[Mlir-commits] [mlir] [MLIR][Mem2Reg] Add support for region control flow and SCF (PR #185036)

[Tobias Gysi]

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@@ -430,13 +480,30 @@ MemorySlotPromotionAnalyzer::computeInfo() {
   // promotion to happen. These operations need to resolve some of their uses,
   // either by rewiring them or simply deleting themselves. If any of them
   // cannot find a way to resolve their blocking uses, we abort the promotion.
-  if (failed(computeBlockingUses(info.userToBlockingUses)))
+  // We also compute at this stage the regions that will be analyzed for
+  // reaching definition information.
+  if (failed(
+          computeBlockingUses(info.userToBlockingUses, info.regionsToPromote)))
     return {};
 
+  // Compute the blocks containing a store for each region, either directly or
+  // inherited from a nested region. As a side effect, `definingBlocks` contains
+  // all regions with at least one store.
+  DenseMap<Region *, SmallPtrSet<Block *, 16>> definingBlocks;
+  for (Operation *user : slot.ptr.getUsers())
+    if (auto storeOp = dyn_cast<PromotableMemOpInterface>(user))
+      if (storeOp.storesTo(slot))
+        definingBlocks[user->getParentRegion()].insert(user->getBlock());
+  for (auto &[region, regionInfo] : info.regionsToPromote)
+    if (regionInfo.hasValueStores)
+      definingBlocks[region->getParentRegion()].insert(
+          region->getParentOp()->getBlock());
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gysit wrote:

Is it sufficient to add the parent block here? Don't we need to add the entire chain of parent blocks?

https://github.com/llvm/llvm-project/pull/185036