The Tor Browser: js/src/jit/x86/Lowering-x86.cpp@6474c204b198 (annotated)

js/src/jit/x86/Lowering-x86.cpp@6474c204b198 (annotated)

js/src/jit/x86/Lowering-x86.cpp

Wed, 31 Dec 2014 06:09:35 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Wed, 31 Dec 2014 06:09:35 +0100
changeset 0: 6474c204b198
permissions: -rw-r--r--

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
  * vim: set ts=8 sts=4 et sw=4 tw=99:
  * 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/x86/Lowering-x86.h"
 #include "jit/MIR.h"
 #include "jit/x86/Assembler-x86.h"
 #include "jit/shared/Lowering-shared-inl.h"
 using namespace js;
 using namespace js::jit;
 LDefinition
 LIRGeneratorX86::tempForDispatchCache(MIRType outputType)
 {
     // x86 doesn't have a scratch register and we need one for the
     // indirect jump for dispatch-style ICs.
     //
     // Note that currently we only install dispatch-style ICs for parallel
     // execution. If this assumption changes, please change it here.
     if (gen->info().executionMode() != ParallelExecution)
         return LDefinition::BogusTemp();
     // If we don't have an output register, we need a temp.
     if (outputType == MIRType_None)
         return temp();
     // If we have a double output register, we need a temp.
     if (outputType == MIRType_Double)
         return temp();
     // Otherwise we have a non-double output register and we can reuse it.
     return LDefinition::BogusTemp();
 }
 bool
 LIRGeneratorX86::useBox(LInstruction *lir, size_t n, MDefinition *mir,
                         LUse::Policy policy, bool useAtStart)
 {
     JS_ASSERT(mir->type() == MIRType_Value);
     if (!ensureDefined(mir))
         return false;
     lir->setOperand(n, LUse(mir->virtualRegister(), policy, useAtStart));
     lir->setOperand(n + 1, LUse(VirtualRegisterOfPayload(mir), policy, useAtStart));
     return true;
 }
 bool
 LIRGeneratorX86::useBoxFixed(LInstruction *lir, size_t n, MDefinition *mir, Register reg1,
                              Register reg2)
 {
     JS_ASSERT(mir->type() == MIRType_Value);
     JS_ASSERT(reg1 != reg2);
     if (!ensureDefined(mir))
         return false;
     lir->setOperand(n, LUse(reg1, mir->virtualRegister()));
     lir->setOperand(n + 1, LUse(reg2, VirtualRegisterOfPayload(mir)));
     return true;
 }
 LAllocation
 LIRGeneratorX86::useByteOpRegister(MDefinition *mir)
 {
     return useFixed(mir, eax);
 }
 LAllocation
 LIRGeneratorX86::useByteOpRegisterOrNonDoubleConstant(MDefinition *mir)
 {
     return useFixed(mir, eax);
 }
 bool
 LIRGeneratorX86::visitBox(MBox *box)
 {
     MDefinition *inner = box->getOperand(0);
     // If the box wrapped a double, it needs a new register.
     if (IsFloatingPointType(inner->type()))
         return defineBox(new(alloc()) LBoxFloatingPoint(useRegisterAtStart(inner), tempCopy(inner, 0),
                                                         inner->type()), box);
     if (box->canEmitAtUses())
         return emitAtUses(box);
     if (inner->isConstant())
         return defineBox(new(alloc()) LValue(inner->toConstant()->value()), box);
     LBox *lir = new(alloc()) LBox(use(inner), inner->type());
     // Otherwise, we should not define a new register for the payload portion
     // of the output, so bypass defineBox().
     uint32_t vreg = getVirtualRegister();
     if (vreg >= MAX_VIRTUAL_REGISTERS)
         return false;
     // Note that because we're using PASSTHROUGH, we do not change the type of
     // the definition. We also do not define the first output as "TYPE",
     // because it has no corresponding payload at (vreg + 1). Also note that
     // although we copy the input's original type for the payload half of the
     // definition, this is only for clarity. PASSTHROUGH definitions are
     // ignored.
     lir->setDef(0, LDefinition(vreg, LDefinition::GENERAL));
     lir->setDef(1, LDefinition(inner->virtualRegister(), LDefinition::TypeFrom(inner->type()),
                                LDefinition::PASSTHROUGH));
