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-rw-r--r--js/src/jit/shared/Lowering-shared.cpp306
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diff --git a/js/src/jit/shared/Lowering-shared.cpp b/js/src/jit/shared/Lowering-shared.cpp
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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: set ts=8 sts=4 et sw=4 tw=99:
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "jit/shared/Lowering-shared-inl.h"
+
+#include "jit/LIR.h"
+#include "jit/MIR.h"
+
+#include "vm/Symbol.h"
+
+using namespace js;
+using namespace jit;
+
+bool
+LIRGeneratorShared::ShouldReorderCommutative(MDefinition* lhs, MDefinition* rhs, MInstruction* ins)
+{
+ // lhs and rhs are used by the commutative operator.
+ MOZ_ASSERT(lhs->hasDefUses());
+ MOZ_ASSERT(rhs->hasDefUses());
+
+ // Ensure that if there is a constant, then it is in rhs.
+ if (rhs->isConstant())
+ return false;
+ if (lhs->isConstant())
+ return true;
+
+ // Since clobbering binary operations clobber the left operand, prefer a
+ // non-constant lhs operand with no further uses. To be fully precise, we
+ // should check whether this is the *last* use, but checking hasOneDefUse()
+ // is a decent approximation which doesn't require any extra analysis.
+ bool rhsSingleUse = rhs->hasOneDefUse();
+ bool lhsSingleUse = lhs->hasOneDefUse();
+ if (rhsSingleUse) {
+ if (!lhsSingleUse)
+ return true;
+ } else {
+ if (lhsSingleUse)
+ return false;
+ }
+
+ // If this is a reduction-style computation, such as
+ //
+ // sum = 0;
+ // for (...)
+ // sum += ...;
+ //
+ // put the phi on the left to promote coalescing. This is fairly specific.
+ if (rhsSingleUse &&
+ rhs->isPhi() &&
+ rhs->block()->isLoopHeader() &&
+ ins == rhs->toPhi()->getLoopBackedgeOperand())
+ {
+ return true;
+ }
+
+ return false;
+}
+
+void
+LIRGeneratorShared::ReorderCommutative(MDefinition** lhsp, MDefinition** rhsp, MInstruction* ins)
+{
+ MDefinition* lhs = *lhsp;
+ MDefinition* rhs = *rhsp;
+
+ if (ShouldReorderCommutative(lhs, rhs, ins)) {
+ *rhsp = lhs;
+ *lhsp = rhs;
+ }
+}
+
+void
+LIRGeneratorShared::visitConstant(MConstant* ins)
+{
+ if (!IsFloatingPointType(ins->type()) && ins->canEmitAtUses()) {
+ emitAtUses(ins);
+ return;
+ }
+
+ switch (ins->type()) {
+ case MIRType::Double:
+ define(new(alloc()) LDouble(ins->toRawF64()), ins);
+ break;
+ case MIRType::Float32:
+ define(new(alloc()) LFloat32(ins->toRawF32()), ins);
+ break;
+ case MIRType::Boolean:
+ define(new(alloc()) LInteger(ins->toBoolean()), ins);
+ break;
+ case MIRType::Int32:
+ define(new(alloc()) LInteger(ins->toInt32()), ins);
+ break;
+ case MIRType::Int64:
+ defineInt64(new(alloc()) LInteger64(ins->toInt64()), ins);
+ break;
+ case MIRType::String:
+ define(new(alloc()) LPointer(ins->toString()), ins);
+ break;
+ case MIRType::Symbol:
+ define(new(alloc()) LPointer(ins->toSymbol()), ins);
+ break;
+ case MIRType::Object:
+ define(new(alloc()) LPointer(&ins->toObject()), ins);
+ break;
+ default:
+ // Constants of special types (undefined, null) should never flow into
+ // here directly. Operations blindly consuming them require a Box.
+ MOZ_CRASH("unexpected constant type");
+ }
+}
+
+void
+LIRGeneratorShared::defineTypedPhi(MPhi* phi, size_t lirIndex)
+{
+ LPhi* lir = current->getPhi(lirIndex);
+
+ uint32_t vreg = getVirtualRegister();
+
+ phi->setVirtualRegister(vreg);
+ lir->setDef(0, LDefinition(vreg, LDefinition::TypeFrom(phi->type())));
+ annotate(lir);
+}
+
+void
+LIRGeneratorShared::lowerTypedPhiInput(MPhi* phi, uint32_t inputPosition, LBlock* block, size_t lirIndex)
+{
+ MDefinition* operand = phi->getOperand(inputPosition);
+ LPhi* lir = block->getPhi(lirIndex);
+ lir->setOperand(inputPosition, LUse(operand->virtualRegister(), LUse::ANY));
+}
+
+LRecoverInfo*
+LIRGeneratorShared::getRecoverInfo(MResumePoint* rp)
+{
+ if (cachedRecoverInfo_ && cachedRecoverInfo_->mir() == rp)
+ return cachedRecoverInfo_;
+
+ LRecoverInfo* recoverInfo = LRecoverInfo::New(gen, rp);
+ if (!recoverInfo)
+ return nullptr;
+
+ cachedRecoverInfo_ = recoverInfo;
+ return recoverInfo;
+}
+
+#ifdef DEBUG
+bool
+LRecoverInfo::OperandIter::canOptimizeOutIfUnused()
+{
+ MDefinition* ins = **this;
+
+ // We check ins->type() in addition to ins->isUnused() because
+ // EliminateDeadResumePointOperands may replace nodes with the constant
+ // MagicValue(JS_OPTIMIZED_OUT).
