linkage.cc

// Copyright 2014 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "src/compiler/linkage.h"

#include "src/ast/scopes.h"
#include "src/code-stubs.h"
#include "src/compilation-info.h"
#include "src/compiler/common-operator.h"
#include "src/compiler/frame.h"
#include "src/compiler/node.h"
#include "src/compiler/osr.h"
#include "src/compiler/pipeline.h"

namespace v8 {
namespace internal {
namespace compiler {

namespace {

LinkageLocation regloc(Register reg, MachineType type) {
  return LinkageLocation::ForRegister(reg.code(), type);
}

}  // namespace


std::ostream& operator<<(std::ostream& os, const CallDescriptor::Kind& k) {
  switch (k) {
    case CallDescriptor::kCallCodeObject:
      os << "Code";
      break;
    case CallDescriptor::kCallJSFunction:
      os << "JS";
      break;
    case CallDescriptor::kCallAddress:
      os << "Addr";
      break;
  }
  return os;
}


std::ostream& operator<<(std::ostream& os, const CallDescriptor& d) {
  // TODO(svenpanne) Output properties etc. and be less cryptic.
  return os << d.kind() << ":" << d.debug_name() << ":r" << d.ReturnCount()
            << "s" << d.StackParameterCount() << "i" << d.InputCount() << "f"
            << d.FrameStateCount() << "t" << d.SupportsTailCalls();
}

MachineSignature* CallDescriptor::GetMachineSignature(Zone* zone) const {
  size_t param_count = ParameterCount();
  size_t return_count = ReturnCount();
  MachineType* types = reinterpret_cast<MachineType*>(
      zone->New(sizeof(MachineType*) * (param_count + return_count)));
  int current = 0;
  for (size_t i = 0; i < return_count; ++i) {
    types[current++] = GetReturnType(i);
  }
  for (size_t i = 0; i < param_count; ++i) {
    types[current++] = GetParameterType(i);
  }
  return new (zone) MachineSignature(return_count, param_count, types);
}

bool CallDescriptor::HasSameReturnLocationsAs(
    const CallDescriptor* other) const {
  if (ReturnCount() != other->ReturnCount()) return false;
  for (size_t i = 0; i < ReturnCount(); ++i) {
    if (GetReturnLocation(i) != other->GetReturnLocation(i)) return false;
  }
  return true;
}

int CallDescriptor::GetStackParameterDelta(
    CallDescriptor const* tail_caller) const {
  int callee_slots_above_sp = 0;
  for (size_t i = 0; i < InputCount(); ++i) {
    LinkageLocation operand = GetInputLocation(i);
    if (!operand.IsRegister()) {
      int new_candidate =
          -operand.GetLocation() + operand.GetSizeInPointers() - 1;
      if (new_candidate > callee_slots_above_sp) {
        callee_slots_above_sp = new_candidate;
      }
    }
  }
  int tail_caller_slots_above_sp = 0;
  if (tail_caller != nullptr) {
    for (size_t i = 0; i < tail_caller->InputCount(); ++i) {
      LinkageLocation operand = tail_caller->GetInputLocation(i);
      if (!operand.IsRegister()) {
        int new_candidate =
            -operand.GetLocation() + operand.GetSizeInPointers() - 1;
        if (new_candidate > tail_caller_slots_above_sp) {
          tail_caller_slots_above_sp = new_candidate;
        }
      }
    }
  }
  return callee_slots_above_sp - tail_caller_slots_above_sp;
}

bool CallDescriptor::CanTailCall(const Node* node) const {
  return HasSameReturnLocationsAs(CallDescriptorOf(node->op()));
}

int CallDescriptor::CalculateFixedFrameSize() const {
  switch (kind_) {
    case kCallJSFunction:
      return PushArgumentCount()
                 ? OptimizedBuiltinFrameConstants::kFixedSlotCount
                 : StandardFrameConstants::kFixedSlotCount;
      break;
    case kCallAddress:
      return CommonFrameConstants::kFixedSlotCountAboveFp +
             CommonFrameConstants::kCPSlotCount;
      break;
    case kCallCodeObject:
      return TypedFrameConstants::kFixedSlotCount;
  }
  UNREACHABLE();
  return 0;
}

