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webkit / WebKit / 1301b5dddcb28e452a3a8911596f68f5704bd0a8 / . / Source / JavaScriptCore / b3 / B3LowerToAir.cpp
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/*
* Copyright (C) 2015-2017 Apple Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. 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.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``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 APPLE INC. OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "config.h"
#include "B3LowerToAir.h"
#if ENABLE(B3_JIT)
#include "AirBlockInsertionSet.h"
#include "AirCCallSpecial.h"
#include "AirCode.h"
#include "AirInsertionSet.h"
#include "AirInstInlines.h"
#include "AirPrintSpecial.h"
#include "AirStackSlot.h"
#include "B3ArgumentRegValue.h"
#include "B3AtomicValue.h"
#include "B3BasicBlockInlines.h"
#include "B3BlockWorklist.h"
#include "B3CCallValue.h"
#include "B3CheckSpecial.h"
#include "B3Commutativity.h"
#include "B3Dominators.h"
#include "B3FenceValue.h"
#include "B3MemoryValueInlines.h"
#include "B3PatchpointSpecial.h"
#include "B3PatchpointValue.h"
#include "B3PhaseScope.h"
#include "B3PhiChildren.h"
#include "B3Procedure.h"
#include "B3SlotBaseValue.h"
#include "B3StackSlot.h"
#include "B3UpsilonValue.h"
#include "B3UseCounts.h"
#include "B3ValueInlines.h"
#include "B3Variable.h"
#include "B3VariableValue.h"
#include "B3WasmAddressValue.h"
#include <wtf/IndexMap.h>
#include <wtf/IndexSet.h>
#include <wtf/ListDump.h>
#if ASSERT_DISABLED
IGNORE_RETURN_TYPE_WARNINGS_BEGIN
#endif
namespace JSC { namespace B3 {
namespace {
namespace B3LowerToAirInternal {
static const bool verbose = false;
}
using Arg = Air::Arg;
using Inst = Air::Inst;
using Code = Air::Code;
using Tmp = Air::Tmp;
// FIXME: We wouldn't need this if Air supported Width modifiers in Air::Kind.
// https://bugs.webkit.org/show_bug.cgi?id=169247
#define OPCODE_FOR_WIDTH(opcode, width) ( \
(width) == Width8 ? Air::opcode ## 8 : \
(width) == Width16 ? Air::opcode ## 16 : \
(width) == Width32 ? Air::opcode ## 32 : \
Air::opcode ## 64)
#define OPCODE_FOR_CANONICAL_WIDTH(opcode, width) ( \
(width) == Width64 ? Air::opcode ## 64 : Air::opcode ## 32)
class LowerToAir {
public:
LowerToAir(Procedure& procedure)
: m_valueToTmp(procedure.values().size())
, m_phiToTmp(procedure.values().size())
, m_blockToBlock(procedure.size())
, m_useCounts(procedure)
, m_phiChildren(procedure)
, m_dominators(procedure.dominators())
, m_procedure(procedure)
, m_code(procedure.code())
, m_blockInsertionSet(m_code)
#if CPU(X86) || CPU(X86_64)
, m_eax(X86Registers::eax)
, m_ecx(X86Registers::ecx)
, m_edx(X86Registers::edx)
#endif
{
}
void run()
{
using namespace Air;
for (B3::BasicBlock* block : m_procedure)
m_blockToBlock[block] = m_code.addBlock(block->frequency());
for (Value* value : m_procedure.values()) {
switch (value->opcode()) {
case Phi: {
m_phiToTmp[value] = m_code.newTmp(value->resultBank());
if (B3LowerToAirInternal::verbose)
dataLog("Phi tmp for ", *value, ": ", m_phiToTmp[value], "\n");
break;
}
default:
break;
}
}
for (B3::StackSlot* stack : m_procedure.stackSlots())
m_stackToStack.add(stack, m_code.addStackSlot(stack));
for (Variable* variable : m_procedure.variables())
m_variableToTmp.add(variable, m_code.newTmp(variable->bank()));
// Figure out which blocks are not rare.
m_fastWorklist.push(m_procedure[0]);
while (B3::BasicBlock* block = m_fastWorklist.pop()) {
for (B3::FrequentedBlock& successor : block->successors()) {
if (!successor.isRare())
m_fastWorklist.push(successor.block());
}
}
m_procedure.resetValueOwners(); // Used by crossesInterference().
// Lower defs before uses on a global level. This is a good heuristic to lock down a
// hoisted address expression before we duplicate it back into the loop.
for (B3::BasicBlock* block : m_procedure.blocksInPreOrder()) {
m_block = block;
m_isRare = !m_fastWorklist.saw(block);
if (B3LowerToAirInternal::verbose)
dataLog("Lowering Block ", *block, ":\n");
// Make sure that the successors are set up correctly.
for (B3::FrequentedBlock successor : block->successors()) {
m_blockToBlock[block]->successors().append(
Air::FrequentedBlock(m_blockToBlock[successor.block()], successor.frequency()));
}
// Process blocks in reverse order so we see uses before defs. That's what allows us
// to match patterns effectively.
for (unsigned i = block->size(); i--;) {
m_index = i;
m_value = block->at(i);
if (m_locked.contains(m_value))
continue;
m_insts.append(Vector<Inst>());
if (B3LowerToAirInternal::verbose)
dataLog("Lowering ", deepDump(m_procedure, m_value), ":\n");
lower();
if (B3LowerToAirInternal::verbose) {
for (Inst& inst : m_insts.last())
dataLog(" ", inst, "\n");
}
}
finishAppendingInstructions(m_blockToBlock[block]);
}
m_blockInsertionSet.execute();
Air::InsertionSet insertionSet(m_code);
for (Inst& inst : m_prologue)
insertionSet.insertInst(0, WTFMove(inst));
insertionSet.execute(m_code[0]);
}
private:
bool shouldCopyPropagate(Value* value)
{
switch (value->opcode()) {
case Trunc:
case Identity:
case Opaque:
return true;
default:
return false;
}
}
class ArgPromise {
WTF_MAKE_NONCOPYABLE(ArgPromise);
public:
ArgPromise() { }
ArgPromise(const Arg& arg, Value* valueToLock = nullptr)
: m_arg(arg)
, m_value(valueToLock)
{
}
void swap(ArgPromise& other)
{
std::swap(m_arg, other.m_arg);
std::swap(m_value, other.m_value);
std::swap(m_wasConsumed, other.m_wasConsumed);
std::swap(m_wasWrapped, other.m_wasWrapped);
std::swap(m_traps, other.m_traps);
}
ArgPromise(ArgPromise&& other)
{
swap(other);
}
ArgPromise& operator=(ArgPromise&& other)
{
swap(other);
return *this;
}
~ArgPromise()
{
if (m_wasConsumed)
RELEASE_ASSERT(m_wasWrapped);
}
void setTraps(bool value)
{
m_traps = value;
}
static ArgPromise tmp(Value* value)
{
ArgPromise result;
result.m_value = value;
return result;
}
explicit operator bool() const { return m_arg || m_value; }
Arg::Kind kind() const
{
if (!m_arg && m_value)
return Arg::Tmp;
return m_arg.kind();
}
const Arg& peek() const
{
return m_arg;
}
Arg consume(LowerToAir& lower)
{
m_wasConsumed = true;
if (!m_arg && m_value)
return lower.tmp(m_value);
if (m_value)
lower.commitInternal(m_value);
return m_arg;
}
template<typename... Args>
Inst inst(Args&&... args)
{
Inst result(std::forward<Args>(args)...);
result.kind.effects |= m_traps;
m_wasWrapped = true;
return result;
}
private:
// Three forms:
// Everything null: invalid.
// Arg non-null, value null: just use the arg, nothing special.
// Arg null, value non-null: it's a tmp, pin it when necessary.
// Arg non-null, value non-null: use the arg, lock the value.
Arg m_arg;
Value* m_value { nullptr };
bool m_wasConsumed { false };
bool m_wasWrapped { false };
bool m_traps { false };
};
// Consider using tmpPromise() in cases where you aren't sure that you want to pin the value yet.
// Here are three canonical ways of using tmp() and tmpPromise():
//
// Idiom #1: You know that you want a tmp() and you know that it will be valid for the
// instruction you're emitting.
//
// append(Foo, tmp(bar));
//
// Idiom #2: You don't know if you want to use a tmp() because you haven't determined if the
// instruction will accept it, so you query first. Note that the call to tmp() happens only after
// you are sure that you will use it.
//
// if (isValidForm(Foo, Arg::Tmp))
// append(Foo, tmp(bar))
//
// Idiom #3: Same as Idiom #2, but using tmpPromise. Notice that this calls consume() only after
// it's sure it will use the tmp. That's deliberate. Also note that you're required to pass any
// Inst you create with consumed promises through that promise's inst() function.
//
// ArgPromise promise = tmpPromise(bar);
// if (isValidForm(Foo, promise.kind()))
// append(promise.inst(Foo, promise.consume(*this)))
//
// In both idiom #2 and idiom #3, we don't pin the value to a temporary except when we actually
// emit the instruction. Both tmp() and tmpPromise().consume(*this) will pin it. Pinning means
// that we will henceforth require that the value of 'bar' is generated as a separate
// instruction. We don't want to pin the value to a temporary if we might change our minds, and
// pass an address operand representing 'bar' to Foo instead.
//
// Because tmp() pins, the following is not an idiom you should use:
//
// Tmp tmp = this->tmp(bar);
// if (isValidForm(Foo, tmp.kind()))
// append(Foo, tmp);
//
// That's because if isValidForm() returns false, you will have already pinned the 'bar' to a
// temporary. You might later want to try to do something like loadPromise(), and that will fail.
// This arises in operations that have both a Addr,Tmp and Tmp,Addr forms. The following code
// seems right, but will actually fail to ever match the Tmp,Addr form because by then, the right
// value is already pinned.
//
// auto tryThings = [this] (const Arg& left, const Arg& right) {
// if (isValidForm(Foo, left.kind(), right.kind()))
// return Inst(Foo, m_value, left, right);
// return Inst();
// };
// if (Inst result = tryThings(loadAddr(left), tmp(right)))
// return result;
// if (Inst result = tryThings(tmp(left), loadAddr(right))) // this never succeeds.
// return result;
// return Inst(Foo, m_value, tmp(left), tmp(right));
//
// If you imagine that loadAddr(value) is just loadPromise(value).consume(*this), then this code
// will run correctly - it will generate OK code - but the second form is never matched.
// loadAddr(right) will never succeed because it will observe that 'right' is already pinned.
// Of course, it's exactly because of the risky nature of such code that we don't have a
// loadAddr() helper and require you to balance ArgPromise's in code like this. Such code will
// work fine if written as:
//
// auto tryThings = [this] (ArgPromise& left, ArgPromise& right) {
// if (isValidForm(Foo, left.kind(), right.kind()))
// return left.inst(right.inst(Foo, m_value, left.consume(*this), right.consume(*this)));
// return Inst();
// };
// if (Inst result = tryThings(loadPromise(left), tmpPromise(right)))
// return result;
// if (Inst result = tryThings(tmpPromise(left), loadPromise(right)))
// return result;
// return Inst(Foo, m_value, tmp(left), tmp(right));
//
// Notice that we did use tmp in the fall-back case at the end, because by then, we know for sure
// that we want a tmp. But using tmpPromise in the tryThings() calls ensures that doing so
// doesn't prevent us from trying loadPromise on the same value.
Tmp tmp(Value* value)
{
Tmp& tmp = m_valueToTmp[value];
if (!tmp) {
while (shouldCopyPropagate(value))
value = value->child(0);
if (value->opcode() == FramePointer)
return Tmp(GPRInfo::callFrameRegister);
Tmp& realTmp = m_valueToTmp[value];
if (!realTmp) {
realTmp = m_code.newTmp(value->resultBank());
if (m_procedure.isFastConstant(value->key()))
m_code.addFastTmp(realTmp);
if (B3LowerToAirInternal::verbose)
dataLog("Tmp for ", *value, ": ", realTmp, "\n");
}
tmp = realTmp;
}
return tmp;
}
ArgPromise tmpPromise(Value* value)
{
return ArgPromise::tmp(value);
}
bool canBeInternal(Value* value)
{
// If one of the internal things has already been computed, then we don't want to cause
// it to be recomputed again.
if (m_valueToTmp[value])
return false;
// We require internals to have only one use - us. It's not clear if this should be numUses() or
// numUsingInstructions(). Ideally, it would be numUsingInstructions(), except that it's not clear
// if we'd actually do the right thing when matching over such a DAG pattern. For now, it simply
// doesn't matter because we don't implement patterns that would trigger this.
if (m_useCounts.numUses(value) != 1)
return false;
return true;
}
// If you ask canBeInternal() and then construct something from that, and you commit to emitting
// that code, then you must commitInternal() on that value. This is tricky, and you only need to
// do it if you're pattern matching by hand rather than using the patterns language. Long story
// short, you should avoid this by using the pattern matcher to match patterns.
void commitInternal(Value* value)
{
if (value)
m_locked.add(value);
}
bool crossesInterference(Value* value)
{
// If it's in a foreign block, then be conservative. We could handle this if we were
// willing to do heavier analysis. For example, if we had liveness, then we could label
// values as "crossing interference" if they interfere with anything that they are live
// across. But, it's not clear how useful this would be.
if (value->owner != m_value->owner)
return true;
Effects effects = value->effects();
for (unsigned i = m_index; i--;) {
Value* otherValue = m_block->at(i);
if (otherValue == value)
return false;
if (effects.interferes(otherValue->effects()))
return true;
}
ASSERT_NOT_REACHED();
return true;
}
template<typename Int, typename = Value::IsLegalOffset<Int>>
Optional<unsigned> scaleForShl(Value* shl, Int offset, Optional<Width> width = WTF::nullopt)
{
if (shl->opcode() != Shl)
return WTF::nullopt;
if (!shl->child(1)->hasInt32())
return WTF::nullopt;
unsigned logScale = shl->child(1)->asInt32();
if (shl->type() == Int32)
logScale &= 31;
else
logScale &= 63;
// Use 64-bit math to perform the shift so that <<32 does the right thing, but then switch
// to signed since that's what all of our APIs want.
int64_t bigScale = static_cast<uint64_t>(1) << static_cast<uint64_t>(logScale);
if (!isRepresentableAs<int32_t>(bigScale))
return WTF::nullopt;
unsigned scale = static_cast<int32_t>(bigScale);
if (!Arg::isValidIndexForm(scale, offset, width))
return WTF::nullopt;
return scale;
}
// This turns the given operand into an address.
template<typename Int, typename = Value::IsLegalOffset<Int>>
Arg effectiveAddr(Value* address, Int offset, Width width)
{
ASSERT(Arg::isValidAddrForm(offset, width));
auto fallback = [&] () -> Arg {
return Arg::addr(tmp(address), offset);
};
static const unsigned lotsOfUses = 10; // This is arbitrary and we should tune it eventually.