     box->setVirtualRegister(vreg);
     return add(lir);
 }
 bool
 LIRGeneratorX86::visitUnbox(MUnbox *unbox)
 {
     // An unbox on x86 reads in a type tag (either in memory or a register) and
     // a payload. Unlike most instructions conusming a box, we ask for the type
     // second, so that the result can re-use the first input.
     MDefinition *inner = unbox->getOperand(0);
     if (!ensureDefined(inner))
         return false;
     if (IsFloatingPointType(unbox->type())) {
         LUnboxFloatingPoint *lir = new(alloc()) LUnboxFloatingPoint(unbox->type());
         if (unbox->fallible() && !assignSnapshot(lir, unbox->bailoutKind()))
             return false;
         if (!useBox(lir, LUnboxFloatingPoint::Input, inner))
             return false;
         return define(lir, unbox);
     }
     // Swap the order we use the box pieces so we can re-use the payload register.
     LUnbox *lir = new(alloc()) LUnbox;
     lir->setOperand(0, usePayloadInRegisterAtStart(inner));
     lir->setOperand(1, useType(inner, LUse::ANY));
     if (unbox->fallible() && !assignSnapshot(lir, unbox->bailoutKind()))
         return false;
     // Note that PASSTHROUGH here is illegal, since types and payloads form two
     // separate intervals. If the type becomes dead before the payload, it
     // could be used as a Value without the type being recoverable. Unbox's
     // purpose is to eagerly kill the definition of a type tag, so keeping both
     // alive (for the purpose of gcmaps) is unappealing. Instead, we create a
     // new virtual register.
     return defineReuseInput(lir, unbox, 0);
 }
 bool
 LIRGeneratorX86::visitReturn(MReturn *ret)
 {
     MDefinition *opd = ret->getOperand(0);
     JS_ASSERT(opd->type() == MIRType_Value);
     LReturn *ins = new(alloc()) LReturn;
     ins->setOperand(0, LUse(JSReturnReg_Type));
     ins->setOperand(1, LUse(JSReturnReg_Data));
     return fillBoxUses(ins, 0, opd) && add(ins);
 }
 bool
 LIRGeneratorX86::defineUntypedPhi(MPhi *phi, size_t lirIndex)
 {
     LPhi *type = current->getPhi(lirIndex + VREG_TYPE_OFFSET);
     LPhi *payload = current->getPhi(lirIndex + VREG_DATA_OFFSET);
     uint32_t typeVreg = getVirtualRegister();
     if (typeVreg >= MAX_VIRTUAL_REGISTERS)
         return false;
     phi->setVirtualRegister(typeVreg);
     uint32_t payloadVreg = getVirtualRegister();
     if (payloadVreg >= MAX_VIRTUAL_REGISTERS)
         return false;
     JS_ASSERT(typeVreg + 1 == payloadVreg);
     type->setDef(0, LDefinition(typeVreg, LDefinition::TYPE));
     payload->setDef(0, LDefinition(payloadVreg, LDefinition::PAYLOAD));
     annotate(type);
     annotate(payload);
     return true;
 }
 void
 LIRGeneratorX86::lowerUntypedPhiInput(MPhi *phi, uint32_t inputPosition, LBlock *block, size_t lirIndex)
 {
     MDefinition *operand = phi->getOperand(inputPosition);
     LPhi *type = block->getPhi(lirIndex + VREG_TYPE_OFFSET);
     LPhi *payload = block->getPhi(lirIndex + VREG_DATA_OFFSET);
     type->setOperand(inputPosition, LUse(operand->virtualRegister() + VREG_TYPE_OFFSET, LUse::ANY));
     payload->setOperand(inputPosition, LUse(VirtualRegisterOfPayload(operand), LUse::ANY));
 }
 bool
 LIRGeneratorX86::visitAsmJSUnsignedToDouble(MAsmJSUnsignedToDouble *ins)
 {
     JS_ASSERT(ins->input()->type() == MIRType_Int32);
     LAsmJSUInt32ToDouble *lir = new(alloc()) LAsmJSUInt32ToDouble(useRegisterAtStart(ins->input()), temp());
     return define(lir, ins);
 }
 bool
 LIRGeneratorX86::visitAsmJSUnsignedToFloat32(MAsmJSUnsignedToFloat32 *ins)
 {
     JS_ASSERT(ins->input()->type() == MIRType_Int32);
     LAsmJSUInt32ToFloat32 *lir = new(alloc()) LAsmJSUInt32ToFloat32(useRegisterAtStart(ins->input()), temp());
     return define(lir, ins);
 }
 bool
 LIRGeneratorX86::visitAsmJSLoadHeap(MAsmJSLoadHeap *ins)
 {
     MDefinition *ptr = ins->ptr();
     LAllocation ptrAlloc;
     JS_ASSERT(ptr->type() == MIRType_Int32);
     // For the x86 it is best to keep the 'ptr' in a register if a bounds check is needed.
