Add m-esr52 at 52.6.0

1 files changed, 277 insertions, 0 deletions

diff --git a/js/src/jit/EffectiveAddressAnalysis.cpp b/js/src/jit/EffectiveAddressAnalysis.cpp
new file mode 100644
index 000000000..a17da8747
--- /dev/null
+++ b/js/src/jit/EffectiveAddressAnalysis.cpp
@@ -0,0 +1,277 @@
+/* -*- 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/EffectiveAddressAnalysis.h"
+#include "jit/IonAnalysis.h"
+#include "jit/MIR.h"
+#include "jit/MIRGraph.h"
+
+using namespace js;
+using namespace jit;
+
+static void
+AnalyzeLsh(TempAllocator& alloc, MLsh* lsh)
+{
+    if (lsh->specialization() != MIRType::Int32)
+        return;
+
+    if (lsh->isRecoveredOnBailout())
+        return;
+
+    MDefinition* index = lsh->lhs();
+    MOZ_ASSERT(index->type() == MIRType::Int32);
+
+    MConstant* shiftValue = lsh->rhs()->maybeConstantValue();
+    if (!shiftValue)
+        return;
+
+    if (shiftValue->type() != MIRType::Int32 || !IsShiftInScaleRange(shiftValue->toInt32()))
+        return;
+
+    Scale scale = ShiftToScale(shiftValue->toInt32());
+
+    int32_t displacement = 0;
+    MInstruction* last = lsh;
+    MDefinition* base = nullptr;
+    while (true) {
+        if (!last->hasOneUse())
+            break;
+
+        MUseIterator use = last->usesBegin();
+        if (!use->consumer()->isDefinition() || !use->consumer()->toDefinition()->isAdd())
+            break;
+
+        MAdd* add = use->consumer()->toDefinition()->toAdd();
+        if (add->specialization() != MIRType::Int32 || !add->isTruncated())
+            break;
+
+        MDefinition* other = add->getOperand(1 - add->indexOf(*use));
+
+        if (MConstant* otherConst = other->maybeConstantValue()) {
+            displacement += otherConst->toInt32();
+        } else {
+            if (base)
+                break;
+            base = other;
+        }
+
+        last = add;
+        if (last->isRecoveredOnBailout())
+            return;
+    }
+
+    if (!base) {
+        uint32_t elemSize = 1 << ScaleToShift(scale);
+        if (displacement % elemSize != 0)
+            return;
+
+        if (!last->hasOneUse())
+            return;
+
+        MUseIterator use = last->usesBegin();
+        if (!use->consumer()->isDefinition() || !use->consumer()->toDefinition()->isBitAnd())
+            return;
+
+        MBitAnd* bitAnd = use->consumer()->toDefinition()->toBitAnd();
+        if (bitAnd->isRecoveredOnBailout())
+            return;
+
+        MDefinition* other = bitAnd->getOperand(1 - bitAnd->indexOf(*use));
+        MConstant* otherConst = other->maybeConstantValue();
+        if (!otherConst || otherConst->type() != MIRType::Int32)
+            return;
+
+        uint32_t bitsClearedByShift = elemSize - 1;
+        uint32_t bitsClearedByMask = ~uint32_t(otherConst->toInt32());
+        if ((bitsClearedByShift & bitsClearedByMask) != bitsClearedByMask)
+            return;
+
+        bitAnd->replaceAllUsesWith(last);
+        return;
+    }
+
+    if (base->isRecoveredOnBailout())
+        return;
+
+    MEffectiveAddress* eaddr = MEffectiveAddress::New(alloc, base, index, scale, displacement);
+    last->replaceAllUsesWith(eaddr);
+    last->block()->insertAfter(last, eaddr);
+}
+
+// Transform:
+//
+//   [AddI]
+//   addl       $9, %esi
+//   [LoadUnboxedScalar]
+//   movsd      0x0(%rbx,%rsi,8), %xmm4
+//
+// into:
+//
+//   [LoadUnboxedScalar]
+//   movsd      0x48(%rbx,%rsi,8), %xmm4
+//
+// This is possible when the AddI is only used by the LoadUnboxedScalar opcode.
+static void
+AnalyzeLoadUnboxedScalar(TempAllocator& alloc, MLoadUnboxedScalar* load)
+{
+    if (load->isRecoveredOnBailout())
+        return;
+
+    if (!load->getOperand(1)->isAdd())
+        return;
+
+    JitSpew(JitSpew_EAA, "analyze: %s%u", load->opName(), load->id());
+
+    MAdd* add = load->getOperand(1)->toAdd();
+
+    if (add->specialization() != MIRType::Int32 || !add->hasUses() ||
+        add->truncateKind() != MDefinition::TruncateKind::Truncate)
+    {
+        return;
+    }
+
+    MDefinition* lhs = add->lhs();
+    MDefinition* rhs = add->rhs();
+    MDefinition* constant = nullptr;
+    MDefinition* node = nullptr;
+
+    if (lhs->isConstant()) {
+        constant = lhs;
+        node = rhs;
+    } else if (rhs->isConstant()) {
+        constant = rhs;
+        node = lhs;
+    } else
+        return;
+
+    MOZ_ASSERT(constant->type() == MIRType::Int32);
+
+    size_t storageSize = Scalar::byteSize(load->storageType());
+    int32_t c1 = load->offsetAdjustment();
+    int32_t c2 = 0;
+    if (!SafeMul(constant->maybeConstantValue()->toInt32(), storageSize, &c2))
+        return;
+
+    int32_t offset = 0;
+    if (!SafeAdd(c1, c2, &offset))
+        return;
+
+    JitSpew(JitSpew_EAA, "set offset: %d + %d = %d on: %s%u", c1, c2, offset,
+            load->opName(), load->id());
+    load->setOffsetAdjustment(offset);
+    load->replaceOperand(1, node);
+
+    if (!add->hasLiveDefUses() && DeadIfUnused(add) && add->canRecoverOnBailout()) {
+        JitSpew(JitSpew_EAA, "mark as recovered on bailout: %s%u",
+                add->opName(), add->id());
+        add->setRecoveredOnBailoutUnchecked();
+    }
+}
+
+template<typename AsmJSMemoryAccess>
+bool
+EffectiveAddressAnalysis::tryAddDisplacement(AsmJSMemoryAccess* ins, int32_t o)
+{
+#ifdef WASM_HUGE_MEMORY
+    // Compute the new offset. Check for overflow.
