MIPS port initial commit

src/mips/virtual-frame-mips.h

+// Copyright 2010 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_MIPS_VIRTUAL_FRAME_MIPS_H_
+#define V8_MIPS_VIRTUAL_FRAME_MIPS_H_
+
+#include "register-allocator.h"
+#include "scopes.h"
+
+namespace v8 {
+namespace internal {
+
+
+// -------------------------------------------------------------------------
+// Virtual frames
+//
+// The virtual frame is an abstraction of the physical stack frame.  It
+// encapsulates the parameters, frame-allocated locals, and the expression
+// stack.  It supports push/pop operations on the expression stack, as well
+// as random access to the expression stack elements, locals, and
+// parameters.
+
+class VirtualFrame : public ZoneObject {
+ public:
+  // A utility class to introduce a scope where the virtual frame is
+  // expected to remain spilled.  The constructor spills the code
+  // generator's current frame, but no attempt is made to require it
+  // to stay spilled.  It is intended as documentation while the code
+  // generator is being transformed.
+  class SpilledScope BASE_EMBEDDED {
+   public:
+    SpilledScope() {}
+  };
+
+  // An illegal index into the virtual frame.
+  static const int kIllegalIndex = -1;
+
+  // Construct an initial virtual frame on entry to a JS function.
+  VirtualFrame();
+
+  // Construct a virtual frame as a clone of an existing one.
+  explicit VirtualFrame(VirtualFrame* original);
+
+  CodeGenerator* cgen() { return CodeGeneratorScope::Current(); }
+  MacroAssembler* masm() { return cgen()->masm(); }
+
+  // Create a duplicate of an existing valid frame element.
+  FrameElement CopyElementAt(int index);
+
+  // The number of elements on the virtual frame.
+  int element_count() { return elements_.length(); }
+
+  // The height of the virtual expression stack.
+  int height() {
+    return element_count() - expression_base_index();
+  }
+
+  int register_location(int num) {
+    ASSERT(num >= 0 && num < RegisterAllocator::kNumRegisters);
+    return register_locations_[num];
+  }
+
+  int register_location(Register reg) {
+    return register_locations_[RegisterAllocator::ToNumber(reg)];
+  }
+
+  void set_register_location(Register reg, int index) {
+    register_locations_[RegisterAllocator::ToNumber(reg)] = index;
+  }
+
+  bool is_used(int num) {
+    ASSERT(num >= 0 && num < RegisterAllocator::kNumRegisters);
+    return register_locations_[num] != kIllegalIndex;
+  }
+
+  bool is_used(Register reg) {
+    return register_locations_[RegisterAllocator::ToNumber(reg)]
+        != kIllegalIndex;
+  }
+
+  // Add extra in-memory elements to the top of the frame to match an actual
+  // frame (eg, the frame after an exception handler is pushed).  No code is
+  // emitted.
+  void Adjust(int count);
+
+  // Forget elements from the top of the frame to match an actual frame (eg,
+  // the frame after a runtime call).  No code is emitted.
+  void Forget(int count) {
+    ASSERT(count >= 0);
+    ASSERT(stack_pointer_ == element_count() - 1);
+    stack_pointer_ -= count;
+    // On mips, all elements are in memory, so there is no extra bookkeeping
+    // (registers, copies, etc.) beyond dropping the elements.
+    elements_.Rewind(stack_pointer_ + 1);
+  }
+
+  // Forget count elements from the top of the frame and adjust the stack
+  // pointer downward.  This is used, for example, before merging frames at
+  // break, continue, and return targets.
+  void ForgetElements(int count);
+
+  // Spill all values from the frame to memory.
+  void SpillAll();
+
+  // Spill all occurrences of a specific register from the frame.
+  void Spill(Register reg) {
+    if (is_used(reg)) SpillElementAt(register_location(reg));
+  }
+
+  // Spill all occurrences of an arbitrary register if possible.  Return the
+  // register spilled or no_reg if it was not possible to free any register
+  // (ie, they all have frame-external references).