     if (ptr->isConstant() && ins->skipBoundsCheck()) {
         int32_t ptrValue = ptr->toConstant()->value().toInt32();
         // A bounds check is only skipped for a positive index.
         JS_ASSERT(ptrValue >= 0);
         ptrAlloc = LAllocation(ptr->toConstant()->vp());
     } else {
         ptrAlloc = useRegisterAtStart(ptr);
     }
     LAsmJSLoadHeap *lir = new(alloc()) LAsmJSLoadHeap(ptrAlloc);
     return define(lir, ins);
 }
 bool
 LIRGeneratorX86::visitAsmJSStoreHeap(MAsmJSStoreHeap *ins)
 {
     MDefinition *ptr = ins->ptr();
     LAsmJSStoreHeap *lir;
     JS_ASSERT(ptr->type() == MIRType_Int32);
     if (ptr->isConstant() && ins->skipBoundsCheck()) {
         int32_t ptrValue = ptr->toConstant()->value().toInt32();
         JS_ASSERT(ptrValue >= 0);
         LAllocation ptrAlloc = LAllocation(ptr->toConstant()->vp());
         switch (ins->viewType()) {
           case ArrayBufferView::TYPE_INT8: case ArrayBufferView::TYPE_UINT8:
             // See comment below.
             lir = new(alloc()) LAsmJSStoreHeap(ptrAlloc, useFixed(ins->value(), eax));
             break;
           case ArrayBufferView::TYPE_INT16: case ArrayBufferView::TYPE_UINT16:
           case ArrayBufferView::TYPE_INT32: case ArrayBufferView::TYPE_UINT32:
           case ArrayBufferView::TYPE_FLOAT32: case ArrayBufferView::TYPE_FLOAT64:
             // See comment below.
             lir = new(alloc()) LAsmJSStoreHeap(ptrAlloc, useRegisterAtStart(ins->value()));
             break;
           default: MOZ_ASSUME_UNREACHABLE("unexpected array type");
         }
         return add(lir, ins);
     }
     switch (ins->viewType()) {
       case ArrayBufferView::TYPE_INT8: case ArrayBufferView::TYPE_UINT8:
         // See comment for LIRGeneratorX86::useByteOpRegister.
         lir = new(alloc()) LAsmJSStoreHeap(useRegister(ins->ptr()), useFixed(ins->value(), eax));
         break;
       case ArrayBufferView::TYPE_INT16: case ArrayBufferView::TYPE_UINT16:
       case ArrayBufferView::TYPE_INT32: case ArrayBufferView::TYPE_UINT32:
       case ArrayBufferView::TYPE_FLOAT32: case ArrayBufferView::TYPE_FLOAT64:
         // For now, don't allow constant values. The immediate operand
         // affects instruction layout which affects patching.
         lir = new(alloc()) LAsmJSStoreHeap(useRegisterAtStart(ptr), useRegisterAtStart(ins->value()));
         break;
       default: MOZ_ASSUME_UNREACHABLE("unexpected array type");
     }
     return add(lir, ins);
 }
 bool
 LIRGeneratorX86::visitStoreTypedArrayElementStatic(MStoreTypedArrayElementStatic *ins)
 {
     // The code generated for StoreTypedArrayElementStatic is identical to that
     // for AsmJSStoreHeap, and the same concerns apply.
     LStoreTypedArrayElementStatic *lir;
     switch (ins->viewType()) {
       case ArrayBufferView::TYPE_INT8: case ArrayBufferView::TYPE_UINT8:
       case ArrayBufferView::TYPE_UINT8_CLAMPED:
         lir = new(alloc()) LStoreTypedArrayElementStatic(useRegister(ins->ptr()),
                                                          useFixed(ins->value(), eax));
         break;
       case ArrayBufferView::TYPE_INT16: case ArrayBufferView::TYPE_UINT16:
       case ArrayBufferView::TYPE_INT32: case ArrayBufferView::TYPE_UINT32:
       case ArrayBufferView::TYPE_FLOAT32: case ArrayBufferView::TYPE_FLOAT64:
         lir = new(alloc()) LStoreTypedArrayElementStatic(useRegisterAtStart(ins->ptr()),
                                                          useRegisterAtStart(ins->value()));
         break;
       default: MOZ_ASSUME_UNREACHABLE("unexpected array type");
     }
     return add(lir, ins);
 }
 bool
 LIRGeneratorX86::visitAsmJSLoadFuncPtr(MAsmJSLoadFuncPtr *ins)
 {
     return define(new(alloc()) LAsmJSLoadFuncPtr(useRegisterAtStart(ins->index())), ins);
 }

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js/src/jit/x86/Lowering-x86.cpp@6474c204b198 (annotated)

js/src/jit/x86/Lowering-x86.cpp