[Mlir-commits] [mlir] [mlir] Add support for staged dataflow analyses (PR #192998)

[Oleksandr Alex Zinenko]

================
@@ -151,13 +230,76 @@ void FooAnalysis::visitOperation(Operation *op) {
   result |= state->set(*prevState);
 
   // Modify the state with the attribute, if specified.
-  if (auto attr = op->getAttrOfType<IntegerAttr>("foo")) {
+  if (auto attr = op->getAttrOfType<IntegerAttr>(kFooAttrName)) {
     uint64_t value = attr.getUInt();
     result |= state->join(value);
   }
   propagateIfChanged(state, result);
 }
 
+LogicalResult BarAnalysis::initialize(Operation *top) {
+  if (top->getNumRegions() != 1)
+    return top->emitError("expected a single region top-level op");
+
+  if (top->getRegion(0).getBlocks().empty())
+    return top->emitError("expected at least one block in the region");
+
+  // Seed the entry state to true before observing any `FooState`.
+  (void)getOrCreate<BarState>(getProgramPointBefore(&top->getRegion(0).front()))
+      ->join(true);
+
+  for (Block &block : top->getRegion(0)) {
+    visitBlock(&block);
+    for (Operation &op : block) {
+      if (op.getNumRegions())
+        return op.emitError("unexpected op with regions");
+      visitOperation(&op);
+    }
+  }
+  return success();
+}
+
+LogicalResult BarAnalysis::visit(ProgramPoint *point) {
+  if (!point->isBlockStart())
+    visitOperation(point->getPrevOp());
+  else
+    visitBlock(point->getBlock());
+  return success();
+}
+
+void BarAnalysis::visitBlock(Block *block) {
+  if (block->isEntryBlock())
+    return;
+
+  ProgramPoint *point = getProgramPointBefore(block);
+  BarState *state = getOrCreate<BarState>(point);
+  ChangeResult result = ChangeResult::NoChange;
+  for (Block *pred : block->getPredecessors()) {
+    const BarState *predState = getOrCreateFor<BarState>(
+        point, getProgramPointAfter(pred->getTerminator()));
+    result |= state->join(*predState);
+  }
+  propagateIfChanged(state, result);
+}
+
+void BarAnalysis::visitOperation(Operation *op) {
+  ProgramPoint *point = getProgramPointAfter(op);
+  BarState *state = getOrCreate<BarState>(point);
+  ChangeResult result = ChangeResult::NoChange;
+
+  const BarState *prevState =
+      getOrCreateFor<BarState>(point, getProgramPointBefore(op));
+  result |= state->join(*prevState);
+
+  if (op->hasAttr(kTagAttrName)) {
+    const FooState *fooState = getOrCreateFor<FooState>(point, point);
+    if (fooState->isUninitialized())
+      return;
+    result |= state->join((fooState->getValue() & 0x3) != 0);
----------------
ftynse wrote:

Why do we need this whole magic with `0x3`? Wouldn't just setting the state to "true" if the foo state is initialized and "false" otherwise enough to demonstrate that the foo state is there? Don't add cognitive complexity to debugging.

https://github.com/llvm/llvm-project/pull/192998