// Only match if the address value isn't used in some large number of places.
if (m_useCounts.numUses(address) > lotsOfUses)
return fallback();
switch (address->opcode()) {
case Add: {
Value* left = address->child(0);
Value* right = address->child(1);
auto tryIndex = [&] (Value* index, Value* base) -> Arg {
Optional<unsigned> scale = scaleForShl(index, offset, width);
if (!scale)
return Arg();
if (m_locked.contains(index->child(0)) || m_locked.contains(base))
return Arg();
return Arg::index(tmp(base), tmp(index->child(0)), *scale, offset);
};
if (Arg result = tryIndex(left, right))
return result;
if (Arg result = tryIndex(right, left))
return result;
if (m_locked.contains(left) || m_locked.contains(right)
|| !Arg::isValidIndexForm(1, offset, width))
return fallback();
return Arg::index(tmp(left), tmp(right), 1, offset);
}
case Shl: {
Value* left = address->child(0);
// We'll never see child(1)->isInt32(0), since that would have been reduced. If the shift
// amount is greater than 1, then there isn't really anything smart that we could do here.
// We avoid using baseless indexes because their encoding isn't particularly efficient.
if (m_locked.contains(left) || !address->child(1)->isInt32(1)
|| !Arg::isValidIndexForm(1, offset, width))
return fallback();
return Arg::index(tmp(left), tmp(left), 1, offset);
}
case FramePointer:
return Arg::addr(Tmp(GPRInfo::callFrameRegister), offset);
case SlotBase:
return Arg::stack(m_stackToStack.get(address->as<SlotBaseValue>()->slot()), offset);
case WasmAddress: {
WasmAddressValue* wasmAddress = address->as<WasmAddressValue>();
Value* pointer = wasmAddress->child(0);
if (!Arg::isValidIndexForm(1, offset, width) || m_locked.contains(pointer))
return fallback();
// FIXME: We should support ARM64 LDR 32-bit addressing, which will
// allow us to fuse a Shl ptr, 2 into the address. Additionally, and
// perhaps more importantly, it would allow us to avoid a truncating
// move. See: https://bugs.webkit.org/show_bug.cgi?id=163465
return Arg::index(Tmp(wasmAddress->pinnedGPR()), tmp(pointer), 1, offset);
}
default:
return fallback();
}
}
// This gives you the address of the given Load or Store. If it's not a Load or Store, then
// it returns Arg().
Arg addr(Value* memoryValue)
{
MemoryValue* value = memoryValue->as<MemoryValue>();
if (!value)
return Arg();
if (value->requiresSimpleAddr())
return Arg::simpleAddr(tmp(value->lastChild()));
Value::OffsetType offset = value->offset();
Width width = value->accessWidth();
Arg result = effectiveAddr(value->lastChild(), offset, width);
RELEASE_ASSERT(result.isValidForm(width));
return result;
}
template<typename... Args>
Inst trappingInst(bool traps, Args&&... args)
{
Inst result(std::forward<Args>(args)...);
result.kind.effects |= traps;
return result;
}
template<typename... Args>
Inst trappingInst(Value* value, Args&&... args)
{
return trappingInst(value->traps(), std::forward<Args>(args)...);
}
ArgPromise loadPromiseAnyOpcode(Value* loadValue)
{
RELEASE_ASSERT(loadValue->as<MemoryValue>());
if (!canBeInternal(loadValue))
return Arg();
if (crossesInterference(loadValue))
return Arg();
// On x86, all loads have fences. Doing this kind of instruction selection will move the load,
// but that's fine because our interference analysis stops the motion of fences around other
// fences. So, any load motion we introduce here would not be observable.
if (!isX86() && loadValue->as<MemoryValue>()->hasFence())
return Arg();
Arg loadAddr = addr(loadValue);
RELEASE_ASSERT(loadAddr);
ArgPromise result(loadAddr, loadValue);
if (loadValue->traps())
result.setTraps(true);
return result;
}
ArgPromise loadPromise(Value* loadValue, B3::Opcode loadOpcode)
{
if (loadValue->opcode() != loadOpcode)
return Arg();
return loadPromiseAnyOpcode(loadValue);
}
ArgPromise loadPromise(Value* loadValue)
{
return loadPromise(loadValue, Load);
}
Arg imm(int64_t intValue)
{
if (Arg::isValidImmForm(intValue))
return Arg::imm(intValue);
return Arg();
}
Arg imm(Value* value)
{
if (value->hasInt())
return imm(value->asInt());
return Arg();
}
Arg bitImm(Value* value)
{
if (value->hasInt()) {
int64_t intValue = value->asInt();
if (Arg::isValidBitImmForm(intValue))
return Arg::bitImm(intValue);
}
return Arg();
}
Arg bitImm64(Value* value)
{
if (value->hasInt()) {
int64_t intValue = value->asInt();
if (Arg::isValidBitImm64Form(intValue))
return Arg::bitImm64(intValue);
}
return Arg();
}
Arg immOrTmp(Value* value)
{
if (Arg result = imm(value))
return result;
return tmp(value);
}
// By convention, we use Oops to mean "I don't know".
Air::Opcode tryOpcodeForType(
Air::Opcode opcode32, Air::Opcode opcode64, Air::Opcode opcodeDouble, Air::Opcode opcodeFloat, Type type)
{
Air::Opcode opcode;
switch (type) {
case Int32:
opcode = opcode32;
break;
case Int64:
opcode = opcode64;
break;
case Float:
opcode = opcodeFloat;
break;
case Double:
opcode = opcodeDouble;
break;
default:
opcode = Air::Oops;
break;
}
return opcode;
}
Air::Opcode tryOpcodeForType(Air::Opcode opcode32, Air::Opcode opcode64, Type type)
{
return tryOpcodeForType(opcode32, opcode64, Air::Oops, Air::Oops, type);
}
Air::Opcode opcodeForType(
Air::Opcode opcode32, Air::Opcode opcode64, Air::Opcode opcodeDouble, Air::Opcode opcodeFloat, Type type)
{
Air::Opcode opcode = tryOpcodeForType(opcode32, opcode64, opcodeDouble, opcodeFloat, type);
RELEASE_ASSERT(opcode != Air::Oops);
return opcode;
}
Air::Opcode opcodeForType(Air::Opcode opcode32, Air::Opcode opcode64, Type type)
{
return tryOpcodeForType(opcode32, opcode64, Air::Oops, Air::Oops, type);
}
template<Air::Opcode opcode32, Air::Opcode opcode64, Air::Opcode opcodeDouble = Air::Oops, Air::Opcode opcodeFloat = Air::Oops>
void appendUnOp(Value* value)
{
Air::Opcode opcode = opcodeForType(opcode32, opcode64, opcodeDouble, opcodeFloat, value->type());
Tmp result = tmp(m_value);
// Two operand forms like:
// Op a, b
// mean something like:
// b = Op a
ArgPromise addr = loadPromise(value);
if (isValidForm(opcode, addr.kind(), Arg::Tmp)) {
append(addr.inst(opcode, m_value, addr.consume(*this), result));
return;
}
if (isValidForm(opcode, Arg::Tmp, Arg::Tmp)) {
append(opcode, tmp(value), result);
return;
}
ASSERT(value->type() == m_value->type());
append(relaxedMoveForType(m_value->type()), tmp(value), result);
append(opcode, result);
}
// Call this method when doing two-operand lowering of a commutative operation. You have a choice of
// which incoming Value is moved into the result. This will select which one is likely to be most
// profitable to use as the result. Doing the right thing can have big performance consequences in tight
// kernels.
bool preferRightForResult(Value* left, Value* right)
{
// The default is to move left into result, because that's required for non-commutative instructions.
// The value that we want to move into result position is the one that dies here. So, if we're
// compiling a commutative operation and we know that actually right is the one that dies right here,
// then we can flip things around to help coalescing, which then kills the move instruction.
//
// But it's more complicated:
// - Used-once is a bad estimate of whether the variable dies here.
// - A child might be a candidate for coalescing with this value.
//
// Currently, we have machinery in place to recognize super obvious forms of the latter issue.
// We recognize when a child is a Phi that has this value as one of its children. We're very
// conservative about this; for example we don't even consider transitive Phi children.
bool leftIsPhiWithThis = m_phiChildren[left].transitivelyUses(m_value);
bool rightIsPhiWithThis = m_phiChildren[right].transitivelyUses(m_value);
if (leftIsPhiWithThis != rightIsPhiWithThis)
return rightIsPhiWithThis;
if (m_useCounts.numUsingInstructions(right) != 1)
return false;
if (m_useCounts.numUsingInstructions(left) != 1)
return true;
// The use count might be 1 if the variable is live around a loop. We can guarantee that we
// pick the variable that is least likely to suffer this problem if we pick the one that
// is closest to us in an idom walk. By convention, we slightly bias this in favor of
// returning true.
// We cannot prefer right if right is further away in an idom walk.
if (m_dominators.strictlyDominates(right->owner, left->owner))
return false;
return true;
}
template<Air::Opcode opcode32, Air::Opcode opcode64, Air::Opcode opcodeDouble, Air::Opcode opcodeFloat, Commutativity commutativity = NotCommutative>
void appendBinOp(Value* left, Value* right)
{
Air::Opcode opcode = opcodeForType(opcode32, opcode64, opcodeDouble, opcodeFloat, left->type());
Tmp result = tmp(m_value);
// Three-operand forms like:
// Op a, b, c
// mean something like:
// c = a Op b
if (isValidForm(opcode, Arg::Imm, Arg::Tmp, Arg::Tmp)) {
if (commutativity == Commutative) {
if (imm(right)) {
append(opcode, imm(right), tmp(left), result);
return;
}
} else {
// A non-commutative operation could have an immediate in left.
if (imm(left)) {
append(opcode, imm(left), tmp(right), result);
return;
}
}
}
if (isValidForm(opcode, Arg::BitImm, Arg::Tmp, Arg::Tmp)) {
if (commutativity == Commutative) {
if (Arg rightArg = bitImm(right)) {
append(opcode, rightArg, tmp(left), result);
return;
}
} else {
// A non-commutative operation could have an immediate in left.
if (Arg leftArg = bitImm(left)) {
append(opcode, leftArg, tmp(right), result);
return;
}
}
}
if (isValidForm(opcode, Arg::BitImm64, Arg::Tmp, Arg::Tmp)) {
if (commutativity == Commutative) {
if (Arg rightArg = bitImm64(right)) {
append(opcode, rightArg, tmp(left), result);
return;
}
} else {
// A non-commutative operation could have an immediate in left.
if (Arg leftArg = bitImm64(left)) {
append(opcode, leftArg, tmp(right), result);
return;
}
}
}
if (imm(right) && isValidForm(opcode, Arg::Tmp, Arg::Imm, Arg::Tmp)) {
append(opcode, tmp(left), imm(right), result);
return;
}
// Note that no extant architecture has a three-operand form of binary operations that also
// load from memory. If such an abomination did exist, we would handle it somewhere around
// here.
// Two-operand forms like:
// Op a, b
// mean something like:
// b = b Op a
// At this point, we prefer versions of the operation that have a fused load or an immediate
// over three operand forms.
