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// Copyright 2009 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
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#ifndef V8_ARM_VIRTUAL_FRAME_ARM_H_
#define V8_ARM_VIRTUAL_FRAME_ARM_H_
#include "register-allocator.h"
namespace v8 {
namespace internal {
// This dummy class is only used to create invalid virtual frames.
extern class InvalidVirtualFrameInitializer {}* kInvalidVirtualFrameInitializer;
// -------------------------------------------------------------------------
// 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:
class RegisterAllocationScope;
// 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, and keeps it spilled.
class SpilledScope BASE_EMBEDDED {
public:
explicit SpilledScope(VirtualFrame* frame)
: old_is_spilled_(is_spilled_) {
if (frame != NULL) {
if (!is_spilled_) {
frame->SpillAll();
} else {
frame->AssertIsSpilled();
}
}
is_spilled_ = true;
}
~SpilledScope() {
is_spilled_ = old_is_spilled_;
}
static bool is_spilled() { return is_spilled_; }
private:
static bool is_spilled_;
int old_is_spilled_;
SpilledScope() { }
friend class RegisterAllocationScope;
};
class RegisterAllocationScope BASE_EMBEDDED {
public:
// A utility class to introduce a scope where the virtual frame
// is not spilled, ie. where register allocation occurs. Eventually
// when RegisterAllocationScope is ubiquitous it can be removed
// along with the (by then unused) SpilledScope class.
inline explicit RegisterAllocationScope(CodeGenerator* cgen);
inline ~RegisterAllocationScope();
private:
CodeGenerator* cgen_;
bool old_is_spilled_;
RegisterAllocationScope() { }
};
// An illegal index into the virtual frame.
static const int kIllegalIndex = -1;
// Construct an initial virtual frame on entry to a JS function.
inline VirtualFrame();
// Construct an invalid virtual frame, used by JumpTargets.
inline VirtualFrame(InvalidVirtualFrameInitializer* dummy);
// Construct a virtual frame as a clone of an existing one.
explicit inline VirtualFrame(VirtualFrame* original);
inline CodeGenerator* cgen() const;
inline MacroAssembler* masm();
// The number of elements on the virtual frame.
int element_count() const { return element_count_; }
// The height of the virtual expression stack.
inline int height() const;
bool is_used(int num) {
switch (num) {
case 0: { // r0.
return kR0InUse[top_of_stack_state_];
}
case 1: { // r1.
return kR1InUse[top_of_stack_state_];
}
case 2:
case 3:
case 4:
case 5:
case 6: { // r2 to r6.
ASSERT(num - kFirstAllocatedRegister < kNumberOfAllocatedRegisters);
ASSERT(num >= kFirstAllocatedRegister);
if ((register_allocation_map_ &
(1 << (num - kFirstAllocatedRegister))) == 0) {
return false;
} else {
return true;
}
}
default: {
ASSERT(num < kFirstAllocatedRegister ||
num >= kFirstAllocatedRegister + kNumberOfAllocatedRegisters);
return false;
}
}
}
// 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 except to bring the
// frame to a spilled state.
void Forget(int count);
// Spill all values from the frame to memory.
void SpillAll();
void AssertIsSpilled() const {
ASSERT(top_of_stack_state_ == NO_TOS_REGISTERS);
ASSERT(register_allocation_map_ == 0);
}
void AssertIsNotSpilled() {
ASSERT(!SpilledScope::is_spilled());
}
// Spill all occurrences of a specific register from the frame.
void Spill(Register reg) {
UNIMPLEMENTED();
}
// 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). Unimplemented.
Register SpillAnyRegister();
// 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, Condition cond = al);
void MergeTo(const VirtualFrame* expected, Condition cond = al);
// Checks whether this frame can be branched to by the other frame.
bool IsCompatibleWith(const VirtualFrame* other) const {
return (tos_known_smi_map_ & (~other->tos_known_smi_map_)) == 0;
}
// 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() {
AssertIsSpilled();
}
// (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() {
AssertIsSpilled();
}
// 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.
inline void PrepareForReturn();
// Number of local variables after when we use a loop for allocating.
static const int kLocalVarBound = 5;
// Allocate and initialize the frame-allocated locals.
void AllocateStackSlots();
// The current top of the expression stack as an assembly operand.
