[IR Container] Phase 2.1 Ownership Fusion Special Vals & Axioms

csrc/fusion.cpp

@@ -7,6 +7,7 @@
 // clang-format on
 #include <fusion.h>
 
+#include <type.h>
 #include <iterator>
 #include <ranges>
 
@@ -19,7 +20,9 @@
 #include <host_ir/container.h>
 #include <instrumentation.h>
 #include <ir/all_nodes.h>
+#include <ir/builder.h>
 #include <ir/cloner.h>
+#include <ir/internal_nodes.h>
 #include <ir/printer.h>
 #include <ir/utils.h>
 #include <iter_visitor.h>
@@ -137,6 +140,16 @@ void Fusion::swap(Fusion& a, Fusion& b) noexcept {
   std::swap(a.outputs_, b.outputs_);
 
   std::swap(a.io_alias_, b.io_alias_);
+
+  // Swap per-Fusion special values (Phase 2)
+  std::swap(a.zero_val_, b.zero_val_);
+  std::swap(a.one_val_, b.one_val_);
+  std::swap(a.true_val_, b.true_val_);
+  std::swap(a.false_val_, b.false_val_);
+  std::swap(a.magic_zero_val_, b.magic_zero_val_);
+
+  std::swap(a.axioms_, b.axioms_);
+  std::swap(a.metadata_, b.metadata_);
 }
 
 std::unique_ptr<SegmentedFusion> Fusion::segment(
@@ -150,6 +163,24 @@ IrCloner Fusion::copy(const Fusion* from, Fusion* to) {
 
   auto ir_cloner = IrContainer::copy(from->ir_container(), to->ir_container());
 
+  // Remap cached special val pointers through the cloner
+  if (from->zero_val_) {
+    to->zero_val_ = ir_cloner.clone(from->zero_val_);
+  }
+  if (from->one_val_) {
+    to->one_val_ = ir_cloner.clone(from->one_val_);
+  }
+  if (from->true_val_) {
+    to->true_val_ = ir_cloner.clone(from->true_val_);
+  }
+  if (from->false_val_) {
+    to->false_val_ = ir_cloner.clone(from->false_val_);
+  }
+  if (from->magic_zero_val_) {
+    to->magic_zero_val_ =
+        ir_cloner.clone(from->magic_zero_val_)->as<NamedScalar>();
+  }
+
   for (auto val : from->vals()) {
     ir_cloner.clone(val)->setDefinition(ir_cloner.clone(val->definition_));
     ir_cloner.clone(val)->setUses(ir_cloner.clone(val->uses_));
@@ -198,6 +229,19 @@ IrCloner Fusion::copy(const Fusion* from, Fusion* to) {
 
   to->expected_dynamic_smem_bytes_ = from->expected_dynamic_smem_bytes_;
 
+  if (from->axioms_ != nullptr) {
+    to->axioms_ = std::make_unique<std::vector<Val*>>();
+    to->axioms_->reserve(from->axioms_->size());
+    for (auto pred : *from->axioms_) {
+      to->axioms_->push_back(ir_cloner.clone(pred));
+    }
+  }
+
+  for (auto& [key, val_expr] : from->metadata_) {
+    to->metadata_[ir_cloner.clone(key)] = std::make_pair(
+        ir_cloner.clone(val_expr.first), ir_cloner.clone(val_expr.second));
+  }
+
   if (from->all_tvs_ptr_ != nullptr) {
     to->all_tvs_ptr_ = std::make_unique<std::vector<TensorView*>>();
     to->all_tvs_ptr_->reserve(from->all_tvs_ptr_->size());
@@ -264,6 +308,17 @@ void Fusion::clear() noexcept {
   managed_data_.clear();
   managed_named_data_.clear();
 
+  // Reset per-Fusion special value caches (the vals themselves are owned by
+  // ir_container and were already destroyed by ir_container()->clear() above).
+  zero_val_ = nullptr;
+  one_val_ = nullptr;
+  true_val_ = nullptr;
+  false_val_ = nullptr;
+  magic_zero_val_ = nullptr;
+
+  axioms_.reset();
+  metadata_.clear();
+
   invalidateTvsAndUses();
 
   is_during_update_uses_ = false;
@@ -297,6 +352,12 @@ void Fusion::removeExpr(Expr* expr) {
 void Fusion::removeVal(Val* val) {
   assertInContainer(val, "Cannot remove val ");
 
+  // Don't remove cached special vals — they are lazily created singletons
+  if (val == zero_val_ || val == one_val_ || val == true_val_ ||
+      val == false_val_ || val == magic_zero_val_) {
+    return;
+  }
+
   NVF_CHECK(
       !val->isFusionInput(),
       "Cannot remove val as it is an input of the fusion.");
@@ -340,6 +401,57 @@ void Fusion::removeVal(Val* val) {
   invalidateTvsAndUses();
 }
 