if (left != right) {
ArgPromise leftAddr = loadPromise(left);
if (isValidForm(opcode, leftAddr.kind(), Arg::Tmp, Arg::Tmp)) {
append(leftAddr.inst(opcode, m_value, leftAddr.consume(*this), tmp(right), result));
return;
}
if (commutativity == Commutative) {
if (isValidForm(opcode, leftAddr.kind(), Arg::Tmp)) {
append(relaxedMoveForType(m_value->type()), tmp(right), result);
append(leftAddr.inst(opcode, m_value, leftAddr.consume(*this), result));
return;
}
}
ArgPromise rightAddr = loadPromise(right);
if (isValidForm(opcode, Arg::Tmp, rightAddr.kind(), Arg::Tmp)) {
append(rightAddr.inst(opcode, m_value, tmp(left), rightAddr.consume(*this), result));
return;
}
if (commutativity == Commutative) {
if (isValidForm(opcode, rightAddr.kind(), Arg::Tmp, Arg::Tmp)) {
append(rightAddr.inst(opcode, m_value, rightAddr.consume(*this), tmp(left), result));
return;
}
}
if (isValidForm(opcode, rightAddr.kind(), Arg::Tmp)) {
append(relaxedMoveForType(m_value->type()), tmp(left), result);
append(rightAddr.inst(opcode, m_value, rightAddr.consume(*this), result));
return;
}
}
if (imm(right) && isValidForm(opcode, Arg::Imm, Arg::Tmp)) {
append(relaxedMoveForType(m_value->type()), tmp(left), result);
append(opcode, imm(right), result);
return;
}
if (isValidForm(opcode, Arg::Tmp, Arg::Tmp, Arg::Tmp)) {
append(opcode, tmp(left), tmp(right), result);
return;
}
if (commutativity == Commutative && preferRightForResult(left, right)) {
append(relaxedMoveForType(m_value->type()), tmp(right), result);
append(opcode, tmp(left), result);
return;
}
append(relaxedMoveForType(m_value->type()), tmp(left), result);
append(opcode, tmp(right), result);
}
template<Air::Opcode opcode32, Air::Opcode opcode64, Commutativity commutativity = NotCommutative>
void appendBinOp(Value* left, Value* right)
{
appendBinOp<opcode32, opcode64, Air::Oops, Air::Oops, commutativity>(left, right);
}
template<Air::Opcode opcode32, Air::Opcode opcode64>
void appendShift(Value* value, Value* amount)
{
using namespace Air;
Air::Opcode opcode = opcodeForType(opcode32, opcode64, value->type());
if (imm(amount)) {
if (isValidForm(opcode, Arg::Tmp, Arg::Imm, Arg::Tmp)) {
append(opcode, tmp(value), imm(amount), tmp(m_value));
return;
}
if (isValidForm(opcode, Arg::Imm, Arg::Tmp)) {
append(Move, tmp(value), tmp(m_value));
append(opcode, imm(amount), tmp(m_value));
return;
}
}
if (isValidForm(opcode, Arg::Tmp, Arg::Tmp, Arg::Tmp)) {
append(opcode, tmp(value), tmp(amount), tmp(m_value));
return;
}
append(Move, tmp(value), tmp(m_value));
append(Move, tmp(amount), m_ecx);
append(opcode, m_ecx, tmp(m_value));
}
template<Air::Opcode opcode32, Air::Opcode opcode64>
bool tryAppendStoreUnOp(Value* value)
{
Air::Opcode opcode = tryOpcodeForType(opcode32, opcode64, value->type());
if (opcode == Air::Oops)
return false;
Arg storeAddr = addr(m_value);
ASSERT(storeAddr);
ArgPromise loadPromise = this->loadPromise(value);
if (loadPromise.peek() != storeAddr)
return false;
if (!isValidForm(opcode, storeAddr.kind()))
return false;
loadPromise.consume(*this);
append(trappingInst(m_value, loadPromise.inst(opcode, m_value, storeAddr)));
return true;
}
template<
Air::Opcode opcode32, Air::Opcode opcode64, Commutativity commutativity = NotCommutative>
bool tryAppendStoreBinOp(Value* left, Value* right)
{
RELEASE_ASSERT(m_value->as<MemoryValue>());
Air::Opcode opcode = tryOpcodeForType(opcode32, opcode64, left->type());
if (opcode == Air::Oops)
return false;
if (m_value->as<MemoryValue>()->hasFence())
return false;
Arg storeAddr = addr(m_value);
ASSERT(storeAddr);
auto getLoadPromise = [&] (Value* load) -> ArgPromise {
switch (m_value->opcode()) {
case B3::Store:
if (load->opcode() != B3::Load)
return ArgPromise();
break;
case B3::Store8:
if (load->opcode() != B3::Load8Z && load->opcode() != B3::Load8S)
return ArgPromise();
break;
case B3::Store16:
if (load->opcode() != B3::Load16Z && load->opcode() != B3::Load16S)
return ArgPromise();
break;
default:
return ArgPromise();
}
return loadPromiseAnyOpcode(load);
};
ArgPromise loadPromise;
Value* otherValue = nullptr;
loadPromise = getLoadPromise(left);
if (loadPromise.peek() == storeAddr)
otherValue = right;
else if (commutativity == Commutative) {
loadPromise = getLoadPromise(right);
if (loadPromise.peek() == storeAddr)
otherValue = left;
}
if (!otherValue)
return false;
if (isValidForm(opcode, Arg::Imm, storeAddr.kind()) && imm(otherValue)) {
loadPromise.consume(*this);
append(trappingInst(m_value, loadPromise.inst(opcode, m_value, imm(otherValue), storeAddr)));
return true;
}
if (!isValidForm(opcode, Arg::Tmp, storeAddr.kind()))
return false;
loadPromise.consume(*this);
append(trappingInst(m_value, loadPromise.inst(opcode, m_value, tmp(otherValue), storeAddr)));
return true;
}
Inst createStore(Air::Kind move, Value* value, const Arg& dest)
{
using namespace Air;
if (auto imm_value = imm(value)) {
if (isARM64() && imm_value.value() == 0) {
switch (move.opcode) {
default:
break;
case Air::Move32:
if (isValidForm(StoreZero32, dest.kind()) && dest.isValidForm(Width32))
return Inst(StoreZero32, m_value, dest);
break;
case Air::Move:
if (isValidForm(StoreZero64, dest.kind()) && dest.isValidForm(Width64))
return Inst(StoreZero64, m_value, dest);
break;
}
}
if (isValidForm(move.opcode, Arg::Imm, dest.kind()))
return Inst(move, m_value, imm_value, dest);
}
return Inst(move, m_value, tmp(value), dest);
}
Air::Opcode storeOpcode(Width width, Bank bank)
{
using namespace Air;
switch (width) {
case Width8:
RELEASE_ASSERT(bank == GP);
return Air::Store8;
case Width16:
RELEASE_ASSERT(bank == GP);
return Air::Store16;
case Width32:
switch (bank) {
case GP:
return Move32;
case FP:
return MoveFloat;
}
break;
case Width64:
RELEASE_ASSERT(is64Bit());
switch (bank) {
case GP:
return Move;
case FP:
return MoveDouble;
}
break;
}
RELEASE_ASSERT_NOT_REACHED();
}
void appendStore(Value* value, const Arg& dest)
{
using namespace Air;
MemoryValue* memory = value->as<MemoryValue>();
RELEASE_ASSERT(memory->isStore());
Air::Kind kind;
if (memory->hasFence()) {
RELEASE_ASSERT(memory->accessBank() == GP);
if (isX86()) {
kind = OPCODE_FOR_WIDTH(Xchg, memory->accessWidth());
kind.effects = true;
Tmp swapTmp = m_code.newTmp(GP);
append(relaxedMoveForType(memory->accessType()), tmp(memory->child(0)), swapTmp);
append(kind, swapTmp, dest);
return;
}
kind = OPCODE_FOR_WIDTH(StoreRel, memory->accessWidth());
} else
kind = storeOpcode(memory->accessWidth(), memory->accessBank());
kind.effects |= memory->traps();
append(createStore(kind, memory->child(0), dest));
}
Air::Opcode moveForType(Type type)
{
using namespace Air;
switch (type) {
case Int32:
return Move32;
case Int64:
RELEASE_ASSERT(is64Bit());
return Move;
case Float:
return MoveFloat;
case Double:
return MoveDouble;
case Void:
break;
}
RELEASE_ASSERT_NOT_REACHED();
return Air::Oops;
}
Air::Opcode relaxedMoveForType(Type type)
{
using namespace Air;
switch (type) {
case Int32:
case Int64:
// For Int32, we could return Move or Move32. It's a trade-off.
//
// Move32: Using Move32 guarantees that we use the narrower move, but in cases where the
// register allocator can't prove that the variables involved are 32-bit, this will
// disable coalescing.
//
// Move: Using Move guarantees that the register allocator can coalesce normally, but in
// cases where it can't prove that the variables are 32-bit and it doesn't coalesce,
// this will force us to use a full 64-bit Move instead of the slightly cheaper
// 32-bit Move32.
//
// Coalescing is a lot more profitable than turning Move into Move32. So, it's better to
// use Move here because in cases where the register allocator cannot prove that
// everything is 32-bit, we still get coalescing.
return Move;
case Float:
// MoveFloat is always coalescable and we never convert MoveDouble to MoveFloat, so we
// should use MoveFloat when we know that the temporaries involved are 32-bit.
return MoveFloat;
case Double:
return MoveDouble;
case Void:
break;
}
RELEASE_ASSERT_NOT_REACHED();
return Air::Oops;
}
#if ENABLE(MASM_PROBE)
template<typename... Arguments>
void print(Arguments&&... arguments)
{
Value* origin = m_value;
print(origin, std::forward<Arguments>(arguments)...);
}
template<typename... Arguments>
void print(Value* origin, Arguments&&... arguments)
{
auto printList = Printer::makePrintRecordList(arguments...);
auto printSpecial = static_cast<Air::PrintSpecial*>(m_code.addSpecial(std::make_unique<Air::PrintSpecial>(printList)));
Inst inst(Air::Patch, origin, Arg::special(printSpecial));
Printer::appendAirArgs(inst, std::forward<Arguments>(arguments)...);
append(WTFMove(inst));
}
#endif // ENABLE(MASM_PROBE)
template<typename... Arguments>
void append(Air::Kind kind, Arguments&&... arguments)
{
m_insts.last().append(Inst(kind, m_value, std::forward<Arguments>(arguments)...));
}
template<typename... Arguments>
void appendTrapping(Air::Kind kind, Arguments&&... arguments)
{
m_insts.last().append(trappingInst(m_value, kind, m_value, std::forward<Arguments>(arguments)...));
}
void append(Inst&& inst)
{
m_insts.last().append(WTFMove(inst));
}
void append(const Inst& inst)
{
m_insts.last().append(inst);
}
void finishAppendingInstructions(Air::BasicBlock* target)
{
// Now append the instructions. m_insts contains them in reverse order, so we process
// it in reverse.
for (unsigned i = m_insts.size(); i--;) {
for (Inst& inst : m_insts[i])
target->appendInst(WTFMove(inst));
}
m_insts.shrink(0);
}
Air::BasicBlock* newBlock()
{
return m_blockInsertionSet.insertAfter(m_blockToBlock[m_block]);
}
// NOTE: This will create a continuation block (`nextBlock`) *after* any blocks you've created using
// newBlock(). So, it's preferable to create all of your blocks upfront using newBlock(). Also note
// that any code you emit before this will be prepended to the continuation, and any code you emit
// after this will be appended to the previous block.
void splitBlock(Air::BasicBlock*& previousBlock, Air::BasicBlock*& nextBlock)
{
Air::BasicBlock* block = m_blockToBlock[m_block];
previousBlock = block;
nextBlock = m_blockInsertionSet.insertAfter(block);
finishAppendingInstructions(nextBlock);
nextBlock->successors() = block->successors();
block->successors().clear();
m_insts.append(Vector<Inst>());
}
template<typename T, typename... Arguments>
T* ensureSpecial(T*& field, Arguments&&... arguments)
{
if (!field) {
field = static_cast<T*>(
m_code.addSpecial(std::make_unique<T>(std::forward<Arguments>(arguments)...)));
}
return field;
}
template<typename... Arguments>
CheckSpecial* ensureCheckSpecial(Arguments&&... arguments)
{
CheckSpecial::Key key(std::forward<Arguments>(arguments)...);
auto result = m_checkSpecials.add(key, nullptr);
return ensureSpecial(result.iterator->value, key);
}
void fillStackmap(Inst& inst, StackmapValue* stackmap, unsigned numSkipped)
{
for (unsigned i = numSkipped; i < stackmap->numChildren(); ++i) {
ConstrainedValue value = stackmap->constrainedChild(i);
Arg arg;
switch (value.rep().kind()) {
case ValueRep::WarmAny:
case ValueRep::ColdAny:
case ValueRep::LateColdAny:
if (imm(value.value()))
arg = imm(value.value());
else if (value.value()->hasInt64())
arg = Arg::bigImm(value.value()->asInt64());
else if (value.value()->hasDouble() && canBeInternal(value.value())) {
commitInternal(value.value());
arg = Arg::bigImm(bitwise_cast<int64_t>(value.value()->asDouble()));
} else
arg = tmp(value.value());
break;
case ValueRep::SomeRegister:
case ValueRep::SomeLateRegister:
arg = tmp(value.value());
break;
case ValueRep::SomeRegisterWithClobber: {
Tmp dstTmp = m_code.newTmp(value.value()->resultBank());
append(relaxedMoveForType(value.value()->type()), immOrTmp(value.value()), dstTmp);
arg = dstTmp;
break;
}
case ValueRep::LateRegister:
case ValueRep::Register:
stackmap->earlyClobbered().clear(value.rep().reg());
arg = Tmp(value.rep().reg());
append(relaxedMoveForType(value.value()->type()), immOrTmp(value.value()), arg);
break;
case ValueRep::StackArgument:
arg = Arg::callArg(value.rep().offsetFromSP());
append(trappingInst(m_value, createStore(moveForType(value.value()->type()), value.value(), arg)));
break;
default:
RELEASE_ASSERT_NOT_REACHED();
break;
}
inst.args.append(arg);
}
}
// Create an Inst to do the comparison specified by the given value.
template<typename CompareFunctor, typename TestFunctor, typename CompareDoubleFunctor, typename CompareFloatFunctor>
Inst createGenericCompare(
Value* value,
const CompareFunctor& compare, // Signature: (Width, Arg relCond, Arg, Arg) -> Inst
const TestFunctor& test, // Signature: (Width, Arg resCond, Arg, Arg) -> Inst
const CompareDoubleFunctor& compareDouble, // Signature: (Arg doubleCond, Arg, Arg) -> Inst
const CompareFloatFunctor& compareFloat, // Signature: (Arg doubleCond, Arg, Arg) -> Inst
bool inverted = false)
{
// NOTE: This is totally happy to match comparisons that have already been computed elsewhere
// since on most architectures, the cost of branching on a previously computed comparison
// result is almost always higher than just doing another fused compare/branch. The only time
// it could be worse is if we have a binary comparison and both operands are variables (not
// constants), and we encounter register pressure. Even in this case, duplicating the compare
// so that we can fuse it to the branch will be more efficient most of the time, since
// register pressure is not *that* common. For this reason, this algorithm will always
// duplicate the comparison.
//
// However, we cannot duplicate loads. The canBeInternal() on a load will assume that we
// already validated canBeInternal() on all of the values that got us to the load. So, even
// if we are sharing a value, we still need to call canBeInternal() for the purpose of
// tracking whether we are still in good shape to fuse loads.
//
// We could even have a chain of compare values that we fuse, and any member of the chain
// could be shared. Once any of them are shared, then the shared one's transitive children
// cannot be locked (i.e. commitInternal()). But if none of them are shared, then we want to
// lock all of them because that's a prerequisite to fusing the loads so that the loads don't
// get duplicated. For example, we might have:
//
// @tmp1 = LessThan(@a, @b)
// @tmp2 = Equal(@tmp1, 0)
// Branch(@tmp2)
//
// If either @a or @b are loads, then we want to have locked @tmp1 and @tmp2 so that they
// don't emit the loads a second time. But if we had another use of @tmp2, then we cannot
// lock @tmp1 (or @a or @b) because then we'll get into trouble when the other values that
// try to share @tmp1 with us try to do their lowering.
//
// There's one more wrinkle. If we don't lock an internal value, then this internal value may
// have already separately locked its children. So, if we're not locking a value then we need
// to make sure that its children aren't locked. We encapsulate this in two ways:
//
// canCommitInternal: This variable tells us if the values that we've fused so far are
// locked. This means that we're not sharing any of them with anyone. This permits us to fuse
// loads. If it's false, then we cannot fuse loads and we also need to ensure that the
// children of any values we try to fuse-by-sharing are not already locked. You don't have to
// worry about the children locking thing if you use prepareToFuse() before trying to fuse a
// sharable value. But, you do need to guard any load fusion by checking if canCommitInternal
// is true.
//
// FusionResult prepareToFuse(value): Call this when you think that you would like to fuse
// some value and that value is not a load. It will automatically handle the shared-or-locked
// issues and it will clear canCommitInternal if necessary. This will return CannotFuse
// (which acts like false) if the value cannot be locked and its children are locked. That's
// rare, but you just need to make sure that you do smart things when this happens (i.e. just
// use the value rather than trying to fuse it). After you call prepareToFuse(), you can
// still change your mind about whether you will actually fuse the value. If you do fuse it,
// you need to call commitFusion(value, fusionResult).