CallDescriptor* Linkage::ComputeIncoming(Zone* zone, CompilationInfo* info) {
  DCHECK(!info->IsStub());
  if (!info->closure().is_null()) {
    // If we are compiling a JS function, use a JS call descriptor,
    // plus the receiver.
    SharedFunctionInfo* shared = info->closure()->shared();
    return GetJSCallDescriptor(zone, info->is_osr(),
                               1 + shared->internal_formal_parameter_count(),
                               CallDescriptor::kNoFlags);
  }
  return nullptr;  // TODO(titzer): ?
}


// static
bool Linkage::NeedsFrameStateInput(Runtime::FunctionId function) {
  switch (function) {
    // Most runtime functions need a FrameState. A few chosen ones that we know
    // not to call into arbitrary JavaScript, not to throw, and not to
    // deoptimize
    // are whitelisted here and can be called without a FrameState.
    case Runtime::kAbort:
    case Runtime::kAllocateInTargetSpace:
    case Runtime::kCreateIterResultObject:
    case Runtime::kDefineGetterPropertyUnchecked:  // TODO(jarin): Is it safe?
    case Runtime::kDefineSetterPropertyUnchecked:  // TODO(jarin): Is it safe?
    case Runtime::kGeneratorGetContinuation:
    case Runtime::kIsFunction:
    case Runtime::kNewClosure:
    case Runtime::kNewClosure_Tenured:
    case Runtime::kNewFunctionContext:
    case Runtime::kPushBlockContext:
    case Runtime::kPushCatchContext:
    case Runtime::kReThrow:
    case Runtime::kStringCompare:
    case Runtime::kStringEqual:
    case Runtime::kStringNotEqual:
    case Runtime::kStringLessThan:
    case Runtime::kStringLessThanOrEqual:
    case Runtime::kStringGreaterThan:
    case Runtime::kStringGreaterThanOrEqual:
    case Runtime::kToFastProperties:  // TODO(conradw): Is it safe?
    case Runtime::kTraceEnter:
    case Runtime::kTraceExit:
      return false;

    // Some inline intrinsics are also safe to call without a FrameState.
    case Runtime::kInlineCreateIterResultObject:
    case Runtime::kInlineFixedArrayGet:
    case Runtime::kInlineFixedArraySet:
    case Runtime::kInlineGeneratorClose:
    case Runtime::kInlineGeneratorGetInputOrDebugPos:
    case Runtime::kInlineGeneratorGetResumeMode:
    case Runtime::kInlineIsArray:
    case Runtime::kInlineIsJSReceiver:
    case Runtime::kInlineIsRegExp:
    case Runtime::kInlineIsSmi:
    case Runtime::kInlineIsTypedArray:
      return false;

    default:
      break;
  }

  // For safety, default to needing a FrameState unless whitelisted.
  return true;
}


bool CallDescriptor::UsesOnlyRegisters() const {
  for (size_t i = 0; i < InputCount(); ++i) {
    if (!GetInputLocation(i).IsRegister()) return false;
  }
  for (size_t i = 0; i < ReturnCount(); ++i) {
    if (!GetReturnLocation(i).IsRegister()) return false;
  }
  return true;
}


CallDescriptor* Linkage::GetRuntimeCallDescriptor(
    Zone* zone, Runtime::FunctionId function_id, int js_parameter_count,
    Operator::Properties properties, CallDescriptor::Flags flags) {
  const Runtime::Function* function = Runtime::FunctionForId(function_id);
  const int return_count = function->result_size;
  const char* debug_name = function->name;

  if (!Linkage::NeedsFrameStateInput(function_id)) {
    flags = static_cast<CallDescriptor::Flags>(
        flags & ~CallDescriptor::kNeedsFrameState);
  }

  return GetCEntryStubCallDescriptor(zone, return_count, js_parameter_count,
                                     debug_name, properties, flags);
}

