[maglev] Support double registers in register allocator

This assumes that Phi nodes never point to untagged values and
TemporaryRegisters are always general registers.

Bug: v8:7700
Change-Id: I74a6c43ff9f1ba87dd258e90a193f683d666b8ec
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3598883Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Victor Gomes <victorgomes@chromium.org>
Cr-Commit-Position: refs/heads/main@{#80144}

src/maglev/maglev-ir.h

@@ -295,11 +295,18 @@ class ValueLocation {
     operand_ = compiler::ConstantOperand(args...);
   }
 
-  Register AssignedRegister() const {
-    return Register::from_code(
-        compiler::AllocatedOperand::cast(operand_).register_code());
+  Register AssignedGeneralRegister() const {
+    DCHECK(!IsDoubleRegister());
+    return compiler::AllocatedOperand::cast(operand_).GetRegister();
   }
 
+  DoubleRegister AssignedDoubleRegister() const {
+    DCHECK(IsDoubleRegister());
+    return compiler::AllocatedOperand::cast(operand_).GetDoubleRegister();
+  }
+
+  bool IsDoubleRegister() const { return operand_.IsDoubleRegister(); }
+
   const compiler::InstructionOperand& operand() const { return operand_; }
   const compiler::InstructionOperand& operand() { return operand_; }
 

src/maglev/maglev-regalloc.h

@@ -38,6 +38,7 @@ class RegisterFrameState {
       AllocatableRegisters<RegisterT>::kRegisters;
   static constexpr RegList kEmptyRegList = {};
 
+  RegList empty() const { return kEmptyRegList; }
   RegList free() const { return free_; }
   RegList used() const {
     // Only allocatable registers should be free.
@@ -133,9 +134,13 @@ class StraightForwardRegisterAllocator {
 
   void AllocateSpillSlot(ValueNode* node);
   void Spill(ValueNode* node);
-  void SpillAndClearRegisters();
   void SpillRegisters();
 
+  template <typename RegisterT>
+  void SpillAndClearRegisters(RegisterFrameState<RegisterT>& registers);
+  void SpillAndClearRegisters();
+
+  void FreeRegistersUsedBy(ValueNode* node);
   void FreeSomeGeneralRegister();
   void FreeSomeDoubleRegister();
 
@@ -152,6 +157,11 @@ class StraightForwardRegisterAllocator {
       RegisterFrameState<RegisterT>& registers, RegisterT reg, ValueNode* node);
   compiler::AllocatedOperand ForceAllocate(Register reg, ValueNode* node);
   compiler::AllocatedOperand ForceAllocate(DoubleRegister reg, ValueNode* node);
+  compiler::AllocatedOperand ForceAllocate(const Input& input, ValueNode* node);
+
+  template <typename Function>
+  void ForEachMergePointRegisterState(
+      MergePointRegisterState& merge_point_state, Function&& f);
 
   void InitializeRegisterValues(MergePointRegisterState& target_state);
   void EnsureInRegister(MergePointRegisterState& target_state,