//
// commitFusion(value, fusionResult): Handles calling commitInternal(value) if fusionResult
// is FuseAndCommit.
bool canCommitInternal = true;
enum FusionResult {
CannotFuse,
FuseAndCommit,
Fuse
};
auto prepareToFuse = [&] (Value* value) -> FusionResult {
if (value == m_value) {
// It's not actually internal. It's the root value. We're good to go.
return Fuse;
}
if (canCommitInternal && canBeInternal(value)) {
// We are the only users of this value. This also means that the value's children
// could not have been locked, since we have now proved that m_value dominates value
// in the data flow graph. To only other way to value is from a user of m_value. If
// value's children are shared with others, then they could not have been locked
// because their use count is greater than 1. If they are only used from value, then
// in order for value's children to be locked, value would also have to be locked,
// and we just proved that it wasn't.
return FuseAndCommit;
}
// We're going to try to share value with others. It's possible that some other basic
// block had already emitted code for value and then matched over its children and then
// locked them, in which case we just want to use value instead of duplicating it. So, we
// validate the children. Note that this only arises in linear chains like:
//
// BB#1:
// @1 = Foo(...)
// @2 = Bar(@1)
// Jump(#2)
// BB#2:
// @3 = Baz(@2)
//
// Notice how we could start by generating code for BB#1 and then decide to lock @1 when
// generating code for @2, if we have some way of fusing Bar and Foo into a single
// instruction. This is legal, since indeed @1 only has one user. The fact that @2 now
// has a tmp (i.e. @2 is pinned), canBeInternal(@2) will return false, which brings us
// here. In that case, we cannot match over @2 because then we'd hit a hazard if we end
// up deciding not to fuse Foo into the fused Baz/Bar.
//
// Happily, there are only two places where this kind of child validation happens is in
// rules that admit sharing, like this and effectiveAddress().
//
// N.B. We could probably avoid the need to do value locking if we committed to a well
// chosen code generation order. For example, if we guaranteed that all of the users of
// a value get generated before that value, then there's no way for the lowering of @3 to
// see @1 locked. But we don't want to do that, since this is a greedy instruction
// selector and so we want to be able to play with order.
for (Value* child : value->children()) {
if (m_locked.contains(child))
return CannotFuse;
}
// It's safe to share value, but since we're sharing, it means that we aren't locking it.
// If we don't lock it, then fusing loads is off limits and all of value's children will
// have to go through the sharing path as well. Fusing loads is off limits because the load
// could already have been emitted elsehwere - so fusing it here would duplicate the load.
// We don't consider that to be a legal optimization.
canCommitInternal = false;
return Fuse;
};
auto commitFusion = [&] (Value* value, FusionResult result) {
if (result == FuseAndCommit)
commitInternal(value);
};
// Chew through any inversions. This loop isn't necessary for comparisons and branches, but
// we do need at least one iteration of it for Check.
for (;;) {
bool shouldInvert =
(value->opcode() == BitXor && value->child(1)->hasInt() && (value->child(1)->asInt() == 1) && value->child(0)->returnsBool())
|| (value->opcode() == Equal && value->child(1)->isInt(0));
if (!shouldInvert)
break;
FusionResult fusionResult = prepareToFuse(value);
if (fusionResult == CannotFuse)
break;
commitFusion(value, fusionResult);
value = value->child(0);
inverted = !inverted;
}
auto createRelCond = [&] (
MacroAssembler::RelationalCondition relationalCondition,
MacroAssembler::DoubleCondition doubleCondition) {
Arg relCond = Arg::relCond(relationalCondition).inverted(inverted);
Arg doubleCond = Arg::doubleCond(doubleCondition).inverted(inverted);
Value* left = value->child(0);
Value* right = value->child(1);
if (isInt(value->child(0)->type())) {
Arg rightImm = imm(right);
auto tryCompare = [&] (
Width width, ArgPromise&& left, ArgPromise&& right) -> Inst {
if (Inst result = compare(width, relCond, left, right))
return result;
if (Inst result = compare(width, relCond.flipped(), right, left))
return result;
return Inst();
};
auto tryCompareLoadImm = [&] (
Width width, B3::Opcode loadOpcode, Arg::Signedness signedness) -> Inst {
if (rightImm && rightImm.isRepresentableAs(width, signedness)) {
if (Inst result = tryCompare(width, loadPromise(left, loadOpcode), rightImm)) {
commitInternal(left);
return result;
}
}
return Inst();
};
Width width = value->child(0)->resultWidth();
if (canCommitInternal) {
// First handle compares that involve fewer bits than B3's type system supports.
// This is pretty important. For example, we want this to be a single
// instruction:
//
// @1 = Load8S(...)
// @2 = Const32(...)
// @3 = LessThan(@1, @2)
// Branch(@3)
if (relCond.isSignedCond()) {
if (Inst result = tryCompareLoadImm(Width8, Load8S, Arg::Signed))
return result;
}
if (relCond.isUnsignedCond()) {
if (Inst result = tryCompareLoadImm(Width8, Load8Z, Arg::Unsigned))
return result;
}
if (relCond.isSignedCond()) {
if (Inst result = tryCompareLoadImm(Width16, Load16S, Arg::Signed))
return result;
}
if (relCond.isUnsignedCond()) {
if (Inst result = tryCompareLoadImm(Width16, Load16Z, Arg::Unsigned))
return result;
}
// Now handle compares that involve a load and an immediate.
if (Inst result = tryCompareLoadImm(width, Load, Arg::Signed))
return result;
// Now handle compares that involve a load. It's not obvious that it's better to
// handle this before the immediate cases or not. Probably doesn't matter.
if (Inst result = tryCompare(width, loadPromise(left), tmpPromise(right))) {
commitInternal(left);
return result;
}
if (Inst result = tryCompare(width, tmpPromise(left), loadPromise(right))) {
commitInternal(right);
return result;
}
}
// Now handle compares that involve an immediate and a tmp.
if (rightImm && rightImm.isRepresentableAs<int32_t>()) {
if (Inst result = tryCompare(width, tmpPromise(left), rightImm))
return result;
}
// Finally, handle comparison between tmps.
ArgPromise leftPromise = tmpPromise(left);
ArgPromise rightPromise = tmpPromise(right);
return compare(width, relCond, leftPromise, rightPromise);
}
// Floating point comparisons can't really do anything smart.
ArgPromise leftPromise = tmpPromise(left);
ArgPromise rightPromise = tmpPromise(right);
if (value->child(0)->type() == Float)
return compareFloat(doubleCond, leftPromise, rightPromise);
return compareDouble(doubleCond, leftPromise, rightPromise);
};
Width width = value->resultWidth();
Arg resCond = Arg::resCond(MacroAssembler::NonZero).inverted(inverted);
auto tryTest = [&] (
Width width, ArgPromise&& left, ArgPromise&& right) -> Inst {
if (Inst result = test(width, resCond, left, right))
return result;
if (Inst result = test(width, resCond, right, left))
return result;
return Inst();
};
auto attemptFused = [&] () -> Inst {
switch (value->opcode()) {
case NotEqual:
return createRelCond(MacroAssembler::NotEqual, MacroAssembler::DoubleNotEqualOrUnordered);
case Equal:
return createRelCond(MacroAssembler::Equal, MacroAssembler::DoubleEqual);
case LessThan:
return createRelCond(MacroAssembler::LessThan, MacroAssembler::DoubleLessThan);
case GreaterThan:
return createRelCond(MacroAssembler::GreaterThan, MacroAssembler::DoubleGreaterThan);
case LessEqual:
return createRelCond(MacroAssembler::LessThanOrEqual, MacroAssembler::DoubleLessThanOrEqual);
case GreaterEqual:
return createRelCond(MacroAssembler::GreaterThanOrEqual, MacroAssembler::DoubleGreaterThanOrEqual);
case EqualOrUnordered:
// The integer condition is never used in this case.
return createRelCond(MacroAssembler::Equal, MacroAssembler::DoubleEqualOrUnordered);
case Above:
// We use a bogus double condition because these integer comparisons won't got down that
// path anyway.
return createRelCond(MacroAssembler::Above, MacroAssembler::DoubleEqual);
case Below:
return createRelCond(MacroAssembler::Below, MacroAssembler::DoubleEqual);
case AboveEqual:
return createRelCond(MacroAssembler::AboveOrEqual, MacroAssembler::DoubleEqual);
case BelowEqual:
return createRelCond(MacroAssembler::BelowOrEqual, MacroAssembler::DoubleEqual);
case BitAnd: {
Value* left = value->child(0);
Value* right = value->child(1);
bool hasRightConst;
int64_t rightConst;
Arg rightImm;
Arg rightImm64;
hasRightConst = right->hasInt();
if (hasRightConst) {
rightConst = right->asInt();
rightImm = bitImm(right);
rightImm64 = bitImm64(right);
}
auto tryTestLoadImm = [&] (Width width, Arg::Signedness signedness, B3::Opcode loadOpcode) -> Inst {
if (!hasRightConst)
return Inst();
// Signed loads will create high bits, so if the immediate has high bits
// then we cannot proceed. Consider BitAnd(Load8S(ptr), 0x101). This cannot
// be turned into testb (ptr), $1, since if the high bit within that byte
// was set then it would be extended to include 0x100. The handling below
// won't anticipate this, so we need to catch it here.
if (signedness == Arg::Signed
&& !Arg::isRepresentableAs(width, Arg::Unsigned, rightConst))
return Inst();
// FIXME: If this is unsigned then we can chop things off of the immediate.
// This might make the immediate more legal. Perhaps that's a job for
// strength reduction?
// https://bugs.webkit.org/show_bug.cgi?id=169248
if (rightImm) {
if (Inst result = tryTest(width, loadPromise(left, loadOpcode), rightImm)) {
commitInternal(left);
return result;
}
}
if (rightImm64) {
if (Inst result = tryTest(width, loadPromise(left, loadOpcode), rightImm64)) {
commitInternal(left);
return result;
}
}
return Inst();
};
if (canCommitInternal) {
// First handle test's that involve fewer bits than B3's type system supports.
if (Inst result = tryTestLoadImm(Width8, Arg::Unsigned, Load8Z))
return result;
if (Inst result = tryTestLoadImm(Width8, Arg::Signed, Load8S))
return result;
if (Inst result = tryTestLoadImm(Width16, Arg::Unsigned, Load16Z))
return result;
if (Inst result = tryTestLoadImm(Width16, Arg::Signed, Load16S))
return result;
// This allows us to use a 32-bit test for 64-bit BitAnd if the immediate is
// representable as an unsigned 32-bit value. The logic involved is the same
// as if we were pondering using a 32-bit test for
// BitAnd(SExt(Load(ptr)), const), in the sense that in both cases we have
// to worry about high bits. So, we use the "Signed" version of this helper.
if (Inst result = tryTestLoadImm(Width32, Arg::Signed, Load))
return result;
// This is needed to handle 32-bit test for arbitrary 32-bit immediates.
if (Inst result = tryTestLoadImm(width, Arg::Unsigned, Load))
return result;
// Now handle test's that involve a load.
Width width = value->child(0)->resultWidth();
if (Inst result = tryTest(width, loadPromise(left), tmpPromise(right))) {
commitInternal(left);
return result;
}
if (Inst result = tryTest(width, tmpPromise(left), loadPromise(right))) {
commitInternal(right);
return result;
}
}
// Now handle test's that involve an immediate and a tmp.
if (hasRightConst) {
if ((width == Width32 && rightConst == 0xffffffff)
|| (width == Width64 && rightConst == -1)) {
if (Inst result = tryTest(width, tmpPromise(left), tmpPromise(left)))
return result;
}
if (isRepresentableAs<uint32_t>(rightConst)) {
if (Inst result = tryTest(Width32, tmpPromise(left), rightImm))
return result;
if (Inst result = tryTest(Width32, tmpPromise(left), rightImm64))
return result;
}
if (Inst result = tryTest(width, tmpPromise(left), rightImm))
return result;
if (Inst result = tryTest(width, tmpPromise(left), rightImm64))
return result;
}
// Finally, just do tmp's.
return tryTest(width, tmpPromise(left), tmpPromise(right));
}
default:
return Inst();
}
};
if (FusionResult fusionResult = prepareToFuse(value)) {
if (Inst result = attemptFused()) {
commitFusion(value, fusionResult);
return result;
}
}
if (Arg::isValidBitImmForm(-1)) {
if (canCommitInternal && value->as<MemoryValue>()) {
// Handle things like Branch(Load8Z(value))
if (Inst result = tryTest(Width8, loadPromise(value, Load8Z), Arg::bitImm(-1))) {
commitInternal(value);
return result;
}
if (Inst result = tryTest(Width8, loadPromise(value, Load8S), Arg::bitImm(-1))) {
commitInternal(value);
return result;
}
if (Inst result = tryTest(Width16, loadPromise(value, Load16Z), Arg::bitImm(-1))) {
commitInternal(value);
return result;
}
if (Inst result = tryTest(Width16, loadPromise(value, Load16S), Arg::bitImm(-1))) {
commitInternal(value);
return result;
}
if (Inst result = tryTest(width, loadPromise(value), Arg::bitImm(-1))) {
commitInternal(value);
return result;
}
}
ArgPromise leftPromise = tmpPromise(value);
ArgPromise rightPromise = Arg::bitImm(-1);
if (Inst result = test(width, resCond, leftPromise, rightPromise))
return result;
}
// Sometimes this is the only form of test available. We prefer not to use this because
// it's less canonical.
