[Mlir-commits] [mlir] [MLIR][SideEffects][MemoryEffects] Modified LICM to be more aggressive when checking movability of ops with MemWrite effects (PR #155344)

[Mehdi Amini]

================
@@ -58,13 +60,170 @@ static bool canBeHoisted(Operation *op,
       op, [&](OpOperand &operand) { return definedOutside(operand.get()); });
 }
 
+/// Merges srcEffect's Memory Effect on its resource into the
+/// resourceConflicts map, flagging the resource if the srcEffect
+/// results in a conflict.
+///
+/// \param resourceConflicts The map to store resources' conflicts status.
+/// \param srcEffect The effect to merge into the resourceConflicts map.
+/// \param srcHasConflict Whether the srcEffect results in a conflict based
+/// on higher level analysis.
+///
+/// resourceConflicts is modified by the function and will be non-empty
+static void
+mergeResource(DenseMap<TypeID, std::pair<bool, MemoryEffects::EffectInstance>>
+                  &resourceConflicts,
+              const MemoryEffects::EffectInstance &srcEffect,
+              bool srcHasConflict) {
+
+  TypeID srcResourceID = srcEffect.getResource()->getResourceID();
+
+  bool srcIsAllocOrFree = isa<MemoryEffects::Allocate>(srcEffect.getEffect()) ||
+                          isa<MemoryEffects::Free>(srcEffect.getEffect());
+
+  bool conflict = srcHasConflict || srcIsAllocOrFree;
+
+  auto dstIt = resourceConflicts.find(srcResourceID);
+
+  // if it doesn't already exist, create entry for resource in map
+  if (dstIt == resourceConflicts.end()) {
+    resourceConflicts.insert(
+        std::make_pair(srcResourceID, std::make_pair(conflict, srcEffect)));
+    return;
+  }
----------------
joker-eph wrote:

```suggestion
  auto [dstIt, inserted] = resourceConflicts.insert(
        std::make_pair(srcResourceID, std::make_pair(conflict, srcEffect)));
  if (inserted)
    return;
```

Nit: reduce the number of hash map lookups.

https://github.com/llvm/llvm-project/pull/155344