[mlir][Transforms][NFC] Remove reconcileUnrealizedCasts forward-declaration (#158291)

This is a follow-up to
https://github.com/llvm/llvm-project/pull/158067/files#r2343711946.

Author: matthias-springer

mlir/lib/Transforms/Utils/DialectConversion.cpp

@@ -3097,6 +3097,151 @@ unsigned OperationLegalizer::applyCostModelToPatterns(
   return minDepth;
 }
 
+//===----------------------------------------------------------------------===//
+// Reconcile Unrealized Casts
+//===----------------------------------------------------------------------===//
+
+/// Try to reconcile all given UnrealizedConversionCastOps and store the
+/// left-over ops in `remainingCastOps` (if provided). See documentation in
+/// DialectConversion.h for more details.
+/// The `isCastOpOfInterestFn` is used to filter the cast ops to proceed: the
+/// algorithm may visit an operand (or user) which is a cast op, but will not
+/// try to reconcile it if not in the filtered set.
+template <typename RangeT>
+static void reconcileUnrealizedCastsImpl(
+    RangeT castOps,
+    function_ref<bool(UnrealizedConversionCastOp)> isCastOpOfInterestFn,
+    SmallVectorImpl<UnrealizedConversionCastOp> *remainingCastOps) {
+  // A worklist of cast ops to process.
+  SetVector<UnrealizedConversionCastOp> worklist(llvm::from_range, castOps);
+
+  // Helper function that return the unrealized_conversion_cast op that
+  // defines all inputs of the given op (in the same order). Return "nullptr"
+  // if there is no such op.
+  auto getInputCast =
+      [](UnrealizedConversionCastOp castOp) -> UnrealizedConversionCastOp {
+    if (castOp.getInputs().empty())
+      return {};
+    auto inputCastOp =
+        castOp.getInputs().front().getDefiningOp<UnrealizedConversionCastOp>();
+    if (!inputCastOp)
+      return {};
+    if (inputCastOp.getOutputs() != castOp.getInputs())
+      return {};
+    return inputCastOp;
+  };
+
+  // Process ops in the worklist bottom-to-top.
+  while (!worklist.empty()) {
+    UnrealizedConversionCastOp castOp = worklist.pop_back_val();
+
+    // Traverse the chain of input cast ops to see if an op with the same
+    // input types can be found.
+    UnrealizedConversionCastOp nextCast = castOp;
+    while (nextCast) {
+      if (nextCast.getInputs().getTypes() == castOp.getResultTypes()) {
+        if (llvm::any_of(nextCast.getInputs(), [&](Value v) {
+              return v.getDefiningOp() == castOp;
+            })) {
+          // Ran into a cycle.
+          break;
+        }
+
+        // Found a cast where the input types match the output types of the
+        // matched op. We can directly use those inputs.
+        castOp.replaceAllUsesWith(nextCast.getInputs());
+        break;
+      }
+      nextCast = getInputCast(nextCast);
+    }
+  }
+
+  // A set of all alive cast ops. I.e., ops whose results are (transitively)
+  // used by an op that is not a cast op.
+  DenseSet<Operation *> liveOps;
+
+  // Helper function that marks the given op and transitively reachable input
+  // cast ops as alive.
+  auto markOpLive = [&](Operation *rootOp) {
+    SmallVector<Operation *> worklist;
+    worklist.push_back(rootOp);
+    while (!worklist.empty()) {
+      Operation *op = worklist.pop_back_val();
+      if (liveOps.insert(op).second) {
+        // Successfully inserted: process reachable input cast ops.
+        for (Value v : op->getOperands())
+          if (auto castOp = v.getDefiningOp<UnrealizedConversionCastOp>())
+            if (isCastOpOfInterestFn(castOp))
+              worklist.push_back(castOp);
+      }
+    }
+  };
+
+  // Find all alive cast ops.
+  for (UnrealizedConversionCastOp op : castOps) {
+    // The op may have been marked live already as being an operand of another
+    // live cast op.
+    if (liveOps.contains(op.getOperation()))
+      continue;
+    // If any of the users is not a cast op, mark the current op (and its
+    // input ops) as live.
+    if (llvm::any_of(op->getUsers(), [&](Operation *user) {
+          auto castOp = dyn_cast<UnrealizedConversionCastOp>(user);
+          return !castOp || !isCastOpOfInterestFn(castOp);
+        }))
+      markOpLive(op);
+  }
+
+  // Erase all dead cast ops.
+  for (UnrealizedConversionCastOp op : castOps) {
+    if (liveOps.contains(op)) {
+      // Op is alive and was not erased. Add it to the remaining cast ops.
+      if (remainingCastOps)
+        remainingCastOps->push_back(op);
+      continue;
+    }
+
+    // Op is dead. Erase it.
+    op->dropAllUses();
+    op->erase();
+  }
+}
+
+void mlir::reconcileUnrealizedCasts(
+    ArrayRef<UnrealizedConversionCastOp> castOps,
+    SmallVectorImpl<UnrealizedConversionCastOp> *remainingCastOps) {
+  // Set of all cast ops for faster lookups.
+  DenseSet<UnrealizedConversionCastOp> castOpSet;
+  for (UnrealizedConversionCastOp op : castOps)
+    castOpSet.insert(op);
+  reconcileUnrealizedCasts(castOpSet, remainingCastOps);
+}
+
+void mlir::reconcileUnrealizedCasts(
+    const DenseSet<UnrealizedConversionCastOp> &castOps,
+    SmallVectorImpl<UnrealizedConversionCastOp> *remainingCastOps) {
+  reconcileUnrealizedCastsImpl(
+      llvm::make_range(castOps.begin(), castOps.end()),
+      [&](UnrealizedConversionCastOp castOp) {
+        return castOps.contains(castOp);
+      },
+      remainingCastOps);
+}
+
+namespace mlir {
+static void reconcileUnrealizedCasts(
+    const DenseMap<UnrealizedConversionCastOp, UnresolvedMaterializationInfo>
+        &castOps,
+    SmallVectorImpl<UnrealizedConversionCastOp> *remainingCastOps) {
+  reconcileUnrealizedCastsImpl(
+      castOps.keys(),
+      [&](UnrealizedConversionCastOp castOp) {
+        return castOps.contains(castOp);
+      },
+      remainingCastOps);
+}
+} // namespace mlir
+
 //===----------------------------------------------------------------------===//
 // OperationConverter
 //===----------------------------------------------------------------------===//
@@ -3118,13 +3263,6 @@ enum OpConversionMode {
 } // namespace
 
