tor-browser

BaselineFrameInfo.cpp (6453B)

---

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* vim: set ts=8 sts=2 et sw=2 tw=80:
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "jit/BaselineFrameInfo.h"

#include <algorithm>

#include "jit/BaselineIC.h"
#ifdef DEBUG
#  include "jit/BytecodeAnalysis.h"
#endif

#include "jit/BaselineFrameInfo-inl.h"
#include "jit/JitFrames.h"
#include "jit/MacroAssembler-inl.h"

using namespace js;
using namespace js::jit;

bool CompilerFrameInfo::init(TempAllocator& alloc) {
 // An extra slot is needed for global scopes because INITGLEXICAL (stack
 // depth 1) is compiled as a SETPROP (stack depth 2) on the global lexical
 // scope.
 size_t extra = script->isGlobalCode() ? 1 : 0;
 size_t nstack =
     std::max(script->nslots() - script->nfixed(), size_t(MinJITStackSize)) +
     extra;
 if (!stack.init(alloc, nstack)) {
   return false;
 }

 return true;
}

void CompilerFrameInfo::sync(StackValue* val) {
 switch (val->kind()) {
   case StackValue::Stack:
     break;
   case StackValue::LocalSlot:
     masm.pushValue(addressOfLocal(val->localSlot()));
     break;
   case StackValue::ArgSlot:
     masm.pushValue(addressOfArg(val->argSlot()));
     break;
   case StackValue::ThisSlot:
     masm.pushValue(addressOfThis());
     break;
   case StackValue::Register:
     masm.pushValue(val->reg());
     break;
   case StackValue::Constant:
     masm.pushValue(val->constant());
     break;
   default:
     MOZ_CRASH("Invalid kind");
 }

 val->setStack();
}

void CompilerFrameInfo::syncStack(uint32_t uses) {
 MOZ_ASSERT(uses <= stackDepth());

 uint32_t depth = stackDepth() - uses;

 for (uint32_t i = 0; i < depth; i++) {
   StackValue* current = &stack[i];
   sync(current);
 }
}

uint32_t CompilerFrameInfo::numUnsyncedSlots() {
 // Start at the bottom, find the first value that's not synced.
 uint32_t i = 0;
 for (; i < stackDepth(); i++) {
   if (peek(-int32_t(i + 1))->kind() == StackValue::Stack) {
     break;
   }
 }
 return i;
}

void CompilerFrameInfo::popValue(ValueOperand dest) {
 StackValue* val = peek(-1);

 switch (val->kind()) {
   case StackValue::Constant:
     masm.moveValue(val->constant(), dest);
     break;
   case StackValue::LocalSlot:
     masm.loadValue(addressOfLocal(val->localSlot()), dest);
     break;
   case StackValue::ArgSlot:
     masm.loadValue(addressOfArg(val->argSlot()), dest);
     break;
   case StackValue::ThisSlot:
     masm.loadValue(addressOfThis(), dest);
     break;
   case StackValue::Stack:
     masm.popValue(dest);
     break;
   case StackValue::Register:
     masm.moveValue(val->reg(), dest);
     break;
   default:
     MOZ_CRASH("Invalid kind");
 }

 // masm.popValue already adjusted the stack pointer, don't do it twice.
 pop(DontAdjustStack);
}

void CompilerFrameInfo::popRegsAndSync(uint32_t uses) {
 // x86 has only 3 Value registers. Only support 2 regs here for now,
 // so that there's always a scratch Value register for reg -> reg
 // moves.
 MOZ_ASSERT(uses > 0);
 MOZ_ASSERT(uses <= 2);
 MOZ_ASSERT(uses <= stackDepth());

 syncStack(uses);

 switch (uses) {
   case 1:
     popValue(R0);
     break;
   case 2: {
     // If the second value is in R1, move it to R2 so that it's not
     // clobbered by the first popValue.
     StackValue* val = peek(-2);
     if (val->kind() == StackValue::Register && val->reg() == R1) {
       masm.moveValue(R1, ValueOperand(R2));
       val->setRegister(R2);
     }
     popValue(R1);
     popValue(R0);
     break;
   }
   default:
     MOZ_CRASH("Invalid uses");
 }
 // On arm64, SP may be < PSP now (that's OK).
 // eg testcase: tests/bug1580246.js
}

void InterpreterFrameInfo::popRegsAndSync(uint32_t uses) {
 switch (uses) {
   case 1:
     popValue(R0);
     break;
   case 2: {
     popValue(R1);
     popValue(R0);
     break;
   }
   default:
     MOZ_CRASH("Invalid uses");
 }
 // On arm64, SP may be < PSP now (that's OK).
 // eg testcase: tests/backup-point-bug1315634.js
}

void InterpreterFrameInfo::bumpInterpreterICEntry() {
 masm.addPtr(Imm32(sizeof(ICEntry)), addressOfInterpreterICEntry());
}

void CompilerFrameInfo::storeStackValue(int32_t depth, const Address& dest,
                                       const ValueOperand& scratch) {
 const StackValue* source = peek(depth);
 switch (source->kind()) {
   case StackValue::Constant:
     masm.storeValue(source->constant(), dest);
     break;
   case StackValue::Register:
     masm.storeValue(source->reg(), dest);
     break;
   case StackValue::LocalSlot:
     masm.loadValue(addressOfLocal(source->localSlot()), scratch);
     masm.storeValue(scratch, dest);
     break;
   case StackValue::ArgSlot:
     masm.loadValue(addressOfArg(source->argSlot()), scratch);
     masm.storeValue(scratch, dest);
     break;
   case StackValue::ThisSlot:
     masm.loadValue(addressOfThis(), scratch);
     masm.storeValue(scratch, dest);
     break;
   case StackValue::Stack:
     masm.loadValue(addressOfStackValue(depth), scratch);
     masm.storeValue(scratch, dest);
     break;
   default:
     MOZ_CRASH("Invalid kind");
 }
}

#ifdef DEBUG
void CompilerFrameInfo::assertValidState(const BytecodeInfo& info) {
 // Check stack depth.
 MOZ_ASSERT(stackDepth() == info.stackDepth);

 // Start at the bottom, find the first value that's not synced.
 uint32_t i = 0;
 for (; i < stackDepth(); i++) {
   if (stack[i].kind() != StackValue::Stack) {
     break;
   }
 }

 // Assert all values on top of it are also not synced.
 for (; i < stackDepth(); i++) {
   MOZ_ASSERT(stack[i].kind() != StackValue::Stack);
 }

 // Assert every Value register is used by at most one StackValue.
 // R2 is used as scratch register by the compiler and FrameInfo,
 // so it shouldn't be used for StackValues.
 bool usedR0 = false, usedR1 = false;

 for (i = 0; i < stackDepth(); i++) {
   if (stack[i].kind() == StackValue::Register) {
     ValueOperand reg = stack[i].reg();
     if (reg == R0) {
       MOZ_ASSERT(!usedR0);
       usedR0 = true;
     } else if (reg == R1) {
       MOZ_ASSERT(!usedR1);
       usedR1 = true;
     } else {
       MOZ_CRASH("Invalid register");
     }
   }
 }
}
#endif