults](
-                                     const MemoryEffects::EffectInstance &it) {
-            // We can drop effects if the value is an allocation and is a result
-            // of the operation.
-            if (allocResults.contains(it.getValue()))
-              return true;
-            // Otherwise, the effect must be a read.
-            return isa<MemoryEffects::Read>(it.getEffect());
-          })) {
-        return false;
-      }
+  // If we get here, none of the operations had effects that prevented marking
+  // 'op' as dead.
+  return true;
+}
+
+bool DeadnessCache::isOpTriviallyDead(Operation *root) {
----------------
Hardcode84 wrote:

done

https://github.com/llvm/llvm-project/pull/231423