6 files changed, 34 insertions, 27 deletions
diff --git a/mlir/lib/Transforms/CSE.cpp b/mlir/lib/Transforms/CSE.cpp
index 3a76594..42ba715 100644
--- a/mlir/lib/Transforms/CSE.cpp
+++ b/mlir/lib/Transforms/CSE.cpp
@@ -127,6 +127,13 @@ LogicalResult CSE::simplifyOperation(ScopedMapTy &knownValues, Operation *op) {
   if (op->isKnownTerminator())
     return failure();
 
+  // If the operation is already trivially dead just add it to the erase list.
+  if (isOpTriviallyDead(op)) {
+    opsToErase.push_back(op);
+    ++numDCE;
+    return success();
+  }
+
   // Don't simplify operations with nested blocks. We don't currently model
   // equality comparisons correctly among other things. It is also unclear
   // whether we would want to CSE such operations.
@@ -135,16 +142,9 @@ LogicalResult CSE::simplifyOperation(ScopedMapTy &knownValues, Operation *op) {
 
   // TODO(riverriddle) We currently only eliminate non side-effecting
   // operations.
-  if (!op->hasNoSideEffect())
+  if (!MemoryEffectOpInterface::hasNoEffect(op))
     return failure();
 
-  // If the operation is already trivially dead just add it to the erase list.
-  if (op->use_empty()) {
-    opsToErase.push_back(op);
-    ++numDCE;
-    return success();
-  }
-
   // Look for an existing definition for the operation.
   if (auto *existing = knownValues.lookup(op)) {
     // If we find one then replace all uses of the current operation with the
diff --git a/mlir/lib/Transforms/LoopInvariantCodeMotion.cpp b/mlir/lib/Transforms/LoopInvariantCodeMotion.cpp
index a452e33..7300948 100644
--- a/mlir/lib/Transforms/LoopInvariantCodeMotion.cpp
+++ b/mlir/lib/Transforms/LoopInvariantCodeMotion.cpp
@@ -49,16 +49,18 @@ static bool canBeHoisted(Operation *op,
   if (auto memInterface = dyn_cast<MemoryEffectOpInterface>(op)) {
     if (!memInterface.hasNoEffect())
       return false;
-  } else if (!op->hasNoSideEffect() &&
-             !op->hasTrait<OpTrait::HasRecursiveSideEffects>()) {
+    // If the operation doesn't have side effects and it doesn't recursively
+    // have side effects, it can always be hoisted.
+    if (!op->hasTrait<OpTrait::HasRecursiveSideEffects>())
+      return true;
+
+    // Otherwise, if the operation doesn't provide the memory effect interface
+    // and it doesn't have recursive side effects we treat it conservatively as
+    // side-effecting.
+  } else if (!op->hasTrait<OpTrait::HasRecursiveSideEffects>()) {
     return false;
   }
 
-  // If the operation doesn't have side effects and it doesn't recursively
-  // have side effects, it can always be hoisted.
-  if (!op->hasTrait<OpTrait::HasRecursiveSideEffects>())
-    return true;
-
   // Recurse into the regions for this op and check whether the contained ops
   // can be hoisted.
   for (auto &region : op->getRegions()) {
diff --git a/mlir/lib/Transforms/Utils/FoldUtils.cpp b/mlir/lib/Transforms/Utils/FoldUtils.cpp
index f374d38..66535ec 100644
--- a/mlir/lib/Transforms/Utils/FoldUtils.cpp
+++ b/mlir/lib/Transforms/Utils/FoldUtils.cpp
@@ -126,6 +126,12 @@ void OperationFolder::notifyRemoval(Operation *op) {
   referencedDialects.erase(it);
 }
 
