Begin counting references to registers, both in the frame and out....

src/register-allocator-ia32.h

+// Copyright 2008 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#ifndef V8_REGISTER_ALLOCATOR_IA32_H_
+#define V8_REGISTER_ALLOCATOR_IA32_H_
+
+#include "macro-assembler.h"
+
+namespace v8 { namespace internal {
+
+// -------------------------------------------------------------------------
+// Register file
+//
+// The register file tracks reference counts for the processor registers.
+// It is used by both the register allocator and the virtual frame.
+
+class RegisterFile BASE_EMBEDDED {
+ public:
+  RegisterFile() { Reset(); }
+
+  void Reset() {
+    for (int i = 0; i < kNumRegisters; i++) {
+      ref_counts_[i] = 0;
+    }
+  }
+
+  // Predicates and accessors for the reference counts.  They take a
+  // register code rather than a register because they are frequently used
+  // in a loop over the register codes.
+  bool is_used(int reg_code) const { return ref_counts_[reg_code] > 0; }
+  int count(int reg_code) const { return ref_counts_[reg_code]; }
+
+  // Record a use of a register by incrementing its reference count.
+  void Use(Register reg) {
+    ref_counts_[reg.code()]++;
+  }
+
+  // Record that a register will no longer be used by decrementing its
+  // reference count.
+  void Unuse(Register reg) {
+    ASSERT(is_used(reg.code()));
+    if (is_used(reg.code())) {
+      ref_counts_[reg.code()]--;
+    }
+  }
+
+  static const int kNumRegisters = 8;
+
+ private:
+  int ref_counts_[kNumRegisters];
+};
+
+
+// -------------------------------------------------------------------------
+// Register allocator
+//
+
+class RegisterAllocator BASE_EMBEDDED {
+ public:
+  RegisterAllocator(CodeGenerator* cgen) : code_generator_(cgen) {}
+
+  int num_registers() const { return RegisterFile::kNumRegisters; }
+
+  int count(int reg_code) { return registers_.count(reg_code); }
+
+  // Explicitly record a reference to a register.
+  void Use(Register reg) { registers_.Use(reg); }
+
+  // Explicitly record that a register will no lonber be used.
+  void Unuse(Register reg) { registers_.Unuse(reg); }
+
+  // Initialize the register allocator for entry to a JS function.  On
+  // entry, esp, ebp, esi, and edi are externally referenced (ie, outside
+  // the virtual frame); and the other registers are free.
+  void Initialize();
+
+  // Allocate a free register if possible or fail by returning no_reg.
+  Register Allocate();
+
+ private:
+  CodeGenerator* code_generator_;
+  RegisterFile registers_;
+};
+
+} }  // namespace v8::internal
+
+#endif  // V8_REGISTER_ALLOCATOR_IA32_H_