CallDescriptor* Linkage::GetCEntryStubCallDescriptor(
    Zone* zone, int return_count, int js_parameter_count,
    const char* debug_name, Operator::Properties properties,
    CallDescriptor::Flags flags) {
  const size_t function_count = 1;
  const size_t num_args_count = 1;
  const size_t context_count = 1;
  const size_t parameter_count = function_count +
                                 static_cast<size_t>(js_parameter_count) +
                                 num_args_count + context_count;

  LocationSignature::Builder locations(zone, static_cast<size_t>(return_count),
                                       static_cast<size_t>(parameter_count));

  // Add returns.
  if (locations.return_count_ > 0) {
    locations.AddReturn(regloc(kReturnRegister0, MachineType::AnyTagged()));
  }
  if (locations.return_count_ > 1) {
    locations.AddReturn(regloc(kReturnRegister1, MachineType::AnyTagged()));
  }
  if (locations.return_count_ > 2) {
    locations.AddReturn(regloc(kReturnRegister2, MachineType::AnyTagged()));
  }

  // All parameters to the runtime call go on the stack.
  for (int i = 0; i < js_parameter_count; i++) {
    locations.AddParam(LinkageLocation::ForCallerFrameSlot(
        i - js_parameter_count, MachineType::AnyTagged()));
  }
  // Add runtime function itself.
  locations.AddParam(
      regloc(kRuntimeCallFunctionRegister, MachineType::Pointer()));

  // Add runtime call argument count.
  locations.AddParam(
      regloc(kRuntimeCallArgCountRegister, MachineType::Int32()));

  // Add context.
  locations.AddParam(regloc(kContextRegister, MachineType::AnyTagged()));

  // The target for runtime calls is a code object.
  MachineType target_type = MachineType::AnyTagged();
  LinkageLocation target_loc =
      LinkageLocation::ForAnyRegister(MachineType::AnyTagged());
  return new (zone) CallDescriptor(     // --
      CallDescriptor::kCallCodeObject,  // kind
      target_type,                      // target MachineType
      target_loc,                       // target location
      locations.Build(),                // location_sig
      js_parameter_count,               // stack_parameter_count
      properties,                       // properties
      kNoCalleeSaved,                   // callee-saved
      kNoCalleeSaved,                   // callee-saved fp
      flags,                            // flags
      debug_name);                      // debug name
}

CallDescriptor* Linkage::GetJSCallDescriptor(Zone* zone, bool is_osr,
                                             int js_parameter_count,
                                             CallDescriptor::Flags flags) {
  const size_t return_count = 1;
  const size_t context_count = 1;
  const size_t new_target_count = 1;
  const size_t num_args_count = 1;
  const size_t parameter_count =
      js_parameter_count + new_target_count + num_args_count + context_count;

  LocationSignature::Builder locations(zone, return_count, parameter_count);

  // All JS calls have exactly one return value.
  locations.AddReturn(regloc(kReturnRegister0, MachineType::AnyTagged()));

  // All parameters to JS calls go on the stack.
  for (int i = 0; i < js_parameter_count; i++) {
    int spill_slot_index = i - js_parameter_count;
    locations.AddParam(LinkageLocation::ForCallerFrameSlot(
        spill_slot_index, MachineType::AnyTagged()));
  }

  // Add JavaScript call new target value.
  locations.AddParam(
      regloc(kJavaScriptCallNewTargetRegister, MachineType::AnyTagged()));

  // Add JavaScript call argument count.
  locations.AddParam(
      regloc(kJavaScriptCallArgCountRegister, MachineType::Int32()));

  // Add context.
  locations.AddParam(regloc(kContextRegister, MachineType::AnyTagged()));

  // The target for JS function calls is the JSFunction object.
  MachineType target_type = MachineType::AnyTagged();
  // When entering into an OSR function from unoptimized code the JSFunction
  // is not in a register, but it is on the stack in the marker spill slot.
  LinkageLocation target_loc =
      is_osr ? LinkageLocation::ForSavedCallerFunction()
             : regloc(kJSFunctionRegister, MachineType::AnyTagged());
  return new (zone) CallDescriptor(     // --
      CallDescriptor::kCallJSFunction,  // kind
      target_type,                      // target MachineType
      target_loc,                       // target location
      locations.Build(),                // location_sig
      js_parameter_count,               // stack_parameter_count
      Operator::kNoProperties,          // properties
      kNoCalleeSaved,                   // callee-saved
      kNoCalleeSaved,                   // callee-saved fp
      CallDescriptor::kCanUseRoots |    // flags
          flags,                        // flags
      "js-call");
}