+/// Clear out any constants cached inside of the folder.
+void OperationFolder::clear() {
+  foldScopes.clear();
+  referencedDialects.clear();
+}
+
 /// Tries to perform folding on the given `op`. If successful, populates
 /// `results` with the results of the folding.
 LogicalResult OperationFolder::tryToFold(
diff --git a/mlir/lib/Transforms/Utils/GreedyPatternRewriteDriver.cpp b/mlir/lib/Transforms/Utils/GreedyPatternRewriteDriver.cpp
index f9a9be5..e40a4d9 100644
--- a/mlir/lib/Transforms/Utils/GreedyPatternRewriteDriver.cpp
+++ b/mlir/lib/Transforms/Utils/GreedyPatternRewriteDriver.cpp
@@ -10,9 +10,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "mlir/Dialect/StandardOps/IR/Ops.h"
-#include "mlir/IR/Builders.h"
 #include "mlir/IR/PatternMatch.h"
+#include "mlir/Interfaces/SideEffects.h"
 #include "mlir/Transforms/FoldUtils.h"
 #include "mlir/Transforms/RegionUtils.h"
 #include "llvm/ADT/DenseMap.h"
@@ -162,11 +161,8 @@ bool GreedyPatternRewriteDriver::simplify(MutableArrayRef<Region> regions,
       if (op == nullptr)
         continue;
 
-      // If the operation has no side effects, and no users, then it is
-      // trivially dead - remove it.
-      if (op->isKnownNonTerminator() && op->hasNoSideEffect() &&
-          op->use_empty()) {
-        // Be careful to update bookkeeping.
+      // If the operation is trivially dead - remove it.
+      if (isOpTriviallyDead(op)) {
         notifyOperationRemoved(op);
         op->erase();
         continue;
@@ -204,7 +200,10 @@ bool GreedyPatternRewriteDriver::simplify(MutableArrayRef<Region> regions,
 
     // After applying patterns, make sure that the CFG of each of the regions is
     // kept up to date.
-    changed |= succeeded(simplifyRegions(regions));
+    if (succeeded(simplifyRegions(regions))) {
+      folder.clear();
+      changed = true;
+    }
   } while (changed && ++i < maxIterations);
   // Whether the rewrite converges, i.e. wasn't changed in the last iteration.
   return !changed;
diff --git a/mlir/lib/Transforms/Utils/LoopUtils.cpp b/mlir/lib/Transforms/Utils/LoopUtils.cpp
index a02c71a..7095e55 100644
--- a/mlir/lib/Transforms/Utils/LoopUtils.cpp
+++ b/mlir/lib/Transforms/Utils/LoopUtils.cpp
@@ -887,7 +887,7 @@ static LogicalResult hoistOpsBetween(loop::ForOp outer, loop::ForOp inner) {
     }
     // Skip if op has side effects.
     // TODO(ntv): loads to immutable memory regions are ok.
-    if (!op.hasNoSideEffect()) {
+    if (!MemoryEffectOpInterface::hasNoEffect(&op)) {
       status = failure();
       continue;
     }
diff --git a/mlir/lib/Transforms/Utils/RegionUtils.cpp b/mlir/lib/Transforms/Utils/RegionUtils.cpp
index 78bb609b..162091c 100644
--- a/mlir/lib/Transforms/Utils/RegionUtils.cpp
+++ b/mlir/lib/Transforms/Utils/RegionUtils.cpp
@@ -12,6 +12,7 @@
 #include "mlir/IR/RegionGraphTraits.h"
 #include "mlir/IR/Value.h"
 #include "mlir/Interfaces/ControlFlowInterfaces.h"
+#include "mlir/Interfaces/SideEffects.h"
 
 #include "llvm/ADT/DepthFirstIterator.h"
 #include "llvm/ADT/PostOrderIterator.h"
@@ -196,9 +197,8 @@ static bool isOpIntrinsicallyLive(Operation *op) {
   if (!op->isKnownNonTerminator())
     return true;
   // If the op has a side effect, we treat it as live.
-  if (!op->hasNoSideEffect())
-    return true;
-  return false;
+  // TODO: Properly handle region side effects.
+  return !MemoryEffectOpInterface::hasNoEffect(op) || op->getNumRegions() != 0;
 }
 
 static void propagateLiveness(Region &region, LiveMap &liveMap);