v8/src/x64/fast-codegen-x64.cc

// Copyright 2009 the V8 project authors. All rights reserved.
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// 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
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//       with the distribution.
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#include "v8.h"

#include "codegen-inl.h"
#include "debug.h"
#include "fast-codegen.h"

namespace v8 {
namespace internal {

#define __ ACCESS_MASM(masm_)

// Generate code for a JS function.  On entry to the function the receiver
// and arguments have been pushed on the stack left to right, with the
// return address on top of them.  The actual argument count matches the
// formal parameter count expected by the function.
//
// The live registers are:
//   o rdi: the JS function object being called (ie, ourselves)
//   o rsi: our context
//   o rbp: our caller's frame pointer
//   o rsp: stack pointer (pointing to return address)
//
// The function builds a JS frame.  Please see JavaScriptFrameConstants in
// frames-x64.h for its layout.
void FastCodeGenerator::Generate(FunctionLiteral* fun) {
  function_ = fun;
  SetFunctionPosition(fun);

  __ push(rbp);  // Caller's frame pointer.
  __ movq(rbp, rsp);
  __ push(rsi);  // Callee's context.
  __ push(rdi);  // Callee's JS Function.

  { Comment cmnt(masm_, "[ Allocate locals");
    int locals_count = fun->scope()->num_stack_slots();
    for (int i = 0; i < locals_count; i++) {
      __ PushRoot(Heap::kUndefinedValueRootIndex);
    }
  }

  { Comment cmnt(masm_, "[ Stack check");
    Label ok;
    __ CompareRoot(rsp, Heap::kStackLimitRootIndex);
    __ j(above_equal, &ok);
    StackCheckStub stub;
    __ CallStub(&stub);
    __ bind(&ok);
  }

  { Comment cmnt(masm_, "[ Declarations");
    VisitDeclarations(fun->scope()->declarations());
  }

  { Comment cmnt(masm_, "[ Body");
    VisitStatements(fun->body());
  }

  { Comment cmnt(masm_, "[ return <undefined>;");
    // Emit a 'return undefined' in case control fell off the end of the
    // body.
    __ LoadRoot(rax, Heap::kUndefinedValueRootIndex);
    SetReturnPosition(fun);
    __ RecordJSReturn();
    // Do not use the leave instruction here because it is too short to
    // patch with the code required by the debugger.
    __ movq(rsp, rbp);
    __ pop(rbp);
    __ ret((fun->scope()->num_parameters() + 1) * kPointerSize);
#ifdef ENABLE_DEBUGGER_SUPPORT
    // Add padding that will be overwritten by a debugger breakpoint.  We
    // have just generated "movq rsp, rbp; pop rbp; ret k" with length 7
    // (3 + 1 + 3).
    const int kPadding = Debug::kX64JSReturnSequenceLength - 7;
    for (int i = 0; i < kPadding; ++i) {
      masm_->int3();
    }
#endif
  }
}


void FastCodeGenerator::DeclareGlobals(Handle<FixedArray> pairs) {
  // Call the runtime to declare the globals.
  __ Push(pairs);
  __ push(rsi);  // The context is the second argument.
  __ Push(Smi::FromInt(is_eval_ ? 1 : 0));
  __ CallRuntime(Runtime::kDeclareGlobals, 3);
  // Return value is ignored.
}


void FastCodeGenerator::VisitBlock(Block* stmt) {
  Comment cmnt(masm_, "[ Block");
  SetStatementPosition(stmt);
  VisitStatements(stmt->statements());
}


void FastCodeGenerator::VisitExpressionStatement(ExpressionStatement* stmt) {
  Comment cmnt(masm_, "[ ExpressionStatement");
  SetStatementPosition(stmt);
  Visit(stmt->expression());
}


void FastCodeGenerator::VisitReturnStatement(ReturnStatement* stmt) {
  Comment cmnt(masm_, "[ ReturnStatement");
  SetStatementPosition(stmt);
  Expression* expr = stmt->expression();
  Visit(expr);

  // Complete the statement based on the location of the subexpression.
  Location source = expr->location();
  ASSERT(!source.is_nowhere());
  if (source.is_temporary()) {
    __ pop(rax);
  } else {
    ASSERT(source.is_constant());
    ASSERT(expr->AsLiteral() != NULL);
    __ Move(rax, expr->AsLiteral()->handle());
  }
  __ RecordJSReturn();
  // Do not use the leave instruction here because it is too short to
  // patch with the code required by the debugger.
  __ movq(rsp, rbp);
  __ pop(rbp);
  __ ret((function_->scope()->num_parameters() + 1) * kPointerSize);
#ifdef ENABLE_DEBUGGER_SUPPORT
  // Add padding that will be overwritten by a debugger breakpoint.  We
  // have just generated "movq rsp, rbp; pop rbp; ret k" with length 7
  // (3 + 1 + 3).
  const int kPadding = Debug::kX64JSReturnSequenceLength - 7;
  for (int i = 0; i < kPadding; ++i) {
    masm_->int3();
  }
#endif
}


void FastCodeGenerator::VisitFunctionLiteral(FunctionLiteral* expr) {
  Comment cmnt(masm_, "[ FunctionLiteral");

  // Build the function boilerplate and instantiate it.
  Handle<JSFunction> boilerplate = BuildBoilerplate(expr);
  if (HasStackOverflow()) return;

  ASSERT(boilerplate->IsBoilerplate());

  // Create a new closure.
  __ Push(boilerplate);
  __ push(rsi);
  __ CallRuntime(Runtime::kNewClosure, 2);

  if (expr->location().is_temporary()) {
    __ push(rax);
  } else {
    ASSERT(expr->location().is_nowhere());
  }
}


void FastCodeGenerator::VisitVariableProxy(VariableProxy* expr) {
  Comment cmnt(masm_, "[ VariableProxy");
  Expression* rewrite = expr->var()->rewrite();
  ASSERT(rewrite != NULL);