+    uint32_t oldOffset = ins->offset();
+    uint32_t newOffset = oldOffset + o;
+    if (o < 0 ? (newOffset >= oldOffset) : (newOffset < oldOffset))
+        return false;
+
+    // The offset must ultimately be written into the offset immediate of a load
+    // or store instruction so don't allow folding of the offset is bigger.
+    if (newOffset >= wasm::OffsetGuardLimit)
+        return false;
+
+    // Everything checks out. This is the new offset.
+    ins->setOffset(newOffset);
+    return true;
+#else
+    return false;
+#endif
+}
+
+template<typename AsmJSMemoryAccess>
+void
+EffectiveAddressAnalysis::analyzeAsmJSHeapAccess(AsmJSMemoryAccess* ins)
+{
+    MDefinition* base = ins->base();
+
+    if (base->isConstant()) {
+        // Look for heap[i] where i is a constant offset, and fold the offset.
+        // By doing the folding now, we simplify the task of codegen; the offset
+        // is always the address mode immediate. This also allows it to avoid
+        // a situation where the sum of a constant pointer value and a non-zero
+        // offset doesn't actually fit into the address mode immediate.
+        int32_t imm = base->toConstant()->toInt32();
+        if (imm != 0 && tryAddDisplacement(ins, imm)) {
+            MInstruction* zero = MConstant::New(graph_.alloc(), Int32Value(0));
+            ins->block()->insertBefore(ins, zero);
+            ins->replaceBase(zero);
+        }
+
+        // If the index is within the minimum heap length, we can optimize
+        // away the bounds check.
+        if (imm >= 0) {
+            int32_t end = (uint32_t)imm + ins->byteSize();
+            if (end >= imm && (uint32_t)end <= mir_->minWasmHeapLength())
+                 ins->removeBoundsCheck();
+        }
+    } else if (base->isAdd()) {
+        // Look for heap[a+i] where i is a constant offset, and fold the offset.
+        // Alignment masks have already been moved out of the way by the
+        // Alignment Mask Analysis pass.
+        MDefinition* op0 = base->toAdd()->getOperand(0);
+        MDefinition* op1 = base->toAdd()->getOperand(1);
+        if (op0->isConstant())
+            mozilla::Swap(op0, op1);
+        if (op1->isConstant()) {
+            int32_t imm = op1->toConstant()->toInt32();
+            if (tryAddDisplacement(ins, imm))
+                ins->replaceBase(op0);
+        }
+    }
+}
+
+// This analysis converts patterns of the form:
+//   truncate(x + (y << {0,1,2,3}))
+//   truncate(x + (y << {0,1,2,3}) + imm32)
+// into a single lea instruction, and patterns of the form:
+//   asmload(x + imm32)
+//   asmload(x << {0,1,2,3})
+//   asmload((x << {0,1,2,3}) + imm32)
+//   asmload((x << {0,1,2,3}) & mask)            (where mask is redundant with shift)
+//   asmload(((x << {0,1,2,3}) + imm32) & mask)  (where mask is redundant with shift + imm32)
+// into a single asmload instruction (and for asmstore too).
+//
+// Additionally, we should consider the general forms:
+//   truncate(x + y + imm32)
+//   truncate((y << {0,1,2,3}) + imm32)
+bool
+EffectiveAddressAnalysis::analyze()
+{
+    for (ReversePostorderIterator block(graph_.rpoBegin()); block != graph_.rpoEnd(); block++) {
+        for (MInstructionIterator i = block->begin(); i != block->end(); i++) {
+            if (!graph_.alloc().ensureBallast())
+                return false;
+
+            // Note that we don't check for MAsmJSCompareExchangeHeap
+            // or MAsmJSAtomicBinopHeap, because the backend and the OOB
+            // mechanism don't support non-zero offsets for them yet
+            // (TODO bug 1254935).
+            if (i->isLsh())
+                AnalyzeLsh(graph_.alloc(), i->toLsh());
+            else if (i->isLoadUnboxedScalar())
+                AnalyzeLoadUnboxedScalar(graph_.alloc(), i->toLoadUnboxedScalar());
+            else if (i->isAsmJSLoadHeap())
+                analyzeAsmJSHeapAccess(i->toAsmJSLoadHeap());
+            else if (i->isAsmJSStoreHeap())
+                analyzeAsmJSHeapAccess(i->toAsmJSStoreHeap());
+        }
+    }
+    return true;
+}