 namespace mlir {
-
-// Predeclaration only.
-static void reconcileUnrealizedCasts(
-    const DenseMap<UnrealizedConversionCastOp, UnresolvedMaterializationInfo>
-        &castOps,
-    SmallVectorImpl<UnrealizedConversionCastOp> *remainingCastOps);
-
 // This class converts operations to a given conversion target via a set of
 // rewrite patterns. The conversion behaves differently depending on the
 // conversion mode.
@@ -3302,149 +3440,6 @@ LogicalResult OperationConverter::convertOperations(ArrayRef<Operation *> ops) {
   return success();
 }
 
-//===----------------------------------------------------------------------===//
-// Reconcile Unrealized Casts
-//===----------------------------------------------------------------------===//
-
-/// Try to reconcile all given UnrealizedConversionCastOps and store the
-/// left-over ops in `remainingCastOps` (if provided). See documentation in
-/// DialectConversion.h for more details.
-/// The `isCastOpOfInterestFn` is used to filter the cast ops to proceed: the
-/// algorithm may visit an operand (or user) which is a cast op, but will not
-/// try to reconcile it if not in the filtered set.
-template <typename RangeT>
-static void reconcileUnrealizedCastsImpl(
-    RangeT castOps,
-    function_ref<bool(UnrealizedConversionCastOp)> isCastOpOfInterestFn,
-    SmallVectorImpl<UnrealizedConversionCastOp> *remainingCastOps) {
-  // A worklist of cast ops to process.
-  SetVector<UnrealizedConversionCastOp> worklist(llvm::from_range, castOps);
-
-  // Helper function that return the unrealized_conversion_cast op that
-  // defines all inputs of the given op (in the same order). Return "nullptr"
-  // if there is no such op.
-  auto getInputCast =
-      [](UnrealizedConversionCastOp castOp) -> UnrealizedConversionCastOp {
-    if (castOp.getInputs().empty())
-      return {};
-    auto inputCastOp =
-        castOp.getInputs().front().getDefiningOp<UnrealizedConversionCastOp>();
-    if (!inputCastOp)
-      return {};
-    if (inputCastOp.getOutputs() != castOp.getInputs())
-      return {};
-    return inputCastOp;
-  };
-
-  // Process ops in the worklist bottom-to-top.
-  while (!worklist.empty()) {
-    UnrealizedConversionCastOp castOp = worklist.pop_back_val();
-
-    // Traverse the chain of input cast ops to see if an op with the same
-    // input types can be found.
-    UnrealizedConversionCastOp nextCast = castOp;
-    while (nextCast) {
-      if (nextCast.getInputs().getTypes() == castOp.getResultTypes()) {
-        if (llvm::any_of(nextCast.getInputs(), [&](Value v) {
-              return v.getDefiningOp() == castOp;
-            })) {
-          // Ran into a cycle.
-          break;
-        }
-
-        // Found a cast where the input types match the output types of the
-        // matched op. We can directly use those inputs.
-        castOp.replaceAllUsesWith(nextCast.getInputs());
-        break;
-      }
-      nextCast = getInputCast(nextCast);
-    }
-  }
-
-  // A set of all alive cast ops. I.e., ops whose results are (transitively)