+  Register SpillAnyRegister();
+
+  // Prepare this virtual frame for merging to an expected frame by
+  // performing some state changes that do not require generating
+  // code.  It is guaranteed that no code will be generated.
+  void PrepareMergeTo(VirtualFrame* expected);
+
+  // Make this virtual frame have a state identical to an expected virtual
+  // frame.  As a side effect, code may be emitted to make this frame match
+  // the expected one.
+  void MergeTo(VirtualFrame* expected);
+
+  // Detach a frame from its code generator, perhaps temporarily.  This
+  // tells the register allocator that it is free to use frame-internal
+  // registers.  Used when the code generator's frame is switched from this
+  // one to NULL by an unconditional jump.
+  void DetachFromCodeGenerator() {
+    RegisterAllocator* cgen_allocator = cgen()->allocator();
+    for (int i = 0; i < RegisterAllocator::kNumRegisters; i++) {
+      if (is_used(i)) cgen_allocator->Unuse(i);
+    }
+  }
+
+  // (Re)attach a frame to its code generator.  This informs the register
+  // allocator that the frame-internal register references are active again.
+  // Used when a code generator's frame is switched from NULL to this one by
+  // binding a label.
+  void AttachToCodeGenerator() {
+    RegisterAllocator* cgen_allocator = cgen()->allocator();
+    for (int i = 0; i < RegisterAllocator::kNumRegisters; i++) {
+      if (is_used(i)) cgen_allocator->Unuse(i);
+    }
+  }
+
+  // Emit code for the physical JS entry and exit frame sequences.  After
+  // calling Enter, the virtual frame is ready for use; and after calling
+  // Exit it should not be used.  Note that Enter does not allocate space in
+  // the physical frame for storing frame-allocated locals.
+  void Enter();
+  void Exit();
+
+  // Prepare for returning from the frame by spilling locals and
+  // dropping all non-locals elements in the virtual frame.  This
+  // avoids generating unnecessary merge code when jumping to the
+  // shared return site.  Emits code for spills.
+  void PrepareForReturn();
+
+  // Allocate and initialize the frame-allocated locals.
+  void AllocateStackSlots();
+
+  // The current top of the expression stack as an assembly operand.
+  MemOperand Top() { return MemOperand(sp, 0); }
+
+  // An element of the expression stack as an assembly operand.
+  MemOperand ElementAt(int index) {
+    return MemOperand(sp, index * kPointerSize);
+  }
+
+  // Random-access store to a frame-top relative frame element.  The result
+  // becomes owned by the frame and is invalidated.
+  void SetElementAt(int index, Result* value);
+
+  // Set a frame element to a constant.  The index is frame-top relative.
+  void SetElementAt(int index, Handle<Object> value) {
+    Result temp(value);
+    SetElementAt(index, &temp);
+  }
+
+  void PushElementAt(int index) {
+    PushFrameSlotAt(element_count() - index - 1);
+  }
+
+  // A frame-allocated local as an assembly operand.
+  MemOperand LocalAt(int index) {
+    ASSERT(0 <= index);
+    ASSERT(index < local_count());
+    return MemOperand(s8_fp, kLocal0Offset - index * kPointerSize);
+  }
+
+  // Push a copy of the value of a local frame slot on top of the frame.
+  void PushLocalAt(int index) {
+    PushFrameSlotAt(local0_index() + index);
+  }
+
+  // Push the value of a local frame slot on top of the frame and invalidate
+  // the local slot.  The slot should be written to before trying to read
+  // from it again.
+  void TakeLocalAt(int index) {
+    TakeFrameSlotAt(local0_index() + index);
+  }
+
+  // Store the top value on the virtual frame into a local frame slot.  The
+  // value is left in place on top of the frame.
+  void StoreToLocalAt(int index) {
+    StoreToFrameSlotAt(local0_index() + index);
+  }
+
+  // Push the address of the receiver slot on the frame.
+  void PushReceiverSlotAddress();
+
+  // The function frame slot.
+  MemOperand Function() { return MemOperand(s8_fp, kFunctionOffset); }
+
+  // Push the function on top of the frame.
+  void PushFunction() { PushFrameSlotAt(function_index()); }
+
+  // The context frame slot.