ArgPromise leftPromise = tmpPromise(value);
ArgPromise rightPromise = tmpPromise(value);
return test(width, resCond, leftPromise, rightPromise);
}
Inst createBranch(Value* value, bool inverted = false)
{
using namespace Air;
return createGenericCompare(
value,
[this] (
Width width, const Arg& relCond,
ArgPromise& left, ArgPromise& right) -> Inst {
switch (width) {
case Width8:
if (isValidForm(Branch8, Arg::RelCond, left.kind(), right.kind())) {
return left.inst(right.inst(
Branch8, m_value, relCond,
left.consume(*this), right.consume(*this)));
}
return Inst();
case Width16:
return Inst();
case Width32:
if (isValidForm(Branch32, Arg::RelCond, left.kind(), right.kind())) {
return left.inst(right.inst(
Branch32, m_value, relCond,
left.consume(*this), right.consume(*this)));
}
return Inst();
case Width64:
if (isValidForm(Branch64, Arg::RelCond, left.kind(), right.kind())) {
return left.inst(right.inst(
Branch64, m_value, relCond,
left.consume(*this), right.consume(*this)));
}
return Inst();
}
ASSERT_NOT_REACHED();
},
[this] (
Width width, const Arg& resCond,
ArgPromise& left, ArgPromise& right) -> Inst {
switch (width) {
case Width8:
if (isValidForm(BranchTest8, Arg::ResCond, left.kind(), right.kind())) {
return left.inst(right.inst(
BranchTest8, m_value, resCond,
left.consume(*this), right.consume(*this)));
}
return Inst();
case Width16:
return Inst();
case Width32:
if (isValidForm(BranchTest32, Arg::ResCond, left.kind(), right.kind())) {
return left.inst(right.inst(
BranchTest32, m_value, resCond,
left.consume(*this), right.consume(*this)));
}
return Inst();
case Width64:
if (isValidForm(BranchTest64, Arg::ResCond, left.kind(), right.kind())) {
return left.inst(right.inst(
BranchTest64, m_value, resCond,
left.consume(*this), right.consume(*this)));
}
return Inst();
}
ASSERT_NOT_REACHED();
},
[this] (Arg doubleCond, ArgPromise& left, ArgPromise& right) -> Inst {
if (isValidForm(BranchDouble, Arg::DoubleCond, left.kind(), right.kind())) {
return left.inst(right.inst(
BranchDouble, m_value, doubleCond,
left.consume(*this), right.consume(*this)));
}
return Inst();
},
[this] (Arg doubleCond, ArgPromise& left, ArgPromise& right) -> Inst {
if (isValidForm(BranchFloat, Arg::DoubleCond, left.kind(), right.kind())) {
return left.inst(right.inst(
BranchFloat, m_value, doubleCond,
left.consume(*this), right.consume(*this)));
}
return Inst();
},
inverted);
}
Inst createCompare(Value* value, bool inverted = false)
{
using namespace Air;
return createGenericCompare(
value,
[this] (
Width width, const Arg& relCond,
ArgPromise& left, ArgPromise& right) -> Inst {
switch (width) {
case Width8:
case Width16:
return Inst();
case Width32:
if (isValidForm(Compare32, Arg::RelCond, left.kind(), right.kind(), Arg::Tmp)) {
return left.inst(right.inst(
Compare32, m_value, relCond,
left.consume(*this), right.consume(*this), tmp(m_value)));
}
return Inst();
case Width64:
if (isValidForm(Compare64, Arg::RelCond, left.kind(), right.kind(), Arg::Tmp)) {
return left.inst(right.inst(
Compare64, m_value, relCond,
left.consume(*this), right.consume(*this), tmp(m_value)));
}
return Inst();
}
ASSERT_NOT_REACHED();
},
[this] (
Width width, const Arg& resCond,
ArgPromise& left, ArgPromise& right) -> Inst {
switch (width) {
case Width8:
case Width16:
return Inst();
case Width32:
if (isValidForm(Test32, Arg::ResCond, left.kind(), right.kind(), Arg::Tmp)) {
return left.inst(right.inst(
Test32, m_value, resCond,
left.consume(*this), right.consume(*this), tmp(m_value)));
}
return Inst();
case Width64:
if (isValidForm(Test64, Arg::ResCond, left.kind(), right.kind(), Arg::Tmp)) {
return left.inst(right.inst(
Test64, m_value, resCond,
left.consume(*this), right.consume(*this), tmp(m_value)));
}
return Inst();
}
ASSERT_NOT_REACHED();
},
[this] (const Arg& doubleCond, ArgPromise& left, ArgPromise& right) -> Inst {
if (isValidForm(CompareDouble, Arg::DoubleCond, left.kind(), right.kind(), Arg::Tmp)) {
return left.inst(right.inst(
CompareDouble, m_value, doubleCond,
left.consume(*this), right.consume(*this), tmp(m_value)));
}
return Inst();
},
[this] (const Arg& doubleCond, ArgPromise& left, ArgPromise& right) -> Inst {
if (isValidForm(CompareFloat, Arg::DoubleCond, left.kind(), right.kind(), Arg::Tmp)) {
return left.inst(right.inst(
CompareFloat, m_value, doubleCond,
left.consume(*this), right.consume(*this), tmp(m_value)));
}
return Inst();
},
inverted);
}
struct MoveConditionallyConfig {
Air::Opcode moveConditionally32;
Air::Opcode moveConditionally64;
Air::Opcode moveConditionallyTest32;
Air::Opcode moveConditionallyTest64;
Air::Opcode moveConditionallyDouble;
Air::Opcode moveConditionallyFloat;
};
Inst createSelect(const MoveConditionallyConfig& config)
{
using namespace Air;
auto createSelectInstruction = [&] (Air::Opcode opcode, const Arg& condition, ArgPromise& left, ArgPromise& right) -> Inst {
if (isValidForm(opcode, condition.kind(), left.kind(), right.kind(), Arg::Tmp, Arg::Tmp, Arg::Tmp)) {
Tmp result = tmp(m_value);
Tmp thenCase = tmp(m_value->child(1));
Tmp elseCase = tmp(m_value->child(2));
return left.inst(right.inst(
opcode, m_value, condition,
left.consume(*this), right.consume(*this), thenCase, elseCase, result));
}
if (isValidForm(opcode, condition.kind(), left.kind(), right.kind(), Arg::Tmp, Arg::Tmp)) {
Tmp result = tmp(m_value);
Tmp source = tmp(m_value->child(1));
append(relaxedMoveForType(m_value->type()), tmp(m_value->child(2)), result);
return left.inst(right.inst(
opcode, m_value, condition,
left.consume(*this), right.consume(*this), source, result));
}
return Inst();
};
return createGenericCompare(
m_value->child(0),
[&] (Width width, const Arg& relCond, ArgPromise& left, ArgPromise& right) -> Inst {
switch (width) {
case Width8:
// FIXME: Support these things.
// https://bugs.webkit.org/show_bug.cgi?id=151504
return Inst();
case Width16:
return Inst();
case Width32:
return createSelectInstruction(config.moveConditionally32, relCond, left, right);
case Width64:
return createSelectInstruction(config.moveConditionally64, relCond, left, right);
}
ASSERT_NOT_REACHED();
},
[&] (Width width, const Arg& resCond, ArgPromise& left, ArgPromise& right) -> Inst {
switch (width) {
case Width8:
// FIXME: Support more things.
// https://bugs.webkit.org/show_bug.cgi?id=151504
return Inst();
case Width16:
return Inst();
case Width32:
return createSelectInstruction(config.moveConditionallyTest32, resCond, left, right);
case Width64:
return createSelectInstruction(config.moveConditionallyTest64, resCond, left, right);
}
ASSERT_NOT_REACHED();
},
[&] (Arg doubleCond, ArgPromise& left, ArgPromise& right) -> Inst {
return createSelectInstruction(config.moveConditionallyDouble, doubleCond, left, right);
},
[&] (Arg doubleCond, ArgPromise& left, ArgPromise& right) -> Inst {
return createSelectInstruction(config.moveConditionallyFloat, doubleCond, left, right);
},
false);
}
bool tryAppendLea()
{
using namespace Air;
Air::Opcode leaOpcode = tryOpcodeForType(Lea32, Lea64, m_value->type());
if (!isValidForm(leaOpcode, Arg::Index, Arg::Tmp))
return false;
// This lets us turn things like this:
//
// Add(Add(@x, Shl(@y, $2)), $100)
//
// Into this:
//
// lea 100(%rdi,%rsi,4), %rax
//
// We have a choice here between committing the internal bits of an index or sharing
// them. There are solid arguments for both.
//
// Sharing: The word on the street is that the cost of a lea is one cycle no matter
// what it does. Every experiment I've ever seen seems to confirm this. So, sharing
// helps us in situations where Wasm input did this:
//
// x = a[i].x;
// y = a[i].y;
//
// With sharing we would do:
//
// leal (%a,%i,4), %tmp
// cmp (%size, %tmp)
// ja _fail
// movl (%base, %tmp), %x
// leal 4(%a,%i,4), %tmp
// cmp (%size, %tmp)
// ja _fail
// movl (%base, %tmp), %y
//
// In the absence of sharing, we may find ourselves needing separate registers for
// the innards of the index. That's relatively unlikely to be a thing due to other
// optimizations that we already have, but it could happen
//
// Committing: The worst case is that there is a complicated graph of additions and
// shifts, where each value has multiple uses. In that case, it's better to compute
// each one separately from the others since that way, each calculation will use a
// relatively nearby tmp as its input. That seems uncommon, but in those cases,
// committing is a clear winner: it would result in a simple interference graph
// while sharing would result in a complex one. Interference sucks because it means
// more time in IRC and it means worse code.
//
// It's not super clear if any of these corner cases would ever arise. Committing
// has the benefit that it's easier to reason about, and protects a much darker
// corner case (more interference).
// Here are the things we want to match:
// Add(Add(@x, @y), $c)
// Add(Shl(@x, $c), @y)
// Add(@x, Shl(@y, $c))
// Add(Add(@x, Shl(@y, $c)), $d)
// Add(Add(Shl(@x, $c), @y), $d)
//
// Note that if you do Add(Shl(@x, $c), $d) then we will treat $d as a non-constant and
// force it to materialize. You'll get something like this:
//
// movl $d, %tmp
// leal (%tmp,%x,1<<c), %result
//
// Which is pretty close to optimal and has the nice effect of being able to handle large
// constants gracefully.
Value* innerAdd = nullptr;
Value* value = m_value;
// We're going to consume Add(Add(_), $c). If we succeed at consuming it then we have these
// patterns left (i.e. in the Add(_)):
//
// Add(Add(@x, @y), $c)
// Add(Add(@x, Shl(@y, $c)), $d)
// Add(Add(Shl(@x, $c), @y), $d)
//
// Otherwise we are looking at these patterns:
//
// Add(Shl(@x, $c), @y)
// Add(@x, Shl(@y, $c))
//
// This means that the subsequent code only has to worry about three patterns:
//
// Add(Shl(@x, $c), @y)
// Add(@x, Shl(@y, $c))
// Add(@x, @y) (only if offset != 0)
Value::OffsetType offset = 0;
if (value->child(1)->isRepresentableAs<Value::OffsetType>()
&& canBeInternal(value->child(0))
&& value->child(0)->opcode() == Add) {
innerAdd = value->child(0);
offset = static_cast<Value::OffsetType>(value->child(1)->asInt());
value = value->child(0);
}
auto tryShl = [&] (Value* shl, Value* other) -> bool {
Optional<unsigned> scale = scaleForShl(shl, offset);
if (!scale)
return false;
if (!canBeInternal(shl))
return false;
ASSERT(!m_locked.contains(shl->child(0)));
ASSERT(!m_locked.contains(other));
append(leaOpcode, Arg::index(tmp(other), tmp(shl->child(0)), *scale, offset), tmp(m_value));
commitInternal(innerAdd);
commitInternal(shl);
return true;
};
if (tryShl(value->child(0), value->child(1)))
return true;
if (tryShl(value->child(1), value->child(0)))
return true;
// The remaining pattern is just:
// Add(@x, @y) (only if offset != 0)
if (!offset)
return false;
ASSERT(!m_locked.contains(value->child(0)));
ASSERT(!m_locked.contains(value->child(1)));
append(leaOpcode, Arg::index(tmp(value->child(0)), tmp(value->child(1)), 1, offset), tmp(m_value));
commitInternal(innerAdd);
return true;
}
void appendX86Div(B3::Opcode op)
{
using namespace Air;
Air::Opcode convertToDoubleWord;
Air::Opcode div;
switch (m_value->type()) {
case Int32:
convertToDoubleWord = X86ConvertToDoubleWord32;
div = X86Div32;
break;
case Int64:
convertToDoubleWord = X86ConvertToQuadWord64;
div = X86Div64;
break;
default:
RELEASE_ASSERT_NOT_REACHED();
return;
}
ASSERT(op == Div || op == Mod);
Tmp result = op == Div ? m_eax : m_edx;
append(Move, tmp(m_value->child(0)), m_eax);
append(convertToDoubleWord, m_eax, m_edx);
append(div, m_eax, m_edx, tmp(m_value->child(1)));
append(Move, result, tmp(m_value));
}
void appendX86UDiv(B3::Opcode op)
{
using namespace Air;
Air::Opcode div = m_value->type() == Int32 ? X86UDiv32 : X86UDiv64;
ASSERT(op == UDiv || op == UMod);
Tmp result = op == UDiv ? m_eax : m_edx;
append(Move, tmp(m_value->child(0)), m_eax);
append(Xor64, m_edx, m_edx);
append(div, m_eax, m_edx, tmp(m_value->child(1)));
append(Move, result, tmp(m_value));
}
Air::Opcode loadLinkOpcode(Width width, bool fence)
{
return fence ? OPCODE_FOR_WIDTH(LoadLinkAcq, width) : OPCODE_FOR_WIDTH(LoadLink, width);
}
Air::Opcode storeCondOpcode(Width width, bool fence)
{
return fence ? OPCODE_FOR_WIDTH(StoreCondRel, width) : OPCODE_FOR_WIDTH(StoreCond, width);
}
// This can emit code for the following patterns:
// AtomicWeakCAS
// BitXor(AtomicWeakCAS, 1)
// AtomicStrongCAS
// Equal(AtomicStrongCAS, expected)
// NotEqual(AtomicStrongCAS, expected)
// Branch(AtomicWeakCAS)
// Branch(Equal(AtomicStrongCAS, expected))
// Branch(NotEqual(AtomicStrongCAS, expected))
//
// It assumes that atomicValue points to the CAS, and m_value points to the instruction being
// generated. It assumes that you've consumed everything that needs to be consumed.