+void Fusion::removeStatementsCreatedAfter(
+    int64_t num_exprs_before,
+    int64_t num_vals_before) {
+  auto* c = ir_container();
+
+  NVF_ERROR(
+      c->exprs_up_.size() == c->exprs_.size(),
+      "exprs_up_ (size ",
+      c->exprs_up_.size(),
+      ") and exprs_ (size ",
+      c->exprs_.size(),
+      ") are out of sync.");
+  NVF_ERROR(
+      std::ssize(c->exprs_up_) >= num_exprs_before,
+      "exprs_up_ size (",
+      std::ssize(c->exprs_up_),
+      ") is less than num_exprs_before (",
+      num_exprs_before,
+      ").");
+
+  // Remove expressions before values because we need to change Val::uses_.
+  while (std::ssize(c->exprs_up_) > num_exprs_before) {
+    Expr* e = c->exprs_up_.back().get();
+    for (Val* in : e->inputs()) {
+      in->removeUse(e);
+    }
+    c->exprs_.erase(e);
+    c->exprs_up_.pop_back();
+  }
+
+  // Null out any special value caches that point to vals about to be destroyed.
+  // This prevents dangling pointers when special vals are lazily created inside
+  // a StatementGuard scope.
+  while (std::ssize(c->vals_up_) > num_vals_before) {
+    Val* v = c->vals_up_.back().get();
+    if (v == zero_val_) {
+      zero_val_ = nullptr;
+    } else if (v == one_val_) {
+      one_val_ = nullptr;
+    } else if (v == true_val_) {
+      true_val_ = nullptr;
+    } else if (v == false_val_) {
+      false_val_ = nullptr;
+    } else if (v == magic_zero_val_) {
+      magic_zero_val_ = nullptr;
+    }
+    c->vals_.erase(v);
+    c->vals_up_.pop_back();
+  }
+}
+
 void Fusion::addInput(Val* input) {
   assertInContainer(input, "Cannot register input ");
 
@@ -689,6 +801,105 @@ void Fusion::printTransforms() {
   t_exprs.handle(this);
 }
 
+Val* Fusion::zeroVal() {
+  if (!zero_val_) {
+    zero_val_ = IrBuilder::createInContainer<Val>(this, 0L, DataType::Index);
+  }
+  return zero_val_;
+}
+
+Val* Fusion::oneVal() {
+  if (!one_val_) {
+    one_val_ = IrBuilder::createInContainer<Val>(this, 1L, DataType::Index);
+  }
+  return one_val_;
+}
+
+Val* Fusion::falseVal() {
+  if (!false_val_) {
+    false_val_ = IrBuilder::createInContainer<Val>(this, false, DataType::Bool);
+  }
+  return false_val_;
+}
+
+Val* Fusion::trueVal() {
+  if (!true_val_) {
+    true_val_ = IrBuilder::createInContainer<Val>(this, true, DataType::Bool);
+  }
+  return true_val_;
+}
+
+NamedScalar* Fusion::magicZeroVal() {
+  if (!magic_zero_val_) {
+    magic_zero_val_ = IrBuilder::createInContainer<NamedScalar>(
+        this, kMagicZeroName, DataType::Index);
+  }
+  return magic_zero_val_;
+}
+
+Val* Fusion::zeroVal(DataType dtype) {
+  if (dtype == DataType::Index) {
+    return zeroVal();
+  } else if (isBooleanType(dtype)) {
+    return falseVal();
+  } else {
+    // NOTE: this does not cache values
+    return IrBuilder::createInContainer<Val>(this, 0L, dtype);
+  }
+}
+
+Val* Fusion::oneVal(DataType dtype) {
+  if (dtype == DataType::Index) {
+    return oneVal();
+  } else if (isBooleanType(dtype)) {
+    return trueVal();
+  } else {
+    // NOTE: this does not cache values
+    return IrBuilder::createInContainer<Val>(this, 1L, dtype);
+  }
+}
+
+Val* Fusion::metadataOf(Val* v) {
+  if (metadata_.count(v) == 0) {
+    auto metadata_val =
+        IrBuilder::createInContainer<Val>(this, metaDataTypeOf(v));
+    auto metadata_expr =
+        IrBuilder::createInContainer<GetMetaData>(this, metadata_val, v);
+    metadata_[v] = std::make_pair(metadata_val, metadata_expr);
+  }
+  return metadata_.at(v).first;
+}
+
+const std::vector<Val*>& Fusion::axioms() {
+  if (!axioms_) {
+    axioms_ = std::make_unique<std::vector<Val*>>();
+    axioms_->reserve(kParallelTypeThreads.size() * 3);
+    auto zero = zeroVal();
+    for (auto p : kParallelTypeThreads) {
+      auto pidx = NamedScalar::getParallelIndex(p);
+      auto pdim = NamedScalar::getParallelDim(p);
+      axioms_->push_back(SimplifyingIrBuilder::geExpr(pidx, zero));
+      axioms_->push_back(SimplifyingIrBuilder::gtExpr(pdim, zero));
+      axioms_->push_back(SimplifyingIrBuilder::ltExpr(pidx, pdim));
+    }
+  }
+  return *axioms_;
+}
+
+void Fusion::assumePositive(Val* val) {
+  NVF_ERROR(inContainer(val));
+  // Lazy init axioms, then add the assumption
+  axioms();
+  axioms_->emplace_back(IrBuilder::gtExpr(val, zeroVal()));
+}
+
+void Fusion::assumeNonNegative(Val* val) {
+  NVF_ERROR(inContainer(val));
+  // Lazy init axioms, then add the assumption
+  axioms();
+  axioms_->emplace_back(IrBuilder::geExpr(val, zeroVal()));
+}
+
 void Fusion::registerVal(Val* val) {
   if (inContainer(val)) {
     return;