+  MemOperand Context() { return MemOperand(s8_fp, kContextOffset); }
+
+  // Save the value of the cp register to the context frame slot.
+  void SaveContextRegister();
+
+  // Restore the cp register from the value of the context frame
+  // slot.
+  void RestoreContextRegister();
+
+  // A parameter as an assembly operand.
+  MemOperand ParameterAt(int index) {
+    // Index -1 corresponds to the receiver.
+    ASSERT(-1 <= index);  // -1 is the receiver.
+    ASSERT(index <= parameter_count());
+    uint16_t a = 0;   // Number of argument slots.
+    return MemOperand(s8_fp, (1 + parameter_count() + a - index) *kPointerSize);
+  }
+
+  // Push a copy of the value of a parameter frame slot on top of the frame.
+  void PushParameterAt(int index) {
+    PushFrameSlotAt(param0_index() + index);
+  }
+
+  // Push the value of a paramter frame slot on top of the frame and
+  // invalidate the parameter slot.  The slot should be written to before
+  // trying to read from it again.
+  void TakeParameterAt(int index) {
+    TakeFrameSlotAt(param0_index() + index);
+  }
+
+  // Store the top value on the virtual frame into a parameter frame slot.
+  // The value is left in place on top of the frame.
+  void StoreToParameterAt(int index) {
+    StoreToFrameSlotAt(param0_index() + index);
+  }
+
+  // The receiver frame slot.
+  MemOperand Receiver() { return ParameterAt(-1); }
+
+  // Push a try-catch or try-finally handler on top of the virtual frame.
+  void PushTryHandler(HandlerType type);
+
+  // Call stub given the number of arguments it expects on (and
+  // removes from) the stack.
+  void CallStub(CodeStub* stub, int arg_count) {
+    PrepareForCall(arg_count, arg_count);
+    RawCallStub(stub);
+  }
+
+  // Call stub that expects its argument in r0.  The argument is given
+  // as a result which must be the register r0.
+  void CallStub(CodeStub* stub, Result* arg);
+
+  // Call stub that expects its arguments in r1 and r0.  The arguments
+  // are given as results which must be the appropriate registers.
+  void CallStub(CodeStub* stub, Result* arg0, Result* arg1);
+
+  // Call runtime given the number of arguments expected on (and
+  // removed from) the stack.
+  void CallRuntime(Runtime::Function* f, int arg_count);
+  void CallRuntime(Runtime::FunctionId id, int arg_count);
+
+  // Call runtime with sp aligned to 8 bytes.
+  void CallAlignedRuntime(Runtime::Function* f, int arg_count);
+  void CallAlignedRuntime(Runtime::FunctionId id, int arg_count);
+
+  // Invoke builtin given the number of arguments it expects on (and
+  // removes from) the stack.
+  void InvokeBuiltin(Builtins::JavaScript id,
+                     InvokeJSFlags flag,
+                     Result* arg_count_register,
+                     int arg_count);
+
+  // Call into an IC stub given the number of arguments it removes
+  // from the stack.  Register arguments are passed as results and
+  // consumed by the call.
+  void CallCodeObject(Handle<Code> ic,
+                      RelocInfo::Mode rmode,
+                      int dropped_args);
+  void CallCodeObject(Handle<Code> ic,
+                      RelocInfo::Mode rmode,
+                      Result* arg,
+                      int dropped_args);
+  void CallCodeObject(Handle<Code> ic,
+                      RelocInfo::Mode rmode,
+                      Result* arg0,
+                      Result* arg1,
+                      int dropped_args,
+                      bool set_auto_args_slots = false);
+
+  // Drop a number of elements from the top of the expression stack.  May
+  // emit code to affect the physical frame.  Does not clobber any registers
+  // excepting possibly the stack pointer.
+  void Drop(int count);
+  // Similar to VirtualFrame::Drop but we don't modify the actual stack.
+  // This is because we need to manually restore sp to the correct position.
+  void DropFromVFrameOnly(int count);
+
+  // Drop one element.