void appendCAS(Value* atomicValue, bool invert)
{
using namespace Air;
AtomicValue* atomic = atomicValue->as<AtomicValue>();
RELEASE_ASSERT(atomic);
bool isBranch = m_value->opcode() == Branch;
bool isStrong = atomic->opcode() == AtomicStrongCAS;
bool returnsOldValue = m_value->opcode() == AtomicStrongCAS;
bool hasFence = atomic->hasFence();
Width width = atomic->accessWidth();
Arg address = addr(atomic);
Tmp valueResultTmp;
Tmp boolResultTmp;
if (returnsOldValue) {
RELEASE_ASSERT(!invert);
valueResultTmp = tmp(m_value);
boolResultTmp = m_code.newTmp(GP);
} else if (isBranch) {
valueResultTmp = m_code.newTmp(GP);
boolResultTmp = m_code.newTmp(GP);
} else {
valueResultTmp = m_code.newTmp(GP);
boolResultTmp = tmp(m_value);
}
Tmp successBoolResultTmp;
if (isStrong && !isBranch)
successBoolResultTmp = m_code.newTmp(GP);
else
successBoolResultTmp = boolResultTmp;
Tmp expectedValueTmp = tmp(atomic->child(0));
Tmp newValueTmp = tmp(atomic->child(1));
Air::FrequentedBlock success;
Air::FrequentedBlock failure;
if (isBranch) {
success = m_blockToBlock[m_block]->successor(invert);
failure = m_blockToBlock[m_block]->successor(!invert);
}
if (isX86()) {
append(relaxedMoveForType(atomic->accessType()), immOrTmp(atomic->child(0)), m_eax);
if (returnsOldValue) {
appendTrapping(OPCODE_FOR_WIDTH(AtomicStrongCAS, width), m_eax, newValueTmp, address);
append(relaxedMoveForType(atomic->accessType()), m_eax, valueResultTmp);
} else if (isBranch) {
appendTrapping(OPCODE_FOR_WIDTH(BranchAtomicStrongCAS, width), Arg::statusCond(MacroAssembler::Success), m_eax, newValueTmp, address);
m_blockToBlock[m_block]->setSuccessors(success, failure);
} else
appendTrapping(OPCODE_FOR_WIDTH(AtomicStrongCAS, width), Arg::statusCond(invert ? MacroAssembler::Failure : MacroAssembler::Success), m_eax, tmp(atomic->child(1)), address, boolResultTmp);
return;
}
RELEASE_ASSERT(isARM64());
// We wish to emit:
//
// Block #reloop:
// LoadLink
// Branch NotEqual
// Successors: Then:#fail, Else: #store
// Block #store:
// StoreCond
// Xor $1, %result <--- only if !invert
// Jump
// Successors: #done
// Block #fail:
// Move $invert, %result
// Jump
// Successors: #done
// Block #done:
Air::BasicBlock* reloopBlock = newBlock();
Air::BasicBlock* storeBlock = newBlock();
Air::BasicBlock* successBlock = nullptr;
if (!isBranch && isStrong)
successBlock = newBlock();
Air::BasicBlock* failBlock = nullptr;
if (!isBranch) {
failBlock = newBlock();
failure = failBlock;
}
Air::BasicBlock* strongFailBlock;
if (isStrong && hasFence)
strongFailBlock = newBlock();
Air::FrequentedBlock comparisonFail = failure;
Air::FrequentedBlock weakFail;
if (isStrong) {
if (hasFence)
comparisonFail = strongFailBlock;
weakFail = reloopBlock;
} else
weakFail = failure;
Air::BasicBlock* beginBlock;
Air::BasicBlock* doneBlock;
splitBlock(beginBlock, doneBlock);
append(Air::Jump);
beginBlock->setSuccessors(reloopBlock);
reloopBlock->append(trappingInst(m_value, loadLinkOpcode(width, atomic->hasFence()), m_value, address, valueResultTmp));
reloopBlock->append(OPCODE_FOR_CANONICAL_WIDTH(Branch, width), m_value, Arg::relCond(MacroAssembler::NotEqual), valueResultTmp, expectedValueTmp);
reloopBlock->setSuccessors(comparisonFail, storeBlock);
storeBlock->append(trappingInst(m_value, storeCondOpcode(width, atomic->hasFence()), m_value, newValueTmp, address, successBoolResultTmp));
if (isBranch) {
storeBlock->append(BranchTest32, m_value, Arg::resCond(MacroAssembler::Zero), boolResultTmp, boolResultTmp);
storeBlock->setSuccessors(success, weakFail);
doneBlock->successors().clear();
RELEASE_ASSERT(!doneBlock->size());
doneBlock->append(Air::Oops, m_value);
} else {
if (isStrong) {
storeBlock->append(BranchTest32, m_value, Arg::resCond(MacroAssembler::Zero), successBoolResultTmp, successBoolResultTmp);
storeBlock->setSuccessors(successBlock, reloopBlock);
successBlock->append(Move, m_value, Arg::imm(!invert), boolResultTmp);
successBlock->append(Air::Jump, m_value);
successBlock->setSuccessors(doneBlock);
} else {
if (!invert)
storeBlock->append(Xor32, m_value, Arg::bitImm(1), boolResultTmp, boolResultTmp);
storeBlock->append(Air::Jump, m_value);
storeBlock->setSuccessors(doneBlock);
}
failBlock->append(Move, m_value, Arg::imm(invert), boolResultTmp);
failBlock->append(Air::Jump, m_value);
failBlock->setSuccessors(doneBlock);
}
if (isStrong && hasFence) {
Tmp tmp = m_code.newTmp(GP);
strongFailBlock->append(trappingInst(m_value, storeCondOpcode(width, atomic->hasFence()), m_value, valueResultTmp, address, tmp));
strongFailBlock->append(BranchTest32, m_value, Arg::resCond(MacroAssembler::Zero), tmp, tmp);
strongFailBlock->setSuccessors(failure, reloopBlock);
}
}
bool appendVoidAtomic(Air::Opcode atomicOpcode)
{
if (m_useCounts.numUses(m_value))
return false;
Arg address = addr(m_value);
if (isValidForm(atomicOpcode, Arg::Imm, address.kind()) && imm(m_value->child(0))) {
append(atomicOpcode, imm(m_value->child(0)), address);
return true;
}
if (isValidForm(atomicOpcode, Arg::Tmp, address.kind())) {
append(atomicOpcode, tmp(m_value->child(0)), address);
return true;
}
return false;
}
void appendGeneralAtomic(Air::Opcode opcode, Commutativity commutativity = NotCommutative)
{
using namespace Air;
AtomicValue* atomic = m_value->as<AtomicValue>();
Arg address = addr(m_value);
Tmp oldValue = m_code.newTmp(GP);
Tmp newValue = opcode == Air::Nop ? tmp(atomic->child(0)) : m_code.newTmp(GP);
// We need a CAS loop or a LL/SC loop. Using prepare/attempt jargon, we want:
//
// Block #reloop:
// Prepare
// opcode
// Attempt
// Successors: Then:#done, Else:#reloop
// Block #done:
// Move oldValue, result
append(relaxedMoveForType(atomic->type()), oldValue, tmp(atomic));
Air::BasicBlock* reloopBlock = newBlock();
Air::BasicBlock* beginBlock;
Air::BasicBlock* doneBlock;
splitBlock(beginBlock, doneBlock);
append(Air::Jump);
beginBlock->setSuccessors(reloopBlock);
Air::Opcode prepareOpcode;
if (isX86()) {
switch (atomic->accessWidth()) {
case Width8:
prepareOpcode = Load8SignedExtendTo32;
break;
case Width16:
prepareOpcode = Load16SignedExtendTo32;
break;
case Width32:
prepareOpcode = Move32;
break;
case Width64:
prepareOpcode = Move;
break;
}
} else {
RELEASE_ASSERT(isARM64());
prepareOpcode = loadLinkOpcode(atomic->accessWidth(), atomic->hasFence());
}
reloopBlock->append(trappingInst(m_value, prepareOpcode, m_value, address, oldValue));
if (opcode != Air::Nop) {
// FIXME: If we ever have to write this again, we need to find a way to share the code with
// appendBinOp.
// https://bugs.webkit.org/show_bug.cgi?id=169249
if (commutativity == Commutative && imm(atomic->child(0)) && isValidForm(opcode, Arg::Imm, Arg::Tmp, Arg::Tmp))
reloopBlock->append(opcode, m_value, imm(atomic->child(0)), oldValue, newValue);
else if (imm(atomic->child(0)) && isValidForm(opcode, Arg::Tmp, Arg::Imm, Arg::Tmp))
reloopBlock->append(opcode, m_value, oldValue, imm(atomic->child(0)), newValue);
else if (commutativity == Commutative && bitImm(atomic->child(0)) && isValidForm(opcode, Arg::BitImm, Arg::Tmp, Arg::Tmp))
reloopBlock->append(opcode, m_value, bitImm(atomic->child(0)), oldValue, newValue);
else if (isValidForm(opcode, Arg::Tmp, Arg::Tmp, Arg::Tmp))
reloopBlock->append(opcode, m_value, oldValue, tmp(atomic->child(0)), newValue);
else {
reloopBlock->append(relaxedMoveForType(atomic->type()), m_value, oldValue, newValue);
if (imm(atomic->child(0)) && isValidForm(opcode, Arg::Imm, Arg::Tmp))
reloopBlock->append(opcode, m_value, imm(atomic->child(0)), newValue);
else
reloopBlock->append(opcode, m_value, tmp(atomic->child(0)), newValue);
}
}
if (isX86()) {
Air::Opcode casOpcode = OPCODE_FOR_WIDTH(BranchAtomicStrongCAS, atomic->accessWidth());
reloopBlock->append(relaxedMoveForType(atomic->type()), m_value, oldValue, m_eax);
reloopBlock->append(trappingInst(m_value, casOpcode, m_value, Arg::statusCond(MacroAssembler::Success), m_eax, newValue, address));
} else {
RELEASE_ASSERT(isARM64());
Tmp boolResult = m_code.newTmp(GP);
reloopBlock->append(trappingInst(m_value, storeCondOpcode(atomic->accessWidth(), atomic->hasFence()), m_value, newValue, address, boolResult));
reloopBlock->append(BranchTest32, m_value, Arg::resCond(MacroAssembler::Zero), boolResult, boolResult);
}
reloopBlock->setSuccessors(doneBlock, reloopBlock);
}
void lower()
{
using namespace Air;
switch (m_value->opcode()) {
case B3::Nop: {
// Yes, we will totally see Nop's because some phases will replaceWithNop() instead of
// properly removing things.
return;
}
case Load: {
MemoryValue* memory = m_value->as<MemoryValue>();
Air::Kind kind = moveForType(memory->type());
if (memory->hasFence()) {
if (isX86())
kind.effects = true;
else {
switch (memory->type()) {
case Int32:
kind = LoadAcq32;
break;
case Int64:
kind = LoadAcq64;
break;
default:
RELEASE_ASSERT_NOT_REACHED();
break;
}
}
}
append(trappingInst(m_value, kind, m_value, addr(m_value), tmp(m_value)));
return;
}
case Load8S: {
Air::Kind kind = Load8SignedExtendTo32;
if (m_value->as<MemoryValue>()->hasFence()) {
if (isX86())
kind.effects = true;
else
kind = LoadAcq8SignedExtendTo32;
}
append(trappingInst(m_value, kind, m_value, addr(m_value), tmp(m_value)));
return;
}
case Load8Z: {
Air::Kind kind = Load8;
if (m_value->as<MemoryValue>()->hasFence()) {
if (isX86())
kind.effects = true;
else
kind = LoadAcq8;
}
append(trappingInst(m_value, kind, m_value, addr(m_value), tmp(m_value)));
return;
}
case Load16S: {
Air::Kind kind = Load16SignedExtendTo32;
if (m_value->as<MemoryValue>()->hasFence()) {
if (isX86())
kind.effects = true;
else
kind = LoadAcq16SignedExtendTo32;
}
append(trappingInst(m_value, kind, m_value, addr(m_value), tmp(m_value)));
return;
}
case Load16Z: {
Air::Kind kind = Load16;
if (m_value->as<MemoryValue>()->hasFence()) {
if (isX86())
kind.effects = true;
else
kind = LoadAcq16;
}
append(trappingInst(m_value, kind, m_value, addr(m_value), tmp(m_value)));
return;
}
case Add: {
if (tryAppendLea())
return;
Air::Opcode multiplyAddOpcode = tryOpcodeForType(MultiplyAdd32, MultiplyAdd64, m_value->type());
if (isValidForm(multiplyAddOpcode, Arg::Tmp, Arg::Tmp, Arg::Tmp, Arg::Tmp)) {
Value* left = m_value->child(0);
Value* right = m_value->child(1);
if (!imm(right) || m_valueToTmp[right]) {
auto tryAppendMultiplyAdd = [&] (Value* left, Value* right) -> bool {
if (left->opcode() != Mul || !canBeInternal(left))
return false;
Value* multiplyLeft = left->child(0);
Value* multiplyRight = left->child(1);
if (canBeInternal(multiplyLeft) || canBeInternal(multiplyRight))
return false;
append(multiplyAddOpcode, tmp(multiplyLeft), tmp(multiplyRight), tmp(right), tmp(m_value));
commitInternal(left);
return true;
};
if (tryAppendMultiplyAdd(left, right))
return;
if (tryAppendMultiplyAdd(right, left))
return;
}
}
appendBinOp<Add32, Add64, AddDouble, AddFloat, Commutative>(
m_value->child(0), m_value->child(1));
return;
}
case Sub: {
Air::Opcode multiplySubOpcode = tryOpcodeForType(MultiplySub32, MultiplySub64, m_value->type());
if (multiplySubOpcode != Air::Oops
&& isValidForm(multiplySubOpcode, Arg::Tmp, Arg::Tmp, Arg::Tmp, Arg::Tmp)) {
Value* left = m_value->child(0);
Value* right = m_value->child(1);
if (!imm(right) || m_valueToTmp[right]) {
auto tryAppendMultiplySub = [&] () -> bool {
if (right->opcode() != Mul || !canBeInternal(right))
return false;
Value* multiplyLeft = right->child(0);
Value* multiplyRight = right->child(1);
if (m_locked.contains(multiplyLeft) || m_locked.contains(multiplyRight))
return false;
append(multiplySubOpcode, tmp(multiplyLeft), tmp(multiplyRight), tmp(left), tmp(m_value));
commitInternal(right);
return true;
};
if (tryAppendMultiplySub())
return;
}
}
appendBinOp<Sub32, Sub64, SubDouble, SubFloat>(m_value->child(0), m_value->child(1));
return;
}
case Neg: {
Air::Opcode multiplyNegOpcode = tryOpcodeForType(MultiplyNeg32, MultiplyNeg64, m_value->type());
if (multiplyNegOpcode != Air::Oops
&& isValidForm(multiplyNegOpcode, Arg::Tmp, Arg::Tmp, Arg::Tmp)
&& m_value->child(0)->opcode() == Mul
&& canBeInternal(m_value->child(0))) {
Value* multiplyOperation = m_value->child(0);
Value* multiplyLeft = multiplyOperation->child(0);
Value* multiplyRight = multiplyOperation->child(1);
if (!m_locked.contains(multiplyLeft) && !m_locked.contains(multiplyRight)) {
append(multiplyNegOpcode, tmp(multiplyLeft), tmp(multiplyRight), tmp(m_value));
commitInternal(multiplyOperation);
return;
}
}
appendUnOp<Neg32, Neg64, NegateDouble, NegateFloat>(m_value->child(0));
return;
}
case Mul: {
appendBinOp<Mul32, Mul64, MulDouble, MulFloat, Commutative>(
m_value->child(0), m_value->child(1));
return;
}
case Div: {
if (m_value->isChill())
RELEASE_ASSERT(isARM64());
if (isInt(m_value->type()) && isX86()) {
appendX86Div(Div);
return;
}
ASSERT(!isX86() || isFloat(m_value->type()));
appendBinOp<Div32, Div64, DivDouble, DivFloat>(m_value->child(0), m_value->child(1));
return;
}
case UDiv: {
if (isInt(m_value->type()) && isX86()) {
appendX86UDiv(UDiv);
return;
}
ASSERT(!isX86() && !isFloat(m_value->type()));
appendBinOp<UDiv32, UDiv64, Air::Oops, Air::Oops>(m_value->child(0), m_value->child(1));
return;
}
case Mod: {
RELEASE_ASSERT(isX86());
RELEASE_ASSERT(!m_value->isChill());
appendX86Div(Mod);
return;
}
case UMod: {
RELEASE_ASSERT(isX86());
appendX86UDiv(UMod);
return;
}
case BitAnd: {
if (m_value->child(1)->isInt(0xff)) {
appendUnOp<ZeroExtend8To32, ZeroExtend8To32>(m_value->child(0));
return;
}
if (m_value->child(1)->isInt(0xffff)) {
appendUnOp<ZeroExtend16To32, ZeroExtend16To32>(m_value->child(0));
return;
}
if (m_value->child(1)->isInt(0xffffffff)) {
appendUnOp<Move32, Move32>(m_value->child(0));
return;
}
appendBinOp<And32, And64, AndDouble, AndFloat, Commutative>(
m_value->child(0), m_value->child(1));
return;
}
case BitOr: {
appendBinOp<Or32, Or64, OrDouble, OrFloat, Commutative>(
m_value->child(0), m_value->child(1));
return;
}
case BitXor: {
// FIXME: If canBeInternal(child), we should generate this using the comparison path.