// TODO(all): Add support for return representations/locations to
// CallInterfaceDescriptor.
// TODO(turbofan): cache call descriptors for code stub calls.
CallDescriptor* Linkage::GetStubCallDescriptor(
    Isolate* isolate, Zone* zone, const CallInterfaceDescriptor& descriptor,
    int stack_parameter_count, CallDescriptor::Flags flags,
    Operator::Properties properties, MachineType return_type,
    size_t return_count) {
  const int register_parameter_count = descriptor.GetRegisterParameterCount();
  const int js_parameter_count =
      register_parameter_count + stack_parameter_count;
  const int context_count = 1;
  const size_t parameter_count =
      static_cast<size_t>(js_parameter_count + context_count);

  LocationSignature::Builder locations(zone, return_count, parameter_count);

  // Add returns.
  if (locations.return_count_ > 0) {
    locations.AddReturn(regloc(kReturnRegister0, return_type));
  }
  if (locations.return_count_ > 1) {
    locations.AddReturn(regloc(kReturnRegister1, return_type));
  }
  if (locations.return_count_ > 2) {
    locations.AddReturn(regloc(kReturnRegister2, return_type));
  }

  // Add parameters in registers and on the stack.
  for (int i = 0; i < js_parameter_count; i++) {
    if (i < register_parameter_count) {
      // The first parameters go in registers.
      Register reg = descriptor.GetRegisterParameter(i);
      MachineType type = descriptor.GetParameterType(i);
      locations.AddParam(regloc(reg, type));
    } else {
      // The rest of the parameters go on the stack.
      int stack_slot = i - register_parameter_count - stack_parameter_count;
      locations.AddParam(LinkageLocation::ForCallerFrameSlot(
          stack_slot, MachineType::AnyTagged()));
    }
  }
  // Add context.
  locations.AddParam(regloc(kContextRegister, MachineType::AnyTagged()));

  // The target for stub calls is a code object.
  MachineType target_type = MachineType::AnyTagged();
  LinkageLocation target_loc =
      LinkageLocation::ForAnyRegister(MachineType::AnyTagged());
  return new (zone) CallDescriptor(     // --
      CallDescriptor::kCallCodeObject,  // kind
      target_type,                      // target MachineType
      target_loc,                       // target location
      locations.Build(),                // location_sig
      stack_parameter_count,            // stack_parameter_count
      properties,                       // properties
      kNoCalleeSaved,                   // callee-saved registers
      kNoCalleeSaved,                   // callee-saved fp
      CallDescriptor::kCanUseRoots |    // flags
          flags,                        // flags
      descriptor.DebugName(isolate));
}

// static
CallDescriptor* Linkage::GetAllocateCallDescriptor(Zone* zone) {
  LocationSignature::Builder locations(zone, 1, 1);

  locations.AddParam(regloc(kAllocateSizeRegister, MachineType::Int32()));

  locations.AddReturn(regloc(kReturnRegister0, MachineType::AnyTagged()));

  // The target for allocate calls is a code object.
  MachineType target_type = MachineType::AnyTagged();
  LinkageLocation target_loc =
      LinkageLocation::ForAnyRegister(MachineType::AnyTagged());
  return new (zone) CallDescriptor(     // --
      CallDescriptor::kCallCodeObject,  // kind
      target_type,                      // target MachineType
      target_loc,                       // target location
      locations.Build(),                // location_sig
      0,                                // stack_parameter_count
      Operator::kNoThrow,               // properties
      kNoCalleeSaved,                   // callee-saved registers
      kNoCalleeSaved,                   // callee-saved fp
      CallDescriptor::kCanUseRoots,     // flags
      "Allocate");
}