  Slot* slot = rewrite->AsSlot();
  ASSERT(slot != NULL);
  { Comment cmnt(masm_, "[ Slot");
    if (expr->location().is_temporary()) {
      __ push(Operand(rbp, SlotOffset(slot)));
    } else {
      ASSERT(expr->location().is_nowhere());
    }
  }
}


void FastCodeGenerator::VisitAssignment(Assignment* expr) {
  Comment cmnt(masm_, "[ Assignment");
  ASSERT(expr->op() == Token::ASSIGN || expr->op() == Token::INIT_VAR);
  Expression* rhs = expr->value();
  Visit(rhs);

  // Left-hand side can only be a global or a (parameter or local) slot.
  Variable* var = expr->target()->AsVariableProxy()->AsVariable();
  ASSERT(var != NULL);
  ASSERT(var->is_global() || var->slot() != NULL);

  // Complete the assignment based on the location of the right-hand-side
  // value and the desired location of the assignment value.
  Location destination = expr->location();
  Location source = rhs->location();
  ASSERT(!destination.is_constant());
  ASSERT(!source.is_nowhere());

  if (var->is_global()) {
    // Assignment to a global variable, use inline caching.  Right-hand-side
    // value is passed in rax, variable name in rcx, and the global object
    // on the stack.
    if (source.is_temporary()) {
      __ pop(rax);
    } else {
      ASSERT(source.is_constant());
      ASSERT(rhs->AsLiteral() != NULL);
      __ Move(rax, rhs->AsLiteral()->handle());
    }
    __ Move(rcx, var->name());
    __ push(CodeGenerator::GlobalObject());
    Handle<Code> ic(Builtins::builtin(Builtins::StoreIC_Initialize));
    __ Call(ic, RelocInfo::CODE_TARGET);
    // Overwrite the global object on the stack with the result if needed.
    if (destination.is_temporary()) {
      __ movq(Operand(rsp, 0), rax);
    } else {
      __ pop(rax);
    }
  } else {
    if (source.is_temporary()) {
      if (destination.is_temporary()) {
        // Case 'temp1 <- (var = temp0)'.  Preserve right-hand-side temporary
        // on the stack.
        __ movq(kScratchRegister, Operand(rsp, 0));
        __ movq(Operand(rbp, SlotOffset(var->slot())), kScratchRegister);
      } else {
        ASSERT(destination.is_nowhere());
        // Case 'var = temp'.  Discard right-hand-side temporary.
        __ pop(Operand(rbp, SlotOffset(var->slot())));
      }
    } else {
      ASSERT(source.is_constant());
      ASSERT(rhs->AsLiteral() != NULL);
      // Two cases: 'temp <- (var = constant)', or 'var = constant' with a
      // discarded result.  Always perform the assignment.
      __ Move(kScratchRegister, rhs->AsLiteral()->handle());
      __ movq(Operand(rbp, SlotOffset(var->slot())), kScratchRegister);
      if (destination.is_temporary()) {
        // Case 'temp <- (var = constant)'.  Save result.
        __ push(kScratchRegister);
      }
    }
  }
}


void FastCodeGenerator::VisitCall(Call* expr) {
  Expression* fun = expr->expression();
  ZoneList<Expression*>* args = expr->arguments();
  Variable* var = fun->AsVariableProxy()->AsVariable();
  ASSERT(var != NULL && !var->is_this() && var->is_global());
  ASSERT(!var->is_possibly_eval());

  __ Push(var->name());
  // Push global object (receiver).
  __ push(CodeGenerator::GlobalObject());
  int arg_count = args->length();
  for (int i = 0; i < arg_count; i++) {
    Visit(args->at(i));
    ASSERT(!args->at(i)->location().is_nowhere());
    if (args->at(i)->location().is_constant()) {
      ASSERT(args->at(i)->AsLiteral() != NULL);
      __ Push(args->at(i)->AsLiteral()->handle());
    }
  }
  // Record source position for debugger
  SetSourcePosition(expr->position());
  // Call the IC initialization code.
  Handle<Code> ic = CodeGenerator::ComputeCallInitialize(arg_count,
                                                         NOT_IN_LOOP);
  __ call(ic, RelocInfo::CODE_TARGET_CONTEXT);
  // Restore context register.
  __ movq(rsi, Operand(rbp, StandardFrameConstants::kContextOffset));
  // Discard the function left on TOS.
  if (expr->location().is_temporary()) {
    __ movq(Operand(rsp, 0), rax);
  } else {
    ASSERT(expr->location().is_nowhere());
    __ pop(rax);
  }
}


void FastCodeGenerator::VisitCallRuntime(CallRuntime* expr) {
  Comment cmnt(masm_, "[ CallRuntime");
  ZoneList<Expression*>* args = expr->arguments();
  Runtime::Function* function = expr->function();

  ASSERT(function != NULL);

  // Push the arguments ("left-to-right").
  int arg_count = args->length();
  for (int i = 0; i < arg_count; i++) {
    Visit(args->at(i));
    ASSERT(!args->at(i)->location().is_nowhere());
    if (args->at(i)->location().is_constant()) {
      ASSERT(args->at(i)->AsLiteral() != NULL);
      __ Push(args->at(i)->AsLiteral()->handle());
    }
  }

  __ CallRuntime(function, arg_count);
  if (expr->location().is_temporary()) {
    __ push(rax);
  } else {
    ASSERT(expr->location().is_nowhere());
  }
}


} }  // namespace v8::internal