+  void Drop() { Drop(1); }
+  void DropFromVFrameOnly() { DropFromVFrameOnly(1); }
+
+  // Duplicate the top element of the frame.
+  void Dup() { PushFrameSlotAt(element_count() - 1); }
+
+  // Pop an element from the top of the expression stack.  Returns a
+  // Result, which may be a constant or a register.
+  Result Pop();
+
+  // Pop and save an element from the top of the expression stack and
+  // emit a corresponding pop instruction.
+  void EmitPop(Register reg);
+  // Same but for multiple registers
+  void EmitMultiPop(RegList regs);  // higher indexed registers popped first
+  void EmitMultiPopReversed(RegList regs);  // lower first
+
+  // Push an element on top of the expression stack and emit a
+  // corresponding push instruction.
+  void EmitPush(Register reg);
+  // Same but for multiple registers.
+  void EmitMultiPush(RegList regs);  // lower indexed registers are pushed first
+  void EmitMultiPushReversed(RegList regs);  // higher first
+
+  // Push an element on the virtual frame.
+  void Push(Register reg);
+  void Push(Handle<Object> value);
+  void Push(Smi* value) { Push(Handle<Object>(value)); }
+
+  // Pushing a result invalidates it (its contents become owned by the frame).
+  void Push(Result* result) {
+    if (result->is_register()) {
+      Push(result->reg());
+    } else {
+      ASSERT(result->is_constant());
+      Push(result->handle());
+    }
+    result->Unuse();
+  }
+
+  // Nip removes zero or more elements from immediately below the top
+  // of the frame, leaving the previous top-of-frame value on top of
+  // the frame.  Nip(k) is equivalent to x = Pop(), Drop(k), Push(x).
+  void Nip(int num_dropped);
+
+  // This pushes 4 arguments slots on the stack and saves asked 'a' registers
+  // 'a' registers are arguments register a0 to a3.
+  void EmitArgumentSlots(RegList reglist);
+
+ private:
+  static const int kLocal0Offset = JavaScriptFrameConstants::kLocal0Offset;
+  static const int kFunctionOffset = JavaScriptFrameConstants::kFunctionOffset;
+  static const int kContextOffset = StandardFrameConstants::kContextOffset;
+
+  static const int kHandlerSize = StackHandlerConstants::kSize / kPointerSize;
+  static const int kPreallocatedElements = 5 + 8;  // 8 expression stack slots.
+
+  ZoneList<FrameElement> elements_;
+
+  // The index of the element that is at the processor's stack pointer
+  // (the sp register).
+  int stack_pointer_;
+
+  // The index of the register frame element using each register, or
+  // kIllegalIndex if a register is not on the frame.
+  int register_locations_[RegisterAllocator::kNumRegisters];
+
+  // The number of frame-allocated locals and parameters respectively.
+  int parameter_count() { return cgen()->scope()->num_parameters(); }
+  int local_count() { return cgen()->scope()->num_stack_slots(); }
+
+  // The index of the element that is at the processor's frame pointer
+  // (the fp register).  The parameters, receiver, function, and context
+  // are below the frame pointer.
+  int frame_pointer() { return parameter_count() + 3; }
+
+  // The index of the first parameter.  The receiver lies below the first
+  // parameter.
+  int param0_index() { return 1; }
+
+  // The index of the context slot in the frame.  It is immediately
+  // below the frame pointer.
+  int context_index() { return frame_pointer() - 1; }
+
+  // The index of the function slot in the frame.  It is below the frame
+  // pointer and context slot.
+  int function_index() { return frame_pointer() - 2; }
+
+  // The index of the first local.  Between the frame pointer and the
+  // locals lies the return address.
+  int local0_index() { return frame_pointer() + 2; }
+
+  // The index of the base of the expression stack.
+  int expression_base_index() { return local0_index() + local_count(); }
+
+  // Convert a frame index into a frame pointer relative offset into the
+  // actual stack.
+  int fp_relative(int index) {
+    ASSERT(index < element_count());
+    ASSERT(frame_pointer() < element_count());  // FP is on the frame.