+ if ((ins->isUnused() || ins->type() == MIRType::MagicOptimizedOut) &&
+ (*it_)->isResumePoint())
+ {
+ return !(*it_)->toResumePoint()->isObservableOperand(op_);
+ }
+
+ return true;
+}
+#endif
+
+#ifdef JS_NUNBOX32
+LSnapshot*
+LIRGeneratorShared::buildSnapshot(LInstruction* ins, MResumePoint* rp, BailoutKind kind)
+{
+ LRecoverInfo* recoverInfo = getRecoverInfo(rp);
+ if (!recoverInfo)
+ return nullptr;
+
+ LSnapshot* snapshot = LSnapshot::New(gen, recoverInfo, kind);
+ if (!snapshot)
+ return nullptr;
+
+ size_t index = 0;
+ for (LRecoverInfo::OperandIter it(recoverInfo); !it; ++it) {
+ // Check that optimized out operands are in eliminable slots.
+ MOZ_ASSERT(it.canOptimizeOutIfUnused());
+
+ MDefinition* ins = *it;
+
+ if (ins->isRecoveredOnBailout())
+ continue;
+
+ LAllocation* type = snapshot->typeOfSlot(index);
+ LAllocation* payload = snapshot->payloadOfSlot(index);
+ ++index;
+
+ if (ins->isBox())
+ ins = ins->toBox()->getOperand(0);
+
+ // Guards should never be eliminated.
+ MOZ_ASSERT_IF(ins->isUnused(), !ins->isGuard());
+
+ // Snapshot operands other than constants should never be
+ // emitted-at-uses. Try-catch support depends on there being no
+ // code between an instruction and the LOsiPoint that follows it.
+ MOZ_ASSERT_IF(!ins->isConstant(), !ins->isEmittedAtUses());
+
+ // The register allocation will fill these fields in with actual
+ // register/stack assignments. During code generation, we can restore
+ // interpreter state with the given information. Note that for
+ // constants, including known types, we record a dummy placeholder,
+ // since we can recover the same information, much cleaner, from MIR.
+ if (ins->isConstant() || ins->isUnused()) {
+ *type = LAllocation();
+ *payload = LAllocation();
+ } else if (ins->type() != MIRType::Value) {
+ *type = LAllocation();
+ *payload = use(ins, LUse(LUse::KEEPALIVE));
+ } else {
+ *type = useType(ins, LUse::KEEPALIVE);
+ *payload = usePayload(ins, LUse::KEEPALIVE);
+ }
+ }
+
+ return snapshot;
+}
+
+#elif JS_PUNBOX64
+
+LSnapshot*
+LIRGeneratorShared::buildSnapshot(LInstruction* ins, MResumePoint* rp, BailoutKind kind)
+{
+ LRecoverInfo* recoverInfo = getRecoverInfo(rp);
+ if (!recoverInfo)
+ return nullptr;
+
+ LSnapshot* snapshot = LSnapshot::New(gen, recoverInfo, kind);
+ if (!snapshot)
+ return nullptr;
+
+ size_t index = 0;
+ for (LRecoverInfo::OperandIter it(recoverInfo); !it; ++it) {
+ // Check that optimized out operands are in eliminable slots.
+ MOZ_ASSERT(it.canOptimizeOutIfUnused());
+
+ MDefinition* def = *it;
+
+ if (def->isRecoveredOnBailout())
+ continue;
+
+ if (def->isBox())
+ def = def->toBox()->getOperand(0);
+
+ // Guards should never be eliminated.
+ MOZ_ASSERT_IF(def->isUnused(), !def->isGuard());
+
+ // Snapshot operands other than constants should never be
+ // emitted-at-uses. Try-catch support depends on there being no
+ // code between an instruction and the LOsiPoint that follows it.
+ MOZ_ASSERT_IF(!def->isConstant(), !def->isEmittedAtUses());
+
+ LAllocation* a = snapshot->getEntry(index++);
+
+ if (def->isUnused()) {
+ *a = LAllocation();
+ continue;
+ }
+
+ *a = useKeepaliveOrConstant(def);
+ }
+
+ return snapshot;
+}
+#endif
+
+void
+LIRGeneratorShared::assignSnapshot(LInstruction* ins, BailoutKind kind)
+{
+ // assignSnapshot must be called before define/add, since
+ // it may add new instructions for emitted-at-use operands.
+ MOZ_ASSERT(ins->id() == 0);
+
+ LSnapshot* snapshot = buildSnapshot(ins, lastResumePoint_, kind);
+ if (snapshot)
+ ins->assignSnapshot(snapshot);
+ else
+ gen->abort("buildSnapshot failed");
+}
+
+void
+LIRGeneratorShared::assignSafepoint(LInstruction* ins, MInstruction* mir, BailoutKind kind)
+{
+ MOZ_ASSERT(!osiPoint_);
+ MOZ_ASSERT(!ins->safepoint());
+
+ ins->initSafepoint(alloc());
+
+ MResumePoint* mrp = mir->resumePoint() ? mir->resumePoint() : lastResumePoint_;
+ LSnapshot* postSnapshot = buildSnapshot(ins, mrp, kind);
+ if (!postSnapshot) {
+ gen->abort("buildSnapshot failed");
+ return;
+ }
+
+ osiPoint_ = new(alloc()) LOsiPoint(ins->safepoint(), postSnapshot);
+
+ if (!lirGraph_.noteNeedsSafepoint(ins))
+ gen->abort("noteNeedsSafepoint failed");
+}
+
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-10 11:26:46 +0000