// https://bugs.webkit.org/show_bug.cgi?id=152367
if (m_value->child(1)->isInt(-1)) {
appendUnOp<Not32, Not64>(m_value->child(0));
return;
}
// This pattern is super useful on both x86 and ARM64, since the inversion of the CAS result
// can be done with zero cost on x86 (just flip the set from E to NE) and it's a progression
// on ARM64 (since STX returns 0 on success, so ordinarily we have to flip it).
if (m_value->child(1)->isInt(1)
&& m_value->child(0)->opcode() == AtomicWeakCAS
&& canBeInternal(m_value->child(0))) {
commitInternal(m_value->child(0));
appendCAS(m_value->child(0), true);
return;
}
appendBinOp<Xor32, Xor64, XorDouble, XorFloat, Commutative>(
m_value->child(0), m_value->child(1));
return;
}
case Depend: {
RELEASE_ASSERT(isARM64());
appendUnOp<Depend32, Depend64>(m_value->child(0));
return;
}
case Shl: {
if (m_value->child(1)->isInt32(1)) {
appendBinOp<Add32, Add64, AddDouble, AddFloat, Commutative>(m_value->child(0), m_value->child(0));
return;
}
appendShift<Lshift32, Lshift64>(m_value->child(0), m_value->child(1));
return;
}
case SShr: {
appendShift<Rshift32, Rshift64>(m_value->child(0), m_value->child(1));
return;
}
case ZShr: {
appendShift<Urshift32, Urshift64>(m_value->child(0), m_value->child(1));
return;
}
case RotR: {
appendShift<RotateRight32, RotateRight64>(m_value->child(0), m_value->child(1));
return;
}
case RotL: {
appendShift<RotateLeft32, RotateLeft64>(m_value->child(0), m_value->child(1));
return;
}
case Clz: {
appendUnOp<CountLeadingZeros32, CountLeadingZeros64>(m_value->child(0));
return;
}
case Abs: {
RELEASE_ASSERT_WITH_MESSAGE(!isX86(), "Abs is not supported natively on x86. It must be replaced before generation.");
appendUnOp<Air::Oops, Air::Oops, AbsDouble, AbsFloat>(m_value->child(0));
return;
}
case Ceil: {
appendUnOp<Air::Oops, Air::Oops, CeilDouble, CeilFloat>(m_value->child(0));
return;
}
case Floor: {
appendUnOp<Air::Oops, Air::Oops, FloorDouble, FloorFloat>(m_value->child(0));
return;
}
case Sqrt: {
appendUnOp<Air::Oops, Air::Oops, SqrtDouble, SqrtFloat>(m_value->child(0));
return;
}
case BitwiseCast: {
appendUnOp<Move32ToFloat, Move64ToDouble, MoveDoubleTo64, MoveFloatTo32>(m_value->child(0));
return;
}
case Store: {
Value* valueToStore = m_value->child(0);
if (canBeInternal(valueToStore)) {
bool matched = false;
switch (valueToStore->opcode()) {
case Add:
matched = tryAppendStoreBinOp<Add32, Add64, Commutative>(
valueToStore->child(0), valueToStore->child(1));
break;
case Sub:
if (valueToStore->child(0)->isInt(0)) {
matched = tryAppendStoreUnOp<Neg32, Neg64>(valueToStore->child(1));
break;
}
matched = tryAppendStoreBinOp<Sub32, Sub64>(
valueToStore->child(0), valueToStore->child(1));
break;
case BitAnd:
matched = tryAppendStoreBinOp<And32, And64, Commutative>(
valueToStore->child(0), valueToStore->child(1));
break;
case BitXor:
if (valueToStore->child(1)->isInt(-1)) {
matched = tryAppendStoreUnOp<Not32, Not64>(valueToStore->child(0));
break;
}
matched = tryAppendStoreBinOp<Xor32, Xor64, Commutative>(
valueToStore->child(0), valueToStore->child(1));
break;
default:
break;
}
if (matched) {
commitInternal(valueToStore);
return;
}
}
appendStore(m_value, addr(m_value));
return;
}
case B3::Store8: {
Value* valueToStore = m_value->child(0);
if (canBeInternal(valueToStore)) {
bool matched = false;
switch (valueToStore->opcode()) {
case Add:
matched = tryAppendStoreBinOp<Add8, Air::Oops, Commutative>(
valueToStore->child(0), valueToStore->child(1));
break;
default:
break;
}
if (matched) {
commitInternal(valueToStore);
return;
}
}
appendStore(m_value, addr(m_value));
return;
}
case B3::Store16: {
Value* valueToStore = m_value->child(0);
if (canBeInternal(valueToStore)) {
bool matched = false;
switch (valueToStore->opcode()) {
case Add:
matched = tryAppendStoreBinOp<Add16, Air::Oops, Commutative>(
valueToStore->child(0), valueToStore->child(1));
break;
default:
break;
}
if (matched) {
commitInternal(valueToStore);
return;
}
}
appendStore(m_value, addr(m_value));
return;
}
case WasmAddress: {
WasmAddressValue* address = m_value->as<WasmAddressValue>();
append(Add64, Arg(address->pinnedGPR()), tmp(m_value->child(0)), tmp(address));
return;
}
case Fence: {
FenceValue* fence = m_value->as<FenceValue>();
if (!fence->write && !fence->read)
return;
if (!fence->write) {
// A fence that reads but does not write is for protecting motion of stores.
append(StoreFence);
return;
}
if (!fence->read) {
// A fence that writes but does not read is for protecting motion of loads.
append(LoadFence);
return;
}
append(MemoryFence);
return;
}
case Trunc: {
ASSERT(tmp(m_value->child(0)) == tmp(m_value));
return;
}
case SExt8: {
appendUnOp<SignExtend8To32, Air::Oops>(m_value->child(0));
return;
}
case SExt16: {
appendUnOp<SignExtend16To32, Air::Oops>(m_value->child(0));
return;
}
case ZExt32: {
appendUnOp<Move32, Air::Oops>(m_value->child(0));
return;
}
case SExt32: {
// FIXME: We should have support for movsbq/movswq
// https://bugs.webkit.org/show_bug.cgi?id=152232
appendUnOp<SignExtend32ToPtr, Air::Oops>(m_value->child(0));
return;
}
case FloatToDouble: {
appendUnOp<Air::Oops, Air::Oops, Air::Oops, ConvertFloatToDouble>(m_value->child(0));
return;
}
case DoubleToFloat: {
appendUnOp<Air::Oops, Air::Oops, ConvertDoubleToFloat>(m_value->child(0));
return;
}
case ArgumentReg: {
m_prologue.append(Inst(
moveForType(m_value->type()), m_value,
Tmp(m_value->as<ArgumentRegValue>()->argumentReg()),
tmp(m_value)));
return;
}
case Const32:
case Const64: {
if (imm(m_value))
append(Move, imm(m_value), tmp(m_value));
else
append(Move, Arg::bigImm(m_value->asInt()), tmp(m_value));
return;
}
case ConstDouble:
case ConstFloat: {
// We expect that the moveConstants() phase has run, and any doubles referenced from
// stackmaps get fused.
RELEASE_ASSERT(m_value->opcode() == ConstFloat || isIdentical(m_value->asDouble(), 0.0));
RELEASE_ASSERT(m_value->opcode() == ConstDouble || isIdentical(m_value->asFloat(), 0.0f));
append(MoveZeroToDouble, tmp(m_value));
return;
}
case FramePointer: {
ASSERT(tmp(m_value) == Tmp(GPRInfo::callFrameRegister));
return;
}
case SlotBase: {
append(
pointerType() == Int64 ? Lea64 : Lea32,
Arg::stack(m_stackToStack.get(m_value->as<SlotBaseValue>()->slot())),
tmp(m_value));
return;
}
case Equal:
case NotEqual: {
// FIXME: Teach this to match patterns that arise from subwidth CAS. The CAS's result has to
// be either zero- or sign-extended, and the value it's compared to should also be zero- or
// sign-extended in a matching way. It's not super clear that this is very profitable.
// https://bugs.webkit.org/show_bug.cgi?id=169250
if (m_value->child(0)->opcode() == AtomicStrongCAS
&& m_value->child(0)->as<AtomicValue>()->isCanonicalWidth()
&& m_value->child(0)->child(0) == m_value->child(1)
&& canBeInternal(m_value->child(0))) {
ASSERT(!m_locked.contains(m_value->child(0)->child(1)));
ASSERT(!m_locked.contains(m_value->child(1)));
commitInternal(m_value->child(0));
appendCAS(m_value->child(0), m_value->opcode() == NotEqual);
return;
}
m_insts.last().append(createCompare(m_value));
return;
}
case LessThan:
case GreaterThan:
case LessEqual:
case GreaterEqual:
case Above:
case Below:
case AboveEqual:
case BelowEqual:
case EqualOrUnordered: {
m_insts.last().append(createCompare(m_value));
return;
}
case Select: {
MoveConditionallyConfig config;
if (isInt(m_value->type())) {
config.moveConditionally32 = MoveConditionally32;
config.moveConditionally64 = MoveConditionally64;
config.moveConditionallyTest32 = MoveConditionallyTest32;
config.moveConditionallyTest64 = MoveConditionallyTest64;
config.moveConditionallyDouble = MoveConditionallyDouble;
config.moveConditionallyFloat = MoveConditionallyFloat;
} else {
// FIXME: it's not obvious that these are particularly efficient.
// https://bugs.webkit.org/show_bug.cgi?id=169251
config.moveConditionally32 = MoveDoubleConditionally32;
config.moveConditionally64 = MoveDoubleConditionally64;
config.moveConditionallyTest32 = MoveDoubleConditionallyTest32;
config.moveConditionallyTest64 = MoveDoubleConditionallyTest64;
config.moveConditionallyDouble = MoveDoubleConditionallyDouble;
config.moveConditionallyFloat = MoveDoubleConditionallyFloat;
}
m_insts.last().append(createSelect(config));
return;
}
case IToD: {
appendUnOp<ConvertInt32ToDouble, ConvertInt64ToDouble>(m_value->child(0));
return;
}
case IToF: {
appendUnOp<ConvertInt32ToFloat, ConvertInt64ToFloat>(m_value->child(0));
return;
}
case B3::CCall: {
CCallValue* cCall = m_value->as<CCallValue>();
Inst inst(m_isRare ? Air::ColdCCall : Air::CCall, cCall);
// We have a ton of flexibility regarding the callee argument, but currently, we don't
// use it yet. It gets weird for reasons:
// 1) We probably will never take advantage of this. We don't have C calls to locations
// loaded from addresses. We have JS calls like that, but those use Patchpoints.
// 2) On X86_64 we still don't support call with BaseIndex.
// 3) On non-X86, we don't natively support any kind of loading from address.
// 4) We don't have an isValidForm() for the CCallSpecial so we have no smart way to
// decide.