+    return (frame_pointer() - index) * kPointerSize;
+  }
+
+  // Record an occurrence of a register in the virtual frame.  This has the
+  // effect of incrementing the register's external reference count and
+  // of updating the index of the register's location in the frame.
+  void Use(Register reg, int index) {
+    ASSERT(!is_used(reg));
+    set_register_location(reg, index);
+    cgen()->allocator()->Use(reg);
+  }
+
+  // Record that a register reference has been dropped from the frame.  This
+  // decrements the register's external reference count and invalidates the
+  // index of the register's location in the frame.
+  void Unuse(Register reg) {
+    ASSERT(is_used(reg));
+    set_register_location(reg, kIllegalIndex);
+    cgen()->allocator()->Unuse(reg);
+  }
+
+  // Spill the element at a particular index---write it to memory if
+  // necessary, free any associated register, and forget its value if
+  // constant.
+  void SpillElementAt(int index);
+
+  // Sync the element at a particular index.  If it is a register or
+  // constant that disagrees with the value on the stack, write it to memory.
+  // Keep the element type as register or constant, and clear the dirty bit.
+  void SyncElementAt(int index);
+
+  // Sync the range of elements in [begin, end] with memory.
+  void SyncRange(int begin, int end);
+
+  // Sync a single unsynced element that lies beneath or at the stack pointer.
+  void SyncElementBelowStackPointer(int index);
+
+  // Sync a single unsynced element that lies just above the stack pointer.
+  void SyncElementByPushing(int index);
+
+  // Push a copy of a frame slot (typically a local or parameter) on top of
+  // the frame.
+  void PushFrameSlotAt(int index);
+
+  // Push a the value of a frame slot (typically a local or parameter) on
+  // top of the frame and invalidate the slot.
+  void TakeFrameSlotAt(int index);
+
+  // Store the value on top of the frame to a frame slot (typically a local
+  // or parameter).
+  void StoreToFrameSlotAt(int index);
+
+  // Spill all elements in registers. Spill the top spilled_args elements
+  // on the frame.  Sync all other frame elements.
+  // Then drop dropped_args elements from the virtual frame, to match
+  // the effect of an upcoming call that will drop them from the stack.
+  void PrepareForCall(int spilled_args, int dropped_args);
+
+  // Move frame elements currently in registers or constants, that
+  // should be in memory in the expected frame, to memory.
+  void MergeMoveRegistersToMemory(VirtualFrame* expected);
+
+  // Make the register-to-register moves necessary to
+  // merge this frame with the expected frame.
+  // Register to memory moves must already have been made,
+  // and memory to register moves must follow this call.
+  // This is because some new memory-to-register moves are
+  // created in order to break cycles of register moves.
+  // Used in the implementation of MergeTo().
+  void MergeMoveRegistersToRegisters(VirtualFrame* expected);
+
+  // Make the memory-to-register and constant-to-register moves
+  // needed to make this frame equal the expected frame.
+  // Called after all register-to-memory and register-to-register
+  // moves have been made.  After this function returns, the frames
+  // should be equal.
+  void MergeMoveMemoryToRegisters(VirtualFrame* expected);
+
+  // Invalidates a frame slot (puts an invalid frame element in it).
+  // Copies on the frame are correctly handled, and if this slot was
+  // the backing store of copies, the index of the new backing store
+  // is returned.  Otherwise, returns kIllegalIndex.
+  // Register counts are correctly updated.
+  int InvalidateFrameSlotAt(int index);
+
+  // Call a code stub that has already been prepared for calling (via
+  // PrepareForCall).
+  void RawCallStub(CodeStub* stub);
+
+  // Calls a code object which has already been prepared for calling
+  // (via PrepareForCall).
+  void RawCallCodeObject(Handle<Code> code, RelocInfo::Mode rmode);
+
+  bool Equals(VirtualFrame* other);
+
+  // Classes that need raw access to the elements_ array.
+  friend class DeferredCode;
+  friend class JumpTarget;
+};
+
+
+} }  // namespace v8::internal
+
+#endif  // V8_MIPS_VIRTUAL_FRAME_MIPS_H_
+