csrc/fusion.h

@@ -59,6 +59,7 @@ namespace nvfuser {
 //! checks.
 
 class Fusion;
+class NamedScalar;
 class TensorView;
 
 class SegmentCandidateFinder;
@@ -549,63 +550,31 @@ class NVF_API Fusion : public PolymorphicBase {
     return ir_container()->numExprs();
   }
 
-  int64_t numVals(bool include_shortcuts) const noexcept {
-    return ir_container()->numVals(include_shortcuts);
+  int64_t numVals() const noexcept {
+    return ir_container()->numVals();
   }
 
   // Shortcut values (frequently used constants)
-  Val* zeroVal() {
-    return ir_container()->zeroVal();
-  }
-
-  Val* oneVal() {
-    return ir_container()->oneVal();
-  }
-
-  Val* falseVal() {
-    return ir_container()->falseVal();
-  }
-
-  Val* trueVal() {
-    return ir_container()->trueVal();
-  }
-
-  NamedScalar* magicZeroVal() {
-    return ir_container()->magicZeroVal();
-  }
-
-  Val* zeroVal(DataType dtype) {
-    return ir_container()->zeroVal(dtype);
-  }
+  Val* zeroVal();
+  Val* oneVal();
+  Val* falseVal();
+  Val* trueVal();
+  NamedScalar* magicZeroVal();
+  Val* zeroVal(DataType dtype);
+  Val* oneVal(DataType dtype);
 
-  Val* oneVal(DataType dtype) {
-    return ir_container()->oneVal(dtype);
-  }
-
-  Val* metadataOf(Val* val) {
-    return ir_container()->metadataOf(val);
-  }
+  Val* metadataOf(Val* val);
 
   // Axioms (CUDA programming assumptions)
-  const std::vector<Val*>& axioms() {
-    return ir_container()->axioms();
-  }
+  const std::vector<Val*>& axioms();
 
-  void assumePositive(Val* val) {
-    ir_container()->assumePositive(val);
-  }
-
-  void assumeNonNegative(Val* val) {
-    ir_container()->assumeNonNegative(val);
-  }
+  void assumePositive(Val* val);
+  void assumeNonNegative(Val* val);
 
   // Statement removal
   void removeStatementsCreatedAfter(
       int64_t num_exprs_before,
-      int64_t num_vals_before) {
-    ir_container()->removeStatementsCreatedAfter(
-        num_exprs_before, num_vals_before);
-  }
+      int64_t num_vals_before);
 
  protected:
   friend SegmentCandidateFinder;
@@ -667,6 +636,16 @@ class NVF_API Fusion : public PolymorphicBase {
 
   inline static const std::string exact_mappings_key = "exact_mappings";
   std::unique_ptr<IrContainer> ir_container_;
+
+  Val* zero_val_ = nullptr;
+  Val* one_val_ = nullptr;
+  Val* true_val_ = nullptr;
+  Val* false_val_ = nullptr;
+  NamedScalar* magic_zero_val_ = nullptr;
+
+  std::unique_ptr<std::vector<Val*>> axioms_;
+
+  std::unordered_map<Val*, std::pair<Val*, Expr*>> metadata_;
 };
 
 // Template implementations for Fusion::manage<T>() that use IrCloner