MemOperand Top() {
AssertIsSpilled();
return MemOperand(sp, 0);
}
// An element of the expression stack as an assembly operand.
MemOperand ElementAt(int index) {
int adjusted_index = index - kVirtualElements[top_of_stack_state_];
ASSERT(adjusted_index >= 0);
return MemOperand(sp, adjusted_index * kPointerSize);
}
bool KnownSmiAt(int index) {
if (index >= kTOSKnownSmiMapSize) return false;
return (tos_known_smi_map_ & (1 << index)) != 0;
}
// A frame-allocated local as an assembly operand.
inline MemOperand LocalAt(int index);
// Push the address of the receiver slot on the frame.
void PushReceiverSlotAddress();
// The function frame slot.
MemOperand Function() { return MemOperand(fp, kFunctionOffset); }
// The context frame slot.
MemOperand Context() { return MemOperand(fp, kContextOffset); }
// A parameter as an assembly operand.
inline MemOperand ParameterAt(int index);
// The receiver frame slot.
inline MemOperand Receiver();
// 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.
inline void CallStub(CodeStub* stub, int arg_count);
// Call JS function from top of the stack with arguments
// taken from the stack.
void CallJSFunction(int arg_count);
// 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);
#ifdef ENABLE_DEBUGGER_SUPPORT
void DebugBreak();
#endif
// Invoke builtin given the number of arguments it expects on (and
// removes from) the stack.
void InvokeBuiltin(Builtins::JavaScript id,
InvokeJSFlags flag,
int arg_count);
// Call load IC. Receiver is on the stack and is consumed. Result is returned
// in r0.
void CallLoadIC(Handle<String> name, RelocInfo::Mode mode);
// Call store IC. If the load is contextual, value is found on top of the
// frame. If not, value and receiver are on the frame. Both are consumed.
// Result is returned in r0.
void CallStoreIC(Handle<String> name, bool is_contextual);
// Call keyed load IC. Key and receiver are on the stack. Both are consumed.
// Result is returned in r0.
void CallKeyedLoadIC();
// Call keyed store IC. Value, key and receiver are on the stack. All three
// are consumed. Result is returned in r0.
void CallKeyedStoreIC();
// Call into an IC stub given the number of arguments it removes
// from the stack. Register arguments to the IC stub are implicit,
// and depend on the type of IC stub.
void CallCodeObject(Handle<Code> ic,
RelocInfo::Mode rmode,
int dropped_args);
// 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);
// Drop one element.
void Drop() { Drop(1); }
// Pop an element from the top of the expression stack. Discards
// the result.
void Pop();
// Pop an element from the top of the expression stack. The register
// will be one normally used for the top of stack register allocation
// so you can't hold on to it if you push on the stack.
Register PopToRegister(Register but_not_to_this_one = no_reg);
// Look at the top of the stack. The register returned is aliased and
// must be copied to a scratch register before modification.
Register Peek();
// Duplicate the top of stack.
void Dup();
// Duplicate the two elements on top of stack.
void Dup2();
// Flushes all registers, but it puts a copy of the top-of-stack in r0.
void SpillAllButCopyTOSToR0();
// Flushes all registers, but it puts a copy of the top-of-stack in r1
// and the next value on the stack in r0.
void SpillAllButCopyTOSToR1R0();
// Pop and save an element from the top of the expression stack and
// emit a corresponding pop instruction.
void EmitPop(Register reg);
// Takes the top two elements and puts them in r0 (top element) and r1
// (second element).
void PopToR1R0();
// Takes the top element and puts it in r1.
void PopToR1();
// Takes the top element and puts it in r0.
void PopToR0();
// Push an element on top of the expression stack and emit a
// corresponding push instruction.
void EmitPush(Register reg, TypeInfo type_info = TypeInfo::Unknown());
void EmitPush(Operand operand, TypeInfo type_info = TypeInfo::Unknown());
void EmitPush(MemOperand operand, TypeInfo type_info = TypeInfo::Unknown());
void EmitPushRoot(Heap::RootListIndex index);
// Overwrite the nth thing on the stack. If the nth position is in a
// register then this turns into a mov, otherwise an str. Afterwards
// you can still use the register even if it is a register that can be
// used for TOS (r0 or r1).
void SetElementAt(Register reg, int this_far_down);
// Get a register which is free and which must be immediately used to
// push on the top of the stack.