// FIXME: https://bugs.webkit.org/show_bug.cgi?id=151052
inst.args.append(tmp(cCall->child(0)));
if (cCall->type() != Void)
inst.args.append(tmp(cCall));
for (unsigned i = 1; i < cCall->numChildren(); ++i)
inst.args.append(immOrTmp(cCall->child(i)));
m_insts.last().append(WTFMove(inst));
return;
}
case Patchpoint: {
PatchpointValue* patchpointValue = m_value->as<PatchpointValue>();
ensureSpecial(m_patchpointSpecial);
Inst inst(Patch, patchpointValue, Arg::special(m_patchpointSpecial));
Vector<Inst> after;
if (patchpointValue->type() != Void) {
switch (patchpointValue->resultConstraint.kind()) {
case ValueRep::WarmAny:
case ValueRep::ColdAny:
case ValueRep::LateColdAny:
case ValueRep::SomeRegister:
case ValueRep::SomeEarlyRegister:
inst.args.append(tmp(patchpointValue));
break;
case ValueRep::Register: {
Tmp reg = Tmp(patchpointValue->resultConstraint.reg());
inst.args.append(reg);
after.append(Inst(
relaxedMoveForType(patchpointValue->type()), m_value, reg, tmp(patchpointValue)));
break;
}
case ValueRep::StackArgument: {
Arg arg = Arg::callArg(patchpointValue->resultConstraint.offsetFromSP());
inst.args.append(arg);
after.append(Inst(
moveForType(patchpointValue->type()), m_value, arg, tmp(patchpointValue)));
break;
}
default:
RELEASE_ASSERT_NOT_REACHED();
break;
}
}
fillStackmap(inst, patchpointValue, 0);
if (patchpointValue->resultConstraint.isReg())
patchpointValue->lateClobbered().clear(patchpointValue->resultConstraint.reg());
for (unsigned i = patchpointValue->numGPScratchRegisters; i--;)
inst.args.append(m_code.newTmp(GP));
for (unsigned i = patchpointValue->numFPScratchRegisters; i--;)
inst.args.append(m_code.newTmp(FP));
m_insts.last().append(WTFMove(inst));
m_insts.last().appendVector(after);
return;
}
case CheckAdd:
case CheckSub:
case CheckMul: {
CheckValue* checkValue = m_value->as<CheckValue>();
Value* left = checkValue->child(0);
Value* right = checkValue->child(1);
Tmp result = tmp(m_value);
// Handle checked negation.
if (checkValue->opcode() == CheckSub && left->isInt(0)) {
append(Move, tmp(right), result);
Air::Opcode opcode =
opcodeForType(BranchNeg32, BranchNeg64, checkValue->type());
CheckSpecial* special = ensureCheckSpecial(opcode, 2);
Inst inst(Patch, checkValue, Arg::special(special));
inst.args.append(Arg::resCond(MacroAssembler::Overflow));
inst.args.append(result);
fillStackmap(inst, checkValue, 2);
m_insts.last().append(WTFMove(inst));
return;
}
Air::Opcode opcode = Air::Oops;
Commutativity commutativity = NotCommutative;
StackmapSpecial::RoleMode stackmapRole = StackmapSpecial::SameAsRep;
switch (m_value->opcode()) {
case CheckAdd:
opcode = opcodeForType(BranchAdd32, BranchAdd64, m_value->type());
stackmapRole = StackmapSpecial::ForceLateUseUnlessRecoverable;
commutativity = Commutative;
break;
case CheckSub:
opcode = opcodeForType(BranchSub32, BranchSub64, m_value->type());
break;
case CheckMul:
opcode = opcodeForType(BranchMul32, BranchMul64, checkValue->type());
stackmapRole = StackmapSpecial::ForceLateUse;
break;
default:
RELEASE_ASSERT_NOT_REACHED();
break;
}
// FIXME: It would be great to fuse Loads into these. We currently don't do it because the
// rule for stackmaps is that all addresses are just stack addresses. Maybe we could relax
// this rule here.
// https://bugs.webkit.org/show_bug.cgi?id=151228
Vector<Arg, 2> sources;
if (imm(right) && isValidForm(opcode, Arg::ResCond, Arg::Tmp, Arg::Imm, Arg::Tmp)) {
sources.append(tmp(left));
sources.append(imm(right));
} else if (imm(right) && isValidForm(opcode, Arg::ResCond, Arg::Imm, Arg::Tmp)) {
sources.append(imm(right));
append(Move, tmp(left), result);
} else if (isValidForm(opcode, Arg::ResCond, Arg::Tmp, Arg::Tmp, Arg::Tmp)) {
sources.append(tmp(left));
sources.append(tmp(right));
} else if (isValidForm(opcode, Arg::ResCond, Arg::Tmp, Arg::Tmp)) {
if (commutativity == Commutative && preferRightForResult(left, right)) {
sources.append(tmp(left));
append(Move, tmp(right), result);
} else {
sources.append(tmp(right));
append(Move, tmp(left), result);
}
} else if (isValidForm(opcode, Arg::ResCond, Arg::Tmp, Arg::Tmp, Arg::Tmp, Arg::Tmp, Arg::Tmp)) {
sources.append(tmp(left));
sources.append(tmp(right));
sources.append(m_code.newTmp(m_value->resultBank()));
sources.append(m_code.newTmp(m_value->resultBank()));
}
// There is a really hilarious case that arises when we do BranchAdd32(%x, %x). We won't emit
// such code, but the coalescing in our register allocator also does copy propagation, so
// although we emit:
//
// Move %tmp1, %tmp2
// BranchAdd32 %tmp1, %tmp2
//
// The register allocator may turn this into:
//
// BranchAdd32 %rax, %rax
//
// Currently we handle this by ensuring that even this kind of addition can be undone. We can
// undo it by using the carry flag. It's tempting to get rid of that code and just "fix" this
// here by forcing LateUse on the stackmap. If we did that unconditionally, we'd lose a lot of
// performance. So it's tempting to do it only if left == right. But that creates an awkward
// constraint on Air: it means that Air would not be allowed to do any copy propagation.
// Notice that the %rax,%rax situation happened after Air copy-propagated the Move we are
// emitting. We know that copy-propagating over that Move causes add-to-self. But what if we
// emit something like a Move - or even do other kinds of copy-propagation on tmp's -
// somewhere else in this code. The add-to-self situation may only emerge after some other Air
// optimizations remove other Move's or identity-like operations. That's why we don't use
// LateUse here to take care of add-to-self.
CheckSpecial* special = ensureCheckSpecial(opcode, 2 + sources.size(), stackmapRole);
Inst inst(Patch, checkValue, Arg::special(special));
inst.args.append(Arg::resCond(MacroAssembler::Overflow));
inst.args.appendVector(sources);
inst.args.append(result);
fillStackmap(inst, checkValue, 2);
m_insts.last().append(WTFMove(inst));
return;
}
case Check: {
Inst branch = createBranch(m_value->child(0));
CheckSpecial* special = ensureCheckSpecial(branch);
CheckValue* checkValue = m_value->as<CheckValue>();
Inst inst(Patch, checkValue, Arg::special(special));
inst.args.appendVector(branch.args);
fillStackmap(inst, checkValue, 1);
m_insts.last().append(WTFMove(inst));
return;
}
case B3::WasmBoundsCheck: {
WasmBoundsCheckValue* value = m_value->as<WasmBoundsCheckValue>();
Value* ptr = value->child(0);
Tmp pointer = tmp(ptr);
Arg ptrPlusImm = m_code.newTmp(GP);
append(Inst(Move32, value, pointer, ptrPlusImm));
if (value->offset()) {
if (imm(value->offset()))
append(Add64, imm(value->offset()), ptrPlusImm);
else {
Arg bigImm = m_code.newTmp(GP);
append(Move, Arg::bigImm(value->offset()), bigImm);
append(Add64, bigImm, ptrPlusImm);
}
}
Arg limit;
switch (value->boundsType()) {
case WasmBoundsCheckValue::Type::Pinned:
limit = Arg(value->bounds().pinnedSize);
break;
case WasmBoundsCheckValue::Type::Maximum:
limit = m_code.newTmp(GP);
if (imm(value->bounds().maximum))
append(Move, imm(value->bounds().maximum), limit);
else
append(Move, Arg::bigImm(value->bounds().maximum), limit);
break;
}
append(Inst(Air::WasmBoundsCheck, value, ptrPlusImm, limit));
return;
}
case Upsilon: {
Value* value = m_value->child(0);
append(
relaxedMoveForType(value->type()), immOrTmp(value),
m_phiToTmp[m_value->as<UpsilonValue>()->phi()]);
return;
}
case Phi: {
// Snapshot the value of the Phi. It may change under us because you could do:
// a = Phi()
// Upsilon(@x, ^a)
// @a => this should get the value of the Phi before the Upsilon, i.e. not @x.
append(relaxedMoveForType(m_value->type()), m_phiToTmp[m_value], tmp(m_value));
return;
}
case Set: {
Value* value = m_value->child(0);
append(
relaxedMoveForType(value->type()), immOrTmp(value),
m_variableToTmp.get(m_value->as<VariableValue>()->variable()));
return;
}
case Get: {
append(
relaxedMoveForType(m_value->type()),
m_variableToTmp.get(m_value->as<VariableValue>()->variable()), tmp(m_value));
return;
}
case Branch: {
if (canBeInternal(m_value->child(0))) {
Value* branchChild = m_value->child(0);
switch (branchChild->opcode()) {
case AtomicWeakCAS:
commitInternal(branchChild);
appendCAS(branchChild, false);
return;
case AtomicStrongCAS:
// A branch is a comparison to zero.
// FIXME: Teach this to match patterns that arise from subwidth CAS.
// https://bugs.webkit.org/show_bug.cgi?id=169250
if (branchChild->child(0)->isInt(0)
&& branchChild->as<AtomicValue>()->isCanonicalWidth()) {
commitInternal(branchChild);
appendCAS(branchChild, true);
return;
}
break;
case Equal:
case NotEqual:
// FIXME: Teach this to match patterns that arise from subwidth CAS.
// https://bugs.webkit.org/show_bug.cgi?id=169250
if (branchChild->child(0)->opcode() == AtomicStrongCAS
&& branchChild->child(0)->as<AtomicValue>()->isCanonicalWidth()
&& canBeInternal(branchChild->child(0))
&& branchChild->child(0)->child(0) == branchChild->child(1)) {
commitInternal(branchChild);
commitInternal(branchChild->child(0));
appendCAS(branchChild->child(0), branchChild->opcode() == NotEqual);
return;
}
break;
default:
break;
}
}
m_insts.last().append(createBranch(m_value->child(0)));
return;
}
case B3::Jump: {
append(Air::Jump);
return;
}
case Identity:
case Opaque: {
ASSERT(tmp(m_value->child(0)) == tmp(m_value));
return;
}
case Return: {
if (!m_value->numChildren()) {
append(RetVoid);
return;
}
Value* value = m_value->child(0);
Tmp returnValueGPR = Tmp(GPRInfo::returnValueGPR);
Tmp returnValueFPR = Tmp(FPRInfo::returnValueFPR);
switch (value->type()) {
case Void:
// It's impossible for a void value to be used as a child. We use RetVoid
// for void returns.
RELEASE_ASSERT_NOT_REACHED();
break;
case Int32:
append(Move, immOrTmp(value), returnValueGPR);
append(Ret32, returnValueGPR);
break;
case Int64:
append(Move, immOrTmp(value), returnValueGPR);
append(Ret64, returnValueGPR);
break;
case Float:
append(MoveFloat, tmp(value), returnValueFPR);
append(RetFloat, returnValueFPR);
break;
case Double:
append(MoveDouble, tmp(value), returnValueFPR);
append(RetDouble, returnValueFPR);
break;
}
return;
}
case B3::Oops: {
append(Air::Oops);
return;
}
case B3::EntrySwitch: {
append(Air::EntrySwitch);
return;
}
case AtomicWeakCAS:
case AtomicStrongCAS: {
appendCAS(m_value, false);
return;
}
case AtomicXchgAdd: {
AtomicValue* atomic = m_value->as<AtomicValue>();
if (appendVoidAtomic(OPCODE_FOR_WIDTH(AtomicAdd, atomic->accessWidth())))
return;
Arg address = addr(atomic);
Air::Opcode opcode = OPCODE_FOR_WIDTH(AtomicXchgAdd, atomic->accessWidth());
if (isValidForm(opcode, Arg::Tmp, address.kind())) {
append(relaxedMoveForType(atomic->type()), tmp(atomic->child(0)), tmp(atomic));
append(opcode, tmp(atomic), address);
return;
}
appendGeneralAtomic(OPCODE_FOR_CANONICAL_WIDTH(Add, atomic->accessWidth()), Commutative);
return;
}
case AtomicXchgSub: {
AtomicValue* atomic = m_value->as<AtomicValue>();
if (appendVoidAtomic(OPCODE_FOR_WIDTH(AtomicSub, atomic->accessWidth())))
return;
appendGeneralAtomic(OPCODE_FOR_CANONICAL_WIDTH(Sub, atomic->accessWidth()));
return;
}
case AtomicXchgAnd: {
AtomicValue* atomic = m_value->as<AtomicValue>();
if (appendVoidAtomic(OPCODE_FOR_WIDTH(AtomicAnd, atomic->accessWidth())))
return;
appendGeneralAtomic(OPCODE_FOR_CANONICAL_WIDTH(And, atomic->accessWidth()), Commutative);
return;
}
case AtomicXchgOr: {
AtomicValue* atomic = m_value->as<AtomicValue>();
if (appendVoidAtomic(OPCODE_FOR_WIDTH(AtomicOr, atomic->accessWidth())))
return;
appendGeneralAtomic(OPCODE_FOR_CANONICAL_WIDTH(Or, atomic->accessWidth()), Commutative);
return;
}
case AtomicXchgXor: {
AtomicValue* atomic = m_value->as<AtomicValue>();
if (appendVoidAtomic(OPCODE_FOR_WIDTH(AtomicXor, atomic->accessWidth())))
return;
appendGeneralAtomic(OPCODE_FOR_CANONICAL_WIDTH(Xor, atomic->accessWidth()), Commutative);
return;
}
case AtomicXchg: {
AtomicValue* atomic = m_value->as<AtomicValue>();
Arg address = addr(atomic);
Air::Opcode opcode = OPCODE_FOR_WIDTH(AtomicXchg, atomic->accessWidth());
if (isValidForm(opcode, Arg::Tmp, address.kind())) {
append(relaxedMoveForType(atomic->type()), tmp(atomic->child(0)), tmp(atomic));
append(opcode, tmp(atomic), address);
return;
}
appendGeneralAtomic(Air::Nop);
return;
}
default:
break;
}
dataLog("FATAL: could not lower ", deepDump(m_procedure, m_value), "\n");
RELEASE_ASSERT_NOT_REACHED();
}
IndexSet<Value*> m_locked; // These are values that will have no Tmp in Air.
IndexMap<Value*, Tmp> m_valueToTmp; // These are values that must have a Tmp in Air. We say that a Value* with a non-null Tmp is "pinned".
IndexMap<Value*, Tmp> m_phiToTmp; // Each Phi gets its own Tmp.
IndexMap<B3::BasicBlock*, Air::BasicBlock*> m_blockToBlock;
HashMap<B3::StackSlot*, Air::StackSlot*> m_stackToStack;
HashMap<Variable*, Tmp> m_variableToTmp;
UseCounts m_useCounts;
PhiChildren m_phiChildren;
BlockWorklist m_fastWorklist;
Dominators& m_dominators;
Vector<Vector<Inst, 4>> m_insts;
Vector<Inst> m_prologue;
B3::BasicBlock* m_block;
bool m_isRare;
unsigned m_index;
Value* m_value;
PatchpointSpecial* m_patchpointSpecial { nullptr };
HashMap<CheckSpecial::Key, CheckSpecial*> m_checkSpecials;
Procedure& m_procedure;
Code& m_code;
Air::BlockInsertionSet m_blockInsertionSet;
Tmp m_eax;
Tmp m_ecx;
Tmp m_edx;
};
} // anonymous namespace
void lowerToAir(Procedure& procedure)
{
PhaseScope phaseScope(procedure, "lowerToAir");
LowerToAir lowerToAir(procedure);
lowerToAir.run();
}
} } // namespace JSC::B3
#if ASSERT_DISABLED
IGNORE_RETURN_TYPE_WARNINGS_END
#endif
#endif // ENABLE(B3_JIT)