-  // used by an op that is not a cast op.
-  DenseSet<Operation *> liveOps;
-
-  // Helper function that marks the given op and transitively reachable input
-  // cast ops as alive.
-  auto markOpLive = [&](Operation *rootOp) {
-    SmallVector<Operation *> worklist;
-    worklist.push_back(rootOp);
-    while (!worklist.empty()) {
-      Operation *op = worklist.pop_back_val();
-      if (liveOps.insert(op).second) {
-        // Successfully inserted: process reachable input cast ops.
-        for (Value v : op->getOperands())
-          if (auto castOp = v.getDefiningOp<UnrealizedConversionCastOp>())
-            if (isCastOpOfInterestFn(castOp))
-              worklist.push_back(castOp);
-      }
-    }
-  };
-
-  // Find all alive cast ops.
-  for (UnrealizedConversionCastOp op : castOps) {
-    // The op may have been marked live already as being an operand of another
-    // live cast op.
-    if (liveOps.contains(op.getOperation()))
-      continue;
-    // If any of the users is not a cast op, mark the current op (and its
-    // input ops) as live.
-    if (llvm::any_of(op->getUsers(), [&](Operation *user) {
-          auto castOp = dyn_cast<UnrealizedConversionCastOp>(user);
-          return !castOp || !isCastOpOfInterestFn(castOp);
-        }))
-      markOpLive(op);
-  }
-
-  // Erase all dead cast ops.
-  for (UnrealizedConversionCastOp op : castOps) {
-    if (liveOps.contains(op)) {
-      // Op is alive and was not erased. Add it to the remaining cast ops.
-      if (remainingCastOps)
-        remainingCastOps->push_back(op);
-      continue;
-    }
-
-    // Op is dead. Erase it.
-    op->dropAllUses();
-    op->erase();
-  }
-}
-
-void mlir::reconcileUnrealizedCasts(
-    ArrayRef<UnrealizedConversionCastOp> castOps,
-    SmallVectorImpl<UnrealizedConversionCastOp> *remainingCastOps) {
-  // Set of all cast ops for faster lookups.
-  DenseSet<UnrealizedConversionCastOp> castOpSet;
-  for (UnrealizedConversionCastOp op : castOps)
-    castOpSet.insert(op);
-  reconcileUnrealizedCasts(castOpSet, remainingCastOps);
-}
-
-void mlir::reconcileUnrealizedCasts(
-    const DenseSet<UnrealizedConversionCastOp> &castOps,
-    SmallVectorImpl<UnrealizedConversionCastOp> *remainingCastOps) {
-  reconcileUnrealizedCastsImpl(
-      llvm::make_range(castOps.begin(), castOps.end()),
-      [&](UnrealizedConversionCastOp castOp) {
-        return castOps.contains(castOp);
-      },
-      remainingCastOps);
-}
-
-static void mlir::reconcileUnrealizedCasts(
-    const DenseMap<UnrealizedConversionCastOp, UnresolvedMaterializationInfo>
-        &castOps,
-    SmallVectorImpl<UnrealizedConversionCastOp> *remainingCastOps) {
-  reconcileUnrealizedCastsImpl(
-      castOps.keys(),
-      [&](UnrealizedConversionCastOp castOp) {
-        return castOps.contains(castOp);
-      },
-      remainingCastOps);
-}
-
 //===----------------------------------------------------------------------===//
 // Type Conversion
 //===----------------------------------------------------------------------===//