// static
CallDescriptor* Linkage::GetBytecodeDispatchCallDescriptor(
    Isolate* isolate, Zone* zone, const CallInterfaceDescriptor& descriptor,
    int stack_parameter_count) {
  const int register_parameter_count = descriptor.GetRegisterParameterCount();
  const int parameter_count = register_parameter_count + stack_parameter_count;

  LocationSignature::Builder locations(zone, 0, parameter_count);

  // Add parameters in registers and on the stack.
  for (int i = 0; i < parameter_count; i++) {
    if (i < register_parameter_count) {
      // The first parameters go in registers.
      Register reg = descriptor.GetRegisterParameter(i);
      MachineType type = descriptor.GetParameterType(i);
      locations.AddParam(regloc(reg, type));
    } else {
      // The rest of the parameters go on the stack.
      int stack_slot = i - register_parameter_count - stack_parameter_count;
      locations.AddParam(LinkageLocation::ForCallerFrameSlot(
          stack_slot, MachineType::AnyTagged()));
    }
  }

  // The target for interpreter dispatches is a code entry address.
  MachineType target_type = MachineType::Pointer();
  LinkageLocation target_loc = LinkageLocation::ForAnyRegister(target_type);
  return new (zone) CallDescriptor(            // --
      CallDescriptor::kCallAddress,            // kind
      target_type,                             // target MachineType
      target_loc,                              // target location
      locations.Build(),                       // location_sig
      stack_parameter_count,                   // stack_parameter_count
      Operator::kNoProperties,                 // properties
      kNoCalleeSaved,                          // callee-saved registers
      kNoCalleeSaved,                          // callee-saved fp
      CallDescriptor::kCanUseRoots |           // flags
          CallDescriptor::kSupportsTailCalls,  // flags
      descriptor.DebugName(isolate));
}

LinkageLocation Linkage::GetOsrValueLocation(int index) const {
  CHECK(incoming_->IsJSFunctionCall());
  int parameter_count = static_cast<int>(incoming_->JSParameterCount() - 1);
  int first_stack_slot = OsrHelper::FirstStackSlotIndex(parameter_count);

  if (index == kOsrContextSpillSlotIndex) {
    // Context. Use the parameter location of the context spill slot.
    // Parameter (arity + 2) is special for the context of the function frame.
    // >> context_index = target + receiver + params + new_target + #args
    int context_index = 1 + 1 + parameter_count + 1 + 1;
    return incoming_->GetInputLocation(context_index);
  } else if (index >= first_stack_slot) {
    // Local variable stored in this (callee) stack.
    int spill_index =
        index - first_stack_slot + StandardFrameConstants::kFixedSlotCount;
    return LinkageLocation::ForCalleeFrameSlot(spill_index,
                                               MachineType::AnyTagged());
  } else {
    // Parameter. Use the assigned location from the incoming call descriptor.
    int parameter_index = 1 + index;  // skip index 0, which is the target.
    return incoming_->GetInputLocation(parameter_index);
  }
}


bool Linkage::ParameterHasSecondaryLocation(int index) const {
  if (!incoming_->IsJSFunctionCall()) return false;
  LinkageLocation loc = GetParameterLocation(index);
  return (loc == regloc(kJSFunctionRegister, MachineType::AnyTagged()) ||
          loc == regloc(kContextRegister, MachineType::AnyTagged()));
}

LinkageLocation Linkage::GetParameterSecondaryLocation(int index) const {
  DCHECK(ParameterHasSecondaryLocation(index));
  LinkageLocation loc = GetParameterLocation(index);

  if (loc == regloc(kJSFunctionRegister, MachineType::AnyTagged())) {
    return LinkageLocation::ForCalleeFrameSlot(Frame::kJSFunctionSlot,
                                               MachineType::AnyTagged());
  } else {
    DCHECK(loc == regloc(kContextRegister, MachineType::AnyTagged()));
    return LinkageLocation::ForCalleeFrameSlot(Frame::kContextSlot,
                                               MachineType::AnyTagged());
  }
}


}  // namespace compiler
}  // namespace internal
}  // namespace v8