[maglev] Create Int32Constant Node

... and fix AddSmi operation.

Bug: v8:7700
Change-Id: If81030e1e0d457076e09db62553342f04477e255
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3581983
Auto-Submit: Victor Gomes <victorgomes@chromium.org>
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/main@{#79921}

src/maglev/maglev-graph-builder.cc

@@ -207,15 +207,17 @@ void MaglevGraphBuilder::VisitBinarySmiOperation() {
 
       if (hint == BinaryOperationHint::kSignedSmall) {
         ValueNode* left = AddNewNode<CheckedSmiUntag>({GetAccumulator()});
-        Smi constant = Smi::FromInt(iterator_.GetImmediateOperand(0));
+        int32_t constant = iterator_.GetImmediateOperand(0);
 
         if (kOperation == Operation::kAdd) {
-          if (constant == Smi::zero()) {
+          if (constant == 0) {
             // For addition of zero, when the accumulator passed the Smi check,
             // it already has the right value, so we can just return.
             return;
           }
-          ValueNode* right = AddNewNode<SmiConstant>({}, constant);
+          // TODO(victorgomes): We could create an Int32Add node that receives
+          // a constant and avoid a register move.
+          ValueNode* right = AddNewNode<Int32Constant>({}, constant);
           ValueNode* result = AddNewNode<Int32AddWithOverflow>({left, right});
           SetAccumulator(AddNewNode<CheckedSmiTag>({result}));
           return;

src/maglev/maglev-ir.cc

@@ -735,6 +735,19 @@ void CheckedSmiTag::GenerateCode(MaglevCodeGenState* code_gen_state,
   EmitEagerDeoptIf(overflow, code_gen_state, this);
 }
 
+void Int32Constant::AllocateVreg(MaglevVregAllocationState* vreg_state,
+                                 const ProcessingState& state) {
+  DefineAsRegister(vreg_state, this);
+}
+void Int32Constant::GenerateCode(MaglevCodeGenState* code_gen_state,
+                                 const ProcessingState& state) {
+  __ Move(ToRegister(result()), Immediate(value()));
+}
+void Int32Constant::PrintParams(std::ostream& os,
+                                MaglevGraphLabeller* graph_labeller) const {
+  os << "(" << value() << ")";
+}
+
 void Int32AddWithOverflow::AllocateVreg(MaglevVregAllocationState* vreg_state,
                                         const ProcessingState& state) {
   UseRegister(left_input());

src/maglev/maglev-ir.h

@@ -79,6 +79,7 @@ class CompactInterpreterFrameState;
   V(CheckedSmiTag)         \
   V(CheckedSmiUntag)       \
   V(Int32AddWithOverflow)  \
+  V(Int32Constant)         \
   GENERIC_OPERATIONS_NODE_LIST(V)
 
 #define NODE_LIST(V) \
@@ -951,6 +952,23 @@ class CheckedSmiUntag : public FixedInputValueNodeT<1, CheckedSmiUntag> {
   void PrintParams(std::ostream&, MaglevGraphLabeller*) const {}
 };
 
+class Int32Constant : public FixedInputValueNodeT<0, Int32Constant> {
+  using Base = FixedInputValueNodeT<0, Int32Constant>;
+
+ public:
+  explicit Int32Constant(uint32_t bitfield, int32_t value)
+      : Base(bitfield), value_(value) {}
+
+  int32_t value() const { return value_; }
+
+  void AllocateVreg(MaglevVregAllocationState*, const ProcessingState&);
+  void GenerateCode(MaglevCodeGenState*, const ProcessingState&);
+  void PrintParams(std::ostream&, MaglevGraphLabeller*) const;
+
+ private:
+  const int32_t value_;
+};
+
 class Int32AddWithOverflow
     : public FixedInputValueNodeT<2, Int32AddWithOverflow> {
   using Base = FixedInputValueNodeT<2, Int32AddWithOverflow>;