Register GetTOSRegister();
// Push multiple registers on the stack and the virtual frame
// Register are selected by setting bit in src_regs and
// are pushed in decreasing order: r15 .. r0.
void EmitPushMultiple(int count, int src_regs);
static Register scratch0() { return r7; }
static Register scratch1() { return r9; }
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.
// 5 states for the top of stack, which can be in memory or in r0 and r1.
enum TopOfStack {
NO_TOS_REGISTERS,
R0_TOS,
R1_TOS,
R1_R0_TOS,
R0_R1_TOS,
TOS_STATES
};
static const int kMaxTOSRegisters = 2;
static const bool kR0InUse[TOS_STATES];
static const bool kR1InUse[TOS_STATES];
static const int kVirtualElements[TOS_STATES];
static const TopOfStack kStateAfterPop[TOS_STATES];
static const TopOfStack kStateAfterPush[TOS_STATES];
static const Register kTopRegister[TOS_STATES];
static const Register kBottomRegister[TOS_STATES];
// We allocate up to 5 locals in registers.
static const int kNumberOfAllocatedRegisters = 5;
// r2 to r6 are allocated to locals.
static const int kFirstAllocatedRegister = 2;
static const Register kAllocatedRegisters[kNumberOfAllocatedRegisters];
static Register AllocatedRegister(int r) {
ASSERT(r >= 0 && r < kNumberOfAllocatedRegisters);
return kAllocatedRegisters[r];
}
// The number of elements on the stack frame.
int element_count_;
TopOfStack top_of_stack_state_:3;
int register_allocation_map_:kNumberOfAllocatedRegisters;
static const int kTOSKnownSmiMapSize = 4;
unsigned tos_known_smi_map_:kTOSKnownSmiMapSize;
// The index of the element that is at the processor's stack pointer
// (the sp register). For now since everything is in memory it is given
// by the number of elements on the not-very-virtual stack frame.
int stack_pointer() { return element_count_ - 1; }
// The number of frame-allocated locals and parameters respectively.
inline int parameter_count() const;
inline int local_count() const;
// 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.
inline int frame_pointer() const;
// 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.
inline int context_index();
// The index of the function slot in the frame. It is below the frame
// pointer and context slot.
inline int function_index();
// The index of the first local. Between the frame pointer and the
// locals lies the return address.
inline int local0_index() const;
// The index of the base of the expression stack.
inline int expression_base_index() const;
// Convert a frame index into a frame pointer relative offset into the
// actual stack.
inline int fp_relative(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);
// If all top-of-stack registers are in use then the lowest one is pushed
// onto the physical stack and made free.
void EnsureOneFreeTOSRegister();
// Emit instructions to get the top of stack state from where we are to where
// we want to be.
void MergeTOSTo(TopOfStack expected_state, Condition cond = al);
inline bool Equals(const VirtualFrame* other);
inline void LowerHeight(int count) {
element_count_ -= count;
if (count >= kTOSKnownSmiMapSize) {
tos_known_smi_map_ = 0;
} else {
tos_known_smi_map_ >>= count;
}
}
inline void RaiseHeight(int count, unsigned known_smi_map = 0) {
ASSERT(known_smi_map < (1u << count));
element_count_ += count;
if (count >= kTOSKnownSmiMapSize) {
tos_known_smi_map_ = known_smi_map;
} else {
tos_known_smi_map_ = ((tos_known_smi_map_ << count) | known_smi_map);
}
}
friend class JumpTarget;
};
} } // namespace v8::internal
#endif // V8_ARM_VIRTUAL_FRAME_ARM_H_